U.S. patent application number 11/444031 was filed with the patent office on 2007-03-22 for rack-mounted power meter having removable metering options module.
This patent application is currently assigned to Power Measurement Ltd.. Invention is credited to Michael D. Bandsmer, Martin A. Hancock, Stewart J. Harding, Daniel N. Loewen, Piotr B. Przydatek.
Application Number | 20070067119 11/444031 |
Document ID | / |
Family ID | 37598129 |
Filed Date | 2007-03-22 |
United States Patent
Application |
20070067119 |
Kind Code |
A1 |
Loewen; Daniel N. ; et
al. |
March 22, 2007 |
Rack-mounted power meter having removable metering options
module
Abstract
A meter for measuring power parameters on one or more electrical
power lines/loads is configured to operate with our without a
removable metering options module. The meter includes a meter
housing designed and dimensioned for rack mounted installation in a
bay of an equipment rack or cabinet, and metering circuitry
configured to provide revenue accurate metering and power quality
analysis for a power line/load. The metering options module may be
mounted to an externally accessible surface of the meter to change
the functionality of the metering circuitry without increasing the
dimensions of an outer envelop of the meter, and without disturbing
tamper-proof seals included on the meter.
Inventors: |
Loewen; Daniel N.; (Sidney,
CA) ; Bandsmer; Michael D.; (Victoria, CA) ;
Harding; Stewart J.; (Victoria, CA) ; Przydatek;
Piotr B.; (Victoria, CA) ; Hancock; Martin A.;
(Victoria, CA) |
Correspondence
Address: |
BRINKS HOFER GILSON & LIONE/PML;INDIANAPOLIS OFFICE
1 INDIANA SQ
SUITE 1600
INDIANAPOLIS
IN
46204-2033
US
|
Assignee: |
Power Measurement Ltd.
|
Family ID: |
37598129 |
Appl. No.: |
11/444031 |
Filed: |
May 31, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60717688 |
Sep 16, 2005 |
|
|
|
Current U.S.
Class: |
702/57 ;
702/60 |
Current CPC
Class: |
G01R 22/06 20130101;
G01R 22/065 20130101 |
Class at
Publication: |
702/057 ;
702/060 |
International
Class: |
G06F 19/00 20060101
G06F019/00; G01R 21/06 20060101 G01R021/06 |
Claims
1. A power meter configured to measure electrical parameters of
electrical energy present in a conductor, the power meter
comprising: a meter housing configured to be rack mounted in a bay
of an equipment rack; and a metering options module configured to
be removably mounted on an externally accessible surface of the
meter housing to be within the dimensions of the bay, the meter
housing comprising a first electrical connector, and the metering
options module comprising a second electrical connector, the first
electrical connector configured to be engaged with the second
electrical connector only when the metering options module is
removably mounted on the meter housing.
2. The power meter of claim 1, comprising a first rack electrical
connector positioned on an external surface of the meter housing,
the first rack electrical connector positioned to engage a second
rack electrical connector in the equipment rack when the meter
housing is installed in the bay.
3. The power meter of claim 1, wherein the first electrical
connector is mounted on an external surface of the meter housing,
and the second electrical connector is mounted on an external
surface of the metering options module.
4. The power meter of claim 3, wherein the external surface of the
meter housing is positioned proximate the external surface of the
metering options module so that the first electrical connector and
the second electrical connector engage when the metering options
module is removably mounted on the meter housing.
5. The power meter of claim 1, further comprising a tamper proof
seal coupled with the meter housing and configured to indicate when
the meter housing has been opened, wherein the metering options
module is removably mountable on the meter housing without
disturbance of the tamper proof seal.
6. The power meter of claim 1, wherein the externally accessible
surface of the meter housing comprises a first portion and a second
portion, the first portion formed as a slot to accommodate the
metering options module.
7. The power meter of claim 6, wherein the first portion is
recessed with respect to the second portion, and a first planar
surface of the metering options module is substantially
contiguously aligned with a planar surface of the first portion
when the metering options module is mounted, and a second planar
surface of the metering options module is in substantially the same
plane with a planar surface of the second portion of the meter
housing.
8. The power meter of claim 1, wherein the metering option module
comprises a tab configured to be coupled with the meter housing,
wherein a ground lug included on the meter housing is configured to
ground the metering options module and fixedly mount the metering
options module on the meter housing via the tab.
9. The power meter of claim 1, wherein the metering options module
comprises a flange configured to be substantially contiguous with
the meter housing when the metering options module is mounted on
the meter housing, the flange further configured to be coupled with
the meter housing by a fastener.
10. The power meter of claim 1, wherein the metering options module
further comprises an options rack electrical connector configured
and positioned on the metering options module to engage an options
rack electrical connector included in the equipment rack when the
meter housing with the metering options module removably mounted
thereto is rack mounted in the bay of the equipment rack.
11. A power meter configured to measure electrical parameters of
electrical energy present in a conductor, the power meter
comprising: a meter housing dimensioned to be mounted in a bay of
an equipment rack, the meter housing having a first electrical
connector positioned on a surface of the meter housing to engage a
second electrical connector positioned in the equipment rack when
the meter housing is mounted in the bay; metering circuitry
disposed in the meter housing that is configured to receive one or
more electrical parameters via the second electrical connector, the
metering circuitry operable to measure and process one or more
electrical parameters; a tamper proof seal coupled with the meter
housing and configured to indicate the occurrence of access to at
least one of the meter housing or the metering circuitry, or a
combination thereof; a slot formed with the meter housing, the slot
configured to receive a metering options module without disturbance
of the tamper proof seal; and a third electrical connector disposed
in the slot and electrically connected with the metering circuitry,
the third electrical connector configured to be coupled with the
metering options module to change the functionality of the metering
circuitry.
12. The power meter of claim 11, wherein the metering options
module is positionable in the slot to extend outwardly no further
than about flush with an outermost external dimension of an
externally accessible surface of the meter housing.
13. The power meter of claim 11, wherein the third electrical
connector is mounted in an externally accessible surface of the
meter housing.
14. The power meter of claim 11, further comprising a bus operable
to couple the third electrical connector with the metering
circuitry.
15. The power meter of claim 14, wherein the bus is a printed
circuit board that is coupled with an edge connector included in
the metering circuitry.
16. The power meter of claim 11, further comprising a removable
cover formed to cover an opening to the slot.
17. The power meter of claim 11, wherein the first and second
electrical connectors each comprise a pluggable panel mount
connector.
18. A power meter configured to measure electrical parameters of
electrical energy present in a conductor, the power meter
comprising: a meter housing dimensioned to be mounted in a bay of
an equipment rack; a processor disposed in the meter housing and
operable to process measured electrical parameters to perform
revenue metering and power quality metering; a tamper proof seal
coupled with an external surface of the meter housing and
positioned to indicate the occurrence of access to the meter
housing; a first electrical connector mounted on an external
surface of the meter housing, the first electrical connector
coupled with the processor and configured to engage an electrical
connector in the equipment rack; and a second electrical connector
mounted on a surface of the meter housing, the second electrical
connector coupled with the processor and configured to engage an
electrical connector mounted on a surface of a metering options
module, the metering options module mountable on the meter housing
without disturbance of the tamper proof seal, to change a
functionality of the processor.
19. The power meter of claim 18, wherein the metering options
module includes an input/output module configured to increase the
input/output capability of the processor.
20. The power meter of claim 18, wherein the metering options
module includes a communications module configured to increase the
communication functionality of the processor.
21. The power meter of claim 18, wherein the metering options
module includes at least one of a hardware authorization or a
software authorization each configured to enable additional
functionality already existing, but previously disabled, in the
processor when sensed by the processor.
22. The power meter of claim 18, wherein the metering options
module includes an option key, the option key readable by the
processor to indicate to the processor the functionality change
providable by the removable options module.
23. The power meter of claim 18, wherein the second electrical
connector is operable to supply power to the metering options
module only when the metering options module is mounted on the
meter housing.
24. A power meter configured to measure electrical parameters of
electrical energy present in a conductor, the power meter
comprising: a metering options module configured to be removably
coupled to a surface of a meter housing; and an electrical
connector positioned on a surface of the metering options module,
the electrical connector positioned to engage an electrical
connector included on a surface of the meter housing when the
metering options module is coupled to the surface of the meter
housing; wherein an external housing of the metering options module
is formed to be mounted external to the surface of the meter
housing and to be substantially within an outermost dimension of
the meter housing.
25. The power meter of claim 24, further comprising a flange
coupled with the metering options module, wherein the flange is
configured to fixedly couple the metering options module to the
surface of the meter housing.
26. The power meter of claim 24, wherein the combination of the
metering options module removably coupled to the meter housing is
dimensioned and configured to be rack mounted in a bay of an
equipment rack.
27. The power meter of claim 26, wherein the electrical connector
is positioned on a first surface of the metering options module and
an options rack electrical connector is positioned on a second
surface of the metering options module, wherein the options rack
electrical connector is positioned to engage an options rack
electrical connector positioned in the equipment rack when the
metering housing, with the metering options module removably
coupled thereto is positioned in the bay of the equipment rack.
28. The power meter of claim 24, wherein the electrical connector
is positioned on a first surface of the metering options module and
a communications connector is positioned on a second surface of the
metering options module.
29. The power meter of claim 24, wherein the electrical connector
is positioned on a first surface of the metering options module and
an input/output connector is positioned on a second surface of the
metering options module.
30. The power meter of claim 24, wherein the metering options
module is configured with functionality that is removably
combinable with functionality present in metering circuitry
included within the meter housing.
31. The power meter of claim 24, wherein the metering options
module is configured with access key functionality, the access key
functionality operable to enable pre-existing functionality present
in metering circuitry included within the meter housing.
32. The power meter of claim 24, wherein the metering options
module is configured with protective relay functionality.
33. The power meter of claim 24, wherein the metering options
module is formed to include alignment apertures, the alignment
apertures are configured to engage corresponding alignment pins
included on the meter housing.
Description
RELATED APPLICATIONS
[0001] The present patent document claims the benefit of the filing
date under 35 U.S.C. .sctn.119(e) of Provisional U.S. Patent
Application Ser. No. 60/717,688, filed Sep. 16, 2005, (Attorney
Ref. No 6270/172) which is hereby incorporated by reference.
BACKGROUND
[0002] 1. Field of the Invention
[0003] The present invention relates to power metering, and more
particularly to a rack-mounted revenue and power quality power
meter with an options module that is removable to provide an
adaptable modular meter.
[0004] 2. Background and Relevant Art
[0005] Power metering technology is evolving towards
multi-functional metering systems. Power meters provide feedback
for voltage, current, and power in one or more power lines. The
meter also may be configured to provide control functions for a
load connected to a power line. Commonly, a meter may be configured
for revenue metering, including circuitry and features that allow
monitoring of energy usage for the purposes of determining energy
costs. Alternatively, a meter may be configured to provide power
quality metering, including precisely calibrated circuitry to
accurately determine dynamics of one or more power lines. Power
meters may include communications features that allow
bi-directional communication with the meter. An integrated
communications circuit allows the meter to communicate with other
devices such as a computer, other meters, control panels and the
like. The communications feature may communicate over an open
network using a communication protocol.
[0006] Certain classes of power meters are physically designed to
be installed, or mounted, in a rack. The enclosure of a
rack-mounted meter has predetermined maximum external dimensions to
allow the meter to be inserted in a standard rack. The rack-mounted
design also has electrical connections having a standardized
configuration that allows the meter to be connected to standard
connections on a rack. The arrangement of the electrical
connections is fixed so that the rack-mounted meter may be used in
standard configuration racks.
[0007] Power metering needs often differ from installation to
installation. The meter may need a customized configuration to be
integrated within an existing power distribution system. Existing
rack-mounted power meters needing such a customized configuration
may have additional hardware installed under a front cover plate of
the meter, or in some other location internal to the meter housing.
Such an installation not only requires the meter be physically
dismantled, but also requires removal of utility or verification
seals. Removal of such seals requires that the meter be sent out to
a verification shop, or otherwise taken out of service until the
meter can be re-verified and/or inspected, and new seals applied by
the appropriate third party.
BRIEF SUMMARY OF THE INVENTION
[0008] By way of introduction only, a rack-mounted power meter
includes a removable, or replaceable, externally mounted metering
options module. The rack-mounted power meter and the metering
options module may be mounted in a bay of an equipment rack. The
architecture of the rack-mounted power meter may be achieved by one
or more apparatuses, devices, systems, methods, and/or
processes.
[0009] The rack-mounted power meter is an adaptable power meter
that may be modified and/or updated to meet current and future
needs without requiring disassembly of the enclosure of the power
meter, or disturbance of tamper-proof seals included on the power
meter. A removable, metering options module may be mounted within a
slot, cutout or shoulder of a meter housing of the power meter. The
metering options module may be externally affixed to the
rack-mounted power meter without exceeding the standard maximum
external dimensions for a rack-mounted meter. Once mounted, the
metering options module may be interfaced with, and enhance/change
the functionality of metering circuitry included in the meter.
[0010] The metering options module includes circuitry that provides
various additional features and functionality to change, enhance or
upgrade the functionality of the meter. The metering options module
is self-enclosed and may be sealed with a tamper-proof seal that is
independent of the power meter. The metering options module may be
coupled with the power meter to provide the additional
functionality. The metering options module may provide functions
not presently provided by the metering circuitry present within the
meter. The metering options module may provide functionality that
may add to, augment, supplement or substitute for an existing
metering circuitry function, whether that function is
communications, metering, monitoring, control or the like. The
metering options module also may provide alternate or new modes to
monitor, measure, or calculate electrical parameters. The metering
options module is removable without substantially affecting the
essential functions of the power meter. In addition, the metering
options module may be installed and removed without disturbing a
tamper proof seal, such as a calibration seal included on the power
meter. The metering options module may have a separate housing that
meets the standard meter enclosure requirements for mounting in an
equipment rack assembly.
[0011] The foregoing summary is provided only by way of
introduction. The features and advantages of the rack-mounted power
meter having a removable metering options module may be realized
and obtained by means of the instrumentalities and combinations
particularly pointed out in the claims. Nothing in this section
should be taken as a limitation on the claims, which define the
scope of the invention. Additional features and advantages of the
present invention will be set forth in the description that
follows, and in part will be obvious from the description, or may
be learned by practice of the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a perspective front view of an example
rack-mounted power meter that includes an external removable
metering options module.
[0013] FIG. 2 is a perspective front view of an example
rack-mounted power meter of FIG. 1 without an external removable
metering options module mounted thereon.
[0014] FIG. 3 is a perspective front view of an example
rack-mounted power meter of FIG. 1 that includes an external
removable options module illustrated with a cover in an open
position.
[0015] FIG. 4 is a perspective rear view of the rack-mounted power
meter of FIG. 1 and an external removable metering options
module.
[0016] FIG. 5 is a perspective rear view of the rack-mounted power
meter of FIG. 1 without an external removable metering options
module mounted thereon.
[0017] FIG. 6 is a perspective rear view of an example rack-mounted
power meter of FIG. 1 illustrated with a cover in an open position
that also includes an external removable metering options
module.
[0018] FIG. 7 is a front view of the rack-mounted power meter of
FIG. 1.
[0019] FIG. 8 is a front view of the rack-mounted power meter of
FIG. 1 with a cover in an open position.
[0020] FIG. 9 is a front view of another example of the
rack-mounted power meter of FIG. 1.
[0021] FIG. 10 is a perspective front view of the rack mounted
power meter of FIG. 9, and a removable metering options module.
[0022] FIG. 11 is a front view of the rack mounted power meter of
FIG. 9, with a removable metering options module mounted
thereon.
[0023] FIG. 12 is a rear view of the rack-mounted power meter of
FIG. 1 that includes an external removable metering options
module.
[0024] FIG. 13 is a rear view of the rack-mounted power meter of
FIG. 1 without an external removable metering options module
mounted thereon.
[0025] FIG. 14 is a perspective partially cutaway view of the
rack-mounted power meter of FIG. 1 illustrating an example of an
internal connection for the rack-mounted meter of FIG. 1.
[0026] FIG. 15 is a perspective rear view of an example of a
metering options module for the rack-mounted power meter of FIG.
1.
[0027] FIG. 16 is a rear view of an example of a metering options
module for the rack-mounted power meter of FIG. 1.
[0028] FIG. 17 is a perspective front view of an example of a
metering options module for the rack-mounted power meter of FIG.
1.
[0029] FIG. 18 is a front view of an example of a metering options
module for the rack-mounted power meter of FIG. 1.
[0030] FIG. 19 is a block diagram of an example of a power meter
and a removable metering options module of FIGS. 1-18.
[0031] FIG. 20 is a block diagram of an example of an input/output
module that may be included in the metering options module.
[0032] FIG. 21 is a block diagram of an example of a communications
module that may be included in the metering options module.
[0033] FIG. 22 is a block diagram of an example of an access key
module that may be included in the metering options module.
[0034] FIG. 23 is a perspective top view of an example of the
rack-mounted power meter of FIGS. 1-8 that includes an external
removable metering options module, and is mounted in an equipment
rack.
[0035] FIG. 24 is a perspective front view of an example of the
rack-mounted power meter of FIGS. 1-8 that includes an external
removable metering options module, and is mounted in an equipment
rack.
[0036] FIG. 25 is a perspective rear view of an example of the
rack-mounted power meter of FIGS. 1-8 that includes an external
removable metering options module, and is mounted in an equipment
rack.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0037] A rack-mounted power meter having an externally mounted
metering options module will now be described with reference to the
accompanying drawings. In each of the following figures,
components, features and integral parts that correspond to one
another each have the same reference number. The drawings of the
figures are not true to scale.
[0038] A rack-mounted power meter having an externally-mounted
removable metering options module may be embodied in many different
forms, formats, and designs, and should not be construed as limited
to the examples set forth herein. The architecture for the
rack-mounted power meter includes apparatuses, distributed
networks, methods, processes, data processing systems, and software
and firmware device. Features of the rack-mounted power meter
having a removable external metering options module may be embodied
as electronic components instructions, software, and/or firmware
utilizing a computer program product on a computer-readable storage
medium, such as memory, solid state memory, hard disks, CD-ROMs,
optical storage devices, or magnetic storage devices.
[0039] Herein, the phrase "coupled with" or "coupled to" is defined
to mean directly connected to or indirectly connected through one
or more intermediate components. Such intermediate components may
include both hardware and software based components. Further, to
clarify the use in the pending claims and to hereby provide notice
to the public, the phrases "at least one of <A>, <B>, .
. . and <N>" or "at least one of <A>, <B>, . . .
<N> or combinations thereof" are defined by the Applicant in
the broadest sense, superseding any other implied definitions
herebefore or hereinafter unless expressly asserted by the
Applicant to the contrary, to mean one or more elements selected
from the group comprising A, B, . . . and N, that is to say, any
combination of one or more elements A, B, . . . or N including any
one element alone or in combination with one or more of the other
elements which may include, in combination, additional elements not
listed.
[0040] The rack-mounted power meter having an externally-mounted
removable metering options module (referred herein as the
rack-mounted meter) may be designed to meet requirements of
national and international standards setting bodies, such as
International Electrotechnical Commission ("IEC"), while providing
a meter that provides a rack mount form factor. The described
examples relate to an apparatus for measuring power parameters on a
conductor, such as a power line. Further, the described examples
relate to a mechanical and electrical design and system that
monitors power parameters on low, medium and high voltage
conductors.
[0041] An example power meter may include metering circuitry
comprising at least one processor capable of executing instructions
stored in a memory of the power meter to direct the receipt and
processing of signal(s) representative of power parameters. The
metering circuitry may also include hardware, firmware and/or
software based signal processing, filtering, and any other
functionality related to monitoring and processing power parameters
related to power quality and/or revenue metering. A global
positioning system ("GPS"), and/or time-synchronization
capabilities, that improve the measuring accuracy of the device
and/or provide additional geo-location based capabilities may also
be included in the metering circuitry of the power meter. Metering
circuitry of example power meters may also include communications
ports, antennas, either planar, GPS or both, facilitating ease of
communication.
[0042] FIGS. 1-3 illustrate a perspective view of an example
rack-mounted meter 100. The rack-mounted meter 100 may be inserted
and mounted to an equipment rack assembly (not shown). The
equipment rack assembly may provide an electrical connector having
an input/output (I/O) interface and operating power for the meter
100. The rack-mounted meter 100 may be designed with a form factor
having maximum external dimensions, such as dimensions that allow
the rack-mounted meter to be used as a 48.3 centimeter equipment
rack mounted meter. The rack-mounted meter 100 may be calibrated,
and its meter housing may be sealed before being installed in a bay
of an equipment rack assembly. The dimensions of the meter 100 are
implementation dependent and may vary depending upon the type of
equipment rack and standard dimensions supported therein.
[0043] Meter 100 may be sealed by including one or more tamper
proof seals on/in/around the meter 100. The seal(s) may be external
or internal to meter 100. The seal(s) may be attached during
manufacture, during installation, or following installation. A
tamper-proof seal is a physical device or mechanism that provides
an indication when the seal(s) has been tampered with, or
disturbed. The seal(s) may be made of various materials, and come
in various designs, such as an adhesive strip design, a wire
design, a lock design, a glass vial design, a plastic tie design,
an electrical fuse design, a gravitational design and/or an
inertial/shock detector design. For example, when the seal is a
plastic tie, the seal may generally include a tab with a unique
identifier, and a locking mechanism that cannot easily be opened
without breaking or otherwise visibly altering the locking
mechanism.
[0044] A tamper-proof seal can be applied to various parts of the
meter 100 to detect tampering. In addition, a seal can be applied
to structure surrounding the meter 100 to indicate removal and/or
relocation of the meter 100 with respect to the surrounding
structure. Example seal applications include application to an
access door or cover included on the meter 100, application to a
reset or other control button included on the meter 100,
application to the casing of the meter 100, application to
input/output points, and/or application to an external enclosure
around at least a portion of the meter 100.
[0045] The meter 100 may have multiple tamper-proof seals that
protect different parts of the device. Types of tamper-proof seals
that may be used include seals used as revenue/verification seals,
utility seals, or metering point identification seals. A
revenue/verification seal may be controlled by a third party and
verifies the accuracy of the meter. In the event a revenue
verification seal is disturbed or broken, the meter 100 may need to
be returned to the third party for re-verification and re-sealing
prior to being further used in revenue calculations. A utility seal
may be controlled by a user of the meter 100, such as an
electrician at a utility, to guard against tampering. A metering
point identification seal is a seal that may be used to uniquely
identify the meter 100 and keep track of the location of the meter
within a facility or system.
[0046] The rack-mounted meter 100 may integrate both power revenue
metering and power quality class metering within an external form
factor that may be rack-mounted in a bay. For example, the
rack-mounted meter 100 may provide power quality analysis that
meets Class A requirements of the IEC 61000-4-30 metering standard.
The rack-mounted meter 100 may also be a revenue device that meets
the requirements of IEC 62053-22. Accordingly, the rack-mounted
meter 100 may provide power quality detection, monitoring,
reporting, recording, analysis and communication along with revenue
accuracy measurement and reporting. The rack-mounted meter 100 may
integrate the features of power quality monitoring and revenue
metering in a single power meter having a meter housing meeting the
form factor requirements for installation and mounting in a bay of
an equipment rack assembly. Examples of a power quality meter
integrated with a revenue meter are described in U.S. Pat. No.
6,615,147, for a REVENUE METER WITH POWER QUALITY FEATURES, issued
on Sep. 2, 2003, and U.S. Pat. No. 6,792,364, for a REVENUE METER
WITH POWER QUALITY FEATURES, issued on Sep. 14, 2004, both of which
are incorporated by reference in their entirety herein.
[0047] In one example, the rack-mounted meter 100 is configured to
meet the IEC 61053-22 standard that also provides power quality
analysis to the IEC 61000-4-30 standard class A. The meter 100 may
be configured to meter single-phase or multi-phase power systems
and loads, or combinations thereof. The meter 100 may be coupled
with one or more conductors. The conductors may be power cables,
high tension lines, bus duct, bus bar, substation terminals,
generator terminals, circuit breaker terminals, and/or any other
mechanism, device, or materials capable of conducting current and
voltage. The conductor may be part of a two-wire, three-wire,
and/or four-wire power system. The meter 100 may provide
measurement of voltage and current to determine active, reactive,
and/or apparent energy over a range of frequencies, or combinations
thereof. In addition, the meter 100 may provide power quality
measurement and processing of power parameters such as voltage and
current harmonics, voltage and current inter-harmonics, voltage and
current anomalies, such as sag/swell(s) or transient(s), and/or any
other power quality related data and analysis.
[0048] The rack mounted meter 100 includes a meter housing 102. The
meter housing 102 may have an external form factor, or frame
structure, that is dimensioned to allow rack-mounting of the meter
100 in a bay of an equipment rack. Thus, an outer envelope of the
meter housing 102 may be formed to fit within at least one bay of
an equipment rack. The meter housing 102 may include at least six
sides, and may be generally characterized by width, height, and
length dimensions. The meter housing 102 provides mechanical
protection for metering circuitry included in the meter housing
102. The meter housing 102 may be configured as an IP51 enclosure
as set forth by IEC 529, providing protection to the metering
circuitry against inadvertent intrusion of tools and/or wires over
1 mm in diameter. The meter housing 102 also may provide protection
against vertically falling drops of water, condensation and other
moisture. The meter housing 102 may be designed to minimize holes,
cutouts, spot welded tabs, folded seams, and connector openings,
and may have a rust inhibiting coating such as a powder coat
finish, paint or other protective coating. The meter housing 102
may provide mechanical protection, fire protection, electromagnetic
protection against radio-frequency interference, and electrical
shock protection.
[0049] The meter housing 102 may include a two-tiered surface 108
that includes a first portion 108a and a second portion 108b. In
FIGS. 1-3, the first portion 108a is a front portion and the second
portion 108b is a rear portion of the meter housing 102. The first
portion 108a may be substantially planar across the width of the
two-tiered surface 108, and extend a predetermined depth of the
meter housing 102 from a front panel 104 of the rack-mounted meter
100 towards a mid portion 110 of the two-tiered surface 108. The
second portion 108b, or slot, may be substantially planar across
the width of the meter housing 102 and extend from the mid portion
110 to an end of the meter housing 102, such as a rear 112 of the
meter housing 102. The second portion 108b may be recessed from the
first portion 108a to form a slot.
[0050] The meter housing 102 may also include an electrical
connector panel 106. The electrical connector panel 106 may include
a first connector panel 106a and a second connector panel 106b. The
first connector panel 106a may be a step or shoulder formed as a
portion of the meter housing 102 that connects the first portion
108a of the two-tiered surface 108 to the second portion 108b. The
first connector panel 106a may be substantially planar across the
width of the meter housing 102, and may be positioned approximately
orthogonal to both the first portion 108a and the second portion
108b of the two-tiered surface 108.
[0051] FIGS. 1 and 3 illustrate a metering options module 114 that
is designed to be coupled with and mounted to the rack-mounted
meter 100. FIG. 2 illustrates the rack-mounted meter 100 without
the metering options module 114 coupled with the rack-mounted meter
100. The enclosure of the metering options module 114 may be
characterized by a width, height, and length dimensions. The
metering options module 114 may include a housing that is designed
to provide mechanical protection for circuitry enclosed within
similar to that described above for the meter housing 102 of the
rack-mounted meter 100. In the illustrated example, the enclosure
of the metering options module 114 has six sides. In another
embodiment, the metering options module 114 may include a housing
that is completed after the metering options module 114 has been
mounted to, or otherwise installed on, the rack mounted meter 100,
e.g. the metering options module 114 features at least one open
face that is covered by a face of the meter 100 when the metering
options module 114 is installed. In this example, the metering
housing 102 may be a sealed unit that is an IP51 enclosure as set
forth by IEC 529. In addition, or alternatively, the housing formed
by the combination of the metering options module 114, and the
meter housing 102 may be an IP51 enclosure as set forth by IEC
529.
[0052] The metering options module 114 may be coupled with the
rack-mounted meter 100 proximate the two-tiered surface 108. The
surface of the second portion 108b of the rack-mounted meter 100
may be recessed from the surface of the first portion 108a a
determined distance that allows the metering options module 114 to
be mounted contiguous with the second portion 108b. In one example,
the uppermost portion of the metering options module 114 may be
substantially flush with the first portion 108a. That is, a height
of the first portion of the first connector panel 106a is at least
the height of an upper surface of the metering options module 114.
In addition, the length of the second portion 108b may be at least
as long as a length of the metering options module 114, and the
width of the metering options module 114 may be no wider than the
width of the rack-mounted meter 100. In the illustrated example,
the length of the second portion 108b is slightly longer than the
metering options module 114 to allow room for connectors and
associated conductors, such as signal cables, to be terminated at
the metering options module 114.
[0053] Accordingly, when the metering options module 114 is affixed
to the meter 100, the metering options module 114 may be
substantially flush with the upper surface 108a. In one example,
the exposed upper surface of the metering options module 114 does
not extend beyond the upper surface 108a. Additionally, or
alternatively, the external dimensions of the meter 100 with the
metering options module 114 mounted thereto may not exceed the
maximum dimensions required for the meter 100 and the metering
options module 114 to be installed in a bay of an equipment rack
assembly. Thus, an outer envelop of the meter 100, with our without
the metering options module 114, may be dimensioned to fit within
the dimensions of a bay of an equipment rack assembly and be
securely mountable therein.
[0054] The metering options module 114 may be coupled with the
meter housing 102 with a fastener 117. The fastener 117 may be a
screw, a rivet, a clasp, a latch, a snap, or any other mechanism
capable of holding the metering options module 114 in position on a
surface of the meter housing 102. In FIGS. 1-3, the fastener 117 is
a plurality of fasteners each formed with a threaded post and a
nut. In other examples, any other form of fastener, in any other
position capable of coupling the metering options module 114 and
the meter housing 102 may be used.
[0055] FIGS. 1 and 3 illustrate an example metering options module
114 mounted substantially flush with the two-tier upper surface 108
of the rack-mounted meter 100. In other examples, the metering
options module 114 may be otherwise coupled with the rack-mounted
meter 100. For example, the metering options module 114 and
rack-mounted meter 100 may be configured with a two-tier side
surface, or a two tiered bottom surface, where the metering options
module 114 is mounted to be no greater than flush with the external
dimensions of the rack-mounted meter 100. Alternatively, or in
addition, additional external surfaces of the meter 100 may be
two-tiered to allow more than one metering options module 114 to be
mounted to the rack-mounted meter 114 and yet stay within the
dimensions of a bay of an equipment rack.
[0056] The metering options module 114, when mounted on the meter
100, may have a first surface that is contiguous with the second
surface 108b, and a second surface opposite the first surface that
is substantially flush with the maximum external dimensions of the
meter housing 102. Thus, first surface of the metering options
module may be substantially parallel with a surface of the second
portion, and the second surface of the metering options module 114
may be in substantially the same plane with the surface of the
first portion 108a of the meter 100.
[0057] In another example, the meter housing 102 may have a slot,
cavity or opening in which the metering options module 114 may be
inserted. The slot may be formed in the front, back, top, bottom or
side of the meter 100, and be an externally accessible surface of
the metering housing 102. The meter housing 102 may form the
cavity. The meter housing 102 may remain a sealed unit that is an
IP51 enclosure as set forth by EEC 529. A hinged or otherwise
movable cover, or trap door, may be positioned to cover an entrance
to the cavity.
[0058] The cover may be moved from a closed position to an open
position to allow the metering options module 114 to be inserted
into the cavity through the entrance. The metering options module
114 may be securely held in the cavity with the cover. The cover
may minimize entry of dust and moisture into the cavity. In
addition, the cover may have a security mechanism such as a lock
and key, a biometric device, such as a fingerprint scanner, or any
other device that provides verification of identity so that only
authorized personnel are allowed access to the cavity. In addition,
or alternatively, the cover could be sealed with a tamper proof
seal, such as a utility seal, and/or a revenue seal once the
metering options module 114 is installed in the cavity and the
cover is moved to a closed position. The number and type of tamper
proof seal(s) is dependent on the operational functionality of the
metering options module 114.
[0059] The metering options module 114 represents self-enclosed,
sealed, additional functionality that may be added to the meter
100. Such functionality may include additional power parameter
processing capability, signal conditioning capability, input/output
capability, and/or any other hardware, firmware and/or software to
reconfigure, enhance, or otherwise change the functionality of the
meter 100. In one example, the metering options module 114 may
provide enhanced communication capability and associated
input/output hardware. In another example, the metering options
module 114 may provide increased capability to transmit and receive
input and/or output signals. In still other examples, the metering
options module may provide hardware, software and input/output
signal capability to enable protective relaying functionality. In
yet another example, the metering options module 114 may provide
power quality event hardware, software and input/output
capability.
[0060] The front panel 104 of the rack-mounted meter 100 may have a
flip-up cover 115. FIGS. 1 and 2 illustrate the rack-mounted meter
100 with the cover 115 in a closed position, and FIG. 3 illustrates
the cover 115 in an open position. The flip-up cover 115 may be
hinged so that the cover 115 swings through an arc to an open
position, exposing a control panel 116. At least a portion of the
control panel 116 may be located underneath or behind the cover
115. Other portions of the control panel 116 may be accessible when
the cover 115 is in a closed position. The control panel 116 may
include connectors, such as analog, digital and/or optical
connectors. In addition, as described later, the control panel 116
may include user interface devices, such as, buttons, knobs,
switches or any other user input/output devices or mechanisms that
provide access and control of the meter 100.
[0061] With the cover 115 closed, one or more connectors, buttons,
switches, and/or other user interface devices for access and
control of the meter 100 may be covered and inaccessible, while
other connectors, buttons, switches, and/or any other user
interfaces may be accessible through the cover 115. In addition,
user interface devices may be included on the cover. Access to
controls when the cover 115 is in the closed position may include
only that functionality that will not affect operation. The
remaining controls may be inaccessible to a user with limited
security access when the cover 115 is closed. When additional
control inputs are to be provided to the meter 100, the cover 115
may be opened, exposing the features beneath.
[0062] A screen 118, such as an LCD, LED, plasma or other digitally
controlled display may be positioned on the front panel 104. The
screen may be a touch-screen device allowing a user to input data
and selections by touching appropriate areas on the screen 118. The
screen 118 may be viewable with the cover 115 in the closed and
opened positions. Thus, the screen 118 may be positioned on the
control panel 116 or mounted on the cover 115. In one example, when
the screen 118 is on the control panel 116, portions of the screen
118 may be blocked when the cover 115 is closed, e.g. to prevent
viewing of particular data.
[0063] The screen 118 may include a graphical user interface that
allows the user to input data, configure parameters for the meter
100, set controls, and/or receive information from the meter 100.
The user may input a selection directly through the screen 118,
and/or may input data using any one of combinations of the other
user interface devices, such as buttons, switches and knobs
included on the control panel 116. For example, using the buttons
provided at the front 104 of the meter 100, the user may scroll or
navigate through an options menu on the screen 118 to configure the
meter 100, assign communications protocols for the meter 100,
display output parameters, set input metering parameters and/or
control any other features of the meter 100. The options menu may
be a cascading or hierarchical menu where selections of options on
a menu may provide a subset of options provided on another menu
that is displayed to the user. The screen 118 may also be used to
provide a visual indication of the operation of the meter 100.
[0064] The meter 100 may be configured to provide multiple levels
of security to protect the meter 100 from being tampered with or
inadvertently or mistakenly mis-programmed. For example, access to
the options menu and/or portions of the options menu may be
accessible only after a user has entered a password or
authentication code. Similarly, where the meter 100 is being
accessed for programming using an external processor in
communication with the meter 100 through a communications port,
access to programming features may be set according to a password
entered. The password may be associated with a high-level
programming or calibrating access, such as by a third party
manufacturer and/or calibrator. Another authorization level may be
associated with general configurations set-up. For example, another
password may be associated with general scrolling or navigating to
select various outputs, and/or restricting inputs or reconfiguring
of the meter 100.
[0065] The level of access may be determined by a password or other
authentication means, such as a biometric device, or any other
mechanism for identifying a user. The meter 100 may be accessed by
multiple users, each having a distinct password. Access to various
parameters of the meter 100 may be determined or restricted by the
password as well. For example, one user may have access only to
power quality parameters based on the password associated with the
user, and another user may have access to revenue parameters based
on the associated password. The password also may restrict the
user's privileges to read, or read and write data provided by the
meter 100.
[0066] The front face 104 may be configured to be mounted and
affixed to corresponding members of a standard equipment rack
system. The front face 104 may have handles or grab bars 120 that
allow an installer to carry the meter 100, and to position the
meter 100 in or with an equipment rack assembly. The handles 120
may be installed at the front face 104 towards the vertical edges
of the front panel 104. The front panel 104 also may include a
mechanical coupler 122, such as a screw, bolt, or wing nut that
allows the meter 100 to be affixed to a rack assembly. The
mechanical coupler 122 may also be used to form a tamper proof
seal, such as a utility seal so that the meter 100 cannot be
removed from the equipment rack without disturbing, damaging, or
otherwise changing the tamper proof seal to indicate such activity
has occurred.
[0067] FIGS. 4-6 illustrate perspective views from the rear of the
rack-mounted meter 100. FIGS. 4 and 5 illustrate the rack-mounted
meter 100 with the cover 115 in a first position that is a closed
position, and FIG. 6 illustrates the rack mounted meter 100 with
the cover 115 in an open position. FIGS. 4 and 6 illustrate the
metering options module 114 attached or otherwise mounted to the
rack-mounted meter 100 at the second portion 108b, and FIG. 5
illustrates the rack-mounted meter 100 without the metering options
module 114 mounted or otherwise affixed to the rack-mounted meter
100.
[0068] FIG. 5 also illustrates the first connector panel 106a of
the metering housing 102. An externally accessible meter housing
electrical connector 130 may be installed on the surface of the
first connector panel 106a to provide an electrical connection from
the rack mounted meter 100 to the metering options module 114. In
one example, the meter housing connector 130 is a multiple-pin
connector providing power to the metering options module 114 as
well as multiple I/O connections, such as communications and
control signals. When the metering options module 114 is installed
on the rack-mounted meter 100, a corresponding electrical connector
is coupled with the meter housing electrical connector 130 on the
rack-mounted meter 100. In one example, the meter housing connector
130 is a pin connector, such as a fifty pin connector, that is
configured to accept an edge connector of the metering options
module 114. The first connector panel 106a may also include guide
pins 131. The guide pins 131 provide for mechanical alignment of
the metering options module 114 with the meter 100 when the
metering options module 114 is being positioned on the meter
housing 102. The guide pins 131 may be provided at the first
connector panel 106a to guide the metering options module 114 to
the meter 100 when the metering options module 114 is mounted to
the meter 100.
[0069] The rear of the meter housing 102 also may include the
second connector panel 106b. The second connector panel 106b
includes at least one rack electrical connector 128 for connecting
the meter 100 to one more rack electrical connectors included in an
equipment rack assembly. The rack connector 128 may be arranged
according to a predetermined and/or standardized configuration or
arrangement. In one example, the rack connector 128 may be a
plurality of pins arranged according to a predetermined
configuration where the position of a pin corresponds with a
signal, power, or ground connection. Through the rack connector
128, signals related to the voltage and/or current of one of more
conductors that the meter 100 may monitor or measure are inputs to
the meter 100. The position of the pins of the rack electrical
connector 128 may be assigned to a particular or discrete voltage,
current, or power input signal. For example, a pin may be assigned
to receive a voltage signal of one phase of a multiphase voltage
system, a voltage signal of a single phase system, or a reference
or neutral of a multi-phase or single phase voltage system.
Similarly, a pin may be assigned to receive signals related to
current on a conductor.
[0070] The rack electrical connector 128 may be one or more pin or
plug-type connectors, sleeve or socket type connectors, or
combinations thereof. The connector 128 may be coupled with one or
more corresponding connectors in an equipment rack assembly (not
shown) when the meter 100 is installed or otherwise mounted in a
bay of an equipment rack assembly. The pins may be slid into
corresponding sleeves or receptacles, and the sleeves may accept
corresponding pins on the equipment rack assembly. In one example,
the rack connector 128 includes multiple Essailec connectors,
manufactured by ABB Entrelec of Irving, Texas, that are arranged in
a predetermined configuration on the second connector panel 106b of
the meter 100. The rack connector 128 may include coding or keying
pins that mate with corresponding keying or coding pins on the rack
electrical connector(s) in the equipment rack assembly when the
meter 100 is installed in the bay of the equipment rack.
[0071] In one example, where the rack connector 128 is a plurality
of Essailec connectors, there are a plurality of coding pins, such
as four coding pins, associated with each Essailec connector. The
coding pins may have an external contour or shape that provides a
unique profile for the coding pin depending on the orientation of
coding pin in its housing. The coding pin may be oriented in one of
several clock positions with respect to the rack connector 128 with
which it is associated. The coding pin will engage with the
corresponding pin in the electrical connector in the equipment rack
assembly, only when both pins have a corresponding orientation. The
coding pins may be oriented or keyed according to the arrangement
or layout of the rack connector 128 on the meter 100. The coding
pins may therefore prevent a meter 100 from being mis-racked or
installed in an improper socket on the equipment rack.
[0072] The coding pins also may be arranged to identify a
configuration of the meter 100, and/or identify a feature set, or
group of functionalities of the meter 100. The identified feature
set may include parameters for how a particular meter 100 is
configured and/or functionality provided by the meter 100. For
example, the feature set may include digital input or output
configurations, analog input or output configurations, Ethernet and
communications configurations, GPS time sync capabilities, antenna
connections for wireless devices (e.g., 802.11 and the like),
wireless mesh networks, Zigbee, Wi-Fi, and the like. The coding
pins may be assigned to each feature set such that a predefined
coding pin, or arrangement of one or more coding pins, may identify
the functionality present within a particular meter 100.
[0073] A ground lug 126 also may be provided on the second
connector panel 106b of the meter 100 to provide grounding and
bonding of the meter 100 to the equipment rack assembly. In one
example, the ground lug 126 is a threaded stud in electrical
continuity with exposed conductive members of the meter housing
102. The ground lug 126 also may be coupled with one or more
grounded buses internal to the meter housing 102. In other
examples, the ground lug 126 may be positioned elsewhere on the
surface of the meter housing 102. In still other examples, one or
more of the fasteners 117 may be used to ground the metering
options module 114 and/or the meter 100.
[0074] The metering options module 114 may be coupled with the
meter 100 with a tab 124 included on the metering options module
114. The tab 124 may be configured to be coupled with the ground
lug 126. In FIGS. 4-5, the tab 124 includes an opening that allows
the tab 124 to be slide over the ground lug 126 on the second
connector panel 106b of the meter 100 and be fastened thereto with
a fastener, such as a nut. The metering options module 114 may be
secured, bonded and grounded with the power meter 100 through the
electrical connection to the ground lug 126. In one example, the
ground lug 126 is a threaded stud and the tab 124 of the metering
options module 114 may be secured to the ground lug 126 through a
paint breaking bonding nut that is secured to a threaded stud that
forms the ground lug 126. The ground lug 126 may also be positioned
to allow grounding and bonding of the meter 100 to an equipment
rack assembly.
[0075] In one example, the second connector panel 106b of the meter
100 includes lances 132. The lances 132 may be projections formed
in, or fasteners coupled with, the meter housing 102 on or in
proximity to the second connector panel 106b of the meter housing
102. The meter 100 may include an internal chassis that is inserted
or slid into the meter housing 102. In FIGS. 4-6, the lances 132
are screws that include an aperture, and may be used to fasten the
internal housing to the meter housing 102. The lances 132 may be
used to couple tamper-proof seals to the meter 100. The meter 100
may be assembled, calibrated and verified by a third party to be
operational and to be capable of use to report on metering
conditions and parameters within predetermined tolerances. Once
verification is complete the internal chassis may be slid into the
meter 100, and one or more tamper-proof seals may be applied to the
lances 132. In one example, the ground lug 126 may also include a
lance capable of being used to install a tamper-proof seal for the
ground lug and/or the slidable chassis.
[0076] After the meter 100 has been verified to operate within
determined tolerances, the meter 100 may be sealed with a
tamper-proof seal. The tamper-proof seal may be a revenue seal that
provides verification that the meter housing 102 has not been
opened or otherwise disturbed following calibration. In one
example, verification sealing of the meter 100 is completed by
threading wire though one or more lances 132 in the second
connector panel 106b of the meter 100. The ends of the wire that is
threaded through the lances 132 may also be threaded through an
aperture formed in a cleat 133 included on the meter housing 102.
The cleat 133 may be positioned on the meter housing 102 and may be
accessible after the meter 100 has been assembled. After the wire
is threaded through the lance 132 and the cleat 133, the ends of
the wire may be tied, clamped or otherwise permanently affixed
together. The lance 132 also may be configured to secure the ends
of the wires. Thus, in the illustrated example, the lance 132
cannot be unscrewed to access the internal chassis without
breaking, or otherwise disturbing the wire threaded through the
lance 132 and the cleat 133, which would indicate tampering had
occurred.
[0077] A wire also may be threaded through a lance (not shown) in
the metering options module 114 and secured to the meter 100 to
create a tamper proof seal. The meter housing 102 of the meter 100
may not be opened without breaking, or otherwise creating
indication of such activity with the tamper-proof seal. In
addition, separation of the metering options module 114 from the
meter 100 may not occur without breaking, or otherwise creating
indication of such activity with the tamper-proof seal. In other
examples, the tamper-proof seal may be omitted to enable
discretionary removal and installation of the metering options
module 114 without disturbing any tamper-proof seals.
[0078] FIGS. 7 and 8 illustrate a front view of an example of the
rack-mounted meter 100 that includes the front panel 104 of the
meter 100. The front panel 104 provides a user interface for the
meter 100. FIG. 7 illustrates an example of the front panel 104 of
the meter 100 with the cover 115 in a closed position. In the
closed position, access to the user interface may be limited,
however a set of input/control buttons 136 may remain
accessible.
[0079] FIG. 8 illustrates the front panel 104 of the meter 100 with
the cover 115 in an open position, exposing input keys 146,
indicators 147 (such as LEDs), and a battery cover or battery
compartment 149, at least some of which may be concealed when the
cover 115 is in a closed position. The cover 115 may be closed to
conceal other buttons, switches, connectors, lights, and the like
on the control panel 116. The cover 115 may be secured in the
closed position by the weight of the cover 115, by a snap fit, by a
mechanical coupler, or any other mechanism for securing the cover
115 in a closed position. The cover 115 may be configured to be
open by hand or through the use of a specialty or off-the-shelf
tool. The cover 115 may also be held in the closed position with a
tamper-proof seal.
[0080] The display 118 is positioned at the front panel 104 to
provide data input and output. The display 118 provides a graphical
interface for the meter 100. Information gathered, metered,
collected or otherwise compiled by the meter 100 may be displayed
on the display 118. For example, the display 118 may display the
current status of power used by a load being monitored by the meter
100. The display 118 may also provide a visual or graphic display
of a phasor diagram for the load and/or supply. A user may also use
the display 118 to input control commands to the meter 100 and/or
scroll through an options menu to configure the meter 100, set
metering parameters and alarm conditions, select communications
protocols, assign communications protocols to input/output
communications ports, and/or select an output from the meter 100
for viewing, control and/or further processing.
[0081] The display 118 may be used in combination with scroll
buttons 136 to scroll through the menus of the meter 100. In one
example, the display 118 is a touch screen that allows the user to
input commands, and otherwise make selections from an options menu
using the display 118. The display 118 may also be configured to
recognize or identify the user, and grant access to features,
functions and parameters of the meter 100 based on recognition of
the user. For example, the display 118 may be configured to
recognize or identify a user by analyzing the user's biometric
data, such as a fingerprint, when the user touches the screen 118.
The meter 100 may include a fingerprint recognition mechanism that
allows identification of a user's fingerprint. After the user is
recognized, the level of access to features and functions of the
meter 100 may be determined based on a predetermined authorization
level. Accordingly, the user's biometric information may be used
for granting access and determining access levels for the user
within the meter 100.
[0082] The display 118 also may provide a visual indication of an
alarm condition. For example, the display 118 may be configured to
have a selected background color during operating conditions, and
another distinct background color when an alarm condition is
detected. The background color of the display 118 may change color
and/or flash when an alarm condition is detected. For example, if
the meter 100 detects a power outage, a low voltage condition, an
overload condition, or measure a parameter outside a preset limit,
the meter 100 may indicate the corresponding alarm condition on the
display 118 by changing the background color on the display 118. A
message also, or alternatively, may be flashed on the display 118.
The visual alarm indicator of the display 118 may be accompanied by
an audible alarm and/or a communications output indicating the
detected alarm condition.
[0083] The user may select from a variety of communications
protocols over which the meter 100 may communicate with other
devices, such as computers, processors, controllers, loads and
meters. The user may select the communications protocol from a
selected menu displayed on the display 118. The communications
protocol also, or alternatively, may be set from a computer or
other controller coupled to the meter 100, either through a rack
assembly, at the factory during assembly, through a universal
serial bus ("USB") port, through an optical port, through a
hard-wired connection, or through a wireless communications
transmission with the meter 100. The meter 100 may be configured to
communicate using one or more communications protocols, including
TCIP, SCADA, Modbus, ION, RS232, RS485, and Device Language Message
Specification ("DLMS"), DNP, IEC 61850 protocols and the like.
[0084] The front panel 104 may include one or more optical
communications ports 142. In one example, the optical
communications ports 142 are configured according to IEC 1107, ANSI
C12, and/or IRDA standards. The optical communications ports 142
may be accessible through openings 138 in the cover 115. The
optical communications ports 142 may provide access to
communications with the meter 100 through the user interface
provided by the front panel 104 of the meter 100.
[0085] The optical communications ports 142 may also be configured
to provide parallel communications. Thus, in the example of FIG. 8,
each optical communications port 142 may be configured to
independently communicate with a communications device external to
the meter 100. The optical communications ports 142 also may be
configured to provide series communications. The series
communication may be duplicative of communications of one of the
other ports 142. Thus, using the optical communications port 142,
the meter 100 may be configured to communicate with a plurality of
external devices, such as three different devices.
[0086] The communications ports 142 may each have a communications
indicator 144 that signals when communication with the
corresponding port 142 is active, such as through a visual
indication. In one example, the communications indicator 144 is one
or more LED's positioned proximate to the optical communications
port 142. The communications indicators 144 may illuminate when the
corresponding communications port 142 is active. Each of the
communications indicators 144 may be encased in a clear diffuser
positioned around each of the optical communications ports 142. The
diffuser may be illuminated when the corresponding communications
indicator 144 illuminates. The communications indicator 144 may be
configured to distinguish between inbound and outbound
communications, such as by corresponding distinguishing colors. The
communications indicator 144 also may be configured to provide a
visual indicator when the communications is lost or to indicate an
alarm condition, such as by flashing.
[0087] The front panel 104 also may provide a universal serial bus
(USB) port 140 for wired communications with other devices. The USB
port 140 enables the meter 100 to be connected to any USB
compatible device, such as, for example, portable computers and
portable communications devices. The meter 100 also may be
configured for wireless communications, such as by using Wi-Fi,
Bluetooth, mesh and Zigbee standard communications protocols and/or
combinations thereof. Using the wireless communications, and/or USB
port, the meter 100 may communicate and share data and control with
other devices.
[0088] The meter 100 may have a redundant, back-up power supply or
reserve energy storage device (not shown). The redundant power
supply may be available to provide power for the operation of the
meter 100 in the event of a power supply failure to the meter 100.
The redundant power supply may automatically take over supplying
power to the meter 100 in the event of a power failure. In one
example, the back-up power supply is a battery back-up.
[0089] In the event of a power failure, the meter 100 may sense the
power failure and switch over to the back-power supply. The meter
100 also may enter into a power down or sleep mode until electrical
energy is sensed on the conductor(s) being monitored by the meter
100. FIG. 8 illustrates an example of a battery compartment 149
which may provide an enclosure for one or more back-up batteries.
The battery compartment 149 is concealed by the cover 115 and is
accessible only when the cover 115 is open. In another example, the
back-up power supply may be a capacitor or capacitor bank that may
store energy that may be used in the event of a power failure. The
meter 100 also may be powered by one or more phases of the power
supplied on the conductor(s) to which the meter 100 is connected to
monitor. The meter 100 also may have a dedicated AC power supply or
dedicated DC supply from a stationary battery.
[0090] FIG. 9 illustrates a front view of another example of the
rack-mounted meter 100 that includes the front panel 104 of the
meter 100. In this example, the cover 115 is illustrated as open,
and in addition to the user interface devices, such as the display
118, the front panel 104 includes a slot 180 formed in the front
panel 104. The slot 180 may be formed in an externally accessible
surface of the meter housing. The meter housing may remain a sealed
unit that is an IP51 enclosure as set forth by IEC 529.
[0091] The slot 180 may be dimensioned to receive the metering
options module 114. The slot 180 may have a removable and/or
retractable slot cover 181 that covers an opening to the slot 180.
The meter housing electrical connector 130 (FIG. 5) may be disposed
in the slot 180 and positioned to engage an electrical connector
mounted on the metering options module 114.
[0092] FIG. 10 is a perspective view of an example meter 100 that
also includes a perspective view of a removable metering options
module 114. In this example, the metering options module 114 is
dimensioned to fit within the slot 180. Thus, the two-tiered
surface 108 (FIG. 1) may be omitted. The metering options module
114 may include a plurality of input/output (I/O) ports 150. As
described later, the I/O ports 150 may provide an interface to
other devices and/or equipment.
[0093] FIG. 11 is a front view of the meter 100 of FIG. 9 with the
metering options module 114 installed in the slot 180. The I/O
ports 150 may be positioned to be accessible when the cover 115 is
in the open position. A tamper-proof-seal may be applied once the
metering options module 114 is positioned in the slot 180. An
electrical connector (not shown) mounted on a surface of the
metering options module 114 may be positioned to engage a surface
mounted electrical connector disposed in the slot 180 when the
metering options module 114 is positioned in the slot 180. The I/O
ports 150 may also include a ground lug. Alternatively, or in
addition, the metering options module 114 may be grounded when the
electrical connectors engage within the slot 180.
[0094] FIGS. 12 and 13 illustrate rear views of an example of the
rack-mounted meter 100 also illustrated in FIGS. 1-6. FIG. 12
illustrates the rack-mounted meter 100 with the metering options
module 114 attached or otherwise coupled with, or mounted to an
externally accessible surface of the rack-mounted meter 100, and
FIG. 13 illustrates the rack-mounted meter 100 without the metering
options module 114 coupled, mounted, or otherwise affixed to the
rack-mounted meter 100.
[0095] FIG. 12 also illustrates one or more I/O ports 150 included
on a rear panel of the metering options module 114. The I/O ports
150 may be communication ports that are enabled for communication
when the metering options module 114 is coupled with the meter
housing 102. Alternatively, or in addition, the I/O ports 150 may
be signal ports, such as analog and/or digital signal ports. In
other examples, the I/O ports 150 may be on any other surface of
the metering options module 114.
[0096] In another example, the I/O ports 150 may be in the form of
one or more options rack electrical connectors. The options rack
electrical connector(s) may be formed and position on the rear
panel of the metering options module 114. In other examples, the
options rack electrical connector may be positioned on any other
externally accessible surface of the metering options module
114.
[0097] When the metering options module 114 is mounted on the meter
100 and racked into a bay of an equipment rack, the options rack
electrical connector may be engaged with an options rack electrical
connector included in the equipment rack. Upon engagement, inputs
and/or outputs external to the meter 100 and/or the metering
options module 114 may be provided to the metering options module
114 via the engaged options rack electrical connectors. The options
rack electrical connectors may be pluggable panel mount connectors
which may include wiring harnesses, or any other form of electrical
connectors, as discussed herein. In one example, the pluggable
panel mount connectors may be Essailec connectors. The options rack
electrical connectors in the equipment rack may be pre-wired in a
predetermined configuration, and/or may be installed and wired for
the metering options module 114.
[0098] The meter 100 may be configured as an intelligent electronic
device (IED). As an IED, the meter 100 may be configured to provide
control of other devices in a Master/Slave arrangement. In one
example, the meter 100 is configured to communicate with other
metering devices using a Modbus and/or Modbus TCP communications
protocol to provide control functions for those devices. The meter
100 may be set up as a Master where other devices on the network
are slaves. The slaves may communicate information back to Master.
The Master (meter 100) may handle communication of the information
through the network to other network coupled devices, such as
controllers. The meter 100 also may be compatible with an
object-oriented architecture.
[0099] The meter 100 also may have modular capability so that it
may be configured to operate according to a limited set of
functions. Examples of such IED, object-oriented architectures,
master/slave power monitoring devices, and module configurations
for power meters are described in U.S. Pat. No. 6,871,150, entitled
Expandable Intelligent Electronic Device, U.S. Pat. No. 5,650,936,
entitled Power Monitor Apparatus and Method With Object Oriented
Structure, and U.S. Pat. No. 5,828,576, entitled Power Monitor
Apparatus and Method With Object Oriented Structure, each of which
is incorporated by reference in its entirety herein.
[0100] FIG. 13 illustrates the first connector panel 106a of the
meter housing having the externally accessible meter housing
electrical connector 130 for providing electrical connection to the
metering options module 114. The externally accessible meter
housing electrical connector 130 may be installed on the first
connector panel 106a to provide an electrical connection from the
rack mounted meter 100 to the metering options module 114. The
electrical connector 130 may provide electrical connections to a
corresponding electrical connector on the metering options module
114.
[0101] As shown in FIGS. 12 and 13, the second connector panel 106b
of the meter housing 102 may provide rack electrical connector 128
for use with the equipment rack assembly. The rack electrical
connector 128 may be one or more electrical connectors arranged in
a standard configuration at the second connector panel 106b of the
meter 100. The rack electrical connectors 128 may be configured to
be coupled to, or engaged with, corresponding rack electrical
connectors provided in the equipment rack assembly in which the
meter 100 may be mounted. The electrical connectors may have a
standard arrangement, or configuration, where the position of an
electrical connector corresponds with a signal, power, or ground
connection in the equipment rack assembly. For example, the
connectors are pins that are slid into corresponding sleeves or
receptacles on the rack assembly, as previously discussed.
[0102] In one example, the electrical connectors are Essailec
connectors that are keyed or arranged to provide an advanced
feature set for input and output between the meter 100, the
equipment rack assembly, and/or devices connected to the meter 100
through the equipment rack assembly. One end of the Essailec
connectors may be mounted and coupled to one or more printed
circuit boards. Each printed circuit board includes traces that
route connections to the connector from a common connection point
on the printed circuit board for all connectors. The printed
circuit board may be installed on the chassis of the meter 100, and
internal connections to the Essailec connectors may be made through
the circuit board to internal connectors of the meter 100. Mounting
the Essailec connectors to the circuit board provides an efficient
quick means for installing or otherwise assembling the connectors
in the meter 100.
[0103] The meter 100 may include a map of the rack connector(s) 128
stored in memory. The map may be used by the processor to determine
whether appropriate connections are made when the meter 100 is
installed in the equipment rack. For example, the meter 100 may be
programmed to detect whether the Essailec pins are connected to a
circuit when the meter 100 is installed in the equipment rack
assembly. In one example, a lookup table may store a bitmap of the
connections of the rack connector(s) 128. When the meter 100 is
installed and configured by a user, the bitmap may be referenced to
ensure that the expected connections at the rack connector(s) 128
are present. The expected connections may be determined based on
measurement of signal and/or voltage levels, measurement of test
signals transmitted through the connections, or any other method,
mechanism or device capable of determining that the connections are
present. For example, if a connection is measured expecting between
100V and 120V, and that is what is measured, the connection is
verified.
[0104] Connection verification may also involve the metering
options module 114 for certain signals, such as communication
signals. In addition, the metering options module 114 may be used
to generate and/or enable the generation of test signals to verify
the connections. For example, the metering options module 114 may
be in communication with an external device capable of generating
test signals to the connections in the equipment rack. Thus, the
metering circuitry may direct the external device via the metering
options module 114 to output test signals to verify the
connections.
[0105] If the expected connection is not present, an alarm or other
indicator may be generated by the metering circuitry. For example,
a message may be displayed to a user through the screen 118. (FIG.
8) The meter 100 also may be configured to display a map of the
rack connector(s) 128 on the screen 118.
[0106] In one example a user may select to display a map of the
connections on the screen 118. The map may be displayed to show
which of the connectors/pins has an electrical connection, when
inserted in a bay of an electrical equipment rack. A pin having an
electrical connection may be displayed in the map with a color or
shading different from a pin without an electrical connection. For
example, all connectors having electrical connections may be
illustrated as black dots on the map and those connectors without a
connection may be displayed in the map as a circle. Alternatively,
or in addition, a signal level value of each connector/pin having
an electrical connection may be displayed.
[0107] At least one of the rack connectors 128 located at the
second connector panel 106b of the meter 100 may be configured to
provide an analog input/output connection. The analog I/O
connection may provide analog communications signals between the
meter 100 and other devices. The analog connection may be used t
provide information from the meter 100. Additionally or
alternatively, the analog connection may be used to receive
information by the meter 100.
[0108] One example, connection to an analog I/O pin may enable the
meter 100 to be aligned with absolute time, independent of an
operating system time of the meter 100. Therefore, an analog pin
may be used as a port for a global positioning system (GPS) signal
for purposes of time synchronization. Using IRIG GPS signals, the
input signals to the meter 100 may be time-stamped and
synchronized. The IRIG GPS signal may be continuously monitored by
the meter 100, or sampled. In one example, an IRIG B GPS signal is
received by the meter 100. A Field Programmable Gate Array ("FPGA")
included in the metering circuitry may decode the received IRIG B
signal, and generate an interrupt signal at a fixed time relative
to the start of an IRIG B packet. A processor, such as a CPU, may
receive or detect the interrupt and thereby generate an accurate
time stamp. The processor reads the IRIG B packet from the FPGA.
The IRIG GPS connection on the rack-mounted meter 100 also may be
provided through other connections to the meter 100 such as
wireless transmission and/or reception, IRIG B, and serial
communications.
[0109] Another connection supported by the rack connector(s) 128
may be a watchdog signal generated by the metering circuitry
included in the meter 100. For example, a "heartbeat" signal may be
periodically provided at one of the connections. The heartbeat
signal may be present when the meter 100 is operational and/or
operating. The signal may be monitored by an external controller or
processor. When the meter 100 is not operating or operational, the
heartbeat signal will cease, triggering an alarm or other indicator
that the meter 100 may have failed or may be in the process of
failing.
[0110] FIG. 14 illustrates a perspective view of an example of the
meter 100 with a portion of the meter housing 102 removed to show
internal connections and configuration of the meter housing
electrical connector 130. As previously discussed, the meter
housing electrical connector 130 is positioned to engage an
electrical connector on the metering options module 114 when the
metering options module 114 is coupled with the meter housing
102.
[0111] The meter housing electrical connector 130 may be internally
coupled to a bus 160. The bus 160 may provide electrical
connectivity from the meter housing connector 130 to metering
circuitry 162 included in meter 100. In FIG. 14, the bus 160 is
coupled with an internal printed wiring/circuit board that is
included in the metering circuitry 162.
[0112] In one example, the bus 160 includes an intermediate printed
circuit board that conducts the signals between the meter 100 and
the metering options module 114. In other examples, the bus 160 may
be a plurality of wires, a serial bus, a universal asynchronous
receiver transmitter (UART), or any other mechanism capable of
communicating electrical signals. The bus 160 may provide a conduit
for the signals between a processor, controller, field programmable
gate array (FPGA) and/or CPU and other components included in the
metering circuitry of the meter 100 and a processor, controller,
and/or central processing unit (CPU) and other components of the
metering options module 114. The bus 160 may terminate at one end
in a multiple pin connector such as a 50 pin header (meter housing
connector 130) that is configured to engage the metering options
module 114. The other end of the bus 160 may be terminated in a
metering circuitry connector 164, such as an edge connector. In one
example, the bus 160 may be coupled with an edge connector that is
a 50 pin header on a CPU circuit board included in the metering
circuitry 162 of the meter 100. The bus 160 therefore extends from
the metering circuitry 162, such as a main CPU board to the meter
housing connector 130 positioned in the first connector panel 106a
formed in the meter housing 102 of the meter 100.
[0113] In one example, the metering circuitry 162 of the meter 100
includes the base circuitry for the meter 100. The base circuitry
may be that metering circuitry needed to perform revenue and power
quality calculations. The metering circuitry 162 may include a CPU
board having programmable processors, controllers, ASIC's, logic
units, memory components gates, logic components and other devices
configured to perform power metering functions, and enable features
and functionality of the meter 100. The metering circuitry 162 may
include expansion ports or connectors (not shown) to allow
functionality of the metering circuitry 162 to be enhanced and/or
expanded. At least a portion of the metering circuitry 162, such as
a CPU board, also may be removable from the meter 100 and/or
replaceable.
[0114] FIG. 15 illustrates a perspective view from the rear of an
example of the metering options module 114, and FIG. 16 illustrates
a rear view of an example of the metering options module 114. FIG.
17 illustrates a perspective view from the front of an example of
the metering options module 114, and FIG. 18 illustrates a front
view of an example of the metering options module 114. As shown in
FIGS. 15-18, the metering options module 114 includes a module
electrical connector 170 that is configured and positioned to
engage with the meter housing electrical connector 130 on the
surface of the meter 100 when the metering options module 114 is
coupled with the meter housing 102.
[0115] The metering options module 114 is configured to provide
optional and/or enhanced features and/or functionality for the
meter 100. For example, the metering options module 114 may provide
desired features and functionality for the meter 100 beyond the
base features of the meter 100. The metering options module 114
additionally or alternatively may be designed to implement one or
more discrete features that are useable by the meter 100. As the
needs for the meter 100 change, the metering options module 114 may
be changed to update or otherwise change the functionality of the
meter 100.
[0116] FIG. 19 is an example block diagram of the functionality of
a meter 100 that includes a metering options module 114. In FIG.
19, a three phase power source 202 includes a plurality of
conductors 204. The conductors 204 may feed a load or a portion of
a power system. The rack mounted meter 100 may be coupled with the
conductors 204 to receive and measure electrical parameters of
electrical energy present in the conductors 204. A plurality of
voltage metering lines 206 may be coupled with the conductors 204
and the meter 100 to provide voltage signals indicative of the
frequency, magnitude, and phase of the voltage present on one or
more of the conductors 204. The meter 100 may also include a
plurality of current transformers (CTs) 208. Alternatively, the CTs
208 may be separated away from the meter 100. The CTs 208 may
provide current signals on a plurality of current lines 210. The
current signals may be indicative of the magnitude of current
flowing in the one or more of the conductors 204.
[0117] The voltage and current signals may be provided to metering
circuitry 212 included in the meter 100. Within the metering
circuitry 212, the voltage and current signals may each be fed to a
filter 214. The filter 214 may reduce noise, transients, harmonics
and any other undesirable signal content that may be present on the
voltage lines 206 and the current lines 208. In one example, the
filters 214 may be low pass filters. In another example, the
filters 214 may be unnecessary, and may be omitted. The filtered or
unfiltered voltage and current signals may be modified by adjusting
the magnitude and/or format with a respective voltage
transducer/amplifier 216 and a current transducer/amplifier 218. In
another example, the filtered or unfiltered current and voltage
signals may be used directly without modification and the voltage
transducer/amplifier and/or the current transducer/amplifier 218
may be omitted. The filtered and modified voltage and current
signals may be converted from analog to digital signals with an
analog to digital converter 220, and provided to a processor
224.
[0118] The processor 224 may include a digital signal processor
(DSP) 226, a field programmable gate array (FPGA) 228, and a
central processing unit (CPU) 230. In other examples, one or more,
or any combination of the DSP 226, the FPGA 228 and the CPU 230 may
be used to form the processor 224. The processor 224 may direct the
operation of the meter 100. In addition, the processor 224 may
process the electrical parameters measured from the conductors 204.
A memory 234 may include a DSP memory 236 and a CPU memory 238. The
memory 234 may include volatile and/or non-volatile memory. The
memory 234 may store instructions executable by the processor 224.
In addition the memory may store power parameters, both measured
and calculated by the processor 224, user profiles, passwords,
configurations, and/or any other data related to meter and power
quality functionality.
[0119] The metering circuitry 212 may also include a line frequency
measurement module 242, a power supply 244 and a user interface
246. The line frequency measurement module 242 may be coupled with
the voltage transducer/amplifier 216 and the processor 224. Based
on the filtered and modified voltage signal, the line frequency
measurement module 242 may generate a line frequency signal
representative of the voltage present in the conductors 204. The
line frequency signal may be provided to the processor 224. The
power supply 244 may be powered by the conductors 204, an auxiliary
supply of power, and/or a back up supply of power. The power supply
244 may produce one or more voltages to power the metering
circuitry 212. In addition, the power supply 244 may supply power
to the metering options module 114. The user interface 246 may
include a display 248 and a key pad 250. In other examples, the
user interface 246 may include any other device and/or mechanism
that provides a man machine interface to the meter 100 and/or other
devices in communication with the meter 100.
[0120] The metering circuitry 212 may also include a printed
circuit board connection 252. The printed circuit board connection
252 may provide an interface to the rack electrical connectors 128
as previously discussed, and be coupled with the processor 224. In
another example, the printed circuit board connection 252 may be
external to the metering circuitry 212.
[0121] The removable metering options module 114 may also be
coupled with the metering circuitry 212. As previously discussed,
the metering options module 114 may include an electrical connector
170 (FIG. 18) that is positioned to engage an electrical connector
on a surface of the metering housing. The metering options module
114 may change the functionality of the metering circuitry 212
and/or the processor 224. In FIG. 19, the metering options module
114 includes one or more of an input/output module 260, a
communications module 262, a protective relay module 264, and an
access key module 266.
[0122] The input/output module 260 may provide the capability to
add additional inputs and/or outputs to the meter 100. Accordingly,
the metering options module 114 may be configured to include
circuitry and other hardware needed to provide such additional
functionality.
[0123] The metering options module 114 may also include a power
supply backup functionality. For example, the metering options
module 114 may include a battery or other energy storage device
that is a backup power supply. The backup power supply may be
configured to supply power to the metering options module 114. In
addition, the backup power supply may be configured to supply power
to the meter 100. In the event of loss of power to the meter 100,
the backup power supply included in the metering options module 114
may be automatically activated, switched, or otherwise enabled to
provide a supply of power to the meter 100 and the metering options
module 114. The backup power supply may power the entire meter 100
and metering options module 114 when enabled to supply power.
[0124] Alternatively, the backup power supply may power only some
of the functionality of the meter 100 or metering options module
114. For example, the backup power supply may provide power to only
the processor 224 to allow communication of a loss of power alarm,
or to only that portion of the metering circuitry 212 that will
enable continued collection and storage of measured data. Any form
of partial powering scheme that prolongs the life of the energy
storage device included in the backup power supply may be employed
to maintain a desired functionality of the meter 100 and/or
metering options module 114 upon loss of the main power source.
[0125] Alternatively, or in addition, the backup power supply may
include monitoring capability of the energy storage device included
with the backup power supply. The meter 100 and/or metering options
module 114 may include the capability to sequentially power down
predetermined and/or pre-selected functionality within the meter
100 and/or the metering options module 114 at predetermined stages,
or thresholds, of depletion of the energy storage device.
[0126] The backup power supply may be accessible from outside the
metering options module 114 to allow replacement and/or testing of
the backup power supply, as well as replacement and/or testing of
the energy storage device included therewith. Replacement and/or
testing of the backup power supply may be accomplished without
disturbing any tamperproof seals included on the metering options
module 114 and/or the meter 100.
[0127] FIG. 20 is a block diagram illustrating the functionality of
an example input/output module 260 that includes a signal
processing module 302, a logic device 304, and an option key 306.
In other examples, additional or less hardware, modules and/or
functionality may be included in the input/output module 260. The
signal processing module 302 may provide digital and/or analog
signal processing capability, which may include filtering,
analog-to-digital conversion, signal isolation, signal conversion,
etc.
[0128] In the illustrated example, a digital input/output module
310, and an analog input/output module 312 are illustrated to
represent processing, receipt and/or transmission of any form of
digital and/or analog signals, such as pulse signals, 4-20 ma
signals, 1-5 volt signals, and/or any other form of digital or
analog signal. The digital input/output module 310 and the analog
input/output module 312 may be coupled with the I/O ports 150. The
I/O ports 150 may include connectors, terminals strips and/or any
other form of coupling mechanism capable of providing a signal
interface to devices external to the metering options module 114.
The digital input/output module 310 and the analog input/output
module 312 also may be coupled with the logic device 304.
[0129] The logic device 304 may be any mechanism or device capable
of providing an interface between the digital input/output module
310 and the analog input/output module 312 and the metering
circuitry 212 (FIG. 19). In one example, the logic device 304 is a
programmable logic device that is programmed to operate as a
multiplexer. In other examples, the logic device may be a buffer, a
UART, etc. The logic device 304 may be configured to communicate
I/O signals between the digital input/output module 310 or the
analog input/output module 312 and the electrical connector 170
mounted on a surface of the metering options module.
[0130] The option key 306 also may be coupled with the electrical
connector 170. The option key 306 may be in communication with the
processor 224 (FIG. 19) via the electrical connector 170. The
option key 306 may identify to the processor 224 that the metering
options module includes the I/O functionality. Thus, when the
metering options module is coupled with the electrical connector
130 (FIG. 5) on the meter housing 102 (FIG. 1), the processor is
able to determine what functionality has been added/changed. In one
example, the option key 306 may include a plurality of option
resistors which are configured to identify the additional
functionality added by the metering options module. In other
examples, a memory, a dip switch, or any other mechanism or device
may be used to identify the metering options module to the
processor. The option key may also define the I/O ports 150, ranges
of the I/O signals present on the I/O ports 150, and/or provide any
other information related to the processor 224 (FIG. 19)
cooperatively operating with the metering options module.
[0131] The electrical connector 170 may also provide one or more
supply voltages 314. The supply voltages 314 may be provided from
the power supply 244 (FIG. 19) included in the metering circuitry
212 (FIG. 19) to power devices, providing wetting voltages, etc. In
addition, the supply voltage 314 may provide power to a backup
power supply 316 included in the metering options module when the
power supply 244 (FIG. 19) is being powered. The backup power
supply 316 may include an energy storage device, such as a battery,
that is maintained in a fully charged state by the supply voltage
314. The backup power supply may include a voltage sensing device
to sense the voltage levels and quality of the supply voltage 314.
Upon loss of power to the supply voltage 314, or degradation of the
quality of power supplied to the supply voltage 316 below a
predetermined level, the backup power supply 316 may be enabled to
supply backup power to the meter 100 and the metering options
module 114. As previously discuss, the backup power supply may
energize all or portions of the meter 100 and/or the metering
options module 114.
[0132] The electrical connector 170 may also be coupled with the
digital input/output module 310 and/or the analog input/output
module 312 via one or more dedicated signal lines 318. The
dedicated signals line(s) 318 may also couple the digital
input/output module 310 and/or the analog input/output module 312
to the I/O ports 150. The dedicated signal line(s) 318 may transmit
signals directly between the I/O ports 150, the digital
input/output module 310 and/or the analog input/output module 312,
and the metering circuitry 212 (FIG. 19) without processing the
signals in the respective digital input/output module 310 and the
analog input/output module 312 or through the logic device 304.
[0133] For example, the digital input/output module 310 may
selectively operate in three modes to process one or more input
signals on one or more respective channels. The three modes may be
operated simultaneously, and/or in any combination within the
digital input/output module 310. A first mode may be a pulse mode,
and a second mode may be a KYZ mode. In the first and second modes
the digital input/output module 310 may operate to detect a DC
level of a signal being received as an input. The input signal may
be digitized by the digital input/output module 310, and then
further processing within the digital input/output module 310 may
occur based on the DC levels that were sampled.
[0134] A third mode may be an "AC" mode in which time varying input
signals are received and processed. In the third mode, the digital
input/output module 310 may operate to provide received AC input
signal(s) to the metering circuitry 212 (FIG. 19). The metering
circuitry 212 may rectify the AC input signal(s) and then digitize
the input signal(s) for further processing. The signal(s) may be
further processed with the metering circuitry 212 based on the
sampling frequency applied during digitization. If an input signal
is within a predetermined frequency range on a given channel, the
status of that channel may be indicated as "ACTIVE" by the metering
circuitry 212.
[0135] The AC input signals may be provided from the I/O ports 150
on the dedicated signal line(s) 318 to pass through the digital
input/output module 310 without processing to the metering
circuitry 212. The AC input signals may be rectified, digitized,
and further processed using code, such as firmware stored in memory
234 (FIG. 19). The firmware may be executable by the processor 224
(FIG. 19) included in the metering circuitry 212. For example, a
sine wave input signal may be rectified, and a peak of each half
cycle may be detected during sampling. In one example, AC input
signals passed through the digital input/output module 310 may be
timestamped with a high accuracy timestamp similar to other DC
digital inputs, before being passed to the metering circuitry 212
to be processed. Because the timestamp can be implemented in the
digital input/output module 310, and the processing of the AC input
signal may occur with firmware in the metering circuitry, both DC
and AC digital inputs may be processed using the same hardware,
namely, the digital input/output module 310. In addition, since the
AC input signals are processed with firmware in the metering
circuitry 212, processing of the AC input signals may be flexibly
selected and varied by updating and/or changing the configuration
of the code included in the firmware.
[0136] Implementation of the third mode (AC input detection) by the
metering circuitry 212 (FIG. 19) may occur in firmware to also
allow AC input detection functionality to be enabled without
compromising the speed at which the digital input/output module 310
can detect signals in the first ("Pulse") mode or the second
("KYZ") mode. Alternatively, the AC input signals may be processed
within the digital input/output module 310. However, implementation
of processing of the AC input signals in the digital input/output
module 310, may use an RC-filter to convert the AC waveform into a
DC signal that can be read by the metering circuitry 212, which may
limit the pulse rate that can be resolved in first ("Pulse") mode
and/or the second ("KYZ") mode.
[0137] Firmware implementation of the AC input processing in the
third mode may also allow flexibility in adjusting a frequency
range to be sensed by the metering circuitry 212 by simply changing
the code within the firmware. In one example, the frequency range
of sensing may be set to a predetermined range of about 5 Hz to
about 210 Hz. Adjustment of the frequency range may be implemented
with a firmware upgrade, or the frequency may be a user selectable
parameter when the meter 100 is operational in the field.
Alternatively, if AC input processing occurs with hardware within
the digital input/output module 310, a low-end frequency limit may
be set.
[0138] The communications module 262 may provide
expanded/additional functionality related to communication with
other devices external to the meter 100. FIG. 21 is a block diagram
illustrating the functionality of an example communications module
262 that includes a communication interface module 402 and an
option key module 404. The example communication interface module
402 includes a first interface that is a first serial interface,
such as an RS232/RS485 interface 406, a second interface that is a
second serial interface, such as a RS485 interface 408, a third
interface that is a modem interface 410, and fourth interface that
is a network interface 412. In other examples, fewer or additional
interfaces, such as proprietary interfaces, may be included in the
communication interface module 402.
[0139] The first and second serial interfaces 402 and 404 may each
include an RS 485 communication interface. The modem interface 406
may be any communications device that converts a signal from one
form to another form that is suitable for transmission over
communication circuits, such as, from digital to analog and then
from analog to digital signals. The modem interface 406 may be a
wired or a wireless device that uses an antenna 314. The antenna
314 may be included in the communications module 262, or may be
externally coupled with the metering options module 114 via the I/O
ports 150. The network interface 412 may be a wired or wireless
interface to any form of LAN, WAN, etc. form of network. For
wireless communication, the network interface 412 may use the
antenna 414. The network interface 412 may include Ethernet
communications, GPS time sync communication capabilities, wireless
devices communications (e.g., 802.11 and the like), wireless mesh
networks, Zigbee, Wi-Fi, and/or any other network communication
standard and/or protocol. The Ethernet communications may be 10
BaseT Ethernet, 10 BaseFL Ethernet and/or any other Ethernet
protocol. In addition, the network interface 412 may support
proprietary protocols.
[0140] Each of the interfaces 406-412 may establish independent or
separate communications with a device external to the meter 100.
Thus, the metering options module may enable multiple instances of
communications with the meter 100. The I/O ports 150 may be
internally coupled directly or indirectly through electrical,
electronic and/or optical components and/or hardware, software, and
firmware components included in the communication interface module
402 to the electrical connector 170. As previously described, the
electrical connector 170 may be coupled to the meter housing
electrical connector 130 on the meter 100 when the metering options
module 114 is installed on the meter 100. Accordingly, the metering
circuitry 212 (FIG. 19) may be enabled to communicate with external
devices through the I/O ports 150 when the metering options module
is installed on the meter 100.
[0141] Within the communication module 262, the I/O ports 150 may
be communication ports that include optical communications ports
(ST) that enable coupling and external communication using optical
fiber, RJ11 (such as for modem communication) and RJ45 jacks (such
as for Ethernet communication), Phoenix connectors (such as for
RS485 communication), DB9 connectors (such as for RS232
communication), RCA jacks, and/or any other type of communication
connector hardware. The electronic and/or optical components of the
interface module 402 coupled with the I/O ports 150 may include,
switches, gates, processor, CPU's, application specific integrated
circuits (ASIC's), controllers, diodes, capacitors, inductors,
resistors, bridges and other electronic and electrical devices used
in communications circuits.
[0142] Referring to FIGS. 19 and 21, the metering circuitry 212
also may be configured to assign a communications protocol to an
I/O port 150 in the metering options module 114 independent of the
type of hardware connector included with the port, and independent
of the communications protocol assigned to other communications
ports 150. For example, the meter 100 may be configured to have
first and second I/O ports 150 included in the metering options
module 114 assigned to communicate with other devices. Each of the
first and second I/O ports 150 may communicate independently of the
other, and each may use a device language message specification
(DLMS) protocol. In another example, each I/O port 150 may be
assigned a different communications protocol. For example, a first
communication port may be assigned to communicate with other
devices using DLMS, a second communication port may be assigned to
communicate using Modbus.RTM. and a third communication port may be
assigned to communicate with a device using ION.RTM. communications
protocol.
[0143] The communications protocol may be assigned to a
communication port, or a communication port may be assigned to a
communications protocol. Assignment may be performed by selecting
an appropriate setting(s) on the options menu presented on the
display 118, by factory settings, and/or by a controller in
communication with the meter 100. An I/O port 150 also may be
configured to communicate using two or more communications
protocols substantially simultaneously. That is, for example, two
communication protocols may co-exist at the same communication port
150. The communications protocols for the communication ports 150
may be changed, modified, updated and/or reprogrammed.
[0144] The communication capabilities available to the metering
circuitry 212 included in the meter 100 from the metering options
module 114 may be almost unlimited. The metering options module 114
may be configured to provide an Ethernet communications for the
rack-mounted meter 100. The Ethernet communications may include 10
BaseT and/or 10 BaseFL. The rack mounted meter 100 may also be
configured to communicate over an open, distributed communications
network with a web server or other devices on the network. The
meter 100, using the communications module 262, also may be
configured to provide web server functions or functionality to
serve other devices on the network. The communication module 262
may also provide for communication functionality using optical
fiber, multiple serial ports and/or any combination thereof. Any
combination of hardware related to communications is possible
within the communication module 262. The communication module 262
also may be configured to provide a SCADA polling system.
[0145] The interface module 402 may be coupled with the metering
circuitry 212 via the electrical connector 170. Alternatively, or
in addition, the interface module 402 may wirelessly communicate
with the metering circuitry 212. The power supply 244 may provide
power to a supply voltage 420 via the electrical connector 170. The
supply voltage 420 may provide power to the interface module 402,
the I/O ports 150 and/or any other power consuming device in the
communication module 262. In addition, the supply voltage 420 may
supply power to a backup power supply 422 included in the metering
options module 114. The backup power supply 422 may supply power to
the meter 100 and/or the metering options module 114 in the event
of degradation and/or loss of supply voltage 420, as similarly
discussed with reference to the backup power supply 316 of FIG. 20.
The option key 404 may provide an indication to the metering
circuitry 212 that the communication module 262 is present. In
addition, the option key 404 may define the signals to be expected
on the I/O ports 150.
[0146] The protective relay module 264 may be any form of hardware,
circuitry, software and/or firmware capable of providing protection
for at least a portion of the meter 100. For example, the
protective relay module 264 may provide fusing or other circuit
interrupting capability for at least portions of the meter 100. One
or more analog signals may be routed through the protective relay
module 264 to protect the meter 100. Since the metering options
module is readily removable, without disturbing any tamper-proof
seals on the meter 100, the protective relay module 264 may be
readily replaced if an event causes the protective relay
functionality, such as a fuse functionality, to occur.
[0147] In addition, or alternatively, the protective relay module
264 may include power quality event tracking capability. For
example, the protective relay module 264 may be equipped with
functionality that interrupts potentially damaging signals from
reaching the metering circuitry 212, while continuing to record the
event and/or disturbance that created the signals. In this
scenario, the protective relay module 264 may include more robust
circuitry and hardware capable of withstanding such an event
without damage. Alternatively, the protective relay module 264 may
include functionality to capture events from start to finish that
otherwise interrupt the receipt and processing of electrical
parameters by the metering circuitry 212, such as when an event
causes damage to the metering circuitry 212. Signals with potential
for such events may be routed through the protective relay module
264, or be provided as a parallel feed to the protective relay
module 264.
[0148] The access key module 266 may enable additional
functionality already present in the metering circuitry 212 by
providing some form of authorization. The authorization may be
hardware and/or software based. Enabling functionality may include
for example, additional power parameter processing or power quality
analysis functionality. Other examples include increased sample
rates, improved hardware functionality, enhanced user interface,
such as additional buttons and/or controls, improved/expanded
graphics capability, and/or any other operational functionality
within a meter 100 that is determined to be an optional
feature.
[0149] FIG. 22 is a block diagram of an example access key module
266 that includes a hardware authorization 502 and a software
authorization 504. The access key module 266 may also include a
supply voltage 518 being supplied power from the power supply 244
(FIG. 19) via the electrical connector 170. The supply voltage 518
may provide power to the access key module 266 and/or the metering
options module 114. In addition, the supply voltage 518 may supply
power to a backup power supply 520 included in the metering options
module 114. The backup power supply 520 may supply power to the
meter 100 and/or the metering options module 114 in the event of
degradation or loss of the supply power 518, similar to the backup
power supply 316 discussed with reference to FIG. 20.
[0150] The hardware authorization 502 may represent a first layer
of authorization that includes an option key 508, and an access key
code 510. The option key 508 may be coupled with the metering
circuitry 212 via the electrical connector 170 to indicate that the
access key module 266 is present. In addition, the option key 508
may provide configuration information, authorization functionality
in the access key module 266 to be verified, or any other
information related to authorization of the additional
functionality. The access key module 266 may be dip switches,
resistors, and/or any other hardware based keying
functionality.
[0151] The software authorization 504 may represent a second layer
of authorization that can include a communication circuitry 512, a
processor 514 and a memory 516. The communication circuitry 512 may
be a UART, a buffer or any other device or mechanism for enabling
communication between the processor 514 and the metering circuitry
212 (FIG. 19). In another example, direct communication between the
processor 514 and the metering circuitry 212 (FIG. 19) may be
possible, and the communication circuitry 512 may be omitted. The
processor 514 may direct communication with the metering circuitry
212 and also access to the memory 516. The processor 514 may
include firmware that contains an access key code that is provided
to the metering circuitry 212 upon installation of the metering
option module. The access key code may unpack, enable, and/or
otherwise turn on additional features and/or functionality in the
meter 100.
[0152] The processor 514 may also have the capability to track and
maintain a database of meters 100 upon which the access key module
266 has been installed to activate additional functionality. For
example, the processor 514 may provide a predetermined number of
functionality activations, and function as a counter to track the
number of activations by storing them in the memory 516.
Alternatively, or in addition, the processor 514 may perform
verification that the previously non-activated portion of the
software of the metering circuitry 212 is an up to date version and
update accordingly. The memory 516 may also include upgrade
software that is downloadable to the metering circuitry 212 by the
processor 514 to upgrade the base functionality of the meter 100.
In other examples, either the hardware authorization 502 or the
software authorization 504 may be separately implemented in a stand
alone capacity to provide authorization and verification of the
mounting and use of the metering options module 114 on the meter
100.
[0153] In another example, the memory 516 may include software to
affect the changed functionality of the metering circuitry 212.
Thus, when the metering options module 414 is installed, the
processor 514 may download the software into the metering circuitry
212. In still other examples, the memory 516 could include patches,
fixes and revisions to the existing base functionality included in
the metering circuitry 212. The revisions could be downloaded by
the processor 514 when the metering options module is installed.
Alternatively, the revisions/updates/improvements could be
maintained in the memory 516 and executed by the metering circuitry
directly from the memory 516.
[0154] The functionality of the previously described modules
260-266, as well as any other functionality, may be mixed or
otherwise combined in the metering options module 414. In addition,
the metering options module 414 may provide standalone
functionality, such as monitoring the operation of the metering
circuitry 212 and providing an indication when an error or fault
occurs within the metering circuitry 212.
[0155] Referring again to FIGS. 15-18, the electrical connector 170
on a surface of the metering options module 114 may engage with the
connector 130 on a surface of the meter house 102 to change the
operational functionality, such as the I/O functionality and/or the
communications functionality, of the meter 100. A housing 182 of
the metering options module 114 may be a substantially rectangular
box, or rectangular parallelepiped that is dimensioned to fit
within the shelf dimensions or dimensional envelop of the meter
100, and/or allow the meter 100 to fit within a bay of an equipment
rack when the metering options module 114 is coupled thereto.
[0156] The metering options module 114 may include one or more
flanges 184. The flange 184 may be fixedly coupled and/or form a
part of the housing 182. In the example metering option module 114
illustrated in FIGS. 14-18, the housing 182 includes a first
surface 186 and a second surface 188 that is opposite the first
surface 186. The first surface 186 may be positioned to be
substantially flush with the first portion 108a of the two tiered
surface 108 (FIG. 1) when the metering options module 114 is
coupled with the meter 100. The second surface 188 may be
contiguous with the second portion 108b of the two-tiered surface
108 (FIG. 1) when the metering options module 114 is coupled with
the meter 100.
[0157] The flange 184 may be positioned substantially parallel with
the second surface 188, and substantially perpendicular with the
second connector panel 106b (FIG. 4) of the meter housing 102. The
flange 184 may be formed to include at least one aperture 190. The
apertures 190 may be aligned with the fastener 117 on the meter
housing 102 (FIG. 2) when the metering option module 114 is mounted
on the meter house 102. The flange 184 may also include one or more
tabs 124. The tab(s) 124 may be formed to be substantially
perpendicular to the flange 184 and substantially parallel to a
surface of the meter housing 102, such as the second connector
panel 106b (FIG. 4). Accordingly, when the metering options module
114 is installed on the surface of the metering housing 102 (FIG.
4), the tab 124 may contiguously align with a portion of the second
connector panel 106b (FIG. 4).
[0158] The tab 124 may include a coupling aperture 194. The
coupling aperture 194 may be alignable with the ground lug 126
(FIG. 4) on the meter housing 102 when the metering options module
114 is coupled with the meter housing 102. The metering options
module 114 may also include at least one alignment aperture 196.
The alignment apertures 196 may be formed to accommodate the
alignment pins 131 on the first connector panel 106a (FIG. 5) when
the metering options module 114 is coupled with the meter housing
102.
[0159] The metering options module 114 may be grounded via the
ground lug 126 as previously described. The metering options module
114 may also include a lug, a lance, a cleat, or some other feature
to be used in conjunction with a tamper-proof seal to couple the
metering options module 114 to the meter 100. The housing 182 of
the metering options module 114 may also be separately sealable
with a tamper proof seal, such as a revenue or verification seal
that is separate from the tamper proof seal, such as a verification
seal, of the meter 100.
[0160] FIG. 23 illustrates a top view of an example meter 100
mounted in a bay 171 of an equipment rack assembly 172. FIG. 24
illustrates a perspective front view of an example of the meter 100
mounted in the bay 171 of the equipment rack assembly 172. FIG. 25
illustrates a perspective rear view of an example of the meter 100
mounted in the bay 171 of the equipment rack assembly 172. In FIGS.
23-25, the equipment rack assembly 172 may be a 48.3 cm equipment
rack designed in accordance with the requirements set forth by DIN
43862. The meter 100 with the metering options module 114 affixed
thereto may fit within the dimensions of a standard 48.3 cm
equipment rack. The meter 100 may plug into a bay electrical
connector 174, such as an Essailec connector, located in a
determined position, such as at the back of the equipment rack
assembly 172. The meter 100 may be mounted to the rack assembly
172, with or without the metering options module 114.
[0161] The meter 100 may be easily or readily removed or mounted to
the equipment rack assembly 172. When inserted, the rack electrical
connector 128 on the second connector panel 106b of the meter 100
(FIG. 6) may engage the bay electrical connector 174 in the rack
assembly 172. When the connectors 128 and 174 are engaged, the
meter 100 may be powered by one of the connections, and receive
signals to allow the meter 100 to perform revenue metering as well
as power quality monitoring for an electrical circuit, such as
multi-phase high voltage power supplied over a conductor to a
dynamic load circuit.
[0162] The metering circuitry included in the meter 100 may log a
time that the meter 100 is installed in the equipment rack assembly
172, as well as a time that the meter 100 is removed from the
equipment rack assembly 172. The log may be accessed using the user
interface of the control panel 116 (FIG. 3) of the meter 100,
and/or through one of the communications ports, such as a
communication port 150 (FIG. 14) provided by the metering options
module 114. The metering circuitry may be configured to detect
whether the meter 100 is installed in the equipment rack 172 using
an analog or digital I/O connection for the meter 100. When
connection or disconnection of any of the I/O between the meter 100
and the equipment rack 172 is detected, the corresponding event may
be time stamped and stored in memory in an event log.
[0163] The metering circuitry of the meter 100 also may determine
whether removal of the meter 100 is appropriate and set an alarm or
indicator when an attempt to remove the meter 100 from the rack
assembly 172 is made when removal is inappropriate. For example,
the metering circuitry may detect that the meter 100 is being
removed, such as due to a disengagement/disconnection of the rack
connector 128 and the bay connector 174. In response to the
detection, the meter 100 may automatically set a visual and/or
audible alarm(s) indicating that disengagement/disconnection is
inappropriate. The meter 100 also may include a mechanical
interlock that actuates to latch or engage the rack assembly 172
after the meter 100 is installed in the bay 171. The interlock may
be released only when the meter 100 is in a state in which the
meter 100 may be removed, as determined by the metering circuitry
based on the I/O received by the meter 100.
[0164] In one example configuration, a secondary electrical
connector (not shown), also or alternatively, may be used on the
equipment rack assembly 172. The secondary connector may be
configured to be positioned between the bay connector 174 and the
rack electrical connector 128. Alternatively, the secondary
connector may be used in place of the bay connector 172 or the rack
electrical connector 128. The secondary connector may provide a
make-before-break functionality to short those inputs that should
be shorted, such as current transformer (CT) inputs, and open those
inputs that should be opened, such as potential transformer (PT)
inputs. Accordingly, with the secondary connector, the rack-mounted
meter 100 may be removed and installed in the bay 171 while the
conductor the meter 100 is monitoring is live or under power. The
secondary connector may operate in reverse when the meter 100 is
installed in the bay 171.
[0165] The metering circuitry of the meter 100 also may be
configured to approximate power usage during a reset of the meter
100, such as after a power failure. Since the meter 100 includes a
clock, the meter 100 may determine when the meter 100 last read
energy usage and how long the meter 100 may have been de-energized.
For example, if the meter 100 is removed from the equipment rack
172, or is otherwise de-energized or removed from service, the
meter 100 can record the event. When the meter 100 is reset and
powered back up, the metering circuitry can compare the time that
the meter 100 last measure power parameters to the present time to
calculate an amount of time that the meter 100 was powered down or
otherwise out of service. The metering circuitry can also review
power usage before it was taken out of service to interpolate or
approximate an amount of power usage while the meter 100 was out of
service. The metering circuitry may also record the approximation
of the amount of power usage, and mark or flag the event for future
review.
[0166] The configuration of the rack-mounted meter 100 with the
externally mounted metering options module 114 provides a
capability to incorporate features and functionality of the meter
100 in a separable module having its own housing. The metering
options module 114 may be field replaceable without disturbing a
tamper proof seal, such as a verification or utility seal included
on the meter 100. The replaceable metering options module 114 may
provide additional communications functionality and connections,
input/output functionality and connections, and/or any other
functionality and connections for the meter 100. Communications
connectors and/or input/output connectors may be directly included
on the housing of the metering options module 114, rather than on
the connector panel of the meter 100. As communications or other
input/output needs change, the metering options module 114 may be
changed or replaced accordingly, without requiring modification to
the meter 100 and/or disturbance of the tamper proof seals.
[0167] The metering options module 114 that is removably installed
flush with the first portion 108a of the two-tiered surface 108 of
the meter 100 enables changing of the functionality of the meter
100 without disturbing the seal on the meter 100. The metering
options module 114 may be mounted outside the meter housing 102 and
may be changed without having to modify or open the meter 100.
Without the metering options module 114, a field retrofit of the
communication or input/output connectors may not be possible,
especially if tamper-proof seals were disturbed. Therefore, a meter
configuration having a separable metering options module 114 offers
great flexibility in providing various alternatives in future
designs, without requiring a redesign or complicated retrofitting
of the meter 100. The metering options module 114 may be used to
expand operation of the meter for options other than communication
or input/outputs. For example, the metering options module 114 may
be changed out to change or provide additional calculated power
parameters, perform additional power quality monitoring, etc.
[0168] When racked into the bay 171 of the equipment rack assembly
172, the rack-mounted meter 100 may receive power for operating as
well as signals corresponding to electrical parameters of one or
more conductors feeding a circuit or load that is to be monitored.
In one example, the metering circuitry included in the rack-mounted
meter 100 may be configured to measure and/or approximate a voltage
that may appear on a grounded line by a comparison of reference
voltage V.sub.ref that is connected to a neutral line of the
circuit or load being monitored with an internal dc voltage.
Ordinarily the reference voltage V.sub.ref should be OV. However,
the reference voltage V.sub.ref may vary in different places in a
building. The reference voltage V.sub.ref may vary with current and
resistance in the neutral line. The reference voltage V.sub.ref can
also indicate 3.sup.rd harmonics, power surges, problems with the
power system, possible wiring problems, and the like. In one
example, a ground voltage V.sub.G may be calculated, by comparing
the reference voltage V.sub.ref to an internal dc reference voltage
V.sub.bias that is referenced to earth ground. The internal dc
reference voltage V.sub.bias may be supplied by a constant voltage
supply. Fluctuations in the ground voltage to neutral may be
determined from V.sub.bias. An existing spare or unused op-amp
included in the metering circuitry of the meter 100 can be biased
with a resistor circuit to provide the reference voltage V.sub.ref
at an output based on the comparison to the V.sub.bias voltage.
Using the spare op-amp utilizes existing circuitry and reduces a
number of terminals or inputs to the meter.
[0169] The input signals provided to the rack-mounted meter 100 may
be scaled based on the strength of the signal. The signals from the
equipment rack assembly 172 often vary over a wide range of
voltages. The metering circuitry included in the meter 100 may
detect the strength of the input signal(s) and process the signals
through a multi-gain stage circuit before the signals are further
processed. The metering circuitry included in the meter 100 may be
configured to monitor the amplitude of an input signal. Based on
the amplitude, the metering circuitry may adjust the gain of the
input signal to provide an input signal for the meter 100 having an
appropriate signal to noise ratio. The metering circuitry may
select an appropriate scaling based on the amplitude of the input
signal. Accordingly, the meter 100 may be used over a wide dynamic
range of input signals.
[0170] When the signals are received, the metering circuitry may
sample the signal to provide a sampled or digital equivalent signal
representing the analog signal. The signals may be sampled at a
sampling frequency that is determined based on the analog frequency
of the input signal. That is, the rack-mounted meter 100 has a
sampling clock that may be adjusted according to the frequency of
the power system being monitored.
[0171] The sampled signal is processed using metering circuitry
that includes a controller, a logic unit, a processor, an ASIC
and/or combinations thereof configured to determine electrical
parameters of the circuit based on the sampled signals. The sampled
signals may be processed according to Fast Fourier Data Processing
techniques. The use of Fourier transforms to process the signals
solves issues of high computational intensity due to continuous
harmonic analysis on the sampled input signals. The input signals
may be continuously sampled and averaged with the metering
circuitry. The averaged signals may be converted or transformed to
the Frequency domain with the metering circuitry. A frequency
average may be determined by averaging in the time domain and
transforming the average once. The Fast Fourier data processing
technique translates/manipulates the data to Radix 2 numbers to
process the data using Fourier transforms.
[0172] The meter 100 may display compliance of a monitored
conductor to multiple power quality standards. The compliance may
be displayed on the screen 118, and updated as service complies or
fails to comply with a power quality standard. Examples of a power
quality standard to which compliance may be displayed include
EN5160, EEC 61000-4-30. The compliance display may be updated in
real time.
[0173] Various embodiments of a rack-mounted power meter having an
externally mounted removable metering options module have been
described and illustrated. However, the description and
illustrations are by way of example only. Many more embodiments and
implementations are possible within the scope of this invention and
will be apparent to those of ordinary skill in the art. The various
embodiments are not limited to the described environments, and can
be applied to a wide variety of activities.
[0174] It is intended in the appended claims to cover all such
changes and modifications which fall within the true spirit and
scope of the invention. Therefore, the invention is not limited to
the specific details, representative embodiments, and illustrated
examples in this description. Accordingly, the invention is not to
be restricted except as necessitated by the accompanying claims and
their equivalents.
* * * * *