U.S. patent application number 13/648924 was filed with the patent office on 2013-02-07 for telecom shelter cooling and control system.
This patent application is currently assigned to MINEBEA CO., LTD.. The applicant listed for this patent is Minebea Co., Ltd., Schroff Technologies International, Inc.. Invention is credited to Henry Riddoch, David Therrien.
Application Number | 20130035031 13/648924 |
Document ID | / |
Family ID | 41445998 |
Filed Date | 2013-02-07 |
United States Patent
Application |
20130035031 |
Kind Code |
A1 |
Therrien; David ; et
al. |
February 7, 2013 |
Telecom Shelter Cooling and Control System
Abstract
A system configured to provide cooling of electronic equipment
in a shelter in combination with an air conditioning (A/C) system.
The system includes one or more blowers for drawing air into the
shelter, a damper arrangement for controlling air exhaust. The
system further includes a DC powered controller coupled to the one
or more blowers, the damper arrangement, and the A/C system. The
controller is configured to receive at least a first analog input
signal associated with a shelter-interior temperature, a second
analog input signal associated with a shelter-exterior temperature,
and a plurality of alarm input signals and to generate the one or
more first control signals to control blower rotational speed, the
second control signal to open/close the damper arrangement, and a
third control signal to inhibit/activate the A/C system based on at
least the first analog input signal, or the second analog input
signal, or a plurality of alarm input signals, or a combination of
these.
Inventors: |
Therrien; David; (North
Kingstown, RI) ; Riddoch; Henry; (Inverurie,
GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Schroff Technologies International, Inc.;
Minebea Co., Ltd.; |
North Kingstown
Nagano |
RI |
US
JP |
|
|
Assignee: |
MINEBEA CO., LTD.
Nagano
RI
SCHROFF TECHNOLOGIES INTERNATIONAL, INC.
North Kingstown
|
Family ID: |
41445998 |
Appl. No.: |
13/648924 |
Filed: |
October 10, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12146409 |
Jun 25, 2008 |
8313038 |
|
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13648924 |
|
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Current U.S.
Class: |
454/257 ;
165/11.1; 236/49.3; 417/14; 454/184; 454/258 |
Current CPC
Class: |
E04H 1/1238 20130101;
H05K 7/207 20130101; F24F 11/0001 20130101; H05K 7/2059
20130101 |
Class at
Publication: |
454/257 ;
165/11.1; 454/258; 454/184; 236/49.3; 417/14 |
International
Class: |
F24F 11/04 20060101
F24F011/04; F04B 49/00 20060101 F04B049/00; H05K 5/00 20060101
H05K005/00; H05K 7/20 20060101 H05K007/20; F24F 7/007 20060101
F24F007/007 |
Claims
1-33. (canceled)
34. A method for providing alternative cooling in addition to an
air conditioning (A/C) system in a cabinet housing electrical
equipment, the method comprising: providing a cooling system to the
cabinet, the cooling system including: a blower subsystem including
one or more blowers for drawing air into the cabinet; a damper
subsystem including a louver arrangement for controlling air
exhaust; and a controller operated from a DC supply, the controller
including a microprocessor having at least a first analog input, a
second analog input, a plurality of alarm inputs, one or more first
control outputs, a second control output, and a third control
output; activating the controller by providing power from the DC
supply; receiving information associated with an interior
temperature from the first analog input and information associated
with an exterior temperature from the second analog input;
monitoring for signals associated with a general alarm and a
plurality of specific alarms received through the plurality alarm
inputs; processing the information associated with the exterior
temperature and information associated with one of the general
alarm or any of the plurality of specific alarms; if the exterior
temperature is lower than a predetermined value, or no general
alarm or one of the plurality of specific alarms is triggered, then
processing information associated with the interior temperature; if
a first criterion based on information associated with the interior
temperature is satisfied, then: inhibiting the A/C system through
the third control output; operating each of the one or more
blowers, respectively through the one or more first control
outputs, at a rotation speed depending on the information
associated with the interior temperature; and closing or opening
the louver arrangement through the second control output when the
rotation speed respectively is or is not zero; if a second
criterion based on information associated with the interior
temperature is satisfied, then: activating the A/C system in
cooling mode through the third control output; and stopping the one
or more blowers through the one or more first control outputs; and
if a third criterion based on information associated with the
interior temperature is satisfied, then: activating the A/C system
in heating mode through the third control output; and stopping the
one or more blowers through the one or more first control
outputs.
35. The method of claim 34 wherein the first criterion is satisfied
when the interior temperature is between a first temperature and a
second temperature, the second temperature being higher than the
first temperature.
36. The method of claim 35 wherein operating each of the one or
more blowers further comprises adjusting the rotation speed from a
first speed to a second speed as the interior temperature is
increased from the first temperature to a second temperature plus a
predetermined amount, the second speed being greater than the first
speed.
37. The method of claim 34 wherein the second criterion is
satisfied when the interior temperature is greater than the second
temperature.
38. The method of claim 34 wherein the second criterion is
satisfied when the interior temperature is greater than the second
temperature and the exterior temperature is less than the
predetermined value.
39. The method of claim 34 wherein the third criterion is satisfied
when the interior temperature is less than the first
temperature.
40. The method of claim 34 further comprising: if the exterior
temperature is less than the predetermined value, then: activating
the A/C system through the third control output; and stopping the
one or more blowers through the one or more first control
outputs.
41. The method of claim 34 further comprising: if one of the
plurality of specific alarms is triggered due to a smoke alarm,
then: stopping the one or more blowers through the one or more
first control outputs; and closing the louver arrangement through
the second control output.
42. The method of claim 34 further comprising: if one of the
plurality of specific alarms is triggered due to a hydrogen alarm,
then: turning on the one or more blowers at a predetermined
rotational speed; and opening the louver arrangement.
43. The method of claim 34 further comprising: if one of the
plurality of specific alarms is triggered due to an AC power
failure, then: operating the one or more blowers at an on state
until DC power from the DC supply is off; opening the louver
arrangement; and closing the louver arrangement by a spring return
in the absence of DC power.
44. The method of claim 34 further comprising: if the general alarm
is triggered but no AC power fail alarm is received, then:
activating the A/C system through the second control output, and
stopping the one or more blowers.
45. The method of claim 44 wherein the general alarm comprises: a
blower fail alarm if a rotation speed of any blower drops below a
predetermined speed level of other blowers; a thermistor fail alarm
if the thermistor linked to either the first analog input or the
second analog input is open/short circuited; and a DC supply fault
alarm if voltage drops below a predetermined level.
46. A cabinet for housing electrical equipment comprising: an air
conditioning (A/C) system; an alternative cooling system
comprising: a blower subsystem including one or more blowers for
drawing air into the cabinet; a damper subsystem including a louver
arrangement for controlling air exhaust; and a controller operated
from a DC supply, the controller including a microprocessor having
at least a first analog input, a second analog input, a plurality
of alarm inputs, one or more first control outputs, a second
control output, and a third control output; wherein the controller
is operative to: receive information associated with an interior
temperature from the first analog input and information associated
with an exterior temperature from the second analog input; monitor
for signals associated with a general alarm and a plurality of
specific alarms received through the plurality alarm inputs;
process the information associated with the exterior temperature
and information associated with one of the general alarm or any of
the plurality of specific alarms; if the exterior temperature is
lower than a predetermined value, or no general alarm or one of the
plurality of specific alarms is triggered, then process information
associated with the interior temperature; if a first criterion
based on information associated with the interior temperature is
satisfied, then: inhibit the A/C system through the third control
output; operate each of the one or more blowers, respectively
through the one or more first control outputs, at a rotation speed
depending on the information associated with the interior
temperature; and close or open the louver arrangement through the
second control output when the rotation speed respectively is or is
not zero; if a second criterion based on information associated
with the interior temperature is satisfied, then: activate the A/C
system in cooling mode through the third control output; and stop
the one or more blowers through the one or more first control
outputs; and if a third criterion based on information associated
with the interior temperature is satisfied, then: activate the A/C
system in heating mode through the third control output; and stop
the one or more blowers through the one or more first control
outputs.
47. The cabinet of claim 46 wherein the first criterion is
satisfied when the interior temperature is between a first
temperature and a second temperature, the second temperature being
higher than the first temperature.
48. The cabinet of claim 46 wherein the second criterion is
satisfied when the interior temperature is greater than the second
temperature.
49. The cabinet of claim 46 wherein the second criterion is
satisfied when the interior temperature is greater than the second
temperature and the exterior temperature is less than the
predetermined value.
50. The cabinet of claim 46 wherein the third criterion is
satisfied when the interior temperature is less than the first
temperature.
51. The cabinet of claim 46 wherein when the exterior temperature
is less than the predetermined value, then the controller:
activates the A/C system through the third control output; and
stops the one or more blowers through the one or more first control
outputs.
52. The cabinet of claim 46 wherein when one of the plurality of
specific alarms is triggered due to a smoke alarm, then the
controller: stops the one or more blowers through the one or more
first control outputs; and closes the louver arrangement through
the second control output.
53. The cabinet of claim 46 wherein when one of the plurality of
specific alarms is triggered due to a hydrogen alarm, then the
controller: turns on the one or more blowers at a predetermined
rotational speed; and opens the louver arrangement.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates generally to system cooling
techniques. In particular, embodiments of the present invention
provide a method and system for providing an alternate cooling to
an outdoor shelter housing electrical equipment. Merely by way of
example, the invention has been applied to telecommunications
shelters, but it would be recognized that the invention has a much
broader range of applicability.
[0002] Telecommunication (telecom) shelters are typically
constructed as an outdoor facility in either steel or pre-cast
concrete structure for housing an electrical system. Physical
dimensions for such shelters are about 20 ft in length, 10 ft in
width, 10 ft in height with an access door and several access
hatches for cable access. These shelters are usually attached to
split system air-conditioning units for providing cooling for the
electrical system therein. A conventional air conditioning (A/C)
system associated with the shelter is typically powered from
standard Alternating Current (AC) power supply and hence only
operates and provides cooling as long as there is AC power
available.
[0003] However, the electrical system within the telecom shelter
usually needs to operate from a Direct Current (DC) voltage
converted from the AC input by one or more DC power supplies
disposed inside the shelter. This DC voltage is typically +24 VDC
or -48 VDC and there are typically banks of batteries provided in
the shelter to store this DC Power. The batteries are installed so
that the systems can operate during events where the AC power is
interrupted to the shelter. Cooling for outdoor telecom shelters is
critical for proper operation of the electronics housed therein.
Typically the telecom equipment installed in the shelters has an
over-temperature shutdown monitor built into the equipment. Thus,
the time that the telecom systems can operate is not limited by the
battery life, but is limited by the time that the system can
operate before it reaches the over-temperature shutdown threshold
when the A/C system for providing cooling to the shelter is no
longer functioning. This time depends on the external ambient
conditions but is typically quite short (approx 20 minutes to 1
hour) for conventional telecom shelter. One potential solution is
to use a DC to AC inverter in the event of a standard AC power
failure. However, this is considered to be not practical, because
it would require a very large battery storage capability.
[0004] It conditions where a large amount of the telecom shelters
lose power at the same time (such as in a hurricane event), the
telecom equipment installed in the shelter is not available for
subsequent rescue efforts. If cellular phone systems are used to
communicate, 20 minutes is not enough time to restore power to so
many systems. Due to a recent event that caused a sustained lack of
communication (hurricane Katrina), the federal regulations have
been changed. Telecom shelters are now required to operate for 4-8
hours after loss of standard AC power.
[0005] Therefore, an alternate system and method for providing
cooling to the outdoor shelter of electrical equipment are
desired.
BRIEF SUMMARY OF THE INVENTION
[0006] The present invention relates generally to system cooling
techniques. In particular, embodiments of the present invention
provide a method and system for providing an alternate cooling to
an outdoor shelter with telecom equipment installed therein.
[0007] Embodiments according to the invention lead to a system
configured to provide controlled cooling of electronic equipment in
an outdoor shelter in combination with an air conditioning (A/C)
system powered by AC power supply. The electronic equipment is
powered by a DC supply. The system includes one or more blowers
configured to be mounted to the outdoor shelter to draw exterior
air into the outdoor shelter. Additionally, the system includes a
damper arrangement configured to be mounted at an air exhaust
region of the outdoor shelter. Moreover, the system includes a
controller powered by the DC supply and coupled to the one or more
blowers, the damper arrangement, and the A/C system. The controller
is configured to receive at least a first analog input signal
associated with a shelter-interior temperature, a second analog
input signal associated with a shelter-exterior temperature, and a
plurality of alarm input signals. The controller is further
configured to generate the one or more first control signals, the
second control signal, and a third control signal based on at least
the first analog input signal, or the second analog input signal,
or a plurality of alarm input signals, or a combination of thereof.
In one embodiment, the one or more first control signals
respectively control an on/off operating state of the one or more
blowers including rotational speeds of the one or more blowers. The
second control signal controls opening and closing of the damper
arrangement in correspondence of the on/off operating state of the
one or more blowers. The third control signal inhibits/activates
the A/C system.
[0008] In an alternative embodiment, the present invention leads to
a system for providing alternative cooling, in addition to an air
conditioning (A/C) system, to a cabinet housing electrical
equipment. The system includes a blower subsystem including one or
more blowers for drawing air into the cabinet. The system further
includes a damper subsystem including a louver arrangement for
controlling air exhaust. Additionally, the system includes a
controller operated from a DC supply. The controller includes a
microprocessor having at least a first analog input, a second
analog input, a plurality of alarm inputs, erne or more first
control outputs, a second control output, and a third control
output. The first analog input connects to a first thermistor to
measure a first temperature inside the cabinet. The second analog
input connects to a second thermistor to measure a second
temperature outside the cabinet. The third control output connects
to the A/C system for inhibiting or re-activating the A/C system
based on at least the first temperature and the second temperature.
The one or more first control outputs connect to the blower
subsystem for respectively operating the one or more blowers based
on at least the first temperature when the A/C system is inhibited
or stopped for any reason. The second control output connects to
the damper subsystem for opening/closing the louver arrangement
when the one or more blowers are operating/stopped.
[0009] In another alternative embodiment, the present invention
provides a method for providing an alternative cooling in addition
to an air conditioning (A/C) system to a cabinet housing electrical
equipment. The method includes providing a cooling system to the
cabinet. The cooling system includes a blower subsystem including
one or more blowers for drawing air into the cabinet and a damper
subsystem including a louver arrangement for controlling air
exhaust. Additionally, the cooling system includes a controller
operated from a DC supply. The controller includes a microprocessor
having at least a first analog input, a second analog input, a
plurality of alarm inputs, one or more first control outputs, a
second control output, and a third control output. The method
further includes activating the controller by starting up power
from the DC supply. Additionally, the method includes receiving
information associated with an interior temperature from the first
analog input and information associated with an exterior
temperature from the second analog input and monitoring information
associated with a general alarm and a plurality of specific alarms
received through the plurality alarm inputs. Moreover, the
microprocessor processes information associated with the exterior
temperature and information associated with a general alarm and a
plurality of specific alarms. If the exterior temperature is lower
than a predetermined value, or no general alarm or one of the
plurality of specific alarms is triggered, the microprocessor
processes information associated with the interior temperature.
[0010] If a first criterion based on information associated with
the interior temperature is satisfied, then the method includes a
process of inhibiting the A/C system through the third control
output. The method also includes another process of operating each
of the one or more blowers, respectively through the one or more
first control outputs, at a rotation speed depending on the
information associated with the interior temperature. The method
further includes a process of closing/opening the louver
arrangement through the second control output when the rotation
speed is/isn't zero.
[0011] If a second criterion based on information associated with
the interior temperature is satisfied, then the method includes a
process of activating the A/C system in cooling mode through the
third control output and a process of stopping the one or more
blowers through the one or more first control outputs.
[0012] If a third criterion based on information associated with
the interior temperature is satisfied, then the method includes a
process of activating the A/C system in heating mode through the
third control output and a process of stopping the one or more
blowers through the one or more first control outputs.
[0013] Many benefits are achieved by way of the present invention
over conventional techniques. For example, embodiments of the
present invention provide an alternate cooling system in place of
conventional air conditioning system, which can be used for cooling
outdoor shelter housing electrical equipment in the events where
standard AC power is interrupted or failed. Certain embodiments of
the present invention significantly reduces energy use and
operation costs of the telecommunication shelter. Some embodiments
further provide sustained operation of the communication
electronics within the shelter in the event of a power failure
during hurricane or earthquake. Under updated field application
requirement for 4-8 hours after loss of power, the exiting telecom
shelter can be kept for using with minimum amount of modification
and installation of the direct air cooling system based on present
invention. Further, some embodiments of the present invention
provide additional cooling system redundancy for providing
controlled cooling in response to various alarming situations. For
example, in the event of an excess hydrogen alarm event, the system
according to an embodiment of the present invention also serves to
accelerate exhausting of the shelter. Or in the event of detecting
fire-related smoke inside the shelter, the system according to an
embodiment of the present invention can has a function to starve
the fire by closing the oxygen supply. Depending upon the
embodiment, one or more of these benefits, as well as other
benefits, may be achieved. These and other benefits will be
described in more detail throughout the present specification and
more particularly below in conjunction with the following
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a schematic diagram showing a side view of a
cooling system according to an embodiment of the present
invention;
[0015] FIG. 2 is a schematic diagram showing the top view of a
cooling system according to the embodiment of the present
invention;
[0016] FIGS. 3A and 3B are simplified diagrams showing a blower
subsystem including four blowers and a controller according to an
embodiment of the present invention;
[0017] FIG. 4 is schematic diagram showing a telecom shelter with a
direct air cooling system according to embodiments of present
invention in addition to a traditional air conditioning system;
[0018] FIG. 5A is a controller functional block diagram according
to an embodiment of the present invention;
[0019] FIG. 5B shows three-angle views of the controller built on a
PC board according to an embodiment of the present invention;
[0020] FIGS. 6A and 6B show a simplified flow chart outlining a
method of providing controlled cooling for an outdoor shelter
according to an embodiment of the present invention; and
[0021] FIGS. 7-11 each is a simplified flow chart showing a method
for providing controlled cooling for an outdoor shelter according
to an alternative embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0022] The present invention relates generally to system cooling
techniques. In particular, embodiments of the present invention
provide a method and system for providing an alternate cooling to
an outdoor shelter housing electrical equipment. Merely by way of
example, the invention has been applied to a telecommunication
shelter, but it would be recognized that the invention has a much
broader range of applicability.
[0023] FIG. 1 is a schematic diagram showing a side view of a
cooling system according to an embodiment of the present invention.
This diagram is merely an illustration and should not limit the
scope of the claims herein. One of skilled in the art should
recognize many alternatives, variations, and modifications. As
shown in one implementation, a direct air cooling system 100 is
structured to be mounted on a position of a shelter door 200 (side
view is shown). At least partially, the direct air cooling system
100, or simply called the cooling system, includes one or more
blowers 101 disposed at an interior side of the shelter door 200
opposing a filter arrangement 103 at an exterior side of the
shelter door 200. In one embodiment, the one or more blowers are
fan trays structured as two channels, each with two blowers. In
particular, each blower can be a DC powered radial blower. For
example, in a specific implementation a NMB 48V 225 mm radial
blower can be used (NMB Part No. 225R103 D0801). The filter
arrangement 103 is configured to cover the air inlet region 102 of
the one or more blowers 101 for the purpose of removing dust and
moisture from the air as it is drawn into the shelter by the one or
more blowers 101. As shown, the cooling system 100 is incorporated
with a damper arrangement 105 including a plurality of louver
blades that are electrically operated to an open position or close
position to control the flow of air exhaust. Though the plurality
of louver blades are shown to be oriented in horizontal direction,
they can be implemented in other orientations. In one embodiment,
the damper arrangement 105 is configured to be mounted at a
location where air is exhausted from within the shelter. This
location can be elsewhere on the shelter other than the same
position where the one or more blowers 101 are mounted. For
example, a cable duet region can utilized for installing the damper
arrangement 105.
[0024] Additionally, the cooling system 100 includes a
microprocessor-based controller 120 disposed within a same
enclosure that houses the one or more blowers 101. In certain
embodiments, the controller 120 is configured to send one or more
control signals to operate the one or more blowers 101 when an
existing air conditioning (A/C) system (not shown) for the shelter
is optionally inhibited (by the same controller 120) or stopped
subjecting to power failure or other electrical or mechanical
faults. In some embodiments, the controller 120 also is configured
to send a control signal through connection 125 to the damper
arrangement 105 to open or close the plurality of louver blades. In
a specific embodiment, the one or more blowers 101 are configured
to draw in cool exterior air into the shelter for cooling the
electrical equipment therein. Accordingly, the damper arrangement
105 is operated to an open position to allow heated air to exhaust
out of the shelter when the one or more blowers 101 are operating,
and can be closed to seal the shelter when the one or more blowers
are not operating. In another specific embodiment, the damper
arrangement 105 can have a spring return feature that allows it to
be open when DC power is on and automatically closed when power is
removed for any reason.
[0025] FIG. 2 is a schematic diagram showing a top view of the
cooling system 100 according to an embodiment of the present
invention. This diagram is merely an illustration and should not
limit the scope of the claims herein. One of skilled in the art
should recognize many alternatives, variations, and modifications.
As shown, the direct air cooling system 100 mounted on the shelter
door 200 is viewed from top of the door looking down. On the
exterior side of the door, now a door handle 201 can be seen.
Similar to FIG. 1, the one or more blowers 101 and the filter
arrangement 103 are respectively disposed on interior side and
exterior side of the shelter door 200.
[0026] In a specific embodiment, the controller 120 of the direct
air cooling system 100 is coupled to one or more temperature
measuring devices. The one or more temperature measuring devices
include at least a first thermistor for measuring a
shelter-interior temperature and a second thermistor for measuring
a shelter-exterior temperature. For example, though not explicitly
shown in FIG. 1 or FIG. 2, the first thermistor can be installed
next to the one or more blowers 101 at the interior side of the
shelter door 200, and the second thermistor may be installed
outside the shelter door 200 near the filter arrangement 103.
Correspondingly, the controller 120 is able to receive at least a
first analog input signal indicative to the shelter-interior
temperature and a second analog input signal indicative to the
shelter-exterior temperature. The controller is configured to
generate control output signals based on at least the first analog
input signal and the second analog input signal for controlling the
one or more blowers 101 as well as the damper arrangement 105 with
options of inhibiting/activating the A/C system. In one example, if
the exterior temperature is too high (exceeding a predetermined
value) then the direct air cooling system 100 may be turned off
while the A/C system can be activated to providing adequate cooling
for the shelter in traditional manner.
[0027] In another specific embodiment, the controller 120 further
is coupled with a plurality of sensing devices disposed at various
locations of the shelter (schematically shown in FIG. 4 below) and
a plurality of alarm output devices disposed on-board
(schematically shown in FIG. 5B below). Examples of the plurality
of sensing devices includes a smoke sensor, a hydrogen sensor, a
pressure sensor, one or more voltage sensors (e.g., AC power
monitoring module and DC supply voltage monitor), a pressure
sensor, and others for detecting various environmental and
operational conditions. The controller 120 is configured to receive
and process a plurality of alarm input signals from the plurality
of sensing devices and output a plurality of alarm output signals
through the plurality of alarm output devices. The plurality of
alarm output devices include on-board contact relays and alarm
display devices. For example, Form C contact relay is used. In
certain implementation, the alarm display devices include several
LEDs which use light color, single color or bi-color, to indicate
normal or certain alarm condition. In addition to the analog input
signals associated to the interior/exterior temperature, the
controller 120 also is configured to modify the control signals for
the one or more blowers 101. the damper arrangement 105, and the
A/C system based on specific alarm input signal received.
[0028] FIGS. 3A and 3B are simplified diagrams showing a blower
subsystem including four blowers and a controller according to an
embodiment of the present invention. These diagrams are merely
illustrations and should not limit the scope of the claims herein.
One of skilled in the art should recognize many alternatives,
variations, and modifications. As shown, the blower subsystem 300
includes four blowers 101 installed within an enclosure made of a
sheet metal structure 107. Each blower 101 is disposed behind an
air inlet region 102 facing exterior side when the blower system is
mounted to a shelter. In one embodiment, the four blowers 101 are
powered by a DC supply (e.g., as shown in FIG. 4 below) and used to
draw the cool exterior air into the shelter, taking out the heat
generated from the operating telecom equipment through an exhaust
region. The DC supply for the blower subsystem can be the same DC
supply conventionally provided for the equipment within the shelter
or a separate DC supply. For example, the DC supply can be an
AC-to-DC inverter, or a battery, a rechargeable battery, a fuel
cell, or a solar cell, and others. In the event of a power failure,
these blowers 101 can continue to operate normally from the battery
backup system of the DC supply, which allows the entire shelter to
operate as long as there is enough power in the batteries.
[0029] In a specific embodiment, each blower 101 can be a DC
powered radial blower. For example, in a specific implementation a
NMB 48V 225 mm radial blower can be used (NMB Part No. 225R103
D0801). In one example, the four blowers 103 are configured into
two channels, each channel has two blowers under closed-loop speed
control by the controller 120. The controller 120 can be seen in
the blower subsystem 300 in FIG. 3B where one side panel of the
sheet metal structure 107 is removed. In a particular
implementation, the controller 120 uses a pulse width modulated
(PWM) speed control signal to control blower rotation speed by
monitoring tachometer signals obtained from each radial blower in
response to one or more speed control input signals. More detail
about a control method of the direct air cooling system in
combination with an existing air conditioning system to provide
cooling for the outdoor telecom shelter can be found in following
paragraphs.
[0030] FIG. 4 is schematic diagram showing a telecom shelter with a
direct air cooling system according to embodiments of present
invention in addition to a traditional air conditioning system.
This diagram is merely an illustration and should not limit the
scope of the claims herein. One of skilled in the art should
recognize many alternatives, variations, and modifications. As
shown, in a perspective view a telecom shelter 401 is an outdoor
structure with a length L, a width W, and a height H that houses
electric equipment for telecommunications. In one application, the
electric equipment in the telecom shelter 401 comprises all user
equipment and software needed for communication with a wireless
telephone network. As shown, optionally an antenna 431 is disposed
above the telecom shelter on a top part of a mast 430 for signal
transmission or reception. The shelter 401 itself can be made from
a pre-cast concrete structure or from a steel structure. In one
example, the length L is about 20 ft and the width and height each
about 10 ft. In another example, the shelter can be used for
housing equipment for many alternate applications other than
telecommunication.
[0031] The telecom shelter 401 includes an access door 200 built on
one side. In one embodiment, a direct air cooling system 100 is
mounted on the access door 200 in a manner the same as one shown in
FIG. 1 and FIG. 2, and a filter arrangement 103 is at least
partially visible from exterior side of the shelter door 200. The
direct air cooling system 100 has a blower subsystem including one
or more blowers disposed at the interior side of the shelter door
200, which are not directly visible in FIG. 4. Of course, the
blower subsystem of the direct air cooling system 100 can be
mounted on any other side or position of the shelter 401. On an
alternative side of the shelter 401, an existing air conditioning
(A/C) system including two independent working units 411 and 413
have been installed. The A/C system 411 and 413 are usually powered
by standard AC power supply connected to a power grid through a
cable box 420. In one embodiment, the telecom shelter 401 also
includes art AC-DC inverter 425 to transform the AC power into a
nominal -48V standard DC power (with -36V to -60V range) which is
normally used for operating telecommunication equipment within the
telecom shelter 401. In another embodiment, the AC power can be
transformed into a nominal +24V standard DC power (with 19V to 29V
range) which can be used for operating various telecommunications
equipment and the like. An electrical connection 115 links the
AC-DC inverter 425 to the direct air cooling system 100 to deliver
DC power for its operation and control functions. In certain
implementation, a separate DC supply can be used for the direct air
cooling system 100. For example, the DC supply can be a battery, a
rechargeable battery, a fuel cell, or a solar cell, and others.
[0032] Referring to FIG. 4 again, on a side of the telecom shelter
401 a damper subsystem 105 can be mounted over an air outlet or
exhaust region, which is coupled to the blower subsystem (e.g., the
blower subsystem 300 shown in FIG. 3A, including filter
arrangement) through another electrical connection 125. In another
embodiment, the damper subsystem 105 is powered by one of several
on-board DC power supplies (e.g., a +24V supply shown in FIG. 5A
below) built on a controller through DC-DC converters from the DC
supply mentioned above. As shown, the damper subsystem 105 includes
a plurality of louver blades that are electrically actuated to open
to allow air exhausting when the blowers of the direct air cooling
system 100 is operating or to close to seal the shelter 401 when
the blowers of the direct air cooling system 100 is not operating.
Other types of damper arrangements other than horizontal orientated
louvers can be implemented. One of skilled in the art should
recognize many alternatives, variations, and modifications. In one
example, the damper subsystem 105 is configured to be mounted over
a cable duct in order to allow the field upgrade of the telecom
shelter without affecting the structural integrity while providing
a minimally invasive rework event. In a particular implementation,
a wind driven rain hood 106 is mounted on the exterior side of the
damper subsystem 105.
[0033] The direct air cooling system 100 described above is
designed to withstand harsh outdoor environmental conditions. In
particular, the direct air cooling system, or simply the cooling
system, should not suffer damage when mounted to a shelter and
exposed to temperatures in the range of about -45 Deg C. to about
+85 Deg C. The cooling system itself should be operational within a
temperature range between about -40 Deg C. and about +50 Deg C.
Additionally, the system is designed to withstand certain external
vibrations. For example, the cooling system should not suffer any
damage and be able to continue operating when it is subjected to
the following vibration conditions. 1) Random vibration during
operating: for 20 minutes along all each of three axes sustain
axial vibration force with a vibration intensity of 0.0001
g.sup.2/Hz within a frequency range from 5 to 350 Hz and a
vibration intensity dropped from its maximum in a rate of -6
dB/octave within a frequency range of 350 to 500 Hz. 2) Random
vibration for survival: for 20 minutes along all each of three axes
sustain axial vibration force with a vibration intensity of 0.015
g.sup.2/Hz within a frequency range from 3 to 100 Hz and a
vibration intensity dropped from its maximum in a rate of -6
dB/octave within a frequency range of 100 to 137 Hz, and a
vibration intensity of 0.008 g.sup.2/Hz within a frequency range
from 137 to 350 Hz and a vibration intensity dropped from its
maximum in a rate of -6 dB/octave within a frequency range of 350
to 500 Hz. 3) Swept sine vibration for survival: 0.5 g acceleration
(from 0 to peak) within a frequency variation from 3 to 500 and to
3 Hz. The test is for resonant search along all three axes with 15
minutes dwell at all resonances and with 1 octave/minute sweep
rate. Furthermore, the cooling system should withstand certain
shock test. For example, the system should not suffer any damage
when subjected to the following test: a half sine shock test with
duration less than 3 milliseconds and a speed difference of about
1.65 meters per second. The shock test should be conducted minimum
3 times on each of 6 faces of the system. Moreover, the cooling
system is designed to meet regulatory requirement of UL/EN 60950.
More detail about a control method of the direct air cooling system
using one or more DC operated blowers in association with a damper
arrangement to provide controlled cooling for the outdoor telecom
shelter can be found in following paragraphs.
[0034] FIG. 5A is a controller functional block diagram according
to an embodiment of the present invention. This diagram is merely
an illustration and should not limit the scope of the claims
herein. One of skilled in the art should recognize many
alternatives, variations, and modifications. As shown, the
controller 500 includes a microprocessor 501 operated by DC power
delivered through a power input port 510. The controller 500 is
designed to monitor the external and internal environment of the
telecom shelter and control one or more blowers or motorized
impellers to draw cold air from exterior to cool the interior
operating equipment. In one implementation of the invention, the
controller 500 is the controller 120 installed with the direct air
cooling system 100. The DC supply is in a range of -36 to -60 VDC
normally found for telecommunication equipment. Subsequently, the
power input 510 to the controller 500 is first coupled through an
Electromagnetic Compatibility (EMC) filter 520. Fuses included in
the EMC filter 520 can be rated at about 20 Amps. The EMC filter
520 is supplement to a corresponding EMC filter fitted in each of
the one or more blowers. The EMC filter 520 can limit the
conduction of controller noise and motor noise to the system. In
one example, the EMC filter 520 is designed to provide sufficient
attenuation to meet the CE requirements for most applications. In
one embodiment, the EMC filter design is dependent on the type of
motor used for the one or more blowers and their installation
locations. The design performance can only be confirmed in the
specific final application.
[0035] In one embodiment, the controller 500 includes function to
monitor the DC supply voltage. In one example, the interface of the
power input 510 is via a connector J1 which has 5 pins J1-1 through
J1-5 shown in Table 1. As shown, connector pins J1-1 and J1-2 are
connected for 0 V Return signal. Connector pin J1-3 is for chassis
ground. Connector pins J1-4 and J1-5 are connected for -DC voltage
supply. The connector can be 1/4 PCB mounted "Fasten" Blade
Terminals. For example, a power connector with AMP Part No 62409-1
can be used.
TABLE-US-00001 TABLE 1 Connector Ref Function Signal type J1-1 0 V
A 0 V Return J1-2 0 V A 0 V Return J1-3 Ground Chassis Ground J1-4
-Ve Supply -DC supply J1-5 -Ve supply -DC supply
[0036] Additionally, the controller 500 incorporates its own
on-board DC power supplies including a +24V supply 540, +10.5V
supply, and a +5V supply 530. The +24V power supply 540 is to
generate the necessary power for the smoke alarm, the hydrogen
alarm and the operation of damper arrangement. The +10.5V supply is
for generating the PWM speed control signals and for energizing
relays. Another on-board +5V supply 530 is directly coupled to the
microprocessor 501 via a connection 535 for logic supply required
by the microprocessor 501.
[0037] The microprocessor 501 is configured to directly couple with
one or more blowers through one or more blower output ports 550. In
one implementation, the controller 500 is designed to control
variable speed blowers and deliver DC power to up to four motorized
impellers which are controlled in two channels of two blowers
dependent on the profile information programmed into the
microprocessor 501. Each blower output 550 can be individually
fused to prevent a single blower failure pulling the whole system
down. The DC voltage supplied to these blowers is the same voltage
supplied from the DC input 510 less any volt drop in the EMC filter
520. The interface associated with each of these blower output
ports between the microprocessor 501 and each of the blowers can be
via a 6-way connector. For example, 4 connectors, named as J2
through J5, are respectively used for four DC-driven radial
blowers. Table 2 shows an example of the pin layout for the
connector J2 though J5. For example, a Molex Minifit Jnr Right
angle PCB mounted connector (Molex Part No. 39-30-0060) can be
used.
TABLE-US-00002 TABLE 2 Connector Ref Function Signal type (on
Controller) Pin 1 No Connection Pin 2 0 V Return +DC Supply to
blowers Pin 3 Speed Control PWM Logic Signal to blower Pin 4 Ground
Chassis Ground connection Pin 5 Tacho Logic Signal from blower Pin
6 -48 V Supply -DC Supply to blowers
[0038] Referring to FIG. 5A, the controller 500 includes two
temperature sensor inputs 560 coupled to the microprocessor 501.
Physically, each of the two temperature sensor inputs 560 is
coupled to a thermistor to transfer information about either a
shelter-interior temperature or a shelter-exterior temperature to
the microprocessor 501 via one of two interface connectors J6 and
J7. In particular, the controller 500 continuously monitors an
analog voltage input from the corresponding thermistor. If the
analog voltage input represents a temperature of less than -43
Degrees of Centigrade, then the controller considers that the
thermistor is short circuited. If the analog voltage input
represents a temperature of +85 Degrees of Centigrade and above,
the controller then considers the thermistor to be open circuited.
In either event, the controller 500 will trigger a thermistor
alarm. Of course, the specific values of those temperature limits
can be custom defined. The interface between the thermistors 560
and the microprocessor 501 can be via a following connector pinout
shown in Table 3. For example, each of the J6 and J7 connector can
be a 2 way Molex KK Type 2.54 mm pitch header with friction lock
connector (Molex Part No. 22-23-2021) can be used.
TABLE-US-00003 TABLE 3 Connector Ref Function Signal type (on
Controller) Pin 1 Signal return Thermistor connection Pin 2 Signal
out Logic +5 V
[0039] Referring again to FIG. 5A, the controller 500 also has
several alarm input and control output ports 570 coupled to the
microprocessor 501. The alarm input ports are used for coupling
with a plurality of sensing devices and the control output ports
include at least one output for controlling a damper arrangement
and another output for inhibit an A/C system. Example of the
plurality of sensing devices used here includes a smoke sensor, a
hydrogen sensor, and one or more AC power monitoring modules.
Correspondingly, in certain alarming condition one or more alarm
input signals can be generated by one or more sensing devices and
sent via the alarm input ports to the microprocessor 501. In one
implementation, the alarm input port is configured to be an
isolated contact relay which is closed when alarming (e.g., when
detecting smoke or excess hydrogen in shelter). A +24V on-board DC
supply 540 is used to provide DC power through one output port for
the smoke sensor, the hydrogen sensor, and a damper actuator. This
output is capable of delivering a maximum power of 450 mA at 24V
and is protected against short circuit by a PTC (Polyswitch
automatically resetting fuse element). A +24V switched output
control signal can be provided through another output port to the
damper arrangement for operating the exhaust damper to open or
close. The power associated with the damper switching control is
about 350 mA. The AC power monitoring module is used by the system
to monitor the AC power delivered to an air conditioning (A/C)
system originally associated with the telecom shelter. For example,
the AC power monitoring module monitors power outputs from two
circuit breakers supplying AC power to two A/C units. Two input
signals associated with the AC power monitoring module are
generated from corresponding two alarm input ports with isolated
contacts. Each isolated contact has a relay coil energized to have
open contact in normal mode and closed contact when alarming
(detecting AC power supply failure/interruption). Moreover, the
controller 500 includes a Form C contact output for
inhibiting/activating the A/C system. The relay coil associated
with this output port is configured to be energized when the A/C
system is inhibited or disabled. As a result the interface
associated with these alarm input and control output ports is via a
10 way connector. For example, connector J8 can be a Molex
connector of KK type 2.54 mm pitch header with friction lock (Molex
Part No. 22-23-2101). Table 4 shows the connector pinout.
TABLE-US-00004 TABLE 4 Connector Ref Function Signal type J8-1 +24
V Power Supply J8-2 Damper +24 V Damper Control J8-3 Smoke Alarm
Alarm contact input J8-4 Hydrogen Alarm Alarm contact input J8-5 AC
Supply 1 Alarm contact input J8-6 AC Supply 2 Alarm contact input
J8-7 0 V Power/logic 0 V J8-8 AC inhibit Common Form C Common J8-9
AC inhibit NO Form C NO J8-10 AC inhibit NC Form C NC
[0040] Furthermore, the controller 500 includes a plurality of
alarm output ports 575 each through an isolated Form C relay
contact to couple with the microprocessor 501. In one embodiment,
the controller 500 is fitted with five isolated Form C relay
contact alarm outputs. The common of each of the alarm outputs is
connected to a single point. The Form C (normally open) NO contact
and (normally closed) NC contact of each alarm relay coil are
available for connection to a corresponding external device. Each
relay coil is characterized by its capability of switching power up
to 500 mA at 30V DC. In a specific embodiment, the alarm output
ports 575 include functions of a general alarm output, a smoke
alarm output, a hydrogen alarm output, an over-temperature alarm
output, and a filter alarm output.
[0041] The general alarm output is triggered to indicate a blower
failure (for example, a blower has stopped or failed to reach a
predefined percentage of its target speed) and a thermistor failure
(when thermistor has open or short circuit), or a DC supply failure
(when DC supply of the system has dropped below a predefined
voltage). The relay coil associated with the general alarm output
is directly controlled from the microprocessor 501 and is typically
energized in the no-alarm condition so that an alarm (associated
with one of above three failures) output will be given in the event
of a total power failure to the controller PCB or a failure in the
controller itself.
[0042] The smoke alarm output provides an isolated output depending
on a smoke alarm input signal from the smoke sensor connected to
the microprocessor 501. In one embodiment, the relay coil
associated with the smoke alarm output is energized during alarm
condition, but open in normal condition.
[0043] The hydrogen alarm output provides an isolated output
depending on a hydrogen alarm input signal from the hydrogen sensor
connected to the microprocessor 501. In one embodiment, the relay
coil of the hydrogen alarm output is energized during alarm
condition, but open in normal condition.
[0044] The over-temperature alarm output provides an isolated
output depending on a temperature measured inside the shelter and a
set point defined in the functionality specification of the
microprocessor 501. In one embodiment, the relay coil of the
over-temperature alarm output is energized during alarm condition,
but open in normal condition.
[0045] The filter alarm output provides an isolated output
depending on an input signal from a pressure switch 580 connected
to the microprocessor 501 for detecting if a filter arrangement
associated with the blowers of the direct air cooling system is
normal or abnormal. In one embodiment, the relay coil of the filter
alarm output is energized during alarm condition, but open in
normal condition.
[0046] In a specific embodiment, the relay contact alarm outputs
are interfaced with the microprocessor 501 via a 12 way connector.
For example, the connector, namely J9, can be a Molex 12 way KK
type 2.54 mm pitch header with friction lock connector (Molex Part
No. 22-23-2121). Table 5 shows an exemplary connector pinout.
TABLE-US-00005 TABLE 5 Connector Ref Function Signal type J9-1
Alarm Common Common Signal J9-2 Smoke Alarm Normally Open Contact
J9-3 Smoke Alarm Normally Close Contact J9-4 Hydrogen Alarm
Normally Open Contact J9-5 Hydrogen Alarm Normally Close Contact
J9-6 Over Temp Alarm Normally Open Contact J9-7 Over Temp Alarm
Normally Close Contact J9-8 General Alarm Normally Close Contact
J9-9 General Alarm Normally Open Contact J9-10 Filter Alarm
Normally Open Contact J9-11 Filter Alarm Normally Close Contact
J9-12 Alarm Common Common Signal
[0047] Furthermore, the controller 500 is configured to receive an
input from a pressure switch 580 which is used monitor the pressure
drop across the filter to detect if the filter is clogged. As
mentioned earlier, the input signal from the pressure switch 580 is
used to directly drive the filter alarm relay and a LED for
indicating filter alarm (to be described later). The pressure
switch 580 is driven by the on-board +5V DC supply 530. The
interface between the microprocessor 501 and the pressure switch
580 is realized by a connector, namely J10. For example, a 2 way
Molex KK type 2.54 mm pitch header with friction lock connector can
be used (Molex Part No. 22-23-2021). Table 6 shows a pinout of the
connector.
TABLE-US-00006 TABLE 6 Connector Ref Function Signal type J10-1
Signal return Alarm signal J10-2 Signal out Logic +5 V
[0048] Moreover, the controller 500 includes an on-board
programming/test port 590 and a communications port 595 associated
with the microprocessor 501. In one embodiment, the on-board
programming/test port 590 is an In Circuit Serial Programming
(ICSP) port which allows the flash memory in the microprocessor 501
to be programmed or reprogrammed alter the controller 500 has been
assembled. The capability of reprogramming with an appropriate
programmer facilitates the production programming of the
microprocessor 501 and also facilitates update of the program at a
later date when necessary. This ICSP port 590 also is used for easy
access to the +5V DC supply 530 and 10.5V DC supply for production
testing (but not using ICSP). The interface between the on-board
programming/test port 590 and the microprocessor 501 can be
established via a 6 way connector, namely J11. For example, the
connector can be a Molex KK type 2.54 mm pitch header friction lock
connector (Molex Part No. 22-23-2061). Table 7 shows an exemplary
connector pinout.
TABLE-US-00007 TABLE 7 Connector Ref Function Signal type J11-1
MCLR Master Clear J11-2 Logic + Ve supply Logic 5 V Supply J11-3
Logic 0 V Logic 0 V Return J11-4 PGC Program Clock J11-5 PGD
Program Data J11-6 +10.5 V Supply 10.5 V Supply (for production
test)
[0049] In another embodiment, the communications port 595 allows
the controller 500 to be connected via an adaptor to the RS232 type
port or USB type port of a personal computer. The communications
port 595 is typically used for production testing of the system
which is managed by the controller 500. The communications post 595
also can be set to broadcast performance and status information
during normal operation and can be used for performance analysis.
The interface to the system through the communications port 595 can
be established via a connector, namely J12. For example, the
connector J12 can be a 3 way Molex KK type 2.54 mm pitch friction
lock header connector (Molex Fart No. 22-23-2031). Table 8 shows an
exemplary pinout for this connector.
TABLE-US-00008 TABLE 8 Connector Ref Function Signal type J12-1 TX
Data Out J12-2 RX Data In J12-3 Logic 0 V Logic Return
[0050] In a specific embodiment, the controller 500 also includes a
plurality of LED displays 577 coupled with the microprocessor 501.
These LED displays 577 are triggered by the plurality of relay
contact alarm outputs 575 to show different colored light. In one
example, the controller 500 is fitted with seven 5 mm diameter
round LED's which will be visible through an aperture on the front
of the fan tray's sheet metal structure (e.g., blower subsystem 300
in FIG. 3B). In one implementation, these LEDs are mounted on the
PCS of the controller 500. FIG. 5B shows three-angle views of the
controller built on a PC-board according to an embodiment of the
present invention. Of course, there can be many variations,
alternatives, and modifications in terms of the layout of various
controller components. This diagram is merely an illustration and
should not limit the scope of the claims herein. For example, the
controller 120 installed in the direct air cooling system 100 shown
in FIG. 1 or 300 shown in FIG. 3B is the same as the controller 500
described in above paragraphs. As shown, the controller 500 is
built on a printed circuit board (PCB) wherein some input/output
interface devices are marked. For example, the input/output
interface devices includes the connectors J1 through J12 and
several LEDs (LED1 through LED7). In particular, these LED's
include the following functions. LED1 is a states LED with bi-color
RED/GREEN display linked with the general alarm relay. Green color
is indicated when the direct air cooling system us powered up and
operating normally. Red color indicator can further include
continuous red light and flashing red light for different alarm
events with different priorities. LED2 is a filter alarm LED which
shows single color RED only in the event of an alarm. LED3 is
over-temperature LED used for indicating the over-temperature
alarm. LED4 and LED5 are respective smoke alarm LED and hydrogen
alarm LED. Each of them is a single color LED normally off and in
red light when alarming. LED6 is an AC inhibit LED used for
indicating an inhibited A/C system with AMBER light but off when
the A/C system is not inhibited or enabled. LED7 is an AC power
fail alarm LED showing single RED color in the event of an alarm
but off during normal operation.
[0051] Alternatively, Embodiments of the present invention disclose
a method for providing direct air cooling of electrical equipment
operated within outdoor shelters supplemental to an existing air
conditioning (A/C) system. In one embodiment, a simplified flow
chart of the control method is illustrated in FIGS. 6A and 6B for
providing a controlled thermal management for an outdoor shelter
with the existing A/C system. This diagram is merely an
illustration and should not limit the scope of the claims herein.
One of skilled in the art should recognize many alternatives,
variations, and modifications. As shown, a method 600 includes
following processes:
[0052] Process 610: Providing a cooling system to a shelter with an
A/C system, the cooling system comprising one or more blowers, a
damper, and a controller;
[0053] Process 615: Activating the controller operated from a DC
supply;
[0054] Process 620: Receiving information associated with an
interior temperature and an exterior temperature;
[0055] Process 625: Monitoring information associated with a
general alarm and a plurality of specific alarms;
[0056] Process 630: Processing information associated with the
exterior temperature and information associated with the general
alarm and the plurality of specific alarms;
[0057] Process 640: Determining whether a general alarm is
triggered, or one or more specific alarms are triggered, or
exterior temperature is greater than a predetermined value;
[0058] Process 645: If none of above occurs, processing information
associated with the interior temperature;
[0059] Process 650: Determining whether a first criterion, or a
second criterion, or a third criterion associated with the interior
temperature is satisfied;
[0060] Process 660: If the first criterion is satisfied, inhibiting
the A/C system; then
[0061] Process 662: Operating the one or more blowers at a rotation
speed depending on the interior temperature; then
[0062] Process 664: Closing/Opening the damper as the rotation
speed of one or more blowers is/isn't zero;
[0063] Process 670: If the second criterion is satisfied,
activating the A/C system in cooling mode; then
[0064] Process 672: Stopping the one or more blowers;
[0065] Process 680: If the third criterion is satisfied, activating
the A/C system in heating mode; then
[0066] Process 682: Stopping the one or more blowers;
Subsequently, the method 600 requires to perform, after each of the
Process 672 and Process 682, the Process 664, followed by rerouted
back to the Process 625 again in a closed loop.
[0067] The above sequence of processes provides a method according
to an embodiment of the present invention. Other alternatives can
also be provided where processes are added, one or more processes
are removed, or one or more processes are provided in a different
sequence without departing from the scope of the claims herein.
[0068] In one example, the cooling system used in the method 600 is
the same as the direct air cooling system 100 shown in FIG. 1 and
300 shown in FIGS. 3A and 3B. Following the method 600, the cooling
system is provided for mounting to a shelter at the Process 610.
The cooling system includes one or more blowers configured to be
mounted on an interior region of an shelter door, a filter
arrangement configured to be mounted at an air inlet of the one or
more blowers, and a damper arrangement configured to be mounted
else where at an air exhaust region of the shelter. The cooling
system further includes a controller. In one implementation, the
controller is a microprocessor based controller operated from a
DC-supply. The microprocessor features at least a first analog
input, a second analog input, a plurality of alarm inputs, one or
more first control outputs, a second control output, and a third
control output. In particular, the controller is the same
controller 500 including microprocessor 501 shown in FIGS. 5A and
5B.
[0069] The method 600 farther includes a process of activating the
controller by starting up DC power from the DC supply (Process 615)
to make the microprocessor ready for executing preprogrammed
control routines. In addition, the activation process involves an
activation of a general alarm relay coil and activations of a
plurality of sensing devices associated with the controller. For
example, a general alarm relay coil is activated and a two-color
LED indicates green during a start up period (approximate 5
seconds). Among the plurality of sensing devices, a first
thermistor and a second thermistor are activated for temperature
measurements. Other sensing devices includes a smoke sensor, a
hydrogen sensor, a pressure switch, one or more AC power monitoring
modules, DC voltage monitor, and the like.
[0070] Subsequently, the controller starts working with the
activated plurality of sensing devices. In particular, at the
Process 620, the microprocessor is receiving information associated
with an interior temperature and from the first analog input and
information associated with an exterior temperature from the second
analog input. In one implementation, the first analog input is a
port called Input Temp 1 connected to the microprocessor for
delivering information associated with the interior temperature for
the controller. Similarly, the second analog input is a port called
Input Temp 2 connected to the microprocessor for delivering
information associated with the exterior temperature for the
controller. This process, in one implementation, is to start
executing a closed-loop PWM control routine for the cooling system.
In particular, the microprocessor, in response to at least the
received information associated with the inferior and exterior
temperatures, should genet-ate adequate control signals for
controlling the speed of the one or more blowers. At the process
625, the controller also monitors Information associated with the
general alarm and a plurality of specific alarms received through
the plurality of alarm inputs. In one implementation, the
microprocessor is able to adjust the control signals based on
received information associated with various alarms indicating
abnormal operational status of the cooling system.
[0071] At the Process 630 following the previous Processes 620 and
625, the microprocessor firstly carries out a step for processing
the received information associated with the exterior temperature
and information associated with the general alarm and the plurality
of specific alarms. In one embodiment, the cooling system sets to
prioritize certain operational and environmental conditions to
generate adequate control signals. For example, a general alarm
involving a blower failure, or thermistor failure, or DC supply
fault, has high priority and needs to be cleared first before
performing rest operations. In certain exceptional case, during the
starting up period, if the interior temperature is such that the
one or more blowers would normally be stopped, the one or more
blowers will start up and run during the start up period to allow
installation engineers to establish that the blower is working
normally. There is about 30 seconds delay to trigger general alarm
to prevent the controller from issuing alarms during the blower
starting up period. After the start up period they will be turned
off or work to follow preprogrammed control routines. Additionally,
some specific alarms including smoke alarm and hydrogen alarm and
the shelter's exterior temperature are determining factors on how
the various control signals are formulated for controlling the
cooling system. More details about the control method at various
environmental and operational conditions can be found below.
[0072] Based on the Process 630, the microprocessor is able to
determine (at the Process 635) whether the exterior temperature is
lower than a predetermined value, or whether a general alarm or one
or more specific alarms is triggered.
[0073] In case that a negative result is obtained at the Process
640, then the microprocessor is to execute the next Process 645 for
processing information associated with the interior temperature.
Based on this process, the microprocessor is able to determine (at
the Process 650) whether one of the three criteria associated with
the interior temperature is satisfied. The three criteria simply
corresponds to three predetermined temperature ranges. If the
interior temperature measured by the first thermistor, determined
by the microprocessor, falls into one particular range, a
particular criterion is satisfied. Accordingly based on the
programmed routine designed for the particular temperature, the
controller generates adequate control signals to inhibit or
re-activate the A/C system, to control a speed of each blower, and
to open/close the damper whenever the speed of each blower isn't/is
zero.
[0074] In an event when the first criterion is satisfied, Process
660 will be executed. In one embodiment, the first criterion is
defined as limiting the interior temperature within a temperature
window between a lower temperature limit and a higher temperature
limit. For example, if the interior temperature is within a range
of 0 Deg C. to 38 Deg C., the first criterion is satisfied. At
Process 660 the microprocessor provides a control signal to inhibit
the operation of the A/C system in this condition. Then (or
essentially at the same time), Process 662 is executed to provide
one or more control signals respectively to control speed of the
blowers. Specific speed control depends on a specific value of the
interior temperature detected by the first thermistor which can be
installed near the one or more blowers at the interior side of the
shelter. Process 664 (also can occur at substantially the same
time) is executed to open the damper when the one or more blowers
are blowing air into the shelter while to close the damper when the
one or more blowers are stopped (for any reason).
[0075] In one example, as the interior temperature is below 7 Deg
C., all blowers will be turned off. If the interior temperature is
rising (as the electrical equipment in operation gradually heats up
the shelter) to 10 Deg C., the controller may decide to start turn
the blowers on at a speed of a certain speed, for example, about
1080 rpm. As the interior temperature further increases above 10
Deg C., the average speed of the blowers will increase linearly to
reach a higher speed, for example, up to about 3000 rpm, at about
35 Deg C. In one embodiment, at temperature above 35 Deg C but
still below the higher temperature limit for the first criterion,
the blowers will operate at the full speed of 3000 rpm unless
stopped by other conditions including unsatisfied first criterion
and some alarming situations.
[0076] If the interior temperature increases (as the electrical
equipment keeps its operation) above the higher temperature limit,
for example 39 Deg C., the second criterion becomes true. The
Process 670 would be triggered in this condition. In particular,
assuming no AC power supply alarm input is received, the controller
would providing a control signal to remove the inhibit of the A/C
system to enable it to take over the cooling of the shelter. In
other words, Process 672 is executed at a substantially same time
to stop the blowers. In fact, this is the condition that the
shelter is cooled under conventional way. However, if the interior
temperature measured by the first thermistor drops from a
temperature above the higher temperature limit to a temperature
below that limit, for example 35 Deg C. or lower, then the
controller will send a control signal to inhibit the A/C system
again and reestablish direct air cooling by turning on the blowers
at the proper speed depending on the interior temperature.
[0077] If the interior temperature is below the lower temperature
limit set for the first criterion, the third criterion is
satisfied. In this condition, the Process 680 is triggered. At this
process the controller is providing a control signal to remove the
inhibit of the A/C system to allow it to operate in its heating
mode to heat up the shelter. Accordingly, Process 682 is executed
to stop the blowers. Usually, this occurs during a cold soak
recovery process after an extended power failure at low temperature
environment. However, it will disable the A/C system again once the
interior temperature is above certain value above 0 Deg C., for
example 5 Deg C.
[0078] In either situation above, the damper arrangement associated
with the direct air cooling system is controlled in response to the
operation status of the blowers. In one embodiment, whenever, the
blower is turned on, the damper arrangement will be instructed to
open by a control signal sent by the controller. Whenever, the
blower stops, the damper arrangement will be instructed to close by
another control signal sent by the controller. In another
embodiment, some events associated with on/off status of the
blowers are related to one or more alarming events.
[0079] Referring back to FIG. 6, in case that the controller
receives a positive result at the Process 640, i.e., either a
general alarm is triggered, or one or more specific alarms is
received by the microprocessor, or simply the exterior temperature
measured by the second thermistor is greater than a predetermined
value, the method 600 will move on to perform one of following
processes: Process 700 through 1100, depending on the specific
conditions. FIG. 7 is a simplified flow chart showing a method for
providing controlled cooling for an outdoor shelter according to an
alternative embodiment of the present invention. In this specific
condition, at the process 640A one specific alarm, a smoke alarm,
is triggered (for example in ease of fire). Then, the
microprocessor generates one or more control signals to turn off
corresponding blowers (Process 710) and close the exhaust damper
(Process 720) to minimize the air supply (for the fire). In one
embodiment, the microprocessor also energizes a contact alarm relay
coil associated with the smoke alarm to generate a smoke alarm
output signal which illuminates a LED in red color. Once the smoke
alarm returns to normal the controller will return to normal
operation (i.e., the process flow would be led back to the Process
620 and on).
[0080] FIG. 8 is another simplified flow chart showing a method for
providing controlled cooling for an outdoor shelter according to
another alternative embodiment of the present invention. In the
situation of another specific alarm, a hydrogen alarm, is received
by the microprocessor (Process 640B), one or more control signals
will be sent to the blowers to speed them up (Process 810) to drive
the hydrogen out of the shelter. In one example, the blowers will
be on at full speed, for example about 3000 rpm. At the same time,
the exhaust damper wilt be kept at an open state (Process 820)
(irrespective of the temperature or any other control parameter) to
vent the shelter. In one embodiment, the microprocessor also
energizes the contact relay coil associated with the hydrogen alarm
and generate a hydrogen alarm output signal to illuminate a
corresponding LED in red color.
[0081] FIG. 9 is another simplified flow chart showing a method for
providing controlled cooling for an outdoor shelter according to
another alternative embodiment of the present invention. In this
situation another specific alarm, an AC power fail alarm, is
received by the microprocessor (Process 640C). Usually, two
redundant AC power monitoring inputs are installed in the cooling
system. If the controller detects an AC power fail on both the AC
power monitoring inputs, it will operate the blowers (or turn them
on if they have been off) (Process 910) at any temperature
condition. At the same time, the damper should be at an open state
(Process 920) and an AC power fail alarm LED will be illuminated in
red color.
[0082] FIG. 10 is yet another simplified flow chart showing a
method for providing controlled cooling for an outdoor shelter
according to another alternative embodiment of the present
invention. This is a situation that the microprocessor receives an
Input Temp 2 signal indicating that the exterior temperature is
greater than a predetermined value (Process 640D). In one example,
the predetermined temperature value is 27 Deg C. for outdoor
telecom shelters. Thus the controller will stop the blowers
(Process 1010) and enable the A/C system (Process 1020) to cool the
shelter until the exterior temperature cools down. Of course, the
damper will be kept at a closed state (Process 1030) during that
period when the conventional A/C system is running. If the exterior
temperature drops below the predetermined value, for example at 26
Deg C. or lower, the direct air cooling system will again replace
the A/C system to provide cooling for the shelter.
[0083] FIG. 11 is still yet another simplified flow chart showing a
method for providing controlled cooling for an outdoor shelter
according to another alternative embodiment of the present
invention. At Process 640E, a general alarm is triggered. In one
embodiment, the general alarm includes a blower fail alarm. If the
speed of any blower drops below 70% of the speed of the other
blowers then a general alarm will be triggered by de-energizing the
general alarm relay and a corresponding general alarm LED will be
changed to continuous red color. The controller will turn off all
blowers (Process 1110) and also remove the inhibit of the A/C
system to allow it to take over the cooling of the shelter (Process
1120) unless there is also an AC power fault in which case the
controller will operate the available blowers at maximum available
speed. In one embodiment, the controller may notify the end user or
a remote manager to send a technician to repair the blower that is
in trouble.
[0084] In another embodiment, the general alarm includes a
thermistor fail alarm. In particular, if the thermistor connected
to either first analog input or the second analog input is detected
as either being open or short circuited then a general alarm is
triggered by de-energizing the general alarm relay coil.
Correspondingly in one implementation, the general alarm LED is
changing color to flashing red color. In this case, the controller
will also remove the inhibit to the A/C system to allow it to take
over the cooling of the shelter unless there is also an AC power
failure. If there is an AC power failure, i.e., the AC power fail
alarm has been triggered, the DC powered controller will keep on
operating the one or more blowers at full speed to draw cool air
from exterior into the shelter.
[0085] In yet another embodiment, the general alarm also includes a
DC supply fail alarm. The controller will monitor the DC supply
voltage to the direct air cooling system and has been programmed to
take action at different supply voltage. In one example, if the DC
supply to the controller drops below 40V the controller will turn
off all the blowers and close the damper to minimize the deep
discharge of the batteries. The controller will also issue a
general alarm in this condition. Thus Process 1100 will be
executed. The controller will resume normal function when the DC
supply voltage to the controller reaches 42.5V.
[0086] In the event that there are multiple alarms priority of the
general alarms must be set. In one example, the controller will
prioritize the alarm Indications as follows. Priority 1 (highest
priority): Blower Fail, indicating by a continuous RED LED;
Priority 2: Thermistor Fail, indicating by a flashing RED LED. In
one embodiment, there is an about 30 seconds delay in blower alarms
to prevent the controller from issuing alarms during the time that
blowers are starting up.
[0087] There are some alarm situations that no immediate actions on
either the operation of blower/damper combination or
inhibit/activation of A/C system. For example, if the controller
detects an input alarm signal from a pressure sensor (or a pressure
switch) the controller will energize a filter alarm relay and
illuminate the corresponding filter alarm LED in red color. The
controller may also sent a message through its communication port
to remote manager to make a request of filter change. Similarly, if
the temperature detected by the thermistor connected to Input Temp
1 reaches 44 Deg C. in reading, the controller will indicate an
over-temperature alarm via an over-temperature alarm relay and turn
the corresponding LED to be illuminated RED. In this situation, the
cooling of the shelter has been taken over by the A/C system
(assuming no AC power fault). However, certain message can be sent
to remote manager through the controller about the status of the
shelter. The over-temperature alarm will be turned off if the
temperature drops to 42 Deg C., all other functions of the
controller will remain as normal.
[0088] Many benefits can be achieved by embodiments of the present
invention. Certain embodiments of the invention provide a simple
addition of a direct air cooling system to existing
telecommunications shelters by mounting the fan tray on the door of
the shelter. The damper arrangement is conveniently mounted over
one of the existing cable ducts in order to allow the field upgrade
of the shelter. This structural design of the direct air cooling
system keeps the structural integrity of the existing telecom
shelter while providing a minimally invasive rework event. Some
embodiments of the present invention utilizing the direct air
cooling to provide a supplemental thermal management with
significant amount of energy saving and reduce overall system
operating cost. Because for quite portion of time period, the
operation of existing A/C system associated with the shelter are
inhibited and the shelter is cooled by the direct air cooling
system based on embodiments of the present invention. In a specific
embodiment, in the event of a power failure, the direct air cooling
system can continue to operate normally from the battery back up
allowing the entire shelter to operate for as long as there is
power in the battery. Comparing to conventional shelter with A/C
system only, the operation of the equipment within the shelter may
quickly become over-heated since no alternate cooling is
provided.
[0089] It is also understood that the examples and embodiments
described herein are for illustrative purposes only and that
various modifications or changes in light thereof will be suggested
to persons skilled in the art and are to be included within the
spirit and purview of this application and scope of the applied
claims.
* * * * *