U.S. patent application number 14/322107 was filed with the patent office on 2014-10-23 for switch-type interlock arrangement for controlling the neutral output of a portable generator.
The applicant listed for this patent is Reliance Controls Corporation. Invention is credited to Neil A. Czarnecki.
Application Number | 20140312695 14/322107 |
Document ID | / |
Family ID | 51301676 |
Filed Date | 2014-10-23 |
United States Patent
Application |
20140312695 |
Kind Code |
A1 |
Czarnecki; Neil A. |
October 23, 2014 |
Switch-Type Interlock Arrangement For Controlling The Neutral
Output Of A Portable Generator
Abstract
An interlock arrangement allows a floating neutral electrical
generator having a receptacle, such as a duplex receptacle, absent
GFCI protection to be used to provide electrical power to the
electrical system of a home or other building during utility power
interruption. The interlock arrangement includes structure to
disable or prevent access to the duplex receptacle when the
electrical generator is coupled to the power cord used to transfer
electrical power from the generator to the electrical system of the
building. Thus, the duplex receptacles cannot be used to power
electrical devices when the generator is connected to supply power
to the electrical system of the building. Conversely, when the
generator is physically disconnected from the electrical system of
the building, the interlock arrangement exposes or supplies power
to the duplex receptacles, and may be configured to close access to
the receptacle used for connecting to a building electrical
system.
Inventors: |
Czarnecki; Neil A.; (Mt.
Pleasant, WI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Reliance Controls Corporation |
Racine |
WI |
US |
|
|
Family ID: |
51301676 |
Appl. No.: |
14/322107 |
Filed: |
July 2, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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|
13038881 |
Mar 2, 2011 |
8810081 |
|
|
14322107 |
|
|
|
|
61393117 |
Oct 14, 2010 |
|
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61309624 |
Mar 2, 2010 |
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Current U.S.
Class: |
307/41 ;
200/50.31 |
Current CPC
Class: |
F02B 63/044 20130101;
H01R 25/006 20130101; H01R 13/447 20130101; H01R 13/703 20130101;
H01R 24/78 20130101; H02J 9/04 20130101; H01R 2103/00 20130101 |
Class at
Publication: |
307/41 ;
200/50.31 |
International
Class: |
H01R 13/703 20060101
H01R013/703; H02J 9/04 20060101 H02J009/04 |
Claims
1. A lockout arrangement to prevent simultaneous power output from
first and second receptacles a portable generator, comprising: a
switch associated with the first receptacle that selectively
disables the second receptacle; and an actuator coupled to the
switch that responds to engagement of a plug with the first
receptacle to trigger operation of the switch.
2. The lockout arrangement of claim 1 wherein the actuator includes
a pin that is biased to an extended position and that is depressed
when a plug is engaged with the first receptacle.
3. The lockout arrangement of claim 2 wherein the switch includes a
first set of contacts, a post operably coupled to the pin and an
armature that reciprocates between a first position and a second
position in response to movement of the post, and wherein the
armature includes a second set of contacts that engage the first
set of contacts when the first receptacle is not in use and are
spaced from the first set of contacts when a plug is engaged with
the first receptacle.
4. The lockout arrangement of claim 3 wherein the pin is biased to
the extended position by a spring.
5. An electrical generator comprising: a first operating
arrangement having a bonded neutral connection; a second operating
arrangement having a floating neutral connection; and a switch for
selectively switching the electrical generator between the first
operating arrangement and the second operating arrangement.
6. An electrical generator comprising: a current source; a first
receptacle electrically connectable to the current source, and
adapted to engage a power plug that controls the flow of electrical
current to a plurality of loads; a second receptacle electrically
connectable to the current source, and adapted to engage a power
supply associated with an electrical device; and a switch
interconnected between the first receptacle, the second receptacle,
and the current source, wherein the switch is movable between a
first position in which the first receptacle is electrically
connected to the current source to receive electrical power from
the current source and a second position in which the second
receptacle is electrically connected to the current source to
receive electrical power from the current source.
7. The electrical generator of claim 6 wherein the generator
includes an electrical circuit having a first line conductor, a
second line conductor, a ground conductor, and a neutral conductor,
and wherein the switch ties the ground conductor to the neutral
conductor when in the first position and wherein the switch
electrically isolates the ground conductor from the neutral
conductor when in the second position.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a divisional of U.S. Ser. No.
13/038,881, filed Mar. 2, 20111, which claims the benefit of U.S.
Ser. No. 61/393,117 filed Oct. 14, 2010 and U.S. Ser. No.
61/309,624 filed Mar. 2, 2010, the disclosures of which are
incorporated herein in their entirety.
BACKGROUND AND SUMMARY OF THE INVENTION
[0002] The present invention relates generally to electrical
generators that can provide backup electrical power to an
electrical system or that can be used as a stand-alone power supply
for powered accessories, such as power tools. More particularly,
the present invention is directed to an apparatus for selectively
disabling outputs of an electrical generator based on the type of
load placed on the electrical generator.
[0003] In today's electrical supply systems, there are occasions
when alternate sources of electrical power are necessary or
desirable. For example, the capability of switching from utility
power to emergency generator power is extremely important for many
businesses, hospitals and industries, as well as residential
dwellings. Engine driven electrical generators are commonly used to
provide backup or emergency electrical power in those instances
when utility power is interrupted. Additionally, portable
electrical generators allow electrical power to be provided at
locations where utility power is not available.
[0004] Electrical generators can generally be categorized as bonded
neutral generators or floating neutral generators. With a bonded
neutral electrical generator, the neutral conductor and the safety
ground conductor of the electrical generator are internally tied or
"bonded" together. For floating neutral generators, on the other
hand, the neutral conductor and the safety ground conductor are not
tied together. Bonded neutral generators are most commonly used on
construction sites and are popular among the professional trades.
Floating neutral generators are typically used by homeowners either
to provide backup power to electrical loads through the wiring
system of the home or building or to power cord connected
devices.
[0005] Portable electrical generators will typically have a
dedicated receptacle or socket that is designed for larger loads
and to engage with a power cord that is electrically coupled either
to the electrical system of the building, typically through a
transfer switch and panel, or to some other distribution system
such as a distribution box for a number of cord connected devices.
For most portable electrical generators, a multipole locking
receptacle is used to engage and lock the male end of the power
cord to prevent accidental disconnection of the power cord from the
electrical generator. Via the interconnection of the male end of
the power cord with the multipole locking receptacle or socket, the
live conductors of the electrical generator will be electrically
connected to appropriate poles of the transfer switch and panel.
When connecting a floating neutral generator to a building's wiring
system as a non separately derived system, the neutral conductor
will be electrically connected to the neutral bus of the service
entrance or main panel generally through the transfer panel and the
ground conductor will be connected to the ground bus of the service
entrance or main panel also generally via the transfer panel. Thus,
the electrical generator is "grounded" via electrical connection
with the ground bus of the service entrance or main panel.
[0006] In a non-separately derived arrangement such as that
described above, when a bonded neutral electrical generator is
supplying electrical power to one or more loads of the building
through the building wiring system, electrical current will return
via the neutral conductor of the load to the neutral bus conductor
of the main electrical panel. A first portion of electrical current
then flows from the neutral bus conductor of the building back to
the neutral conductor of the generator, thus completing a circuit
path. A remaining portion of electrical current flows from the
neutral bus conductor of the building to a neutral-to-ground tie
bar at the electrical panel, through the grounding bus conductor,
back through the safety ground-to-neutral bonding conductor of the
generator, and then through the neutral conductor of the generator,
completing another circuit path. As provided in the United States
National Electrical Code, Article 250, a power system should be
electrically grounded in such a manner that prevents a flow of
electrical current via the neutral conductor of the building back
to the safety grounding conductor of the generator, in all
situations except for an electrical power fault (q.v., Article 250
of the National Electrical Code). The safety grounding conductor is
expected to be pristine or absent of the normal flow of electrical
current, and instead is to be used to conduct electrical current
safely to ground only when there is an electrical fault occurrence.
Thus, the use of bonded neutral generators to supply backup
electrical power to the electrical system of a home or other
building requires a system that switches the neutral, know as a
separately derived system. This system is more costly to buy and
install.
[0007] Portable electric generators will typically have one or more
duplex receptacles in addition to the multipole locking receptacle
for receiving the male end of an extension cord or the power cord
of an electrical device. As known in the art, the duplex
receptacles allow electrical devices to be powered directly by the
electrical generator rather than through a building wiring system.
In most instances, the duplex receptacles are designed to receive a
three-prong plug of a power cord. In this regard, each socket of
the duplex receptacle is designed to receive a hot conductor,
neutral conductor, and ground conductor of a conventional male end
of a three-prong plug. As is known, each socket of the duplex
receptacle is also capable of receiving a non-grounded plug of a
power cord.
[0008] Floating neutral electrical generators are typically not
grounded, i.e., not only is the neutral not connected to the safety
ground but the safety ground is also not connected to earth because
the generator frame is not conductively connected to earth such as
through a grounding rod. As a result, when the generator is used as
a stand-alone power supply or providing electrical power directly
to one or more electrical devices without an electrical connection
to the electrical wiring system of the building, ground fault
protection is unnecessary because a path for current to flow back
to the generator does not exist through the ground. In other words,
ground fault protection is built into the system through isolation
of the neutral wire from the ground thereby eliminating the need
for duplex receptacles incorporating ground fault circuit
interrupter (GFCI) devices. However, when a floating neutral
generator is connected to the electrical system of a building, the
generator becomes grounded through its electrical connection to the
electrical system of the building. As a result, there can be a
ground fault risk when a floating neutral generator is connected to
the electrical system of a building. One way to reduce this risk on
floating neutral generators is to equip them with duplex
receptacles that include GFCI devices, which can be costly and are
only needed when the generator is connected to a building.
[0009] Increasingly, the professionals and homeowners have demanded
a single generator capable of being used for both construction and
for backup power supply for the electrical system of a home,
apartment, or other building when utility power is interrupted.
They all would prefer to install the generator in a non separately
derived system as this is the most common and economical
installation. For a floating neutral generator to accomplish this
task, costly GFCI protected duplex receptacles should be used for
ground fault protection when the generator is connected to the
electrical system of the home or building. Since bonded neutral
generators internally bond the neutral and ground conductors,
costly GFCI devices are also used to provide ground fault
protection primarily in construction applications where they are
now required by the NEC. Moreover, it has been found that
connecting a bonded neutral generator to the electrical system of a
home or building as a non separately derived system can result in
"false" triggering of ground faults. That is, the flow of
electrical current to the safety grounding conductor of the
generator has been known to trigger a ground fault circuit
interrupter at the generator. When triggered, the ground fault
circuit interrupter will de-energize the live conductors of the
generator and prevent the supply of electrical power to the
circuits connected to the transfer equipment. To avoid this
nuisance tripping of the GFCI, the consumer must un-tie the bonding
of the generator neutral and the generator ground. Many consumers
are hesitant to tackle such a task and, moreover, it requires the
consumer to remember to retie the generator neutral and the
generator ground when the electrical generator is used to power
electrical equipment directly rather than through the wiring of the
home or building.
[0010] The present invention provides an interlock arrangement that
allows a floating neutral electrical generator having a receptacle,
such as a duplex receptacle, absent GFCI protection to be safely
used to provide electrical power to the electrical system of a home
or other building during utility power interruption. More
particularly, the interlock arrangement includes structure to
prevent access to the duplex receptacle when the electrical
generator is coupled to the power cord used to transfer electrical
power from the generator to the electrical system of the home.
Thus, the duplex receptacles cannot be used to power tools or other
electrical devices when the generator is connected to supply power
to the electrical system of the home or building. However, when the
generator is physically disconnected from the electrical system of
the home or building, the interlock arrangement exposes the duplex
receptacles thereby enabling their use.
[0011] The invention also provides structure to switch an
electrical generator between a bonded neutral arrangement and a
floating neutral arrangement. Moreover, the structure prevents the
simultaneous availability of electrical power at both the multipole
locking (or similar) receptacle used to connect the electrical
generator to the electrical system of the home or building and the
duplex receptacle(s). In this regard, the invention provides
structure that unties the generator neutral and generator ground
when the electrical generator is being used to supply backup or
emergency electrical power to a home or building through its
electrical system and ties the generator neutral and the generator
ground when the electrical generator is disconnected from the
electrical system of the home or building.
[0012] It is therefore an object of the invention to provide an
interlock arrangement for use with an electrical generator that
expands the usability of the electrical generator without requiring
user modification of the internal wiring of the electrical
generator.
[0013] It is another object of the invention to provide an
interlock arrangement that prevents use of duplex receptacles of
the generator when the generator is connected to provide emergency
or backup power to a home or building.
[0014] It is a further object of the invention to provide an
electrical generator switchably usable as a floating neutral
generator or a bonded neutral generator.
[0015] Various other features, objects and advantages of the
present invention will be made apparent from the following detailed
description of the drawing figures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The drawings illustrate one preferred embodiment presently
contemplated for carrying out the present invention.
[0017] In the drawings:
[0018] FIG. 1 is a schematic representation showing a power
management system for switchably providing electrical power from a
utility and an auxiliary power supply, such as a portable
electrical generator, to a load center or electrical panel
associated with a building;
[0019] FIG. 2 is a side elevation view of the electrical generator
for use with the power management system of FIG. 1 according to one
aspect of the invention;
[0020] FIG. 3 is a partial enlarged elevation view of the
electrical generator showing an interlock arrangement preventing
access to a duplex receptacle according to one embodiment of the
invention;
[0021] FIG. 4 is an enlarged elevation view of the electrical
generator similar to FIG. 3, showing the interlock arrangement
preventing access to a multipole locking receptacle according to
one embodiment of the invention;
[0022] FIG. 5 is a section view of the electrical generator taken
along line 5-5 of FIG. 2;
[0023] FIG. 6 is a front elevation view of a multipole locking
receptacle according to another embodiment of the invention;
[0024] FIG. 7 is a section view of the multipole locking receptacle
taken along line 7-7 of FIG. 6;
[0025] FIG. 8 is a schematic diagram of a power distribution
arrangement for the electrical generator using the twist-lock
receptacle of FIGS. 6-7 according to an embodiment of the
invention;
[0026] FIG. 9 is a schematic diagram of a switch arrangement to
selectively energize outputs of the electrical generator according
to another embodiment of the invention; and
[0027] FIG. 10 is a schematic diagram of a switch arrangement for
switching an electrical generator between a bonded-neutral
configuration and a floating-neutral configuration.
DETAILED DESCRIPTION
[0028] FIG. 1 shows a power inlet arrangement for interconnecting a
portable generator 10 with a main electrical panel or load center
12 located in the interior of a building 14. In the power inlet
arrangement of FIG. 1, a power transfer panel 16 is mounted
adjacent main panel 12, and is interconnected therewith via a
series of wires enclosed by a conduit 18 extending between main
panel 12 and transfer panel 16. Transfer panel 16 may
illustratively be a panel such as that manufactured by Reliance
Controls Corporation of Racine, Wis.
[0029] A power inlet box 20 is mounted to the wall of building 14,
shown at 22. Power inlet box 20 includes an external housing
including a series of walls such as 24, and a receptacle 26 mounted
to a front wall of the housing. A cover 28 is mounted to the front
wall of the housing via a hinge structure, and is movable between
an open position as shown in FIG. 1 and a closed position in which
cover 28 encloses receptacle 26 when not in use. A conduit 30
extends between inlet box 20 and a junction box 32, and a flexible
cord 38 is attached at one end to junction box 32. At its opposite
end, flexible cord 38 has a connector 42 engageable with a power
inlet receptacle provided on transfer panel 16. Appropriate wiring
and connections are contained within inlet box 20, conduit 30 and
junction box 32 for providing an electrical path between inlet box
20 and transfer panel 16 when cord 38 is engaged with the inlet
receptacle of transfer panel 16.
[0030] A power cord 44 extends between generator 10 and power inlet
box 20. Cord 44 includes a plug 46 at one end, which is engageable
with the power outlet of generator 10. As will be described more
fully below, the electrical generator 10 has a multipole locking
receptacle (not shown) with which the plug 46 is engaged and
locked, in order to electrically connect the generator 10 to the
power inlet box 20. Cord 44 further includes a connector 48 at the
end opposite plug 46. Connector 48 is engageable with receptacle 26
for transferring power generated by generator 10 to power inlet box
20, which is then supplied through the wiring in conduit 30,
junction box 32, cord 38 and connector 42 to transfer panel 16, and
from transfer panel 16 through the wiring in conduit 18 to main
panel 12. In this manner, generator 10 functions to provide power
to selected circuits of main panel 12 during a power outage. In
this arrangement, the user first connects cord 38 to the power
input of transfer panel 16 utilizing connector 42, and then exits
the building, connects cord 44 between generator 10 and power inlet
20, and then commences operation of generator 10. In addition to
the aforementioned multipole locking receptacle 46, the electrical
generator 10 also includes duplex receptacles 50 that allow the
electrical generator 10 to provide electrical power to one or more
power accessories when such accessories are plugged into the duplex
receptacles 50. As will be described, the electrical generator 10
includes structure that prevents simultaneous use of the multipole
locking receptacle 46 and the duplex receptacles 50.
[0031] Turning now to FIG. 2, the electrical generator 10 is
designed to be a portable power supply and thus has a frame 52
supported by a wheels 54. Forward of the wheels 54 are feet 56 that
are mounted to a lower portion of the frame 52 and provide
stability for the electrical generator 10 when placed in position.
As known in the art, the electrical generator 10 has an internal
combustion engine (not shown) enclosed within a housing structure
58 that is carried by the frame 52 in a conventional manner. The
internal combustion engine creates mechanical energy that is
converted in a known manner to electrical energy that is made
available at multipole locking receptacle 46 and duplex receptacle
50. In contrast to conventional electrical generators, the present
invention provides an electrical generator 10 having structure that
prevents simultaneous use of the multipole locking receptacle 46
and the duplex receptacles 50. In this regard, when the multipole
locking receptacle 46 is being used to feed electrical current to
power cord 44, electrical accessories or devices cannot be powered
through the duplex receptacles 50. Similarly, when electrical
accessories or devices are plugged into the duplex receptacles 50,
electrical power cannot be provided to the power cord 44.
[0032] In one embodiment of the invention, the electrical generator
10 has a pair of duplex receptacles 50; however, the invention is
not so limited and may have any number of duplex receptacles. In
addition, it is understood that the generator 10 may have
receptacles other than duplex receptacles, although it is
understood that duplex receptacles are most commonly employed. Each
duplex receptacle 50 may include a pair of outlets or sockets 60
that are stacked vertically. The sockets 60 could also be oriented
horizontally. The sockets 60 are mounted to the housing 58 in a
conventional manner and are located generally adjacent the
multipole locking receptacle 46. As known in the art, each socket
60 typically has a live conductor, a neutral conductor, and a
ground conductor. In one embodiment, the neutral conductors for
each of the sockets 60 are not connected to the generator frame 52.
The generator frame 52 itself is typically not grounded (connected
to Earth) so, in accordance with the invention, the duplex
receptacles 50 do not have GFCI devices. That is, when the
generator is used without an electrical connection to the building
wiring system, GFCI protection is not needed because a path for
current to flow back to the generator does not exist through the
ground. Essentially, ground fault protection is built into the
system through isolation of the neutral wire from the ground, thus
eliminating the need for a GFCI device. The multipole locking
receptacle 46, on the other hand, is only used when providing
electrical power to the building wiring system and is afforded
ground fault protection via that connection. However, when the
generator 10 is electrically connected to the building wiring
system, the generator neutral becomes connected to the ground.
Conventional electrical generators can avoid ground faults in such
an instance by relying upon a GFCI device, which is relatively
costly. As will be described more fully below, the present
invention avoids the need for such a GFCI device by locking out use
of the duplex receptacles 50 when the electrical generator 46 is
coupled to power cord 44.
[0033] The present invention provides a lockout arrangement that
disables or locks out operation of the non-GFCI duplex receptacles
50 when the generator 10 is coupled to the wiring system of a
building (and therefore is grounded). In other words, when the
power supply 44 that is interconnected with the building wiring
system is engaged with the multipole locking receptacle 46, the
lockout arrangement disables or locks out operation of the outlets
60 and thus prevents an electrical device from being powered by the
generator using the duplex receptacles 50. Thus, the non-grounded
receptacles 50 cannot be used when the multipole locking receptacle
46 is connected to power cord 44. On the other hand, when the
electrical generator 10 is not connected to power cord 44, the
outlets 50 are available for use.
[0034] The disabling or lockout arrangement of the present
invention may take many forms, a few of which will be described
herein. It should be understood, however, that the embodiments
described herein are merely exemplary and are not intended to limit
the invention as defined by the appending claims in any way.
[0035] With reference now to FIGS. 2-5, in one embodiment, a
lockout arrangement 62 includes a lockout member in the form of a
plate 64 that is movably mounted to the generator 10. In the
illustrated embodiment, the lockout plate 64 is slidable between
two positions, although it is understood that any other
satisfactory type of movement may be employed. In the first
position, the plate 64 is positioned over the duplex receptacles
50, but exposes the multipole locking receptacle 46, as shown in
FIG. 3. In the second position, the plate 64 is positioned over the
multipole locking receptacle 46, but exposes the duplex receptacles
50, as shown in FIGS. 2 and 4. The lockout plate 64 is configured
such that only one of the multipole locking receptacle 46 and the
duplex receptacles 50 can be exposed at a time. As a result, to
expose the multipole locking receptacle 46, the lockout plate 64
must be manually moved to the first position, which results in the
lockout plate 64 covering the duplex receptacles 50 so that the
duplex receptacles 50 cannot be accessed. Similarly, to expose the
duplex receptacles 50, the lockout plate 64 must be manually moved
to the second position, which results in the lockout plate 64
covering the multipole locking receptacle 46 so that the multipole
locking receptacle 46 cannot be accessed. Accordingly, it is not
possible for both the multipole locking receptacle 46 and the
duplex receptacles 50 to be exposed and used at the same time.
[0036] In accordance with this embodiment, the lockout arrangement
62 includes a pin 66 that extends outwardly from the face of the
generator housing 58. The lockout plate 64 includes a slot or
channel 68, and the pin 66 extends through the channel 68 in a
manner that allows the plate 64 to slide along the pin 66 between
the first and second positions by engagement of the pin 66 with the
ends of the channel 68. It is understood, of course, that pin 66
and channel 68 are representative of any number of satisfactory
movable engagement arrangements that may be interposed between
generator housing 58 and lockout plate 64 for providing movement of
lockout plate 64 between the first and second positions.
[0037] In the illustrated embodiment, the duplex receptacles 50 and
the multipole locking receptacle 46 are positioned side-by-side and
thus the lockout arrangement 62 is oriented so that that the
lockout plate 64 slides side-to-side. It is also contemplated that
the duplex receptacles and the multipole locking receptacle can
also be in a stacked (up-down) or angularly offset configuration.
In a stacked configuration, the lockout arrangement 62 would be
oriented so that the channel 68 is oriented vertically, i.e.,
perpendicular to the orientation shown in FIGS. 3-4. This
orientation would allow the lockout plate 64 to slide vertically to
selectively expose the multipole locking receptacle 46 and the
duplex receptacles 50. In an angularly offset configuration, the
lockout arrangement 62 would slide at an angle to selectively
expose the multipole locking receptacle 46 and the duplex
receptacles 50.
[0038] While lockout arrangement 62 is shown and described as an
external assembly that is configured to overlie the openings of
multipole locking receptacle 46 and duplex receptacles 50, it is
also understood that an internal lockout arrangement is
contemplated as being within the scope of the present invention. In
such an arrangement, for example, it is contemplated that the
openings of the multipole locking receptacle 46 and the duplex
receptacles 50 may be exposed but that the lockout member would
prevent the plug prongs from being inserted into the receptacle
openings.
[0039] It will be appreciated that the lockout arrangement 62
mechanically closes off access to one of the duplex receptacles 50
or the multipole locking receptacle 46. In this regard, electrical
power is simultaneously available at both receptacles but only one
of the receptacles can be accessed.
[0040] Referring now to FIGS. 6-8, in accordance with another
embodiment of the invention, the lockout arrangement is in the form
of a multipole locking receptacle 70 usable with the electrical
generator 10 and having a pushbutton 72 that is generally centered
between the slotted openings 74 formed in the front face 76 of the
receptacle 14. As shown at FIG. 8, the pushbutton 20 is biased
toward an outward or extended position. In the default position,
the lockout arrangement allows electrical power to be available at
the outlets 60 of the duplex receptacles 50. On the other hand,
when the pushbutton 72 is depressed (pushed inward), such as due to
engagement by the plug 46 of the power cord 40, electrical power is
unavailable at the outlets 60 so that even if a power plug of an
accessory (not shown) is plugged into one of the outlets 60, the
accessory will not be powered. The pushbutton 72 is automatically
pushed inward when the power cord 44 is plugged into the receptacle
70. Thus, the outlets 60 are automatically disabled and a user is
not required to separately engage the pushbutton 72.
[0041] With particular reference to FIG. 7, the pushbutton 72 is
generally comprised of a post 78 and an armature 80 coupled to a
distal end of the post 78 and that is biased in the extended
position by a spring 82. The armature 80 is made of electrically
conductive material and includes a pair of contacts 84(a), 84(b)
that selectively engage stationary contacts 86(a), 86(b),
respectively, when the pushbutton 72 is in the extended position.
In this regard, when the spring 82 biases the post 78, and thus the
pushbutton 72, to the extended position, the armature 80 is drawn
outwardly so that its contacts 84 are in engagement with contacts
86. In this position, the armature 80 and the contacts 84, 86
effectively close the circuit path between the contacts 86(a) and
86(b). As schematically shown in FIG. 8, contacts 86(a) and 86(b)
are coupled to respective portions of the "hot" wire 88 that
carries electrical current to the duplex receptacles 50, of which
only one is shown for illustration purposes. More particularly,
contact 86(a) through wire portion 88(a) is connected to the
current generator 90 of the generator 10 whereas contact 86(b)
through wire portion 88(b) is connected to the duplex receptacle(s)
50. When contacts 84, 86 are engaged, electrical current is
permitted to flow from the current generator 90 to the duplex
receptacle(s) 50.
[0042] On the other hand, when power plug 44 is plugged into the
multipole locking receptacle 70, the pin 72 is depressed which
causes the post 78 to overcome the bias of the spring 82 and move
inwardly (left-to-right in FIG. 7). This movement of post 78 causes
the armature 80 to move away from contacts 86, and thus form a gap
between contacts 84 and 86. This movement of post 78 thus creates
an open circuit condition in wire 88 and prevents the flow of
electrical current to the duplex receptacle(s) 50. In this manner,
power is not supplied to duplex receptacles 50 when power plug 44
is plugged into multipole locking receptacle 70.
[0043] When the power plug 44 is unplugged from the multipole
locking receptacle 70, the force tending to maintain pin 72 in the
depressed position is removed, and the bias of the spring 82 forces
the post 78 and thus pin 72 outwardly (right-to-left in FIG. 7).
This movement of post 78 causes the armature 80 to follow such
movement, and results in engagement of contacts 84 against contacts
86. This movement effectively resets the lockout arrangement,
whereupon electrical current is free to flow to the duplex
receptacle(s) 50. Thus, when the multipole locking receptacle 70 is
not in use, power can be available at the duplex receptacles
50.
[0044] It will thus be appreciated that the pushbutton 72, post 78,
and armature 80 effectively form a switch that is switchable
between an ON position when multipole locking receptacle 70 is not
in use, and an OFF position when multipole locking receptacle 70 is
in use. In the ON position, contacts 84 and 86 are held against
each other to allow electrical current flow through wire 88 to
duplex receptacle(s) 50. In the OFF position, the contacts 84 and
86 are spaced from each other to create an open circuit in wire 88
that prevents the flow of electrical current to duplex
receptacle(s) 50. It will be appreciated that other types of
switching arrangements may be used and are considered within the
scope of the invention. For example, a proximity sensor could be
used to sense insertion of a power plug into the multipole locking
receptacle 46 and the sensor could provide control signals to a
switch (not shown) to create an open circuit in wire 88.
[0045] Turning now to FIG. 9, in another embodiment, the lockout
arrangement includes a three-pole switch 92 mounted to the
generator 10 that is used to selectively switch the duplex
receptacle(s) 50 and the multipole locking receptacle 46 to the
electrical output of the generator 10, schematically shown at 94.
The three-pole switch 92 has a generally conventional design, and
thus includes movable "hot" contacts 96, 98, and a neutral contact
100 that interface with either stationary contacts 102, 104, and
106, respectively, for the duplex receptacle 50 or with stationary
contacts 108, 110, and 112, respectively, of the multipole locking
receptacle 46. In one embodiment, the movable contacts 96, 98, and
100 are mounted to a common bridge (not shown) so that the movable
contacts switch in unison.
[0046] The three-pole switch 92 is switchable between two
positions. In the first position, the movable contacts 96, 98, 100
are engaged with the contacts 102, 104, 106, respectively, of the
duplex receptacle 50 so that electrical power from the generator
output 94 is available at the duplex receptacle 50. In the second
position, the movable contacts 96, 98, 100 are engaged with
contacts 108, 110, 112, respectively, of the multipole locking
receptacle 46 so that electrical power from the generator output 94
is available at the multipole locking receptacle 46. The three-pole
switch 92 cannot be in both the first and second positions at the
same time. Thus, regardless of whether power plugs are engaged with
both the duplex receptacle 50 and the multipole locking receptacle
46, electrical power will only be available at one of the
receptacles, as determined by the position of the three-pole switch
92.
[0047] As referenced above, the three-pole switch 92 includes a
movable contact 100 for the neutral conductors (contacts) of the
duplex receptacle 50 and the multipole locking receptacle 46. In
this regard, the three-pole switch 92 switches the "neutrals". This
is necessary when the building power cord is engaged with the
multipole locking receptacle 46 but utility power is being used to
power the loads in the building, and a user desires to use the
generator 10 to power an accessory via the duplex receptacle 50
without disconnecting the building power cord from the generator
10. In such a situation, the generator neutral feeding the duplex
receptacle 50 would not be grounded by the cord connected to both
the multipole locking receptacle 46 and the building wiring system.
When the neutral contact 100 is switched to engage contact 106 for
the duplex receptacle 50, the connection between the neutral
contact 100 and the multipole locking receptacle 46 would be lost,
and the duplex receptacle 50 would be protected against ground
fault without the need for a GFCI device. For such an embodiment,
it is preferred that a throw or similar mechanism (not shown) be
incorporated into the three-pole switch 92 such that switching the
hot contacts 96, 98 to engage contacts 108, 110 for the multipole
locking receptacle 46 would cause the neutral contact 100 to
disengage from contact 106 for the duplex receptacle 50 and engage
contact 112 for the multipole locking receptacle 46. Thus, anytime
the three-pole switch 92 connects the generator output 94 to the
multipole locking receptacle 46, the neutral contact 100 is engaged
with corresponding neutral contact 112.
[0048] As described above, bonded-neutral generators may have
duplex receptacles with GFCI protection, whereas floating neutral
generators typically do not. GFCI protection may be needed to
provide ground fault protection when the generator is electrically
connected to the electrical system of a building. GFCI devices can
be costly and thus add to the cost of the generator, which is
ultimately passed onto the consumer. As described above, in one
embodiment of the invention, a switching and lockout arrangement is
provided that allows a bonded neutral generator without GFCI
devices to be electrically connected to the electrical system of a
building. The switching and lockout arrangement prevents access to
and/or operation of the non-GFCI protected duplex receptacles of
the generator when the generator is electrically connected to the
electrical system of the building.
[0049] In another embodiment, the invention provides a switching
and lockout arrangement that, in addition to selectively disabling
one or the other of the receptacles, selectively switches the
generator between a bonded neutral arrangement and a floating
neutral arrangement. As will be made apparent from the following
description, the present invention allows a user to selectively
take advantage of the benefits of a bonded neutral generator and a
floating neutral generator in a single generator machine. In one
embodiment, the generator has duplex receptacles 50, which
typically will be provided with GFCI protection. As will be
described, however, the duplex receptacles are isolated from the
generator output when the generator is electrically connected to
the electrical system of a building via the multipole locking
receptacle.
[0050] Referring now to FIG. 10, the switching and lockout
arrangement employs a three-pole switch 114 movable between a first
position in which line conductors L.sub.1, L.sub.2 are connected to
the corresponding input conductors of the duplex receptacles 50 and
a second position in which the line conductors L.sub.1, L.sub.2 are
connected to the corresponding input conductors of the multipole
locking receptacle 46. The three-pole switch 114 also selectively
switches the ground conductor G to be bonded or "tied" to the
neutral conductor of the generator or electrically isolated
("floating") from the neutral conductor of the generator. When the
three-pole switch 114 is in the first position, i.e. the bonded
neutral position, which is illustrated in FIG. 10, the ground
conductor is electrically connected to the neutral conductor. In
this first position, the electrical output of the generator is
therefore available at the duplex receptacles 50. On the other
hand, when the three-pole switch 114 is in the second or floating
position (not shown), the ground conductor is disconnected from the
neutral conductor and thus "floating". Moreover, in this second
position, the electrical output is available at the multipole
locking receptacle 46. It will therefore be appreciated that the
invention provides a generator that provides power at one or the
other of the duplex receptacles 50 (in a bonded neutral
configuration) or the multipole locking receptacle 46 (in a
floating neutral configuration), and that is switchable between the
bonded neutral configuration and the floating neutral configuration
depending on the location of the power output, i.e. duplex
receptacles 50 or multipole locking receptacle 46.
[0051] The three-pole switch 114 can be of known design, and thus
includes movable contacts 116, 118, and 120 corresponding to line
conductor L.sub.1, line conductor L.sub.2, and ground conductor G,
respectively. The contacts 116, 118, and 120 are preferably carried
by a shared or interlinked contact bridge (not shown), so that the
contacts 116, 118, and 120 move in unison when the switch 114 is
moved between positions. In this regard, when the three-pole switch
114 is in the first position so that electrical power is available
at the duplex receptacles 50, the ground conductor is automatically
tied to the neutral conductor. On the other hand, when the
three-pole switch 114 is in the second position, electrical power
is only available at the multipole locking receptacle 46 and the
ground conductor is not tied to the neutral conductor, i.e.,
"floating".
[0052] It is understood that the switching and lockout arrangements
described above can incorporate one or more of the lockout devices
and features described herein to mechanically prevent physical
access to the duplex receptacles and the multipole locking
receptacle. In one embodiment, the lockout and the three-pole
switch 114 may be interlinked.
[0053] Many changes and modifications could be made to the
invention without departing from the spirit thereof. The scope of
these changes will become apparent from the appended claims.
* * * * *