Information
-
Patent Grant
-
6680445
-
Patent Number
6,680,445
-
Date Filed
Thursday, December 26, 200221 years ago
-
Date Issued
Tuesday, January 20, 200420 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
-
CPC
-
US Classifications
Field of Search
US
- 200 4301
- 200 4311
- 200 4314
- 200 4316
- 200 4319
- 200 4322
-
International Classifications
-
Abstract
A circuit breaker mechanical interlock apparatus is provided for preventing an electrical system from being energized by more than one of a plurality of power sources at any given time. The apparatus includes a housing that defines a receptacle for receiving two or more circuit breakers having actuating switches for energizing the electrical system. The apparatus further includes one or more interlock slides movably mounted on the housing and a faceplate for restricting unauthorized access to the slides. The number of interlock slides is one fewer than the number of circuit breakers so that the slides can be positioned to provide access to only one of the switches of the circuit breakers, while the remaining switches of the circuit breakers cannot be accessed. Each of the switches of the circuit breakers can be individually accessed without the slides extending beyond the periphery of the housing.
Description
FIELD OF THE INVENTION
The present invention relates generally to a mechanical interlock apparatus for two or more circuit breakers. More particularly, the invention relates to an improved mechanical interlock for two or more switch-type circuit breakers that reduces the amount of space required to operate the mechanical interlock, while still providing easy access for replacement of individual circuit breakers and preventing dismantling using ordinary hand tools.
BACKGROUND OF THE INVENTION
It is common to restrict the movement, and thereby prevent the unintended operation, of switch-type circuit breakers. It is particularly desirable to prevent the unintended operation of a switch-type circuit breaker when more than one power source is available to provide electrical service. For example, secondary power sources, such as emergency or back-up generators, are commonly employed to maintain LifeLine Support (e.g., 911 emergency telephone service) in the event that the primary power source, typically commercial utility power, is interrupted. If the primary and secondary power sources are not prevented from being energized at the same time, referred to herein as “interlocked,” electrical power can flow unexpectedly and cause damage to equipment or serious injury to personnel. A circuit breaker interlock apparatus is utilized to ensure that no more than one power source energizes the electrical system at the same time. Although electrically activated circuit breaker interlocks may be utilized to automatically isolate multiple power sources, there are situations when a mechanically activated interlock is preferred. A mechanically activated circuit breaker interlock, referred to herein as a “circuit breaker mechanical interlock,” is typically less costly to install and maintain, and is equally reliable as long as there are service personnel present to operate the mechanical interlock.
Known circuit breaker mechanical interlock apparatus isolate one or more circuit breakers and thereby prevent more than one power source from energizing an electrical system at the same time. In particular, known mechanical interlock apparatus prevent more than one switch-type circuit breaker from being operated at any given time. An example of such a circuit breaker mechanical interlock apparatus is shown and described in U.S. Pat. No. 6,069,328, which is assigned to the assignee of the present invention. The circuit breaker mechanical interlock apparatus includes a housing that defines a receptacle for receiving two or more switch-type circuit breakers mounted in parallel, linear alignment and an interlock plate positioned adjacent the switches of the circuit breakers. The interlock plate has an opening that is sized to provide access to only one of the switches at a time. The interlock plate is moveable on the housing relative to the circuit breakers between a first position wherein one of the switches of the switch-type circuit breakers is accessible through the opening, but the remaining switches are not, and a second position wherein a different one of the switches of the switch-type circuit breakers is accessible through the opening, but the remaining switches are not.
The interlock plate shown and described in U.S. Pat. No. 6,069,328 cannot be moved from the first position to the second position unless all of the switches are in an “OFF” or “NEUTRAL” position such that the electrical system is not energized. Once the interlock plate is moved from the first position to the second position, the switch that is accessible through the opening in the second position may then be moved to the “ON” position. However, as illustrated by the phantom lines in FIG. 2 of the U.S. Pat. No. 6,069,328 , the interlock plate extends substantially beyond the perimeter of the housing when the interlock plate is positioned to access the left-most circuit breaker. Obviously, the interlock plate will extend substantially beyond the perimeter of the housing when the interlock plate is similarly positioned to access the right-most circuit breaker. As a result, a lateral space greater than the width defined by the perimeter of the housing is required to operate the circuit breaker mechanical interlock. Of course, the width of the housing could simply be increased to accommodate the lateral movement of the interlock plate. Alternatively, the circuit breakers could be mounted vertically to conserve lateral space. However, the increased width of the housing (or the increased height of the housing if the circuit breakers are arranged vertically) would likewise interfere with the operation and/or placement of other components of the electrical power system whenever dense packaging is required. Thus, while the apparatus of the U.S. Pat. No. 6,069,038 is suitable for use in many instances, there are situations in which there is insufficient space available adjacent the housing to operate such a circuit breaker mechanical interlock. Accordingly, a circuit breaker mechanical interlock apparatus is needed that reduces the amount of space required to operate the mechanical interlock, without unnecessarily increasing the overall width of the apparatus.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be described in conjunction with the accompanying drawings in which like reference numerals represent the same or similar parts in the various views. The drawings, which are incorporated in and constitute a part of this specification, provide a further understanding of the invention, illustrate various embodiments of the invention, and, together with the description, help to fully explain the principles and objects thereof. More specifically:
FIG. 1
is a perspective view of a circuit breaker mechanical interlock apparatus according to the invention mounted within an exemplary electrical enclosure;
FIG. 2
is a perspective view of a preferred embodiment of a circuit breaker mechanical interlock apparatus constructed in accordance with the invention;
FIG. 3
is a front elevation view of the circuit breaker mechanical interlock apparatus of
FIG. 2
;
FIG. 4
is a partial sectional view of the circuit breaker mechanical interlock apparatus of
FIG. 2
taken along the line
4
—
4
of
FIG. 3
;
FIG. 5
is a partial sectional view of the circuit breaker mechanical interlock apparatus of
FIG. 2
taken along the line
5
—
5
of
FIG. 4
;
FIG. 6
is a partial sectional view of the circuit breaker mechanical interlock apparatus of
FIG. 2
taken along the line
6
—
6
of
FIG. 3
;
FIG. 7
is a top view of the circuit breaker mechanical interlock apparatus of
FIG. 2
;
FIG. 8
is a front view of the circuit breaker mechanical interlock apparatus of
FIG. 2
illustrating a first operational position of the interlock slides wherein the switch of the right-hand circuit breaker is accessible, but the switches of the remaining circuit breakers are not;
FIG. 9
is a front view of the circuit breaker mechanical interlock apparatus of
FIG. 2
illustrating a second operational position of the interlock slides wherein the switch of the center circuit breaker is accessible, but the switches of the remaining circuit breakers are not; and
FIG. 10
is a front view of the circuit breaker mechanical interlock apparatus of
FIG. 2
illustrating a third operational position of the interlock slides wherein the switch of the left-hand circuit breaker is accessible, but the switches of the remaining circuit breakers are not.
DETAILED DESCRIPTION OF THE INVENTION
The invention is described more fully hereinafter with reference to the accompanying drawings, in which one or more preferred embodiments of the invention are shown. The invention may, however, be embodied in many different forms, and therefore, should not be construed as being limited to the any embodiment shown and described herein. One or more illustrative embodiments are set forth herein so that this description will be thorough and complete, and will fully convey the best mode of the claimed invention, while enabling those skilled in the art to make and practice the invention without undue experimentation.
Referring now to the accompanying drawings, a circuit breaker mechanical interlock apparatus, indicated generally at
10
, is shown in
FIG. 1
mounted within a conventional electrical enclosure
100
. The electrical enclosure
100
may be any structure for housing power equipment, such as a power and transfer switch cabinet, examples of which include the PowerPedestal™ Universal AC Power and Transfer Switch Cabinet and the SlimPed™ Universal Power Transfer Pedestal available from Corning Cable Systems of Hickory, N.C. Typically, the electrical enclosure
100
is mounted to a wall inside a building, for example, a power transfer facility or a telephone company network office, by a plurality of mounting flanges
102
. However, the electrical enclosure
100
may also be pad mounted or pole mounted, as is well known to those skilled in the art. Regardless, the electrical enclosure
100
is electrically connected to more than one source of electrical power for energizing an electrical system, such as a telephone network. Furthermore, other electrical components (not shown) are mounted within the electrical enclosure
100
adjacent to the mechanical interlock apparatus
10
for receiving, switching and distributing electrical power to at least one electrical system.
A preferred embodiment of the mechanical interlock apparatus
10
constructed in accordance with the invention is shown in
FIGS. 2-7
. The mechanical interlock apparatus
10
comprises a housing
20
and an interlock assembly
40
. The interlock assembly
40
comprises at least one interlock slide
42
that is movably mounted on the housing
20
, for a purpose to be described hereinafter. The housing
20
is made of a rigid material such as metal, plastic or composite, and preferably is made of a relatively thin sheet metal, such as aluminum. The housing
20
comprises a back wall
22
and a pair of side walls
24
that are spaced apart and depend outwardly from the back wall
22
. As shown, the side walls
24
are generally perpendicular to the back wall
22
. However, the side walls
24
may instead depend from the back wall
22
at any convenient acute or obtuse angle. The back wall
22
and the side walls
24
may be formed and joined in any conventional manner, but preferably, are formed from a single sheet of aluminum that is bent into a U-shape, commonly referred to as a “hat-section.” The housing
20
may further comprise a top wall and/or a bottom wall. Preferably, however, the top and the bottom of the housing
20
are at least partially open, as shown herein. The front of the housing
20
opposite the back wall
22
is also substantially open for a purpose to be described hereinafter. Regardless of its configuration or geometry, the housing
20
defines an interior cavity, referred to herein as a receptacle
30
, for receiving at least two switch-type circuit breakers
12
(indicated generally in FIG.
1
). In the preferred embodiments shown and described herein, the receptacle
30
is sized to receive exactly three switch-type circuit breakers
12
. However, the receptacle
30
may be sized to receive any convenient number of suitably sized switch-type circuit breakers
12
that may be required for a particular installation. Furthermore, the side walls
24
define an outer perimeter of the housing
20
in the lateral directions. As is shown herein and will be described in greater detail hereinafter, the interlock slide(s)
42
are movable on the housing
20
such that the switch-type circuit breakers
12
are individually accessible, yet the interlock slide(s)
42
do not extend beyond the outer perimeter defined by the housing
20
in any position. Accordingly, the mechanical interlock apparatus
10
is suitable for use in a high density electrical enclosure
100
.
Preferably, the switch-type circuit breakers (referred to hereinafter simply as circuit breakers
12
) are “main disconnect breakers” or “main breakers” of the type commonly utilized in the aforementioned power and transfer switch cabinets. The circuit breakers
12
may be any size (i.e., amperage), for example up to about 300 amp rated. In the exemplary embodiments shown and described herein, the circuit breakers
12
are preferably 10-125 amp main circuit breakers available from Square D Company, the North American Division of Schneider Electric of Paris, France. Each circuit breaker
12
is provided with a manually operable actuating switch
13
(indicated generally in
FIG. 1
) for electrically connecting the circuit breaker
12
to the electrical system. The switch
13
may be electrically connected to the electrical system in any suitable manner. Preferably, however, circuit breaker
12
is provided with a plurality of wire openings
14
(
FIGS. 6 and 7
) for receiving and terminating electrical conductors (not shown) in a conventional manner. The switch
13
has at least an “OFF” position and an “ON” position as is well known, and may further have a “NEUTRAL” position between the OFF and ON positions. In the exemplary embodiments shown and described herein, the circuit breaker
12
is in the OFF position when the switch
13
is in its lowermost location (see
FIGS. 3-5
) and is in the ON position when the switch
13
is in its uppermost location (see FIGS.
8
-
10
). If provided, the circuit breaker
12
is in the NEUTRAL position when the switch
13
is located medially between its lowermost location and its uppermost location. As is conventional, the electrical system is not energized when the switch
13
is in the OFF position or the NEUTRAL position, and is energized when the switch
13
is in the ON position. Such circuit breakers having two-way or three-way switches are well known, and thus, their design and/or configuration forms no part of the present invention, except as described hereinafter.
The circuit breakers
12
may be mounted within the receptacle
30
defined by the housing
20
in any suitable manner. As shown herein, the circuit breakers
12
are mounted to the back wall
22
of the housing
20
by adjustable mounting plates
16
. Mounting plates
16
preferably have elongated slots
18
formed therein that permit fasteners
17
to be positioned immediately adjacent the top and bottom of the circuit breaker
12
. Accordingly, the location of the circuit breaker
12
is fixed and the circuit breaker
12
cannot move vertically relative to the back wall
22
unless the fasteners
17
are first loosened and removed, and the mounting plates
16
are removed. In the preferred embodiments shown and described herein, the left-hand circuit breaker
12
a
and the center circuit breaker
12
b
are high ampere Type QOU Class 720 thermal magnetic miniature circuit breakers, such as Model No. QOU2100 manufactured by the aforementioned Square D Company, while the right-hand circuit breaker
12
c
is a low ampere Type QOU Class 720 thermal magnetic miniature circuit breaker, such as Model No. QOU230 likewise manufactured by the Square D Company. As previously mentioned, however, the circuit breakers
12
may be any size, shape or type of electrical power circuit breaker that is suitable for a particular application. Furthermore, the circuit breakers
12
may all be the same, may all be different, or as shown, may comprise two different sizes, shapes and types. If necessary, the size and configuration of the housing
20
may be modified without departing from the invention to accommodate the desired circuit breakers
12
. Regardless, the circuit breakers
12
are mounted within the receptacle
30
such that the switches
13
are accessible adjacent the front of the housing
20
between the side walls
24
. As will be described more fully hereinafter, the switches
13
are individually accessible at the front of the housing
20
through the interlock assembly
40
. However, no more than one of the switches
13
is accessible through the interlock assembly
40
at any given time.
Interlock assembly
40
comprises one or more interlock slides
42
(indicated generally in
FIG. 1
) and a faceplate
44
that defines a window
43
on the front of the housing
20
for operating the interlock slides
42
and for accessing the switches
13
of the circuit breakers
12
. Each interlock slide
42
is made of a rigid material such as metal, plastic or composite, and preferably is made of a relatively thin sheet metal, such as aluminum. It should be noted that the number of interlock slides
42
is always one fewer than the number of circuit breakers
12
. Therefore, if the number of circuit breakers
12
is mathematically defined as n, where n is an integer equal to two or more, then the number of interlock slides
42
is mathematically defined as n−1. As shown and described herein, there are three circuit breakers
12
, and thus, two interlock slides
42
. The interlock slides, also referred to herein as “slides,”
42
are movably mounted on the housing
20
to permit selective access to only one of the switches
13
at any given time. Each slide
42
may be movably mounted on the housing
20
in any suitable manner. For example, the housing may be provided with a laterally extending slot and the slides
42
provided with pins that protrude into and engage the slot. Alternatively, the slides
42
could be provided with a lip that hangs from and engages a laterally extending rail. As best shown in
FIGS. 4 and 6
, each slide
42
comprises at least one externally threaded shoulder bolt
46
and a pair of internally threaded cup washers
48
. Preferably, each slide
42
comprises an upper pair of shoulder bolts
46
and a lower pair of shoulder bolts
46
. Each shoulder bolt
46
is secured to the slide
42
and engages the cup washers
48
such that a narrow space is defined between the cup washers
48
. The housing
20
comprises an inner flange
26
and an outer flange
28
adjacent both the top and the bottom of the housing
20
, at least one of which is secured, for example by welding, to the side walls
24
. As shown herein in
FIG. 4
, the inner flanges
26
are secured to the side walls
24
adjacent the top and bottom of the housing
20
, and the outer flanges
28
are secured to the inner flanges
26
by fasteners
27
, for example rivets. The free ends of the inner flanges
26
and the outer flanges
28
define a slot therebetween that extends laterally between the side walls
24
. The pair of cup washers
48
are positioned on either side of the inner flanges
26
and the outer flanges
28
such that the shoulder bolts
46
are received within the slot defined by the inner flanges
26
and the outer flanges
28
. As a result, the slides
42
are substantially free to move laterally along the slot between the side-walls
24
of the housing
20
.
Each slide
42
further comprises at least one, and preferably a pair, of handles
50
for moving the slide
42
in the lateral direction. The handles
50
may be secured to the slide
42
in any suitable manner. Preferably, however, the slide
42
and the handles
50
are integrally formed by bending the side edges of the slide
42
outwardly. Accordingly, the slide
42
has a generally U-shaped cross-section in the region defined by the window
43
. The faceplate
44
may be secured to the housing
20
in any suitable manner. As best shown in
FIG. 7
, the side walls
24
of the housing
20
are each provided with an outwardly extending flange
23
having at least one hole that receives a fastener
25
, for example a rivet, to secure the faceplate
44
to the housing
20
. The rivets
25
prevent the faceplate
44
from being removed from the housing
20
with ordinary hand tools, such as a screwdriver. Thus, the rivets
25
restrict unauthorized access to the shoulder bolts
46
to remove the slides
42
and thereby gain access to more than one of the switches
13
of the circuit breakers
12
at a given time. As a result, the mechanical interlock apparatus
10
is considered to be “tamper-proof,” as that term is commonly understood by one of ordinary skill in the art. In turn, housing
20
is mounted within electrical enclosure
100
using threaded studs
21
. Furthermore, faceplate
44
may be provided with one or more internally threaded holes
45
that receives a fastener, for example an externally threaded thumb screw, to secure a cover
104
(FIG.
1
), commonly referred to as a “dead front,” over the housing
20
. The housing
20
is concealed by the dead front
104
once the mechanical interlock apparatus
10
is installed within the electrical enclosure
100
, thereby restricting access to the faceplate
44
and the housing
20
.
The interlock assembly
40
further comprises a locking bar
52
affixed to the underside of each interlock slide
42
. The locking bar
52
is made of a rigid material, such as metal, and may be secured to the slide
42
in any suitable manner. As best shown herein in
FIG. 4
, the locking bar
52
comprises a thin Z-shaped flange having a first leg
51
secured to the slide
42
by fasteners
54
that engage holes provided through the slide
42
. The locking bar
52
has a second leg
53
opposite the first leg
51
that is positioned adjacent the switches
13
of the circuit breakers
12
. The second leg
53
of the locking bar
52
extends laterally across the width of the slide
42
, and as best shown in
FIG. 5
, preferably extends laterally substantially the entire width of the slide
42
. The locking bar
52
prevents the slide
42
from being moved laterally past a switch
13
when the switch
13
is in the ON position. Accordingly, the switch
13
must first be moved to a position other than the ON position (i.e., the NEUTRAL or OFF position) before the slide
42
can be moved in a lateral direction. As shown in
FIGS. 4 and 5
, all three of the switches
13
of the circuit breakers
12
are in the NEUTRAL or OFF positions.
It should be noted that
FIGS. 2-7
illustrate the interlock assembly
40
of the mechanical interlock apparatus
10
in a predetermined position wherein all of the switches
13
of the circuit breakers
12
are in the NEUTRAL or OFF position and none of the switches
13
are accessible. As is most apparent in
FIG. 4
, the switch
13
a
of the left-hand circuit breaker
12
a
and the switch
13
b
of the center circuit breaker
12
b
are shown in the NEUTRAL position, while the switch
13
c
of the right-hand circuit breaker
12
c
is shown in the OFF position. Accordingly, none of the switches
13
can be actuated (i.e., moved to the “ON” position) to energize the electrical system. This position is commonly referred to as the “lock-out” or “safety” position and is desirable to prevent the electrical system from being energized by any power source during, for example, repair of an electrical component electrically connected to the power sources. As best shown in
FIG. 3
, the safety position is achieved by moving the right-hand slide
42
b
laterally to the right until it overlies the switch
13
c
of the right-hand circuit breaker
12
c
. The left-hand slide
42
a
is then moved laterally to the left or right until it partially overlies the switch
13
b
of the center circuit breaker
12
b
and partially overlies the switch
13
a
of the left-hand circuit breaker
12
a
. The slides
42
may be retained in the safety position in any suitable manner. As shown herein, the left-hand slide
42
a
is provided with an L-shaped flange
56
and the faceplate
44
is provided with a complimentary L-shaped flange
58
. The flanges
56
,
58
may be secured to the left-hand slide
42
a
and the faceplate
44
, respectively, in any suitable and tamper-proof manner, for example by rivets, that prevents the flanges
56
,
58
from being easily removed using ordinary hand tools. Each flange
56
,
58
is provided with at least one hole
57
,
59
(
FIGS. 6 and 7
) for receiving the shank of a padlock
60
(
FIG. 2
) to lock the left-hand slide
42
a
to the faceplate
44
. Accordingly, the left-hand slide
42
a
cannot be moved laterally in either direction relative to the housing
20
, and thus, relative to the switches
13
of the circuit breakers
12
. As a result, none of the switches
13
of the circuit breakers
12
can be accessed to energize the electrical system. If desired, the above configuration can be modified such that the left-hand slide
42
a
overlies the left-hand circuit breaker
12
a
and the right-hand slide
42
b
partially overlies the switch
13
b
of the center circuit breaker
12
b
and partially overlies the switch
13
c
of the right-hand circuit breaker
12
c
by simply securing the flange
56
to the right-hand slide
42
b
and re-positioning the flange
58
on the faceplate
44
.
FIG. 8
illustrates a first operational position of the mechanical interlock apparatus
10
wherein the switch
13
c
of the right-hand circuit breaker
12
c
is accessible, but the switch
13
b
of the center circuit breaker
12
b
and the switch
13
a
of the left-hand circuit breaker
12
a
are not accessible. Accordingly, the switch
13
c
of the right-hand circuit breaker
12
c
can be moved between the OFF, NEUTRAL and ON positions as desired to de-energize, neutralize and/or energize the electrical system. The mechanical interlock apparatus
10
is positioned in the first operational position by first accessing each of the circuit breakers
12
in turn and placing the switch
13
of the circuit breaker
12
in the OFF or NEUTRAL position. The left-hand slide
42
a
is then moved laterally between the inner flanges
26
and the outer flanges
28
to the left as indicated by the arrows thereon until the left-hand slide
42
a
overlies the switch
13
a
of the left-hand circuit breaker
12
a
. The right-hand slide
42
b
is then moved laterally between the inner flanges
26
and the outer flanges
28
to the left as indicated by the arrows thereon until the right-hand slide
42
b
overlies the switch
13
b
of the center circuit breaker
12
b
. As shown in
FIG. 8
, the switch
13
c
of the right-hand circuit breaker
12
c
is in the ON position and, as required, the switch
13
b
of the center circuit breaker
12
b
and the switch
13
a
of the left-hand circuit breaker
12
a
are in the NEUTRAL or OFF position. It should be noted that with the left-hand slide
42
a
positioned over the left-hand circuit breaker
12
a
and the right-hand slide
42
b
positioned over the center circuit breaker
12
b
as shown, the switch
13
c
of the right-hand circuit breaker
12
c
can be moved to the OFF position or to the NEUTRAL position. The corresponding fasteners
17
can then be loosened and the mounting plates
16
separated so that the right-hand circuit breaker
12
c
can be removed through the window
43
defined by the faceplate
44
. Accordingly, the right-hand circuit breaker
12
c
can be replaced without dismantling either of the interlock slides
42
a
,
42
b
, thereby preserving the tamper-proof safety features of the invention previously described.
FIG. 9
illustrates a second operational position of the mechanical interlock apparatus
10
wherein the switch
13
b
of the center circuit breaker
12
b
is accessible, but the switch
13
c
of the right-hand circuit breaker
12
c
and the switch
13
a
of the left-hand circuit breaker
12
a
are not accessible. Accordingly, the switch
13
b
of the center circuit breaker
12
b
can be moved between the OFF, NEUTRAL and ON positions as desired to de-energize, neutralize and/or energize the electrical system. The mechanical interlock apparatus
10
is positioned in the second operational position from the first operational position by first moving the switch
13
c
of the circuit breaker
12
c
from the ON position to the OFF position or to the NEUTRAL position. The right-hand slide
42
b
is then moved laterally between the inner flanges
26
and the outer flanges
28
to the right as indicated by the arrows thereon until the right-hand slide
42
b
overlies the switch
13
c
of the right-hand circuit breaker
12
c
. As shown in
FIG. 9
, the switch
13
b
of the center circuit breaker
12
b
is in the ON position and, as required, the switch
13
a
of the left-hand circuit breaker
12
a
and the switch
13
c
of the right-hand circuit breaker
12
c
are in the NEUTRAL or OFF position. It should be noted that with the left-hand slide
42
a
positioned over the left-hand circuit breaker
12
a
and the right-hand slide
42
b
positioned over the right-hand circuit breaker
12
c
as shown, the switch
13
b
of the center circuit breaker
12
b
can be moved to the OFF position or to the NEUTRAL position. The corresponding fasteners
17
can then be loosened and the mounting plates
16
separated so that the center circuit breaker
12
b
can be removed through the window
43
defined by the faceplate
44
. Accordingly, the center circuit breaker
12
b
can be replaced without dismantling either of the interlock slides
42
a
,
42
b
, thereby preserving the tamper-proof safety features of the invention previously described.
FIG. 10
illustrates a third operational position of the mechanical interlock apparatus
10
wherein the switch
13
a
of the left-hand circuit breaker
12
a
is accessible, but the switch
13
b
of the center circuit breaker
12
b
and the switch
13
c
of the right-hand circuit breaker
12
c
are not accessible. Accordingly, the switch
13
a
of the left-hand circuit breaker
12
a
can be moved between the OFF, NEUTRAL and ON positions as desired to de-energize, neutralize and/or energize the electrical system. The mechanical interlock apparatus
10
is positioned in the third operational position from the second operational position by first moving the switch
13
b
of the circuit breaker
12
b
from the ON position to the OFF position or to the NEUTRAL position. The left-hand slide
42
a
is then moved laterally between the inner flanges
26
and the outer flanges
28
to the right as indicated by the arrows thereon until the left-hand slide
42
a
overlies the switch
13
b
of the center circuit breaker
12
b
. As shown in
FIG. 10
, the switch
13
a
of the left-hand circuit breaker
12
a
is in the ON position and, as required, the switch
13
b
of the center circuit breaker
12
b
and the switch
13
c
of the right-hand circuit breaker
12
c
are in the NEUTRAL or OFF position. It should be noted that with the left-hand slide
42
a
positioned over the center circuit breaker
12
b
and the right-hand slide
42
b
positioned over the right-hand circuit breaker
12
c
as shown, the switch
13
a
of the left-hand circuit breaker
12
a
can be moved to the OFF position or to the NEUTRAL position. The corresponding fasteners
17
can then be loosened and the mounting plates
16
separated so that the left-hand circuit breaker
12
a
can be removed through the window
43
defined by the faceplate
44
. Accordingly, the left-hand circuit breaker
12
a
can be replaced without dismantling either of the interlock slides
42
a
,
42
b
, thereby preserving the tamper-proof safety features of the invention previously described.
As is readily apparent, the interlock slides
42
can be positioned so that each of the switches
13
of the circuit breakers
12
is individually accessible, while the remaining switches
13
of the circuit breakers
12
are not accessible. The slides
42
can only be moved past the switches
13
of the circuit breakers
12
when the switches
13
are in the OFF position or in the NEUTRAL position. Accordingly, no more than one of the switches
13
of the circuit breakers
12
can be actuated at any given time to energize the electrical system electrically connected to the power sources. An important feature of the invention is that the number of interlock slides
42
movably mounted on the housing
20
is one fewer than the number of circuit breakers
12
. Thus, the slides
42
can be moved laterally relative to the housing
20
to access any of the switches
13
of the circuit breakers
12
without the slides
42
extending beyond the periphery of the housing
20
. As a result, the circuit breaker mechanical interlock apparatus
10
does not require additional space within the electrical enclosure
100
to operate. Accordingly, other electrical components can be located within the electrical enclosure
100
adjacent to the mechanical interlock apparatus
10
without interfering with the operation of the interlock slides
42
, thereby increasing the density of electrical components that can be located within the electrical enclosure
100
. In addition, the faceplate
44
prevents access to the slides
42
with the use of ordinary hand tools.
Many modifications and other embodiments of the invention will come to mind to one skilled in the art to which this invention pertains having the benefit of the teachings presented in the foregoing descriptions and the accompanying drawings. Accordingly, it is to be understood that the invention is not to be limited to the specific embodiments disclosed herein and that further modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only, and not for purposes of limitation.
Claims
- 1. A circuit breaker mechanical interlock apparatus comprisinga housing defining an outer perimeter and a circuit breaker receptacle; a plurality of switch-type circuit breakers, each received within the circuit breaker receptacle and having a manually operable switch that is movable between at least two positions; an interlock slide movably mounted on the housing between a first position wherein the interlock slide overlies a first one of the circuit breakers and thereby prevents movement of a first switch corresponding to the first circuit breaker and a second position wherein the interlock slide overlies a second one of the circuit breakers and thereby prevents movement of a second switch corresponding to the second circuit breaker; and a faceplate secured to the housing; wherein the interlock slide is retained between the housing and the faceplate.
- 2. An apparatus according to claim 1 wherein the interlock slide is secured to the housing in a third position such that the interlock slide partially overlies the first circuit breaker and the second circuit breaker and thereby prevents movement of the first switch and the second switch.
- 3. An apparatus according to claim 1 wherein the second switch is accessible in the first position and the first switch is accessible in the second position.
- 4. An apparatus according to claim 3 wherein the second circuit breaker is removable from the receptacle defined by the housing in the first position and the first circuit breaker is removable from the receptacle defined by the housing in the second position.
- 5. An apparatus according to claim 1 wherein the interlock slide does not extend beyond the outer perimeter defined by the housing in the first position and the second position.
- 6. An apparatus according to claim 1 wherein the interlock slide comprises at least one shoulder bolt and at least a pair of cup washers that engage the shoulder bolt to retain the interlock slide between the housing and the faceplate.
- 7. An apparatus according to claim 6 wherein the housing comprises an inner flange and an outer flange that define a laterally extending slot therebetween and wherein the shoulder bolt is received within the slot so that the interlock slide is laterally movable relative to the housing.
- 8. An apparatus according to claim 1 wherein the interlock slide comprises a locking bar positioned adjacent the first switch in the first position and wherein the locking bar prevents lateral movement of the interlock slide from the first position to the second position when the second switch is in one of the at least two positions.
- 9. An apparatus according to claim 1 wherein the interlock slide comprises a locking bar positioned adjacent the second switch in the second position and wherein the locking bar prevents lateral movement of the interlock slide from the second position to the first position when the first switch is in one of the at least two positions.
- 10. A circuit breaker mechanical interlock apparatus comprisinga housing having a back wall and a pair of side walls depending from the back wall, the back wall and the side walls defining a receptacle for receiving a plurality of switch-type circuit breakers, each of the switch-type circuit breakers having a manually operable switch that is movable between at least two positions; an interlock slide mounted on the housing and movable between a first position wherein the interlock slide overlies a first circuit breaker of the switch-type circuit breakers and thereby prevents manual operation of a first switch corresponding to the first circuit breaker and a second position wherein the interlock slide overlies a second circuit breaker of the switch-type circuit breakers and thereby prevents manual operation of a second switch corresponding to the second circuit breaker; and a faceplate secured to the housing; wherein the interlock slide is retained between the housing and the faceplate.
- 11. An apparatus according to claim 10 wherein the interlock slide is secured to the housing in a third position such that the interlock slide partially overlies the first circuit breaker and the second circuit breaker and thereby prevents movement of the first switch and the second switch.
- 12. An apparatus according to claim 10 wherein the second switch is accessible in the first position and the first switch is accessible in the second position.
- 13. An apparatus according to claim 12 wherein the second circuit breaker is removable from the receptacle defined by the housing in the first position and the first circuit breaker is removable from the receptacle defined by the housing in the second position.
- 14. An apparatus according to claim 10 wherein the interlock slide does not extend laterally beyond the side walls in the first position and the second position.
- 15. An apparatus according to claim 10 wherein the interlock slide comprises at least one shoulder bolt and at least a pair of cup washers that engage the shoulder bolt to retain the interlock slide between the housing and the faceplate.
- 16. An apparatus according to claim 15 wherein the housing comprises an inner flange and an outer flange that define a laterally extending slot therebetween and wherein the shoulder bolt is received within the slot so that the interlock slide is laterally movable relative to the housing.
- 17. An apparatus according to claim 10 wherein the interlock slide comprises a locking bar positioned adjacent the first switch in the first position and wherein the locking bar prevents lateral movement of the interlock slide from the first position to the second position when the second switch is in one of the at least two positions.
- 18. An apparatus according to claim 10 wherein the interlock slide comprises a locking bar positioned adjacent the second switch in the second position and wherein the locking bar prevents lateral movement of the interlock slide from the second position to the first position when the first switch is in one of the at least two positions.
- 19. An interlock slide for a circuit breaker mechanical interlock apparatus having a housing that defines a receptacle for receiving a plurality of manually operable switch-type circuit breakers, the interlock slide comprisinga locking bar that overlies a first circuit breaker of the switch-type circuit breakers and thereby prevents manual operation of a first switch corresponding to the first circuit breaker when the interlock slide is in a first position; means supporting the interlock slide on the housing such that the interlock slide is movable from the first position to a second position wherein the locking bar overlies a second circuit breaker of the switch-type circuit breakers that is parallel to and linearly adjacent to the first circuit breaker and thereby prevents manual operation of the second circuit breaker; and a faceplate secured to the housing; wherein the interlock slide is retained between the housing and the faceplate.
- 20. An interlock slide according to claim 19 wherein the second circuit breaker is accessible and removable from the receptacle when the interlock slide is in the first position and the first circuit breaker is accessible and removable from the receptacle when the interlock slide is in the second position.
- 21. An interlock slide according to claim 19 wherein the interlock slide does not have an opening therethrough.
- 22. An interlock slide according to claim 19 further comprising at least one shoulder bolt and at least a pair of cup washers that engage the shoulder bolt to retain the interlock slide between the housing and the faceplate.
- 23. An interlock slide according to claim 22 wherein the housing comprises an inner flange and an outer flange that define a laterally extending slot therebetween and wherein the shoulder bolt is received within the slot so that the interlock slide is laterally movable relative to the housing.
- 24. A circuit breaker mechanical interlock apparatus for preventing more than one power source from energizing an electrical system at any given time, the apparatus comprisinga housing defining a receptacle for receiving a plurality of switch-type circuit breakers, each of the circuit breakers having a manually operable switch that is movable between at least two positions for actuating one of a plurality of power sources electrically connected to a first circuit breaker of the switch-type circuit breakers and to the electrical system; and at least one interlock slide movably mounted on the housing adjacent the receptacle and opposite the switches of the circuit breakers, each interlock slide being movable relative to the circuit breakers to a first position wherein the interlock slide overlies the first circuit breaker and thereby prevents movement of a first switch corresponding to the first circuit breaker and to a second position wherein the interlock slide overlies a second circuit breaker of the switch-type circuit breakers and thereby prevents movement of a second switch corresponding to the second circuit breaker; and a faceplate secured to the housing; wherein each interlock slide is retained between the housing and the faceplate.
- 25. An apparatus according to claim 24 wherein only one of the switch-type circuit breakers is accessible and removable from the receptacle in the first position and the second position.
- 26. An apparatus according to claim 24 wherein the housing defines an outer perimeter and wherein each interlock slide does not extend beyond the outer perimeter defined by the housing in the first position and the second position.
US Referenced Citations (11)