Circuit breaker switchboard, single row group mounted

Details Circuit breaker switchboard, single row group mounted Circuit breaker switchboard, single row group mounted

1999-03-05

2001-03-20

Thompson, Gregory (Department: 2835)

Electricity: electrical systems and devices

Housing or mounting assemblies with diverse electrical...

For electrical power distribution systems and devices

C361S639000, C361S648000, C361S650000, C361S678000, C174S0720TR, C174S016200

Reexamination Certificate

active

06205019

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to an improved switchboard for mounting, and supplying electrical power to, a plurality of circuit breakers. In this particular invention the switchboard includes a power stack assembly defining a plurality of ventilation passageways to facilitate cooling of the power stack and the breakers mounted thereon. The circuit breakers are installed in a single row.
BACKGROUND OF THE INVENTION
Switchboards for mounting and supplying electrical power to a plurality of circuit breakers are well known in the art. However, the total amperage which can be handled by a switchboard is limited due to heat radiated by the breakers. In this regard, attempts in the 1970's to develop a 3,000 ampere alternating current switchboard failed due to excessive heat within the circuit breakers. More specifically, the failure was in meeting the specified Underwriters Laboratories temperature limits on the circuit breaker load cables, or at the line side plug-on connectors. Moreover, heretofore access to the various lug assemblies of conventional switchboards has been restrictive, making cable connections and other wiring tasks difficult and time consuming.
U.S. Pat. No. 5,166,861 issued to the inventor of the present application discloses a switchboard which provides for cooler circuit breaker operation, such that a longer power stack can be used and more and larger circuit breakers can be mounted in a single switchboard. It discloses a switchboard that is inexpensive to manufacture and maintain that affords ready access to the neutral bus bar assembly, the ground bus lug mounting assembly, and the other components of the switchboard.
The switchboard of the '861 patent comprises a frame including a center mounting pan, and including at least first and second circuit breaker mounting pans for engaging and supporting the rear end portions of the circuit breakers. The first circuit breaker mounting pan is selectively spaced from the center mounting pan so as to define an open area therebetween, and the second circuit breaker mounting pan is oppositely disposed with respect to the first circuit breaker mounting pan relative to the center mounting pan and is selectively spaced from the center mounting pan so as to define an open area therebetween. The switchboard also comprises a power stack assembly mounted on the center mounting pan of the frame. The power stack assembly includes first, second and third, substantially vertical, elongated main bus bar members for being connected to a source of electrical power and for releasably engaging the circuit breakers. The first main bus bar member is selectively spaced from the center mounting pan with insulator members so as to define a first ventilation passageway therebetween. The second main bus bar member is selectively spaced from the first main bus bar member with insulator members so as to define a second ventilation passageway therebetween. Similarly, the third main bus bar member is selectively spaced from the second main bus bar member with insulator members so as to define a third ventilation passageway therebetween. The power stack assembly further including a channel vent cover selectively spaced from the third main bus bar member with insulating members so as to define a forth ventilation passageway therebetween. Each of the first, second and third ventilation passageways defines an opening at the lower end of the power stack assembly and an opening at the upper end of the power stack assembly. The fourth ventilation passageway defines an opening proximate the lower end of the channel vent cover and an opening proximate the upper end of the channel vent cover. Resultantly, convection air is allowed to rise within the ventilation passageways to cool the power stack assembly. In addition, the center mounting pan and the main bus bars are provided with ventilation openings along their lengths to further facilitate air flow through the power stack assembly.
As illustrated in
FIGS. 1 and 2
the switchboard
10
of the '861 patent is provided with a front assembly, including, in the preferred embodiment, upper and lower vented covers
30
and
32
, respectively, and top and bottom covers
34
and
36
, respectively, which are engaged to and extend between the front portions of the vertical support channels
18
and
20
. Also included are removable cover panels
38
,
40
and
42
, which provide access to various components of the switchboard
10
. Further, as illustrated by the phantom lines
44
in
FIG. 2
, the switchboard
10
can also be provided with a suitable enclosure for housing the frame
16
and various components of the switchboard
10
. It will be recognized that the enclosure
44
can be formed by securing wall panels to the frame
16
.
Located behind the panel
40
of switchboard
10
is a power stack assembly
12
for releasably mounting the circuit breakers
14
. As shown in
FIG. 3
the multi-pan mounting assembly includes a center pan
46
which supports the power stack assembly
12
. The center pan
46
is secured to the mounting channels
22
of the frame
16
such that the center pan
46
is vertically disposed. Further, the center pan
46
is provided with a plurality of selectively spaced holes (not shown) for receiving suitable fasteners for securing the power stack assembly
12
, and a plurality of ventilation openings (not shown) for providing air circulation through the power stack assembly
12
.
As best illustrated in
FIG. 3
, the power stack assembly
12
includes three vertically disposed main bus bars
52
,
54
and
56
to accommodate a three phase power supply. The main bus bars
52
,
54
and
56
are secured together in selectively spaced, substantially parallel alignment with insulating means being provided between the bus bars to electrically insulate the bus bars from one another. The resulting assembly
12
is secured, in selectively spaced, substantially parallel alignment, to the center pan
46
, with suitable insulation means being provided between the inner bus bar
52
and the center pan
46
.
As seen in
FIG. 3
, the main bus bar
56
is connected to a main bus connecting member
124
which consists of a pair of vertically separated connecting members for conveying power from a through bus connector at the rear of the circuit breaker (not shown) to the bus bar
56
: the through bus connector is in turn connected to one of the phases of the power supply. The use of a pair of main bus connecting members is required to handle the power requirements while, at the same time, avoiding an excessive temperature rise. Other main bus connecting members, located behind the main bus connecting member
124
, provide power connection to the main bus bars
52
and
54
for the other two phases. Further, a stack top channel vent cover
88
is provided to cover the outer bus bar
56
, with two spaced rows of outer insulating members
90
being provided between the bus bar
56
and the cover
88
. The bus bars
52
,
54
and
56
, and the cover
88
, with insulating members therebetween, are secured together and mounted on the center pan
46
with suitable fasteners (not shown in FIG.
3
).
The main bus connecting members in the '861 invention are connected to corresponding lug pad connectors secured to a bus support channel carrying three lug pads: the lug pads, in turn, facilitate the connection of electrical cables from the electrical supply source.
As seen in
FIGS. 1-3
, circuit breakers are arranged on both sides of the power stack assembly
12
. Due to the location of thee main bus connecting members on the right side of the switchboard when viewed from the front, there is less space available for mounting circuit breakers on the rights side of the power stack assembly
12
. The circuit breakers
14
are provided with electrical connecting jaws (not shown) which releasably engage the outer edges (not shown) of the bus bars
52
,
54
and
56
. Suitable provision is made for supporting the circuit breakers by means of additional mounting pans.
It would be d

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