Note: Descriptions are shown in the official language in which they were submitted.
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MODULAR INSULATIVE SUPPORT BASE
FOR ELECTRICAL SWITCHGEAR
BACKGROUND OF THE INVENTION
.
The present invention relates to electrical switchgear
and particularly to a modular base which is assembled with
like bases in end-to-end vertical relation to the frame
of a switchgear vertical section such as to provide insulative
rear barrier walls for the various cubicles to one side
thereof and to provide electrically isolated support for
plural vertical busbars to the other side thereof.
The subject modular insulative support base is
analogous to the modular mounting panel disclosed and claimed
in commonly assigned Patent No. 4,031,433 to William Francis
Olashaw, issued June 21, 1977 and is uniquely structured for
application in the larger size switchboards commonly
referred to as "switchgear". Generally speaking, switchgear
involves electrical distribution equipment of extreme short-
circuit current withstand and thus the electrical devices,
buswork, etc., are of great~r physical size and weight.
Thus, extra attention must be given to accommodating and
supporting the greater component size and weight, as well as
to insulating and isolating live parts from each other and
from inadvertent contact by operating and maintenance
personnel.
It is accordingly an object of the present invention
to provide an improved insulative support base for electrical
switchgear.
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2 41DA-~08
A further object is to provide a support base of
the above character which is of modular construction such
that plural bases may be mounted to a switchgear frame in
interfitting, vertical end-to-end relation to serve as
5 individual backwalls for a stacked array of cublcles in a
switchgear vertical section.
Another object is to provide modular support
bases of the above character having the requisite physical
strength to mount the vertical busbars of a switchgear
vertical section in insulated/isolated side-by-side parallel
relation.
An additional object is to provide support bases of
the above character which are individually apertured to
accomodate and support run-in straps in respective, electrical
connection with the vertical bus and to which the live
terminals of electrical devices within the cubicles
electrically connect.
Yet another object is to provide support bases of the
above character which support runback straps to which the
load terminals of electrical devices within the cubicles
electrically connect and which extend rearwardly through
apertures in the bases and insulatively through openings
in the vertical bus.
An additional object is to provide support bases of
the above character which are structured to provide side-
by-side channels in their back sides for accommodating and
supporting H-shaped vertical busbars.
Yet another object is to provide a support base of
the above character which is efEicient in construction and
convenient to assemble -to a switchgear frame.
Other objects will in part be obvious and in part
appear hereinafter.
UMMARY OF THE INVENTION
In accordance with the present invention, there is
provided improved electrical distribution equipment, in
particular electrical switchgear, which utilizes modular
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structurally rigid, insulative support bases which are
assembled to a switchgear frame in end-to-end vertical
relation to serve as a succession of rear barrier walls for
a stacked array of switchgear cubicles as well as to
insulatively support the switchgear buswork. Each support
base is lntegrally formed with a plurality of vertically
elongated, laterally spaced, parallel walls outstanding
from its back side to define at least three side-by-side
channels in which El-shaped vertical busbars, of the switch-
gear buswork are individually accommodated. A pair ofparallel running troughs are created in the floor of each
channel to accept the forwardly extending portions of the
vertical busbar flanges, while the web joining the flanges
in H cross-sectional configuration rests against the channel
floor.
In the front side of each base there is formed a set
of at least three transversely aligned, line-side depressions,
each straddled by the troughs in the opposed channel and
including an opening exposing the web of the H-shaped
vertical busbar therein. These depressions accommodate
run-in electrical connectors which are electrically
connected to the exposed vertical busbar webs and physically
supported by the base in positions to make electrical
connections with the line terminals of an electrical device
accommodated in the associated cubicle. Vertical patterns
of holes preformed in the channel floors register with
preformed holes in the vertical busbar webs such as to
accommodate bolts clamping the vertical busbars in their
respective channels. Preferably, these preformed bolt
holes in the base are countersunk from the front side so
as to accept insulative caps isolating the line bol-t heads.
Also formed in the front side of each base is a se-t
of three transversely arranged load-side depressions in
respective vextically spaced relation wi-th the line-s~de
depressions. Each of these load-side depressions is like-
wise straddled by the troughs in the opposed channel and
communicate with the open interior of a sleeve integrally
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formed with the base to extend rearwardly into the opposed
channel through a gap in the web of the vertical busbar
therein. Supported in each load-side depression is a
runback electrical connector which extends rearwardly through
the associated sleeve in isolated relation with the vertical
busbar in the opposed channel. The forward ends of these
runback connectors are disposed to make electrical connection
with the electrical device in the associated cubicle.
To enhance the isolatin~ capacity of the support bases,
their upper and lower edges are provided with tongue and
groove formations which interfit when the bases are assembled
in end-to-end vertical relation. Also, tLansverse walls
outstanding from the front side of each base along its
upper and lower edges cooperate with horizontal barrier
panels to afford complete separation between vertically
adjacent cubicles.
The invention accordingly comprises the features of
construction and arrangement of parts which will be
exemplified in the construction hereinafter set forth, and
the scope of the invention will be indicated in the claims.
For a better understanding of the nature and objects
of the invention, reference should be had to the following
detailed description taken in conjunction with the
accompanying drawings in which:
DESCRIPTION OF THE DRi~WINGS
.
Figure 1 is a perspective view of an electrical
switchgear including a pair of side-by-side vertical
sections;
E'igure 2 is a perspective view looking into one oE
the cubicles of the switchgear of Figure l;
Figure 3 is a front view of a modular insulative
support base utilized in the switchgear of Figure l;
Figure 4 is an end view of the support base of
Figure 3;
Figure 5 is a sectional view taken along line 5-5
of Figure 3;
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41DA-6086
-- 5 --
Figure 6 is a sectional view taken along line 6-6
of Figure 3;
Figure 7 is a sectional view taken along line 7-7
of Figure 3;
Figure 8 is a vertical sectional view taken along the
centerline of one of the riser busbar channels provided in
the rear face of the base of Figure 3;
Figure 9 is a fragmentary perspective view of the
runback supporting portion of the base of Figure 3;
Figure 10 is a perspective view of one of the run-
backs utilized in the switchgear of Figure l;
Figure 11 is a perspective view, partially broken away,
of a copper riser busbar utilizable in the switchgear of
Figure l;
Figure 12 is a perspective view, partially broken away,
of an e~truded aluminium riser busbar utilizable in the
switchgear of Figure l;
Figure 13 is a plan view of an electrical joint
between a horizontal busbar and the riser busbar of Figure
11;
Figure 14 is a perspective view of the power connector
utilized in the bus joint of Figure 13;
Figure 15 is a simplified elevational view illustrating
the horizontal bus runs interconnecting adjacent switch-
gear vertical sections;
Figure 16 is an exploded perspective view of an isolating
enclosure for the bus joint of Figure 13;
Figure 17 is an exploded, fragmentary perspective view
illustrating the asembly of isolating barriers to the
horizontal bus runs of Figure 15;
Figure 18 is a plan view, partially broken away, of
the bus joint of Figure 13 as adapted with the isolating
enclosure of Figure 16 and a horizontal bus run as adapted
with the isolating barriers of Figure 17;
Figure 19 is an elevational view of the isolated bus
joint and horizontal bus run of Figure 18;
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Figure 20 is a sectional view taken along line 20-20
of Figure 19; and
Figure 21 is a sectional view taken along line 21-21
of Figure 19.
Corresponding reference numerals refer to like parts
throughout the several view of the drawings.
DETAILED DESCRIPTION
_
The present invention is embodied in an electrical
switchgear, generally indicated at 20 in Figure 1 and
comprising one or more vertical sections 20a. Each vertical
section includes a cubical steel framework consisting of
width posts 22, depth posts 24 and vertical posts 26 rigidly
joined at the frame corners in mutually perpendicular
relation. Secured to these posts are suitable panels, such
as side panel 27 seen in Figure 1, to provide a cubical
enclosure, as well as partitions to create individual
compartments or cubicles accessed by doors 28 hinged to the
vertical posts. ~ithin each cubicle is an electrical device,
such as a circuit breaker 30 whose operating handle 30a
protrudes through a central opening 28a in the cubicle door.
Looking into a representative cubicle of one of the
switchgear vertical sections, as seen in Figure 2, the rear
wall thereof is provided by a modular support base, generally
indicated at 32, of a structurally rigid electrically
insulative material, such as glass fiber polyester, formed
for example, by a molding process. These bases are moun-ted
in end-to-end vertical relation to vertical stringers 34
by self-tapping screws 35 utilizing vertical pat-terns of
holes 35a preformed in the lateral edge portions of the
bases (Figure 5); the stringers being affixed to the
switchgear section framework at an appropriate depth. As
seen in both Figures 2 and 3, the front face of each
base is ~ormed to provide three rectangular, vertically
elongated, relatively deep depressions 36, in side-by-side
relation for accommodating L-shaped, run-in line straps
38 (Figure 2) which are respectively electrically connected
il 1'7975~;
- 7 - 41DA-6086
with separate vertical or riser busbars and, together with
these riser busbars, are physically mounted to the base, as
will be described in connection with Figure 8. Also formed in
the fron side of base 32 in vertical alignement below
depressions 36 are side-by-side depressions 42 in which are
mounted load-side runbacks 44, as will be detailed in
conjunction with Figures 8 through 10. The line straps 38
are electrically joined with and physically support separate
male stabs 39 using bolts 3ga, while the runbacks 44 physica:Lly
mount and are electrically joined by bolts 45a with separate
male stabs 45. These stationary male stabs are disposed
to mate with line terminal disconnects 30b and load terminal
disconnects 30c of a drawout circuit breaker 30, as seen in
Figure 8; racking movement of the breaker being supported
by side rails 30d seen in Figure 2.
Still referring to Figures 2 and 3, interphase
isolation is provided by the base in the form of a pair of
barrier walls 46 separating depressions 36 and 42, while
phase to frame isolation is afforded by outboard barrier
walls 48. A pair of rectangular wells 50 located between
each vertically spaced pair of depressions 36 and 42 serve
to recess the heads of bolts 49 securing the riser busbars to
the base 32, as also will be seen in connection with Figures
5 and 8. The bolt heads, being live, are isolated by caps
one seen at 51 in Figure 3, which are press-fitted in the
countersunk portions of the bolt holes 50a preformed in the
base. Rectangular recesses 52 in the front surface of the
base constitute coring, while appropria-tely located, preEromed
holes 53 may be utilized to mount current transformers
(not shown) in embracing relation with either the line
straps 38 or the runbacks 44 of each phase. The horizontal
pattern of preformed holes 54 may be utilized to secure a
transverse brace (not shown~ to each base should additional
bracing be needed to withstand the extreme electrod~namic
forces associated with extraordinarily high levels of short
circuit fault current.
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As will be described, bases 32, once amounted to
the switchgear frame in end-to-end vertical relation, serve
to support in parallel, side-by-side, isolated relation
typically three vertical or riser busbars, which are seen
in Figures 11 and 12 to be of H-shaped cross-sectionO The
riser busbar 56 of Figure 11 is formed of copper with its
H-shaped cross-section created by assembling a pair of
copper rectangular cross-sectioned bars or flanges 56a to
a series of interconnecting U-shaped copper webs 56b
utilizing bolts 56c. Figure 12 depicts an alternative,
aluminium busbar 58 extruded in H-shaped cross-section with
flanges 58a interconnected by an integral web 58b. As will
be seen, a series of holes 56d preformed in the separate
webs 56b of each copper riser busbar or the preformed holes
58c in the web of each aluminium busbar are utilized in
affixing the riser busbars to the bases 32 and to accommodate
bolted joints with line straps 38 (Figures 2 and 3). The
separations 56e between the copper busbar webs 56b and the
openings 58d created in the aluminium busbar web 58b are so
located as to accommodate the rearward extension of run-
backs 44, as will be described.
Referring to Figures 4 and 5, the back side of each
base 32 is integrally formed with four outstanding, vertically
extending walls 60 arranged in equally spaced, parallel
relation such to define three channel 62 coextensive with
the length of each base. When the bases are assembled in
vertical, end-to-end relation to stringers 34 (Figure 2),
these channels are continuous for the full height of the
switchgear vertical section. In this connection, as seen
in Figure 3, the lower edge of each base is provided
with tongues 63a which interfit with grooves 64a created in
the upper edge of each base incident to their end-to-end
assembly. Also as seen in Figures 3 and 8, a transverse
wall 64 outstanding from the front side of each base at
its upper edge and a transverse wall 63 outstanding from
its lower edge cooperate with partitions 65, seen in
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Figures 2 and 8, in fully separating vertically adjacent
cubicles.
Returning to Figure 5, the floor 62a of each channel
62 is formed with a pair of deep, parallel running troughs
62b which receive the forwardly extending portions of the
copper busbar flanges 56a or the aluminium busbar flanyes
58a depending on which of the H-shaped riser busbars 56
or 58 are laid in the channels. While Figure 5 shows a
copper riser busbar 56 laid in the left channel 62 and
an aluminium riser busbar 58 in the center channel, it
will be appreciated that for a particular installation the
riser bus will either be all copper or all aluminium. The
width of the troughs 62b is illustrated as being greater
than the flange thickness to show that flanges of increased
thickness and greater ampacity can be accommodated. The
depth of the troughs 62b is such that the forward edges
of the riser bus flanges are spaced from the groove bottoms
while the busbar webs rest on the channel floors 62a, as
illustrated in Figure 5. Centrally located in the wells
50 noted in Figures 2 and 3 are the preformed through-holes
50a, countersunk from both sides, for accommodating the
bolts 49 inserted from the front side of the base (see also
Figure 8). Nuts 49a are then threaded down on the bolt
shanks 49b so as to clamp the bolts to the base with their
shanks projecting out beyond the floors 62a of their
respective channels 62. Thus, when the riser busbars
are laid in the channels the bolt shanks 49b project
through the preformed holes in the busbar webs. Second nuts
49c are then torqued down on these bolt shanks to securely
clamp the riser busbars, either the copper busbars 56 as
seen in Figure 5 of the aluminium busbars 58, to the bases
32.
In addition to bolts 49, a pair of spline bolts 66
are utilized to further secure each riser bus to the bases
32 and also to support and electrically connect an L-shaped
line strap 38 to each riser busbar, which in Fi~ure 8 is
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seen to be a copper busbar 56. Thus, one of each pair of
spline bolts 66 has its intermediate spline portion 66a
swaged into a preformed hole 67 located in the lower portion
of each line strap depression 36 formed in the front side
of base 32. The other one of each spline bolt pair has
its spline portion 66a swaged into a countersunk hole 68a
formed in a rectangular copper spacer 68 which is accommodated
in a close-fitting opening 36a in the channel floor 62a
otherwise separating each front side line strap depression
36 from its associated riser bus channel 62. The upper and
lower edges of opening 36a are forwardly offset to create
lips 36b (see also Figure 6) which cooperate with upper
and lower spacer projections 68b to seat spacer 68 with its
rear surface flush with the channel floor 62a and its
front surface flush with the bottom surface 36c of line
strap depression 36. The forwardly extending threaded
shanks 66b of spline bolts 66 are inserted through holes
38a in line strap 38 and nuts 66c are applied to clamp the
line strap to the base and to effect a bolted electrical
joint with spacer 68. The rearwardly extending threaded
shanks of the spline bolts project through the copper riser
bus web holes 56d to receive nuts 66d further clamping the
riser bus to the base and effecting a bolted electrical
joint with spacer 68.
When aluminium riser busbars 58 are utilized, their
electrical joints with the ]ine straps or run-ins may be
of a bolted-welded configuration, such as disclosed in
commonly assigned, Canadian Serial No. 375,171 filed
April 10, 1981.
To isolate the rearward extensions of runbacks 44
from the riser busbars, the base is integrally formed with
a rearwardly extending, rectangular sleeve 70 outstanding
from the floor 62a of each channel 62, as seen in Figures
7, 8 and 9. Riser bus clearance for these sleeves is
afforded by the gaps 56e in the copper busbar webs 56b
(Figure 11) or the openings 58d in the aluminium busbar
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- 11 - 41DA-6086
webs 58b (Figure 12). An integral, vertical oriented
partition 70a divides the sleeve interior into two
rectangular passageways 70b, as best seen in Figures 7 and
9, which open into associated depression 42 in the front
side of base 32. As seen in Figure 10, each runback is
constituted by a pair of copper bars 44a whose forward
terminations are clamped by bolts 45a in electrical
connection with an intervening tongue 45b integrally formed
with male stab 45. At an appropriate intermediate point,
a pair of brackets 72 are clamped together between the
runback bars by bolts 72a to thus create a runback assembly
with bars 44a secured in closely spaced, parallel relation
Each bracket is equipped with a pair of laterally turned,
apertured ears 72b which rest on four pedestals 42a out-
standing from the floor of each depression 42, as best seenin Figure 3, when the runback assemblies are inserted
through sleeves 70 from the front side of the base. As seen
in Figure 8, self-tapping screws 42c are driven into blind
holes 42b formed in these pedestals to clamp ears 72b
thereto and, in turn, secure the runback assemblies to base
32.
The utilization of a pair of bars in each runback 44
is seen to promote more secure support of the runbacks by
the base; the sleeve partitions 70a being a significant
factor in this regard. Moreover, greater conductor surEace
area is created to afford increased current carrying
capacity without having to enlarge the vertical dimension
of the runback conductors. As seen in Figure 10, the
rearward terminations of the runback bars 44a are apertured
for bolted electrical connection with cable bus connectors
(not shown) which, incidentally, further serve to secure
the bars in parallel, closely spaced relation.
In Figures 13 and 1~ there is illustrated a power
connector 80 which is utilized to make the elec-trical
connections or bus ~oints between the copper riser busbars
56 of Figure 11 and horizontal busbars 82 which in Figure
15 are seen to run between corresponding riser busbars of
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adjacent switchgear vertical sections 20a (Figure 1) and to
a power source (not shown) feeding the switchgear sections
in parallel. The connectors are generally U-shaped having
legs 80a appropriately relieved, as indicated at 80b, to
seat on the rearward edges of the riser bus flanges 56a.
Weld fillets 81 are then laid down to join the connector
legs with the riser bus flanges pursuant to creating a
welded electrical joint between the power connector and the
riser busbar. The planar rearwardly facing surface 80c
of the power connector is provided with tapped bores 80d
accommodating bolts 83 for effecting a bolted electrical
joint between the power connector and a horizontal busbar
82. In the case of the aluminium riser busbars, electrical
joints with the horizontal busbars may be effected in the
manner disclosed in commonly assigned, U.S. Patent No.
4,298,771 issued November 3, 1981.
To isolate the riser-horizontal bus joints from
contact by humans and foreign objects, an insulative
enclosure therefore, seen in Figures 16, 18 and 19, is
provided. This enclosure is constituted by a moled rectangular
collar 86, a molded cover 88, and, in those situations
where a horizontal bus run terminates at a particular power
connector, an end panel 90. To protect and isolate the
horizontal bus runs between power connectors, a pair of
elongated, insulative barriers 92, best seen in Figure 17,
are assembled in partially enclosing relation thereto.
Finaliy, to isolate the riser busbars, a barrier sheet 94,
seen in Figure 15, is secured to the back side of each base
32 to close oEf the riser bus channels 62. Rectangular
openings 94a (Figure 18~ in the barrier sheet provide
clearance for the power connectors 80 so that -the welded
joints between the power connectors and the riser busbars
may be made before the barrier sheet is secured to the
base.
Before the -Joint between the power connectors and
the horiæontal busbars 82 are made, collars 86 of the bus
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joint enclosures are slipped over the power connectors.
Once the bus joints are made, covers 88 are applied. From
Figures 16 and 18, it is seen that the upper and lower
sidewalls of the collar to fully ~solate the bus joint from
above and below. The length of these skirts is made
sufficient to isolate bus joints involving double-bar
horizontal bus runs, as seen in Figure 18. A conductive
spacer 95 is incorporated in the bus joint to maintain the
horizontal busbars in closely spaced, parallel relation
for high ampacity, cool running performance. The face of
the cover is formed having a rectangular cavity 88b to afford
clearance for the heads of the joint bolts 83. Also molded
into the cover face is a rectangular, horizontally elongated,
hollow extension 88c which serves to accommodate the projection
flange of the aluminium power connector utilized in the
bolted-welded aluminium bus joint of the above-noted U.S.
Patent No. 4,298,771. Extension 88c also serves as a
convenient handle for safely removing the cover for in-
service joint inspection. To acccmmodate those situations
where the horizontal bus run terminates at a bus joint,
collar 86 is molded with opposed, laterally extending ears
86a, while the cover is molded with opposed, laterally
extending tangs 88d having a slot 88e therein. Panel 90 is
equipped with a projection 90a, which is inserted in this
tang slot, and an L-shaped bracket 90b, which is apertured
to receive a screw 91 (Figure 18) threaded into a bore
91a provided in collar ears 96a. The panel, thus assembled
to the bus joint enclosure, effectively closes off the other-
wise open side of the enclosure beyond the horizontal bus
run termination to isolate the bus joint from inadvertant
human contact.
Turning to Figure 17, except for their terminations,
the surfaces of the individual horizontal busbars 82 are
coated with a layer 82a of primary insulation which also
covers the surfaces of holes 82b punched therein. As seen
in Figure 20, these holes provide clearance for a series
of screws 96 serving to clamp barriers 92 against the
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- 14 - 41DA-6086
front and back sides of the horizontal busbars throughout
their runs between bus joints. As seen in Figure 18, the
upper and lower skirts 92a of these barriers do not close
off the gap between the horizontal busbars so as not to
obstruct connection thereof. The primary purpose of
these barriers is to protect the busbar primary insulation
82a from impact damage, and thus are preferably formed of
high impact resistant plastic material.
The barriers are molded with a co-extensive track 92b
configured to slidingly receive an insulative strip 97
effective in concealing screws 96 when positioned with its
access holes 97a in non-registry with the screw heads as
seen in Figure 19.
To interconnect the horizontal bus run barriers with
the bus joint enclosure, barrier track 92b is formed with
opposed undercuts 92c (Figures 17 and 21) serving to
slidingly mount a clip 98, also seen in Figures 18 and 19.
With joint enclosure cover 88 in place, its tangs 88d are
received in the recessed portion of tracks 92b on barriers
92 to each side of the bus joint. The clips are then
slid toward the bus joint to capture the tangs and hold
cover 88 in place. To preserve the captive positions of
the clips, they are dimpled, as indicated at 98a in Figure
21, for detenting engagement with holes 98b molded into
the tangs.
It will thus be seen that the objects set forth above,
among those made apparent in the preceding description, are
efficiently attained and, since certain changes may be
made in the above construction without departing from the
scope of the invention, it is intended -that all matter
contained in the above description or shown in -the
accompanying drawings shall be interpreted as illustrative
and not in a limiting sense.
