Note: Descriptions are shown in the official language in which they were submitted.
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Th:is invention relates generally to bus duct
systems o~ ~lectric power distribution and, more particu-
larly, to an improved bus duct plug-in assembly.
The invention deals especially with the kind
of bus duct plug-in assembly comprising an opening formed
in a wall portion of the bus duct, and a plug-in unit
adapted to be mounted on the bus duct such that connectors
forming part of the plug-in unit extend through said open-
ing to make electrical contact with the bus bars in the
duct. With the plug-in unit thus mounted in place, a cir-
cuit control device, such as a circuit breaker, may be
inserted therein and thereby connected to sbab-like termi-
nal portions of the plug-in unit connectors, as well known
in the art and as disclosed, for example, in Applicant's
U.S. patent specification N 3,213,405.
Since plug-in units are removable from the asso-
ciated bus duct, it is customary to provide the latter
with covers for closing the openings in the plug-in regions
when the plug-in units are not in place. Heretofore, such
covers have been either of the sliding kind supported on
the bus duct housing so as to slide thereon between cover-
open and cover-closed positions, or, as shown in Applicant's
U.S. patent specification N 3,710,302, of the hinged type
made to pivot through 180 between cover-closed and cover-
open positions. Of course, the purpose of closing the ~l -
openings in the plug-in regions when the plug-in units
are removed therefrom is to prevent accidental contact with
the live parts within the bus duct housing. ~ 1
It is the principal object of the invention to ~ -
provide an improved bus duct plug-in assembly which will
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protect persons al~o rrom making accidental contact with
live parts in the act of inserting or removing a plug-in
unit at a bus duct plug-in region.
The invention accordingly resides in a bus duct
plug-in assembly comprising a bus duct including a housing
which contains conductive bus bars and has formed therein
an opening giving access to said bus bars, a plug-in unit
including connectors protruding therefrom, said plug-in
unit being removably mountable upon said housing such that
the connectors extend through said opening to make electri-
cal contact with the respective bus bars, and a cover
pivotally supported on said housing and movable to open
and closed positions with respect to the opening therein,
said cover having associated therewith means for limiting
pivotal movement of the cover to an extent causing the
cover in the open position thereof to extend substantially
perpendicular with respect to a plane parallel to said - ;~
openings, and the pivot axis of the cover being located
sufficiently near said opening to enable the cover, when ~ ~
; 20 in the open position thereof, to prevent human fingers -^
from being inserted between the cover and said plug-in unit
; as the latter is being mounted on or removed from said bus
duct.
With this arrangement according to the invention,
the cover, when in its open position? is not completely
out of the way, as are the conventional sliding and hinged
covers which in their open positions lie flat against - ~-
the surface of the bus duct housing, but instead is utilized~
to positively prevent persons inserting or removing the
3 plug-in unit from touching any live parts.
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For added protection, the plug-in unit prefer-
ably is provided with a pair of ~langes extending there-
from in the same direction as said connectors, and which
flanges are spaced apart slightly more than corresponds
to the width of said housing, whereby movement o~ the plug-
in unit toward its mounted position on the bus duct will
cause said flanges to slide over side wall portions o~
said housing before the connectors make electrical contact
with the bus bars therein, and thereby render the connec-
tors completely inaccessible to the person installing theplug-in unit on the duct.
A preferred embodiment of the invention will now
be described, by way of example only, with reference to
the accompanying drawing, in which:
Figure 1 is a side view, partly in section, of
a bus duct plug-in assembly embodying the invention, and
Fig. 2 is a vertical sectional view taken along
the line II-II of Fig. 1.
In the illustrated embodiment, the invention is
shown applied to a bus duct plug-in assembly of the general
type disclosed in the above-mentioned U.S. patent speci-
fication N 3,213,405. As seen from the drawings, the
assembly comprises a bus duct section generally designated
with reference numeral 3, and a plug-in unit generally
designated with numeral 4. The bus duct section 3 comprises
a housing formed of two parts 5 and 7 made of sheet metal
and secured, e.g. bolted, together along lateral flange
portions 9 thereof. Disposed within the bus duct housing
are three main bus bars 13 and a neutral bus bar 14, which
bus bars are supported by insulating support members of
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the plug-in type, one of which is shown at 17.
The plug-in type bus ~)ar support member 17 is
a one-piece molded insulating body having a front wall
19, two side walls 21, and two end walls 23. The end
walls 23 have extensions 33 which form legs for supporting
the bus bar support member 17 upon the rear wall of the
duct formed by the housing part 7. The bus bars 13, 14
extending through the generally trough-shaped support mem-
ber 17 are isolated therein from each other by insulating
barriers 29 formed integral with the member 17, and they
are lodged in recesses 31 formed in the end walls 23.
Formed in the front wall 19 of the member 17 are three
openings 25 aligned with the respective main bus bars 13,
and a further opening 27 aligned with the neutral bus bar
14. All four of the openings 25 and 27 are accessible
from the front of the bus duct 3 through an opening 79 formed
in the housing part 5 thereof.
The plug-in unit 4, shown in the drawings as
mounted on the bus duct housing 5, 7 over the plug-in
type support member 17, comprises a housing 35 having a
cover 37 secured thereto by suitable means such as screws
39 shown threadedly engaged with tapped openings in in-
turned flanges 41 of the housing 35.
Secured in position within the housing 35 is
an insulating block 45 which supports three main connectors
47 and a neutral connector 55. The main connectors 47 are
elongated conductors each having a stab-like inner terminal ~"
portion 53, and an outer connecting portion with a clip -
49 secured thereto, e.g. by means of rivets 51. The neutral
connector 55 comprises a similar conductor which likewise
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has an outer connecting portion with a clip 49 secured
thereto, but has its inner end connected to a terminal
57-
W~th the plug-in unit 4 mounted on the bus duct ;
3 as shown, the electrical connectors 47 and 55 extend
through the openings 25, 27 in the plug-in type support `~
member 17, and their clips 49 are engaged with the respec-
tive bus bars 13 and 14. The plug-in unit 4 is fastened
to the bus duct housing 5, 7 by suitable means, such as
screws 59 passing through openings in two generally L-shaped
brackets 61 on the housing 35, and threadedly engaged
with tapped openings in two generally L-shaped brackets
63 which are anchored to the housing 5, 7 by means of
stamped-out bracket portions 65 cooperating with the
flanges 9 o~ the housing. -
A three-pole circuit breaker indicated in phantom
at 67 is shown supported, at one end thereof, on the in- -
sulating block 45 and, at its other end, on a bracket 69
suitable secured to the base of the plug-in unit housing
35. Thus mounted in position, the circuit breaker 67 has
terminal clips thereo~, generally indicated at 71 in Fig.
2, frictionally engaged with the stab-like terminal por- ~-
tions 53 of the respective main connectors 47 so that
power supplied through the bus bars can be delivered through
the circuit breaker to a load (not shown) connected there-
to when the circuit breaker contacts (not shown) are closed
by means of a handle 73, as well known in the art.
The bus duct 3, at each plug-in region thereof,
is provided with a cover 75 which is pivotally supported
on, e.g. hinged to, the housing part 5 at 77 so as to be movable to
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an open position and a closed position (indicated in
Fig. 1 by phantom lines 75a) wlth respect to the open- ~ -
ing 79 in the duct housing. According to the invention,
there are pro~ided means (in the illustrated embodiment,
a surface portion 81 of the housing part 5 forming an
abutment, and an adJacent edge portion of the cover 75
cooperating with the abutment)for limiting the pivotal
movement of the cover 75 about its pivot axis 77 to an
extent such that, when in its open position, the cover
75 extends substantially prependicular with respect to
a plane parallel to the opening 79, as seen from Fig. 1.
In other words, pivotal movement of the cover 75 between
its open and closed positions is limited to about 90.
Furthermore, the hinge or pivot axis 77 of the cover 75
is located sufficiently near the opening 79 to enable the
cover, when in its open position, to prevent human fingers
from being inserted between the cover 75 and the plug-in
unit 4 while the latter is in its mounted position or is
being moved thereto or removed therefrom, so that a person
plugging-in or unplugging the unit 4 cannot inadvertently
touch any of the ccnnectors 47, 55 as they make initial
contact, or are still engaged, respectively, with the
bus bars within the duct.
For added protection, the plug-in unit 4 prefer-
ably is provided with a pair of flanges 85, 87 (Fig. 2)
which e~tend therefrom in the same direction as the connec-
tors 47, 55 and are spaced apart slightly more than corre-
sponds to the width of the bus duct 3. Thus, as the plug-
in unit 4 is moved toward its fully mounted position on
the bus duct, the flanges ~85 will slide over the side walls
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of the bus duct housing before the connectors 47, 55
make initial contact with the bus bars within the duct
so that, again, therewill be insufficient clearance for
human ringers to slip between the plug-in unit and the
bus duct to make accidental contact with live parts. The
flanges 85, 87 are secured to the plug-in unit housing
35 (which, as shown, is wider than the bus duct 3) by
any suitable means, such as spot welds, for example.
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