Note: Descriptions are shown in the official language in which they were submitted.
This application is a divisional of Canadian
patent application Serial No. 232, 970 filed August 6,
1975.
The field of the invention is disconnect switches,
and more particularly, manually Gperated disconnect
switches having a set of movable contact blades which
are pivoted by rotating a crossbar between an opened
and closed position.
As illustrated in U.S. Patent No. 1,918,248, the
crossbar which carries the movable contact blades is
rotatably mounted to an in-sulating block that is typi-
call~ mounted inside a cabinet and the crossbar is
coupled to a handle mounted on the exterior of the
cabinet through a spring loaded trip mechanism. The
handle and associated trip mechanism may be mounted
to one side of the disconnect switch, or as shown in
U.S. Patent No. 3,602,676, the handle may be mounted
to the front of the cabinet and its trip mechanism
coupled to a point intermediate the ends of the crossbar.
When in their closed position, the movable contact
blades electrically connect with a set of stationary
contacts to conduct electric current from a set of
input terminals to a set of output terminals. As illus-
trated in the above cited U.S. Patent No. 3,602,576,
each movable contact blade is typically connected to an
output terminal through a flexible conductive strap,
or pigtail, that allows the movable contact blade to
be freely pivoted between its opened and closed positions.
As illustrated in U.S. Patent No. 3,684,849, the
current carrying capacity of disconnect switches is often
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enhanced by employing arc chutes. Such arc chutes
are comprised of a series of metallic deionization
plates which are mounted to the insulating block and
positioned directly above each movable contact blade.
~rcs which may result when the disconnect switch is
opened are cooled and eventually extinguished by the
deionization plates in each arc chute.
Disconnect switches are often employed with other
electrical components to form control circuits such as
motor starters. In such control circuits the disconnect
switch serves not only to control the main electrical
power through the operation of its movable contact
blades, but also, to control the operation of other
elements in the control circuit through the operation
of auxiliary contacts which are mounted to the insulating
block. The number and nature of such auxiliary contacts
vary with each particular application of the disconnect
switch and, therefore, these are typically fastened to
the insulating block at any point which allows them to
be mechanically coupled to the rotatable crossbar.
Prior disconnect switches are difficult to maintain
and service. For example, if a movable contact blade
is to be replaced, the arc chute located directly above
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it must be removed and the flexible strap which connects
it with the output terminal must be unfastened before
the blade can be detached from the crossbar. Although
some prior art structures allow the arc chutes to be
removed and replaced as an integral unit, the fastening
devices which hold such arc chutes to insulating blocks
are often accessible only by removing the insulating
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bloc~ ~rom its enclosure. Also, although prior
au~iliary contacts are typically enclosed in self-
contained cartridges, these cartridges are mounted
to the front or s.ide of the insulating block using
S fastening means which may not be easily accessible
when the disconnect switch is mounted within its
enclosure.
The present invention relates to an improved
disconnect switch which is particularly easy to
service and maintain. More specifically, the discon-
nect switch includes a base having a pair of integrally
formed side walls which de~ine a housing and an
integrally formed divider wall which defines a pair
of compartments within the housing; a crossbar mounted
to the base for rotation about a horizontal actuation
axis, the crossbar extending horizontally through each
of the compartments; a plurality of movable contact
blades, one disposed in each of the compartments and
each fastened to the crossbar for swinging motion
about the actuation axis between an opened and a closed
position; a plurality of stationary line contacts
mounted to the base, each of the stationary line con-
tacts being disposed in one of the compartments to make
electrical contact with the movable contact blade therein .
when the movable contact blade is in its closed position;
and a plurality of modular arc chutes, each separately
mounted to the base and disposed within one of the
compartments, and each including a case which supports
a plurality of deionization plates in vertical, spaced
relation immediately above the movable contact blade
within the compartment.
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The present invention will enable one to provide
a disconnect switch in which assembly and maintenance
of its elements is facilitated. The modular arc
chutes are easily removed by pulling them from their
mating cavities. The deionization plates are thus
easy to inspect as well as the stationary line contacts
which are located behind the modular arc chutes.
The present invention, in conjunction with that
described in copending Canadian application Serial No.
232,970, filed August 6, 1975, will now be described
with reference to the accompanying drawings, in which~
Fig. 1 is a perspective view of the disconnect
switch with parts removed and parts cut away,
Fig. 2 is a front view of the disconnect switch
of Fig. 1,
Fig. 3 is an exploded side view of the disconnect
switch of Fig. 1,
Fig. 4 i9 a side view with parts cut away of the
disconnect switch of Fig. 1,
Fig. 5 is a perspective view of the crossbar and
associated movable contact blades which form a part of
the disconnect switch of Fig. 1,
Fig. 6 is a side view of the disconnect switch of
Fig. 1,
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Fig. 7 is a perspective view of a modular arc
chute which forms part of the disconnect switch of
Fig. 1,
Fig. 8 is a bottom view of the modular arc chute
of Fig. 7,
Fig. 9 is a bottom view of an auxiliary contact ~
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cartridge which forms part of the disconnect switch
of Fig. 1,
Fig. 10 is a side view with parts cut away of the
auxi]iary contact cartridge of Fig. 9, and
Fig. 11 is a view in cross section of the auxiliary
contact cartridge taken along the line 11-11 in Fig. 10.
Referring particularly to Figs. 1-3, a two-part
housing 1 is formed by a base 2 and a back 3 which are
fastened to a mounting plate (not shown in the drawings)
by a set of screws 4O The base 2 and back 3 are each
molded from an electrically insulating thermoset phenolic
material such as that sold commercially under the
trademarks "SI 45 DUREZ" and "Plenco 509." The housing
1 rotatably supports a crossbar 5 which is journaled to
a pair of spaced side walls 6 and 7 and which runs
transversely through the interior of the housing 1
along a horizontal actuator axis 8. The housing 1 is
divided into three compartments 9, 10 and 11 by a pair
of integrally molded vertical divider walls 12 and 13.
The houslng 1 encloses a three-pole, single throw
disconnect switch and each of the compartments 9-11
encloses the elements of one pole. The three poles are
identical, and as shown best in Figs. 1 and 4, each
includes a movable contact blade 15 which is fastened
to the crossbar 5 and pivoted about the actuator axis 8
between an opened and a closed position. The movable
contact blade 15 is made of copper and includes an
operating end which is received between the jaws of a
stationary contact 16. The stationary contact 16 is
made of copper and is mounted to a metal strap 19 in
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the plane of the movable contact blad~ 15. The metal
strap 19 is fastened to a back wall 17 by a screw 18
that is reeeived in a threaded opening formed therein
and it supports an input terminal 21 that is fastened
to the strap 19 by a screw 22. When the crossbar 5
is rotated to its closed position, the movable contact .- :: -
blades 15 are pivoted about the actuator axis 8 and
the operating end 23 on each movable contact blade 15 ~.
is received by the jaws of its associated stationary ~ .
line contacts 16. Electrical connection is thus made .
between the three input terminal lugs 21 and the movable . ~ ~
contaet blades 15. -~ ; -
Located within each of the compartments 9-11 is a ~ ::
stationary connector 25 which electrically connects
each movable contact blade 15 with an output terminal :~
26. As shown best in Figs. 1, 2 and 4, the connectors
25 are identical in construction to the stationary
contacts 16 and they are fastened to a metal strap 27
which is in turn fastened to the base 2 by a serew 29.
The output terminal lug 26 fastens to the lower end of
the strap 27 by means of a screw 30 and the strap 27
loops upward and forward to provide an integral mounting
plate 31 for a fuse assembly (not shown in the drawings)
whieh may be mounted dlrectly beneath the disconnect
switch~. Whereas the jaws of the stationary contacts
16 extend forward, the jaws of each connector 25 extend ~ :~
rearward and reeeive the lower end 32 of the movable
eontaet blade 15. As the movable eontact blades 15 are
pivoted between the opened and closed positions, the
lower end 32 on each maintains continuous electrical
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contact with the jaws of its associa~ed connector 25.
Therefore, when electrical connection is made between
the movable contact blades 15 and stationary contacts
16, three conductive paths are completed between the
input terminals 21 and output terminals 26 on the dis-
connect switch.
To facilitate the removal of the movable contact
blades 15 for inspection and, if necessary replacement,
each blade 15 is removably fastened to the crossbar 5.
Referring specifically to Fig. 5, each movable contact
blade 15 is inserted through a transverse opening 35
in the crossbar 5 which is substantially rectangular
in shape and which contains a detent mechanism that
holds the blade 15 in place. The transverse openings
are positioned along the actuator axis 8 to align the
movable contact blades 15 in the planes of their associ-
ated stationary contacts 16. The detent mechanisms
include a pair of opposing metal retaining springs 36
each of which has a convex face 37 that is bounded at
its ends by outwardly extending ears 38. A semispherical
protrusion 39 is formed in the center of each face 37
and is received in an opening 40 which is formed through
the movable contact blade 15. The retaining springs
36 are positioned within each transverse opening 35 to
face one another. The ears 38 wrap around and clamp
against recessed surfaces 41 that are formed in the
crossbar 5 alongside the transverse openings 35, and
the protrusions 39 are sprung towards one another to
pinch the movable contact blade therebetween. By grasping
the movable contact blade 15 with a suitable instrument,
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i~ can be removed by pulling it from between the
retaining springs 36. The movable contact blade 15 -'
is replaced by sliding it into ~he transverse opening
35 until the protrusions 39 snap into place in the
opening 40.
Positioned within each compartment 9-11 and
located directly above each movable contact blade 15
is a modular arc chute 44 which serves to extinguish
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any electrical arc that may be generated when the
movable contact blades 15 are pivoted from their closed
position to their opened position. Referring particularly
to Figs. 1, 7 and 8, each modular arc chute 44 includes
a two-part case 45a and b which is molded from a suit-
able thermoset polyester insulating material and which
is held together by a pair of rivets 43. The case 45
includes an overhang portion 46 which extends rearward
and provides an insulating barrier directly above its
associated stationary contact 16. The case 45 also
includes a pair of side walls 47 which extend downward
to form an archway 48 through which the operating end
23 of the movable contact blade 15 swings when pivoting
between its opened and closed positions. A set of six
rectangular slots 49 are formed vertically through the
case 45 and each slot 49 receives a metal deionization
plate 50. The plates 50 are thus aligned one in back
of the other in closely spaced vertical planes, and
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each is retained in its associated slot 49 by a pair of
outwardly extending ears 51 which rest in pockets (not
shown in the drawings) formed in each slot 49. Each
deionization plate 50 includes a pair of downward extending
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legs 52 which form an arch through which the operating
end 23 of the movable contact blade 15 passes. AS is
well known in the art, the electrical arc which is
generated when the movable contact blade 15 opens
circuit is broken into a seri~s of short arcs by the
successive deionization plates 50, and these are
extinguished by the cooling effect which the deionization
plates 50 provide. It can be appreciated by those
skilled in the art that the number and spacing of the
deionization plates can be varied to alter -the current
interrupting capability of the switch.
Each modular arc chute 44 is slidably received in
a mating cavity 53 which is integrally formed within
each of the compartments 9-ll above the crossbar 5.
Referring particularly to Fig. l, each cavity 53 is a
substantially rectangular cavity which is defined along
one of its vertical boundaries by one of the upright
walls 12, 13 or 7 and which is defined along its top by
an overhang 54 that is integrally formed on each of the
walls 12, 13 and 7. Step-shaped barrier walls 55 are
integrally formed to the base 2 within each compartment
9, lO and ll, and these form both the lower boundary
of each cavity 53 and its left side. The outer dimensions
of each modular arc chute 44 are slightly tapered to
provide a wedging effect when the arc chute 44 is inserted
into its cavity 53 from the front. Each modular arc
chute 44 may be removed separately by pulling it straight
forward from its cavity 53.
As shown best in Figs. 1-3, a cover 58 is mounted
to the front of the housing l to substantially enclose
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that portion of each compartment 9, 10 and 11 above
the barrier wall 55. The cover 58 is rnolded from a
thermoplastic, flame retardant, polypropylene material,
and it is fastened -to the base 2 by two pairs of
integrally molded prongs 59 and a pair of captive
screws 60. As shown best in Fig. 1, the prongs 59
are received in openings 61 which are formed on the
front edges of the divider walls 12 and 13 and the
screws 60 are received in openings 62 which contain
threaded inserts. Referring particularly to Fig. 2,
a set of three windows 63 are formed in the cover 58
and each is aligned directly in front of the archway
48 of a modular arc chute 44. Thus, when in their
opened position, the operating end 23 of each movable
contact blade 15 is readily visible through one of the
windows 63 and can be easily inspected for wear. As
shown in Figs. 3 and 4, a set of three stops 64 are
integrally molded on the back side of the cover 58
directly above the windows 63. When the screws 60 are
tightened, the stops 64 bear against the forward ends
of the modular arc chutes 44 to retain them tightly ~-
in their cavities 53. When the arc chutes 44 are to be
removed, the captive screws 60 are unfastened and the ;
cover 58 is folded downward about a hinge 65 to expose
these cavities 53.
As indicated above, when the disconnect switch is
used in control circuits it is often necessary to operate
auxiliary contacts. In the preferred embodiment described
herein, provisions are made to mount a pair of auxiliary
contact cartridges to the housing 1 and couple their
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operating elements to the crossbar 5. Referrin~
particularly to Figs. 1, ~ and 4, a pair of auxiliary
chambers 67 are formed in the housing 1 between the
poles contained within the compartments 9, 10 and 11.
Each auxiliary chamber 67 is substantially rectangular
in shape and extends rearward from the front of the
base 2 to its back wall 17~ The top and one side
boundary of each chamber 67 are de~ined by the stepped
barrier walls 55 in the compartments 10 and 11, the
other side boundary of each is defined by a portion of
the divider walls 12 and 13, and the bottom boundary
of each is defined by a ledge 68 which is formed in
each of the divider walls 12 and 13. A pair of rectangular
openings 63 are formed in the cover 58 directly in front
of the auxiliary chambers 67 and an auxiliary cartridge
70 is inserted into either chamber 67 through one of
the openings 63. As shown best in Fig. 3, a pair of
locking mechanisms 71 are integrally formed on the -~
back side of the cover 5g, and each locking mechanism
71 extends rearwardly into one of the auxiliary chambers -~
67. The locking mechanism 71 engages and firmly retains
the auxiliary cartridge 70 in place.
Referring particularly to Figs. 5 and 9-11, each
auxiliary cartridge 70 includes a relatively long slender
case 72 which is molded from a thermoplastic polyester
insulating material. A cam member 73 is slidably
mounted to the bottom wall of the cartridge 70 and it
includes a rectangular coupling element 74 which extends
downward therefrom to engage one of two actuator elements
75 on the crossbar 5. As shown best in ~ig. 5, each
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actuator elemen~ 75 includes a pair oE closely spaced
helical walls 76 which are integrally formed to the
crossbar 5 and extend radially outward therefrom to
define a channel therebetween for the coupling element
74. When the crossbar 5 is rotated about the actuator
axis 8, the cam member 73 on each auxiliary cartridge
70 slides along an axis which is parallel to the ;
actuator axis and which is indicated in Fig. ll by the
arrows 77.
The sliding motion of the cam member 73 operates
a set of auxiliary contacts 78 and 79 which are mounted
inside the case 72 of each auxiliary cartridge 70.
Reerring particularly to Figs. lO and ll~ one of the
contacts 79 is stationary and is connected to a terminal
lug 80 by a bus 81 and the other contact 78 is supported
by a movable contact arm 82 which connects to a terminal
lug 83 through a bus 84. A cam follower element 85 is
pivotally mounted to the case 72 and located directly
beneath the movable contact arm 82. As the cam member
73 slides along its axis 77 in response to the rotation
of the crossbar 5, the cam follower 85 operates the
movable contact 78 to open and close the auxiliary contacts.
It should be apparent to those skilled in the art that
many variations can be made in the contact structure
within the auxiliary cartridges 70 and for a more detailed
description of the particular auxiliary cartridge 70
described herein, reference is made to copending Canadian
patent application Serial No. 220,229 which was filed on
February 17, 1975, and which is entitled "Auxiliary
Switch ~or Electromagnetic Contactor." Referring particularly
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to Figs. 1, 2, 5 and 6, a trip mecharlism 88 is mounted
to the left side wall 6 of the housing 1 to couple the
crossbar 5 of the disconnect switch with a manually
operated handle (not shown in the drawings). The trip
mechanism 88 includes a metal frame 89 which is mounted
by a set of screws 91 to ears 90 that are integrally
formed on the side wall 6. The frame 89 is symmetrical
about a vertical plane and it may be mounted in a similar
manner to the right side wall 7 of the disconnect switch.
10 A set of four integrally molded ears 90 are formed on
the right side wall 7 to mount the trip mechanism 88.
The handle (not shown in the drawings) operates through
a coupling arm 92 which fastens to the upper end of
a pivot plate 93 that is rotatably attached to the frame
89. A trip spring guide 96 connects the bottom end of
the pivot plate 93 to the frame 89 and when the handle
is operated, the pivot plate 93 is rotated about the
actuator axis 8 between an opened and closed position.
A trip spring 94 surrounds the guide 96 and provides
a strong snap action in both directions. The pivot
plate 93 is connected to the crossbar 5 by a pair of tabs
95 that engage arcuate coupling slots 97 which are integrally ~:
molded to the ends of the crossbar 5. The mounting ears
90 are symmetrical with respect to the actuator axis
8 to allow the trip mechanism 88 to be mounted to ei~her
side of the disconnect switch and to couple with the ;~
exposed end of the crossbar 5.
A disconnect switch has been described which embodies
the present invention. It should be apparent to those
skilled in the art, however, that many variations can be
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made in this structure without departing from the spirit
of the invention, and reference is therefore made to
the following claims.
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