Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
41DA-3037
107Z16Z
Drawout apparatus are well known expedients to
facilitating the installation and removal of physically
large electrical devices, such as switches and circuit breakers,
with respect to switchboards and panelboards. The device is
provided with plug-in or stab-type disconnect primary contacts
which mate in electrical interconnection with complementary
switchboard primary disconnect contacts incident to racking
movement of the device to its innermost, engaged position,
thereby making the electrical joints requisite to electrically
connecting the device into the switchboard.
In higher current applications, the devices become
quite large and heavy, thus rendering the bodily movement
of the devices necessary to electrically connect and dis-
connect them from the switchboard extremely cumbersome without
structure supporting the device in its racking movement.
Moreover, as current ratings increase, the requisite high
contact pressures embodied in the primary disconnect contacts
become extremely difficult, if not impossible, to overcome
without mechanical assistance. Thus, drawout apparatus
for accommodating these larger electrical devices typically
include not only provisions for supporting the device during
racking movement, but also various camming or levering
mechanisms operating to mechanically assist the racking
movement of the device at least during that segment of travel
necessary to engage and disengage the device-switchboard
primary disconnect contacts.
The principle limitation to the utilization of
drawout apparatus is the ability of the plug-in primary
terminal joints to carry the increasingly higher currents
called for in many applications. These joints are sources
of heat which can contribute to an intolerable high
temperature condition within the switchboard. Consequently,
~ 3
~ 41DA-3037
` 107Z16;i~
'`f~ bolted terminal joints must be resorted to, and, as a result,
the signal advantage in drawout installations of being able
to connect and disconnect a device from a live switchboard
without having to operate directly on the primary terminal
. joint is lost.
It is accordingly an object of the present invention
~` to provide improved drawout apparatus capable of racking
~ large, heavy duty electrical devices into and out of an
`` enclosure.
A further object of the present invention is to
provide drawout apparatus of the above character, which is
equipped with a racking mechanism for assisting racking
movement of the device into and away from an engaged position
i with respect to primary terminals of an electrical switchboard.
Yet another object of the present invention is to
provide drawout apparatus of the above character which
includes a joint clamping mechanism manually operable to
effect cool running electrical joints between the device and
` switchboard primary terminals.
An additional object is to provide drawout apparatus
of the above character, which includes interlocking means
for regulating human access to the racking and joint clamping
mechanisms to insure proper and safe operation of the apparatus.-
Still another object of the present invention is to
provide drawout apparatus of the above character, which is
inexpensive to manufacture, efficient in design, rugged in
construction, and safe and reliable in operation.
Other objects of the invention will in part be
- obvious and in part appear hereinafter.
In accordance with the present invention, there i5
provided drawout apparatus for racking relatively large,
he~fvy duty electrical devices into and out of a switch~oard
- 2 -
,~
l~q~16Z 41DA-3037
compartment and having provision for effecting plural cool
running joints between the device primary terminals and the
switchboard primary terminals. These terminal joints are
effected substantially concurrently in relative safety, even
while the switchboard is live. Generally stated, the drawout
apparatus of the invention includes a carriage on which the
electrical device, for example, a large circuit breaker, is
mounted. The carriage, in turn, is supported on opposed,
telescoping rails mounted to the electrical switchboard.
` 10 The rails accommodate facile movement of the circuit breaker-
carriage assembly from a fully extended position to a test
position just short of inter-engagement of connectors affixed
to the circuit breaker and switchboard primary load current
carrying terminals. setween the test position and the engaged
position, racking movement of the circuit breaker-carriage
assembly is mechanically assisted by a racking mechanism lead
screw which affords ample mechanical advantage while precisely
positioning the circuit breaker with its primary terminal
- connectors in joint-making relation with the switchboard
primary terminal connectors.
The drawout apparatus further includes a manually
operable joint clamping mechanism, effective while the
circuit breaker is in the engaged position, to achieve
forceful clamping pressures on lapped contact elements of
associated circuit breaker and switchboard primary terminal
connectors, such as to achieve cool running joints in the
manner of bolted joints. More specifically, the drawout
apparatus includes a joint clamping mechanism utilizing a
second, clamping lead screw which is torqued at the front of
the carriage by the operator to develop equal and oppositely
directed forces on the lapped contact elements of associated
breaker-switchboard terminal connectors, thereby pressing
107~16Z 41DA-3037
:~
" same in secure electrical interconnection.
An access control assembly, mounted to the carriage,
is interlocked with the racking and clamping mechanisms, and
the carriage position to regulate operator access ~ the - -
racking and clamping lead screws and thus insure proper and
~,` safe operation.
; The invention accordingly comprises the featuresof construction and arrangement of parts which will be
exemplified in the construction hereinafter set forth, and
la the scope of the invention will be indicated in the claims.
For a fuller understanding of the nature and objects
- of the invention, reference should be had to the following
detailed descr1ption, taken in connection with the accompanying
drawings, in which:
` FIGURE 1 is a front perspective view of a switch-
board compartment equipped with circuit breaker drawout
apparatus embodying the present invention;
FIGURE 2 is a rear perspective view of the drawout
apparatus of FIGURE l;
FIGURES 3 and 4 are side elevational views of a
circuit breaker carriage utilized in the drawout apparatus
~; of FIGURE 1, these figures portraying the operation of a
racking mechanism included in the drawout apparatus;
.~ .
FIGURE 5 is a fragmentary perspective view of a
, .
- portion of the drawout apparatus of FIGURE 1 mounted by the
switchboard;
FIGURE 6 is a fragmentary, somewhat diagramatic,
side elevational view of a portion of FIGURE 5, illustrating
the action of a gate in controlling the racking movement of
. 30 the circuit breaker-carriage assembly between its test and
''~
` disengaged position;
FIGURES 7 is a fragmentary, perspective view of a
-- 4 --
: . .~ 41DA-3037
107Z162
portion of a joint clamping mechanism incorporated in the
drawout apparatus of FIGURE l;
` FIGURE 8 is an isometric view of the back wall of
.~ the switchboard cubical accommodating the drawout apparatus
. of FIGURE l;
` FIGURE 9 is an exploded, perspective view of a
4 portion of the joint clamping mechanism of FIGURE 7;
FIGURE 10 is a fragmentary, perspective view of a
-~ portion of the joint clamping mechanism of FIGURE 7 depicted
in its joint clamping condition;
~- FIGURE 11 is a fragmentary, plan view, partially
broken away, of a portion of the joint clamping mechanism of
; FIGURE 7;
--~ FIGURE 12 is a plan view, partially broken away, of
a portion of the joint clamping mechanism of FIGURE 7, depicted
in its joint clamping condition;
FIGURE 13 is an exploded, perspective view of a
portion of an access control assembly incorporated in the
.~ drawout apparatus of FIGURE 1;
FIGURE 14 is a perspective view of a portion of
the access control assembly of FIGURE 13, illustrating
different relative positions of the various parts;
FIGURE 15 is a fragmentary, perspective view of the
access control assembly of FIGURE 13, illustrating the
relative positions of the various parts assumed when the
circuit breaker-carriage assembly arrives at its engaged
: position;
FIGURES16 through 19 are a series of perspective
views of the access control assembly in its various conditions
to control access to the racking and joint clamping mechanisms;
; FIGURES 20 through 23 are a series of side
elevational views illustrating the operation of a position
-- 5 --
- . , -- - . . .
.
62 4lDA-3037
indicator assembly utilized in the drawout apparatus of
FIGURE l;
FIGURE 24 is a front elevational view of the position
indicator apparatus of FIGURES 20 through 23;
: FIGURE 25 is a plan view of a position indicia
bearing label displayed by the position indicator apparatus
of FIGURES 20 through 23;
FIGURES 26 and 27 are plan views, partially braken
away, of a portion of the drawout apparatus of FIGURE 1
illustrating the manner in which a trip interlock assembly and
the position indicator assembly of FIGURES 20 through 23 are
controlled by the joint clamping mechanism of FIGURE 7; -- -
; FIGURES 28 and 29 are sectional views of the trip
interlock assembly of FIGURES 26 and 27, illustrating the
manner in which the trip interlock assembly is controlled
by the racking mechanism of 3 and 4; and
FIGURE 30 is an exploded, fragmentary perspective
view of a portion of the trip interlock assembly of FIGURES
26 and 27.
Corresponding reference numerals re er to like
parts throughout the several views of the drawings.
Referring first to FIGURE 1, the invention is
:~ embodied in a drawout apparatus for facilitating racking -
movement of a large, industrial-type circuit breaker 20
into and out of a cubical or compartment of an electrical
enclosure or switchboard 22. The circuit breaker is mounted
. .
by a carriage, generally indicated at 24, which in turn is
supported for racking movement by opposed telescoping rail
assemblies, generally indicated at 26 and mounted to the
`-- 30 compartment sidewalls 22a. The rail assemblies are preferably
constructed in the manner disclosed in the commonly assigned,
Canadian application Serial No. 249,917, filed April 9, 1976,
- Ericson et al. These rail assemblies accommodate racking
.
,
b 10'~162 4lDA-3037
`: `
movement of circuit breaker 20 between a withdrawn or extended
position and a retracted or "engaged" position, wherein the
breaker-switchboard load current carrying primary contact
terminals are in engageable relation, ready to be made into
` cool running joints by a clamping mechanism generally
indicated at 27. As disclosed in the above-noted Canadian
application, the rail assemblies accommodate positioning of
the circuit breaker in an intermediate position, commonly
referred to as the "test" position, wherein the primary
contact terminals are disengaged, while circuit breaker-
: switchboard secondary contacts remain engaged to permit
operational testing of various accessorial or auxiliary
functions embodied in the circuit breaker. Intermediate the
extended and test positions is a so-called "disengaged"
`~ position wherein both the primary and secondary contacts are
disengaged. These engaged, test and disengaged positions of
`: the circuit breaker are displayed frontally to the operator
of the drawout apparatus by an indicator assembly, generally
indicated herein at 30 in FIGURE 1. Racking movement of the
. 20 circuit breaker between its extended and test positions is
:~ readily effected manually through the convenience of the rail
-- assemblies 26. However, in order to achieve precise positioning
of the circuit breaker in its engaged and test positions,
:~ racking movement therebetween is effected by operation of
a racking mechanism, generally indicated at 32 in FIGURE 1.
: Carriage 24, as seen in FIGURES 1 and 2, includes
a pair of spaced sideplates 34 interconnected across the back
by a series of horizontal stringers 36. Bolts 37 clamp
laterally extending flanges 20a, integral with the circuit
~ 30 breaker base, to the carriage stringers 36 pursuant to affixing
the circuit breaker to the carriage. As best seen in FIGURE 3,
a horizontally elongated bracket 38 is affixed to each sideplate
: - 7 -
'72162 4lDA-3037
34 for the purpose of moun*ing front and rear carriage
support pins 39. As disclosed in the above-noted Canadian
application, these pins are received in slots provided in the
inner rails of each rail assembly in mounting the circuit
breaker-carriage assembly thereon. As seen in FIGURES 3 and
4 herein, a mounting plate 40, affixed to the right carriage
sideplate 34, is formed with a turned out frontal flange 40a
which serves to rotatably mount a lead screw 42 included in
racking mechanism 32. A collar 43, fitted on lead screw
42 behind flange 40a, cooperates with the lead screw head
to preclude axial movement of the lead screw. A slideplate
44 is provided with a longitudinally elongated slot 44a which
receives a laterally outstanding pin 46 carried by mounting
plate 40. A bracket 47 is affixed to slideplate 44 and
captures a travelling nut 48 through which lead screw 42 is
- threaded. It is seen that slideplate 44 is thusly mounted to
reciprocate horizontally as the lead screw is rotated in
opposite directions via a suitable tool, such as a conventional
socket wrench.
Racking mechanism 32 further includes a crank shaft
50 tFIGURE 2) extending across the back of the circuit breaker
and journaled adjacent its ends in carriage sideplates 34.
To the ends of the crank shaft are affixed right and left crank
arms 52. The right crank arm as seen in FIGURES 3 and 4,
carries an inwardly extending pin 54 which is received in a
vertically elongated slot 44b in slideplate 44. It is thus
seen that reciprocation of slideplate 44 by rotation of
lead screw 42 swings the right crank arm 52 through an arc
centered about the crank shaft axis via the pin 54 and slot
44b interconnection. Thus, rotation of the lead screw 42 in
a direction to move the slide to the left from its position
in FIGURE 3 to its position in FIGURE 4 swings the right crank
*
; 10~16Z 4lDA-3037
" arm 52 in the clockwise direction. Crank shaft 50 is thus
also rotated in the clockwise direction, and the left crank
` arm affixed to its other end is swung through a corresponding
arc. The crank arms mount outwardly extending crank pins
56 which, as described in detail in the above-noted Canadian
application, operate on stationary cam surfaces to achieve
racking movement of the circuit breaker-carriage assembly
between the test and engaged positions via operation of
racking mechanism 32.
Each rail assembly, as seen in FIGURE 5, includes
two sets of vertically opposed rollers 62 which are mounted
to the compartment sidewall 22a. These rollers serve to
movably mount an intermediate rail 64 which, in turn, mounts
a series of rollers 66. These rollers, in turn, movably
mount an inner rail 70. It is thus seen that the intermediate
rail rides on stationary rollers 62, while the inner rail 70
rides on rollers 66 carried by the intermediate rail, thus
- accommodating telescopic movement of the two rails of each
- rail assembly in and out. To mount carriage 24 to the rail
assemblies, each inner rail 70 is provided with front and
rear upwardly opening notches 72 which receive the carriage
support pins 39 (FIGURE 3~.
As disclosed in the above-noted Canadian application
Serial No. 249,917, the rail assemblies 26 include provisions
for limiting the telescopic movements of the intermediate and
inner rails, locking the carriage in its supported position
on the rail assemblies, and latching means for latching the
rail assemblies in their extended and compacted conditions in
the absence of the circuit breaker carriage. Also, the rail
assemblies are structured such that the circuit breaker-
carriage assembly may be swung over on the two forward carriage
support pins 39 to an inverted orientation, thereby facilitating
_ 9 _
:107Z16Z 41DA-3037
inspection and maintenance of the circuit breaker and
switchboard primary contact terminals.
That portion of the racking mechanism 32 carried
by carriage 24, namely the racking screw 42, slideplate 44,
crank arms 52, crank pins 56, etc. have already been
described in connection with FIGURES 3 and 4. The remaining,
stationary portion of the racking mechanism is supported by
each compartment sidewall 22a. Thus, as seen in FIGURE 5
and as described in detail in the above-noted Canadian
;
- 10 application, a plate 90, affixed to each compartment sidewall,
is provided with a double-acting cam slot 92 extending from
an upwardly directed mouth downwardly and somewhat rearwardly.
Crank pins 56 (FIGURES 3 and 4) operate in these cam slots
as illustrated in FIGURE 6; acting on the forward edges thereof
to draw the circuit breaker-carriage assembly from the test
position inwardly to the engaged position and acting on the
rearward edges thereof to draw the assembly back to the test
position. This action is implemented by rotation of the
` racking mechanism lead screw 42 in one direction to swing
,. .;
~ 20 the crank pins downwardly in slots 92 and draw the circuit
,: !
breaker into the engaged position and by rotation in the
opposite direction to swing the crank pins upwardly in the
slots to back the circuit breaker off to the test position.
.i
Entry and exit of the crank pins 56 from their
associated cam slots 92 are controlled by pivotally mounted
; gates 94. Positioning of each gate g4 i5 manually controlled
; by a separate, elongated gate operator arm 98 extending out
~ to the front side edge of the switchboard compartment~ As
.
described more clearly in the above-noted Canadian application,
arms 98 are pulled out in order to pivot the gates 94 to their
open position seen in FIGURE 5 and in phantom in FIGURE 6.
Latches 100 are provided to hold the operator arms in their
- lQ -
. lO'Y~162 41DA-3037
pulled out positions against the bias of return springs 101,
such as to sustain the gates in their open positions and thus
accommodate movement of the crank pins 56 into the mouths of
cam slots 92 as the circuit breaker-carriage assembly is
; manually pushed in from the disengaged position to the test
`~ position. Latches 100 also sustain the gates in their open
` positions to accommodate exiting of the crank pins 56 as the
circuit breaker-carriage assembly is manually pulled away
from the test position into the disengaged position. The
- lQ latches 100 are also equipped to automatically release the
arms 98 for retraction by springs 101 to close the gates 94
once the crank pins 56 have either entered or left the mouth
-~ of cam slots 92. To this end, the latches lQ0 are provided
with rearward extensions 112. When the latches are positioned
to latch the arms 98 in their pulled out positions, the
extensions are elevated into positions where they are engaged
by a gate actuating pin 58 CFIGURES 3 and 4~ carried by each
crank arm 52 as the circuit breaker-carriage assembly makes
- its final approach into the test position and as the assembly
exits the test position enroute to the disengaged position.
This engagement unlatches the latches to release the arms, and
the gates close, all as more clearly described in the above-
noted Canadian application, Serial No. 249,917.
To prevent undesirable rocking and skewing of the
circuit breaker-carriage assembly during its racking movement,
a longitudinally elongated guide channel, generally indicated
at 114 in FIGURES 3 and 4, is affixed to each carriage sideplate
34. Each guide channel consists of vertically spaced, laterally
extending flanges 116a and 116b. The channel 118 defined by
these flanges is bottomed by a series of spaced posts 12Q.
As seen in FIGURE 5, a longitudinally elongated guide flange
122 is mounted to each compartment sidewall 22a. Guide flange
lO'~'~i6'~ 4lDA-3037
122 is made up of two flange halves between which are captured
a series of rollers 124. During racking movement of the
;~
circuit breaker-carriage assembly, guide flange 122 is
received in the guide channel 118 with rollers 124 rolling
against the upper and lower channel defining flanges 116a,
116b to prevent rocking motion of the circuit breaker-
carriage assembly during racking movement without adding
noticeably to the required racking force. Posts 120 situated
in the bottoms of the guide channels 118 engage the free
edges of guide flanges 122 so as to inhibit appreciable
skewing motion of the circuit breaker-carriage assembly
during racking movement.
Returning to FIGURES 1 and 2, circuit breaker
20 is provided with massive line terminal straps 130 extending
upwardly from the breaker case and a plurality of downwardly
extending load terminal straps 132. To each line terminal
strap there is clamped in electrical connection, by means of
bolts 131, a separate stab connector 134 (FIGURE 22. Similarly,
bolts 131 secure individual stab connectors 134 to each of
the load straps 132. As will be seen, the line stab connectors
are ganged together to provide a line connector stack assembly
135, while the load stab connectors are ganged together to
provide a load connector stack assembly 137; both assem~lies
being included in the joint clamping mechanism 27. As best
seen in FIGURE 7, each stab connector 134 comprises a base
134a which is provided with tapped bores into which the bolts
131 are threaded pursuant to clamping the connector in electrical
connection with its associated terminal strap. Integrally
formed with connector base 134a are a plurality of parallel
spaced contact fingers 134b. As seen in FIGURE 8, the switch-
board 22 is equipped with line and load receiver connectors
136 respectively electrically connected to line and load bus
- 12 -
.
~ 41DA-3037
`. lO'~Z162
(not shown). These switchboard line and load receiver
connectors are similarly provided with a series of parallel
spaced contact fingers 136a. Returning to FIGURE 7,
when the circuit breaker-carriage assembly is in the engaged
position, the contact fingers of the associated circuit
breaker stab connectors and switchboard receiver connectors
interleave. The spacings between the contact fingers of the
associated stab and receiver connectors are such that they
slide freely relative to each other in assuming their
interleaved relationships. Preferably, the line and load stab
connectors are individually secured to elongated insulative
bars 139 affixed to the carriage stringers 36 as best seen in
FIGURE 2, and thus the line and load connector stack assemblies
may be supported as completed assemblies by the carriage 34,
independently of the circuit breaker terminal straps.
Referring jointly to FIGURES 7 and 9 through 12,
the contact fingers 134b of each of the identically
constructed line and load connector stack assemblies 135, 137
are provided with transversely registered apertures 134c
through which extends an elongated clamping rod 140 (FIGURE 11).
An insulating sleeve 142 encompasses the clamping rod 140
- so as to electrically insulate the rod from the individual
- contact fingers. Centrally apertured insulator blocks 144
are loosely fitted on clamping rod 140 to take up the space
between adjacent stab connectors 134. Similar, centrally
apertured insulator blocks 144 are loosely received on each
end portion of clamping rod 140 beyond the outboard stab
connectors 134. The left end of clamping rod 140 passes
through a central opening in a U-shaped clamping plate 146
and terminates in a threaded portion accommodating a nut 148.
Captured on the left end of clamping shaft 140 intermediate
nut 148 and clamping plate 146 are a series of four Belleville
- 13 -
`~ ' 10~16X 4lDA-3037
washers 150. A sheet 151 of insulation is interposed between
clamping plate 146 and the left most insulator block 144
so as to increase the over surface clearance between the
outboard connector and the metal part therebeyond.
` The right end of clamping rod 140 of each connector
stack assembly passes through another U-shaped clamping
plate 146, an insulative sheet 151, and a series of four
Belleville washers, terminating in a tongue 152 having
. formed therein a rectangular opening 152a, as best seen in
- 10 FIGURE 9. A U-shaped clamping element 154 is formed having
an aperture 154a in its bight portion 154b through which the
' right end clamping rod 140 freely passes. The legs 154c of
clamping element 154 are spaced apart sufficiently to receive
'; therebetween tongue 152 at the right end of clamping rod 140.
` Rectangular openings 154d are provided in the clamping element
legs 154c in opposed relation with rectangular opening 152a
in tongue 152.
As best seen in FIGURE 2, a vertically oriented
clamping shaft 160, also included in the joint clamping
mechanism 27, is journaled for axial rotation by brackers 162
affixed to the upper and lower carriage stringers 36. The
upper and lower terminal portions of this clamping shaft are
provided with opposed flats 160a C~IGURE 9~, with these
~ terminal portions extending through the rectangular openings
-- in the clamping element 154 and tongue 152 of both line and
load connector stack assemblies 135, 137. In ~e quiescent
condition of joint clamping mechanism 27, clamping shaft 160
is angularly oriented as seen in FIGURE 7, such that the
flat~ 16Qa at its terminal end portions are arranged
perpendicular to the axis of clamping rod 140. Thus, these
flats engage the outer edges of the rectangular openings
152a in tongues 152 and the inner edges of rectangular
- 14 -
iO'7Z16Z 4lDA-3037
openings 154d in clamping elements 154.
Still considering the joint clamping mechanism 27,
a bracket 170 is attached to the inner side of the right
carriage sideplate 34, as seen in FIGURE 11. The forward
portion of this bracket is laterally turned to provide a
flange 170a for rotatably mounting a lead screw 172. A
collar 174 fitted to lead screw 172 behind flange 170a
prevents axial movement of the lead screw. A sideplate 176
is mounted for reciprocating movement by a bracket mounted
pin 177 received in a longitudinally elongated slot 176a
visible in FIGURE 16. The slideplate captures a travelling
nut 178 through which lead screw 172 is threaded. A
transversely elongated slot 176b formed in slideplate 176
receives a pin 180 carried at the free end of a crank arm
182 affixed at its other end of clamping shaft 160, as best
seen in FIGURE 9. It is thus seen that rotation of clamping
screw 172 via a suitable tool, such as a socket wrench,
reciprocates slide 176, which in turn, via crank arm 182,
rotates clamping shaft 160.
With the contact fingers of the switchboard receiver ~-
connectors and the line and load connector stack assemblies
interleaved, rotation of the clamping shaft 160 swings the
rounded portions of its shaft terminations into engagement
with the opposed edges of the rectangular openings in the
tongues 152 and clamping elements 154 of both stack assemblies.
As a result, tongues 152 are cammed to the right as seen in
FIGURE 10, pulling with it clamping rod 140 and thereby
loading the Belleville washers 150 at the left ends of both
the line and load connector stack assemblies. At the same
time, clamping elements 154 are cammed to the left as seen in
FIGURE 10 to load the Belleville washers 150 at the right
ends of the line and load connector stack assemblies. These
;
-, , :' , ,
41DA-3037
IO~Z16Z
Belleville washers at each end of the joint stack assembly
develop oppositely directed clamping forces effective to
' clamp the interleaved contact fingers of the circuit breaker
stab and switchboard receiver connectors in secure electrical
connection.
~i While the joint clamping mechanism together with
its line and load connector stack assemblies are disclosed
as being mounted by the carriage, it will be appreciated that
this mechanism could be mounted instead by the switchboard.
Preferably, the stab connectors 134 are each provided with
one more contact finger 134b than is provided in each of the
receiver connectors 136, as illustrated herein, and consequently
the stab contact fingers can effectively define all of the slots
into which the receiver contact fingers 136a are inserted.
It will be appreciated that the disclosed joint
clamping mechanism offers numerous advantages. m e designed
differential in the effective diameters of the clamping
,"
` shafts 160a versus the rounded portions of the shaft
`~ terminations is operative to impart a predetermined and very
repeatable loading or compression of the sets of Belleville
: washers at each end of both stack assemblies. Thus, the
clamping forces developed by the opposed sets of spring
washers are equally predetermined and repeatable. Since these
clamping forces are essentially equal and oppositely directed,
there is no significant resultant forces acting on the
connector stack assemblies. Joint clamping forces of as
~-~ much as 3,000 pounds have been achieved utilizing the disclosed
-.... ;
, joint clamping mechanism. The nuts 148, threaded on the ends
of the clamping rods 140, are turned to readily establish the
desired clamp force magnitude. While Belleville washers
are illustrated herein, it will be understood that other
forms of joint clamping force generating springs may be
- 16 -
41A-3037
iO'~62
utilized. Also to be noted is the fact that the disclosed
joint clamping mechanism affords the opportunity to perfect
high current carrying primary terminal joints from the front
of the switchboard in complete safety even while the switch-
board line receiver connectors are live. Moreover, all phases
of both the line and load primary terminal joints are
perfected concurrently in convenient fashion, with the joints
having all the attributes of bolted joints. While the
joint clamping mechanism is herein disclosed in its application
; 10 to effecting electrical joints between a switchboard and an
electrical device, it will be appreciated that the teachings
may be readily applied to the making of high current carrying
electrical joints in general, such as between busway sections
and between busway and busway plugs.
As a safety measure, it is deemed appropriate to
interlock the operations of the racking mechanism 32 and the
; joint clamping mechanism 27, depending upon the position of
the circuit breaker-carriage assembly. That is, it is very
important that the clamping screw 172 not be rotated to exert
clamping pressures on the line and load connector stack
assemblies until the circuit breaker is in its engaged
position with the contact fingers of the sta~ and receiver
connectors fully interleaved. It will be appreciated that
permanent deformation of the circuit breaker stab connector
fingers could well result if clamping pressure is exerted
absent the interleaved switchboard-receiver contact fingers.
Also, interleaving of the contact fingers could not be achieved
- as the circuit breaker is racked into its engaged position if
- the connector stack assemblies were pre-clamped, and attempts
to do so would damage the racking mechanism 32. By the same
token, attempts to rack the circuit breaker-carriage assembly
away from its engaged position without first unclamping the
41DA-3037
``` 10~'~16Z
joint stack assemblies could also damage the racking mechanism.
To this end, an access control assembly, generally
indicated at 179 in FIGURES 1 and 16 through 19, is provided
to include a first access control plate 18a having vertically
elongated slots 180a through which are received pins 181
~ pursuant to vertically reciprocatively mounting the plate to
r the inner side of the right carriage sideplate 34 as best seen
in FIGURES 13 through 15. This access control plate further
includes an offset and upwardly extending barrier 180b which,
~- lQ with the plate in its elevated position, partially overlies
the head of clamping screw 172, thus denying access thereto.
Riveted to access control plate 180 is a faceplate 182, which
~ is provided with a lower offset tab 182a to serve as a handle
- for manually vertically positioning the access control assembly
179. A second access control plate 184 is mounted by a pivot
pin 185 between the first access control plate 18Q and face-
plate 182. The second access control plate 184 is provided
~- with an offset and depending barrier 184a which is adapted
to control access to the head of racking screw 42, depending
upon the vertical position of the access control assem~ly and
the angular position of the second access control plate. A
spacer rivei 186 extending between faceplate 182 and acce
control plate 180 through an elongated slot 184b in the
second access control plate 184 ~FIGURE 17~ holds these
plates in spaced relation to accommodate plate 184. A clamping
- screw 187 is adjusted to squeeze the two outer plates together
so as to exert a light frictional drag on the pivotal movement
of the second access control plate and thus discourage
- spurious pivotal movement of access control plate 184 during
vertical reciprocation of the access control assembly 179.
From the description thus far, it iæ seen that
while the second access control plate 184 is in its counter-
- 18 -
1 07Z16Z 4lDA-3037
clockwise most pivotal position seen in FIGURE 16, its
barrier 184a is in position to deny access to the racking or
drawout screw 42 while the access control assembly 179 is
in its depressed position. However, barrier 180b is then
,
ducked away from the head of clamping screw 172 such as to
afford access thereto. When the access control assembly is
in its elevated position seen in FIGURE 19, barrier 180b
is in position to deny access toclamping screw 172, while
~- barrier element 184a is elevated away from the head of racking
screw 42 to admit access thereto. With the access control
assembly in its elevated position and the control plate 184
pivoted to its clockwise-most position as illustrated in
FIGURE 17, access to both racking screw 42 and clamping
screw 172 is denied. In this condition, aperture 182b in
faceplate 182, aperture 184d in control plate 184, and
aperture 180c in control plate 180 (FIGURE 13) are in registry
to receive the hasp of a padlock 188.
To interlockingly regulate the movement of the
access control assembly according to the circuit breaker-
~arriage assembly position, a slide 190 is mounted to the
underside of the lower guide channel flange 116b (FIGURES 3,
4 and 13 through 15~ for limited fore and aft movement. A
spring 192, operating between a turned down tab l90a at the
rear end of slide 190 and a post 193 depending from guide
channel flange 116b, biases the slide to its rearward
; position. An arm 194 adjustably mounted to the underside of
guide flange 122 (FIGURES 5 and 13), carries a laterally
extending tab 194a which is positioned to engage a turned down
tab l90a, shifting slide 190 to its forward position as the
circuit breaker-carriage assembly is racked to its engaged
position. The forward end of arm 194 is turned up to provide
a convenient handle for adjusting the mounting position of
-- 19 --
.
~; 10~162 41DA-3037
~,
the arm such that slide 190 is shifted sufficiently forward
~` upon arrival of the circuit breaker-carriage assembly in its
engaged position to register a notch 190b formed therein with
a laterally turned tab 180d carried by access control plate
180. A tab 190c depending from slide 190 just forward of
notch 190b, prevents access control plate tab 180d from
- getting caught under the slide. Once the appropriate
position of arm 194 is established, it is immovably clamped
to the underside of guide flange 122. It is seen from FIGURE
13, that until slideplate 190 is shifted to its forward
. position by engagement with arm tab 194a upon arrival of the
circuit breaker in its engaged position, notch 190~ is out
of registry with tab 180d, and access control assembly 179
cannot, under this circumstance, be shifted downwardly to
afford access to clamping screw 172.
As an additional precautionary measure, a flange
lg6 is riveted to the racking screw slideplate 44, as seen
in FIGURES 3, 4, 14 and 15. The upper elongated edge 196a
of this flange is pos;tioned in underlying relation to access
i~ 20 control plate tab 18Qd, such as to prevent downward movement
of the access control assemhly until the racking mechanism has
~ ~een operated to draw the circuit breaker-carriage assem~ly
- into the engaged position. Once in the engaged position,
m ov cl
flange lg6 has ~Kwe completeIy forward of the access control
plate ta~ 18Qdt as seen in FIGURES 4 and 15, thus clearing
ta~ 18Qd to move downwardly through notch l9Qh and heyond
r ~ the back edge of flange 196. These two separate, but
functionally related interlocking provisions are seen to
prevent inadvertant, untoward operation of the joint clamping
mechanism, ~Qth while the circuit breaker-carriage assemhly
is mounted or dismounted with respect to the rail assem~lies
26.
- 20 -
41DA-3037
~ lO'~Z16;~
With the circuit breaker-carriage assembly in its
engaged position and the access control assembly freed to be
shifted downwardly to access the clamping screw while, at
` the same time, denying access to the racking screw, clamping
; operation of the connector stack assemblies then may proceed.
As the clamping mechanism slideplate 176 is drawn forwardly
by rotation of clamping screw 172, it moves over an upstanding
tab 180e carried by access control plate 180 (FIGURES 15 and
16) so as to prevent elevation of the access control assembly
during the time that clamping pressures are being exerted on
the connector stack assemblies, and consequently, access
to the racking screw 42 is, under this circumstance, denied.
It is preferred that the access control assembly
- can only be locked by padlock 188 when the circuit breaker-
carriage assembly is in either its test or engaged positions.
To this end, the pivotal access control plate 184 is provided
with a laterally extending tab 184c which is received in one
of two sets of notches 20Qa and 200b formed in the upper
~- edges of both the right gate control arm 98 and a bracket 202
supporting same, as seen in FIGURES 5, 16 and 17. These
notches are positioned such that the set 200a is aligned
with tab 184c when the circuit breaker-carriage assembly is
in its test position and the set 200b is aligned with the ta~
when the assem~ly is in its disengaged position. For the
engaged position of the assembly, ta~ 184c is not registerable - --
with either of these notch sets, and consequently access
' control plate 184 cannot be pivoted sufficiently clockwise
to align its hasp aperture 184d with the hasp apertures in
- the faceplate and access control plate 180 such as to permit
padlocking. However, with tab 184c lodged in eïther of the
notches sets 200a, 200b and the padlock applied, racking
movement of the c;rcuit breaker-carriage assembly and operation
- 21 -
10~7216~ 41DA-3037
of the gate control arm are both precluded, and the access
control assembly is locked in the condition denying access to
` both lead screws 42 and 172.
The present drawout apparatus includes position
indicating apparatus similar to that disclosed and claimed in
the commonly assigned, Canadian application, Serial No. 248,381,
.
~ filed March 17, 1976, Ericson et al. In the drawout apparatus
, "
of this Canadian application, there were only three significant
circuit breaker-carriage positions, namely, the disengaged,
test and engaged positions. In the instant drawout apparatus,
there is an additional position, which is in actuality a
condition, namely, the joint clamped position. In terms of
circuit breaker-carriage assembly position, the engaged and
clamped positions are the same. The clamped position
~` pertains when the circuit breaker stack connector assemblies
are clamped in electrical connection with the switchboard
receiver connectors. Accordingly, the position indicating
apparatus 30 of the present drawout apparatus is structured
so as to indicate not only the disengaged, test and engaged
positions of the circuit breaker-carriage assembly, but also
-~ the clamped condition of the circuit breaker-switchboard
primary contact terminals.
'- To this end, the position indicator assembly 30
includes, as seen in FIGURES 20 through 23, an arm 210
pivotally mounted at 212 to a bracket 213 affixed to the left
carriage sideplate 34. The forward portion of arm 210 is
laterally offset away from bracket 213 and terminates in a
bent back flag 214 to which is affixed label 214a CFIGURE 25~
bearing the words "Disengaged', "Test", "Engaged" and "Clamped",
one below the other. A laterally turned front end portion
213a of bracket 213 is provided with a rectangular opening
213b (FIGURE 24) behind which is affixed a mask 215 having a
- 22 -
41DA-3037
lOq2162
window 215a in which the label indicia is separately
displayed. A flange 216 turned back from the side edge of
flag 214 opposite its junction with arm 210 carries an upper
stop 216a and a lower stop 216b which engage a stop pin 217
carried by bracket 213 to determined the limits of pivotal
movement of indicator arm 210, as best seen in FIGURE 20. me
arm is biased downwardly in the clockwise direction by a spring
220 anchored to a post 221 carried by bracket 213.
As disclosed in the above-noted Canadian application,
Serial No. 248,381, the bottom edge of indicator arm 210 is
~ machined to provide a step cam having a series of straight
- cam segments 210a, 21ab, 210c and 210d interconnected by
sharply angled cam segments 210e. Operating against this step
cam is a stationary indicator actuator 222 fixedly mounted
by the compartment sidewall. It is thus seen that as the
circuit breaker-carriage assembly is moved in and out, the
indicator arm 120 is variously angularly positioned depending
upon which step cam segment is riding on actuator 222. By
correlating the positioning of the indicia on the label 214a
affixed to flag 214 with these cam segments, the position of
the circuit breaker-carriage assembly can be read through the
window 215a in mask 215. Thus, when cam segment 210a is
riding on actuator 222 CFIGURE 23), the word "disengaged" is
- visible in window 215a. As the circuit breaker-carriage
assembly is pushed into the test position, cam segment 210b
rides onto actuator 222 and arm 210 is pivoted upwardly to
index the word "test" into registry with window 215a. By
virtue of the sharply angled transistion cam segment 210e the
change in position indication is rather abrupt, occurring
essentially upon arrival of the circuit breaker-carriage
assembly at its test position. From the test position, the
;~ circuit breaker-carriage assembly is drawn toward the engaged
- 23 -
~` - iO~Z162 41DA-3037
position by the racking mechanism 32. Cam segment 210c then
rides onto actuator 222, and the indicator arm 210 is pivoted
upwardly to register the blank space between the words "test"
` and "engage" in window 215a. This blank indication advises
the operator that the circuit breaker-carriage assembly is
in neither the test position nor the engaged position, but
is in transient therebetween. Upon arrival at the engaged
position, cam segment 210d rides onto actuator 222, pivoting
arm 210 upwardly still another increment to register the
~`~ 10 word "engaged" in window 215a. Though in the engaged
position, the circuit breaker must not be turned on until the
switchboard-circuit breaker primary contact terminals are
clamped in electrical interconnection by operation of joint
clamping mechanism 27.
In order to indicate achievement of the clamped
condition, the fact of completed operation of the clamping
joint clamping mechanism must be communicated to the indicator
assembly. To this end, a slide 230, elongated to extend
substantially the full width of the carriage 24, is mounted
by one of the rear carriage stringers 36, as seen in FIGURE 2.
More specifically, and as best seen in FIGURES 26 and 27, slide
230 is formed having a series of longitudinally elongated
slots 230a in which are received pins 232 carried by the
slide supporting stringer 36. This mounting affords limited
longitudinal movement of the slide against the force of a
- spring 236 normally biasing the slide to its right-most
position seen in FIGURE 27. The left end of this slide seen
in FIGURES 26 and 27 mounts a bracket 234 carrying an arm
234a. An adjusting screw 235 threaded through a laterally
turned flange portion 234b of bracket 234 bears against arm
234a to adjust its positioning so as to bear against the
periphery of clamping shaft 160 when the slide is in its
- 24 -
lO'~Z162 4lDA-3037
right-most position. Clamping shaft 160 is provided with a
bolt 238 extending diametrically through the clamping shaft
at an elevation aligned with arm 234a bracket 234. Upon
operation of the joint clamping mechanism to perfect the
circuit breaker-switchboard primary contact terminals,
clamping shaft 160 is rotated, bringing the head of the bolt
around into engagement with arm 234a, as seen in FIGURE 26,
` thereby shifting slide 230 to its left-most position at the
conclusion of the joint clamping operation.
la An arm 240 is pivotally mounted at 240a to the slide
mounting stringer 36 adjacent the right end of the slide 230
seen in FIGURES 26 and 27 and is provided at one end with an
elongated slot 240b in which is received a pin 242 carried
by the slide. It is thus seen that the lateral shifting of
the slide position produces pivotal movement of arm 240. The
other end of arm 240 from post 242 carries a laterally extending
tab 24Qc which extends through an opening 243 in the adjacent
carriage sideplate 34. A wire link 244 is hooked at one end
to tab 240c of arm 240 and extends through an aperture in a
bracket 246 carried by indicator arm 213, as seen in FIGURES
- 20 through 23. The free end of link 244 is threaded to
receive nuts 248 which are adjustably positioned to establish
the appropriate length of lînk 244. In comparing FIGURES 20
and 21, it is seen that with the circuit breaker-carriage
assembly in the engaged position and its primary contact
terminal joints with the switch~oard still to ~e clamped, cam
surface 210d is riding on actuator 222. Upon actuation of the
clamping mechanism to its complete joint clamping condition,
the bolt head 238 carried by shaft 160 shifts slide 230 to the
left as seen in FIGURE 26, pivoting arm 240 in a direction to
draw the link 244 to the left as seen in FIGURE 20, thereby
lifting indicator arm 210 upwardly off of actuator 222
- 25 -
41DA-3037
iO'~Z162
sufficiently to register the word "clamped " in window 215a.
As the joint clamping mechanism is operated to relax the joint
clamping pressure, clamping shaft 160 rotates to swing the
head of bolt 238 away from arm 234a, and slide 230 is returned
to the right by its spring 236. Arm 240 is thus pivoted in
the opposite direction to shift link 244 to the right as
seen in FIGURE 21, permitting arm 210 to drop back down onto
actuator 222 under the bias of spring 220, thereby again
registering the term "engaged" in window 215a.
`; 10 In addition to the safety interlocking features
provided by the access control assembly 179 operating to
control access to the joint clamping mechanism 27 and the
racking mechanism 32 depending upon the position of the circuit
breaker-carriage assembly, the instant drawout apparatus also
includes circuit breaker trip interlocking provisions similar
,~
to that disclosed and claimed in the commonly assigned,
,.
Canadian application,Serial No. 267,440, filed December 8, 1976.
In this Canadian application, the trip interlock functioned
- to automatically enable closure of thecircuit breaker while
in either its test or engaged positions and to automatically
trip the circuit breaker, should it be in its ON condition,
` during initial racking movement from the test position toward
` the enqaged position and from the engaged position toward the
test position. Thus the trip interlock functions to insure
that the circuit breaker contacts are open during racking
movement between the test and engaged positions, so as to
preclude the possibility of load current flowing through the
plug-in primary disconnect contacts while they are in the
process of being engaged and disengaged. In the case of the
drawout apparatus disclosed in the present application,
circuit breaker trip interlocking, insofar as the test position
is concerned, is performed in the manner described in the
- 26 -
41DA-3037
-lC)q2162
above-noted Canadian application. However, to defeat the
trip interlock upon arrival of the circuit breaker-carriage
. assembly at its engaged position, as was done in the drawout
apparatus of the Canadian application, would create a hazardous
`; situation, since inadvertent closure of the circuit breaker
. contacts before the circuit breaker-switchboard primary
contact terminals have been clamped could have disastrous
A consequences.
Accordingly, as described below, the trip interlock
of the instant drawout apparatus is conditioned by the rackinq
- mechanism to permit closure of the circuit breaker contacts
. . - -. .
while in the test position and to trip the circuit breaker
should its contacts be left closed as racking movement is
initiated from the test position toward the engaged position.
Once in the engaged position, the trip interlock is controlled
by the joint clamping mechanism such as to prevent closure of
the circuit breaker contacts until the circuit breaker-
switchboard primary contact terminals have been completely clamped
in electrical interconnection and to trip the circuit breaker
should its contacts be closed during initial operation of the
joint clamping mechanism toward relaxing the joint clamping
pressure.
A trip interlock, generally indicated at 250 in
FIGURES 2, 26 and 27, includes a bracket 252 affixed by suitable
means Cnot shownl to the same rear carriage stringer which
mounts slide 230. This bracket mounts a plunger 254 which is
. normally biased rearwardly in FIGURE 27 or to the left in
~ 2~
FIGURE 28 by a spring 256. The outer end of plunger 2~8 is
necked down for engagement with an elongated lever ~
pivotally mounted a-t 259 to bracket 252. The spring 256 is
thus effective through plunger 254, to bias the free, right
end of lever 258 rearwardly away from circuit breaker 20, as
- 27 -
41DA-3037
: 10~162
seen in FIGURE 27. The inner end of plunger 254 carries a
cam follower plate 260 having a crooked end 260a which is
urged by spring 256 into engagement with the periphery of
crank shaft 50, as best seen in FIGURE 28.
An extension 258a of lever 258 is engaged under
the head of a screw 262 adjustably threaded into the end
of a plunger 264 which is suitably slideably mounted for
protrusion through the circuit breaker case into controlling
engagement with a circuit breaker tripping element 266.
A spring 268 acting between the lever extension arm 258a and
plunger 264 accommodates any over travel of the lever 258
in operating the circuit breaker tripping element 266, as
occasioned by manufacturing tolerances.
To operate trip interlock 250 off the racking
mechanism 32, a bolt 269, mounted transversely through
crank shaft 50, is so positioned that its head engages the
crooked end 260a of cam follower plate 260 thereby depressing
plunger 254 when the racking mechanism accommodates the
circuit breaker-carriage assembly to its test position.
Depression of plunger 254 pivots lever 258 toward the circuit
breaker forcing plunger 264 inwardly, or to the right as
seen in FIGURE 29, thereby depressing the tripping element
266 to enable closure of the circuit breaker contacts. As
the racking mechanism is operated to move the circuit breaker-
carriage assembly away from the test position toward the
engaged position, the head of bolt 269 carried by crank
shaft 50 swings away from cam follower plate 26Q, and spring
256 returns lever 258 and plunger 264 to their positions shown
in FIGURE 28. Tripping eIement 266 is thus released and
the circuit breaker is automatically tripped and cannot be
reset and closed.
The above described construction and operation of
- 2~ -
10~7Z162 41DA-3037
trip interlock 250 are similar to that disclosed in the
above-noted Canadian application. However, instead of
mounting a second transverse bolt in the crank shaft to
actuate the trip interlock upon arrival of the circuit
breaker-carriage assembly at its engaged position, the
instant trip interlock utilizes a second lever 270 which is
operated by slide 230 moving in response to operation of - -
the joint clamping mechanism 27. Thus, as seen in FIGURES 26
and 27, lever 270 is pivotally mounted by a pin 272 affixed
to rear carriage stringer 36 through a longitudinally
elongated slot 273 in slide 230. A spring 274 normally
;
-Y~ biases lever 270 in the counterclockwise direction as seen inFIGURES 26 and 27. A wire link 276 interconnects the free
end of lever 270 and slide 230 to translate longitudinal
movement of the slide into pivotal movement of the lever.
The free end of lever 270 carries an actuating
tab 278 poised to engage and depress plunger 254 when lever
270 is pivoted in the clockwise direction by link 276 in
response to the slide 230 being shifted to the left as seen
- 20 in FIGURE 26 by the clamping shaft mounted bolt head 238 uponcompletion of the joint clamping operation. Depression of
plunger 254 pivots lever 258 inwardly to achieve depression
- plunger 264, which, in turn, depresses tripping element 266
to enable operation of the circuit breaker to its ON condition.
As the joint clamping mechanism 27 is operated preparatory
to relaxing the joint clamping pressure, bolt head 238
releases slide 230, which is returned to the right by its
spring 236. Link 276 thus releases the free end of lever
270, and spring 274 pivots this lever around in the counter-
3Q clockwise direction, releasing plunger 254. Its return spring
256 then acting through lever 258, retracts plunger 264,
releasing the tripping element 266. The circuit breaker is
- 29 -
~-
.~OqZ16Z 4lDA-3037
thus automatically tripped, as well as being disabled from
being reset and turned on until the joint clamp pressure
is fully relaxed and the circuit breaker-carriage assembly
backed out to the test position.
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 accompany-
ing drawings shall be interpreted as illustrative and not
in a limiting sense.
- 30 -
