US3815058A

US3815058A - Shunt trip device with integrally mounted auxiliary switch

Info

Publication number: US3815058A
Application number: US00356828A
Authority: US
Inventors: P Stetsuk
Original assignee: ITE Imperial Corp
Current assignee: Siemens Energy and Automation Inc
Priority date: 1973-05-03
Filing date: 1973-05-03
Publication date: 1974-06-04
Anticipated expiration: 1991-06-04

Abstract

A multipole molded case circuit breaker is provided with a subassembly that includes a shunt trip device and a switch for opening the energizing circuit for the operating coil of the shunt trip electromagnet after opening of the circuit breaker. This subassembly is disposed in a single housing compartment that houses one pole of the circuit breaker.

Description

United States Patent n91v Stetsuk SHUNT TRIP DEVICE WITH INTEGRALLY' MOUNTED AUXILIARY SWITCH Paul Stetsuk, Philadelphia, Pa.

I-T-E Imperial Corporation, Spring House,

Filed: May 3, 1973 Appl. No.: 356,828

Inventor:

Assignee:

US. Cl. 335/8 Int. Cl. H0lh 83/00 Field of Search 335/8, 9, 10, 20

References Cited UNITED STATES PATENTS Myers 335/20 June 4, 1974 9/1970 Gryctko 335/8 3/1973 Primary E.mminer-Harold Broome Attorney, Agent, or Firm0strolenk, Faber, Gerb &

Soffen [57] ABSTRACT A multipole molded case circuit breaker is provided with a subassembly that includes a shunt trip device and a switch for opening the energizing circuit for the operating coil of the shunt trip electromagnet after opening of the circuit breaker. This subassembly is disposed in a single housing compartment that houses one pole of the circuit breaker.

10 Claims, 8 Drawing Figures PATENIHIM 4 I924 SHEET 3 BF 7 PAIENTEDJUM 41w 318i5L058 SHEET 70$ 7 SHUNT TRIP DEVICE WITH INTEGRALLY MOUNTED AUXILIARY SWITCH This invention'relates to multipole molded case circuit breakers in general and more particularly relates to breakers of this type having axuiliary trip devices and auxiliary switches;

In molded case circuit breakers of the prior art, a shunt trip device and its, associated auxiliary switch for protecting the shunt trip coil against overheating were located in separate pole compartments and were electrically connected outside of the breaker housing. With this arrangement there is poor utilization of space within the breaker, and the making of electrical connections is unnecessarily complicated. In particular, the prior art required auxiliary mounting parts in each of two pole compartments, and two wire outlets were required in the breaker housing.

In accordance with the instant invention, the shunt trip device and its associated auxiliary switch are located in the same pole compartment. They are constructed as portions of a subassembly mounted within the breaker compartment as a unitary structure. This structure includes an electrical connection between the switch and the operating coil for the shunt trip device. Allexternal connections to both the switch and shunt trip device pass through a single opening in the circuit breaker housing.

When remote electrical tripping of the circuit breaker is desired, the shunt trip is actuated, which in turn operates the common trip bar of the circuit breaker overload trip unit. When the circuit breaker contacts reach the open position, they actuate the auxiliary switch to its open position, thereby interrupting the energizing circuit for the shunt trip coil to limit its duty cycle.

Accordingly, a primary object of the instant invention is to provide a multipole molded case circuit breaker with a novel arrangement for a circuit breaker auxiliary trip device and an auxiliary switch device.

Another object is to provide an arrangement of that type in which both the auxiliary trip and switch devices are disposed in a housing compartment for one pole of the breaker.

Still another object is to provide an arrangement of that type in which the auxiliary trip and switch devices are parts of a subassembly.

These objects as well as other objects of this invention will become readily apparent after reading the following description of the accompanying drawings in which:

FIG. I is a plan view of a circuit breaker including auxiliary trip and switch units..constructed in accordance with teachings of the instant invention.

FIG. 2 is a longitudinal cross-section taken through line 2-2 of FIG. I,'looking in the direction of arrows 2-2 and including a handle operating mechanism, not shown in FIG. 1.

FIG. 3 is an exploded perspective of one overcenter contact operating toggle mechanism and selected. elements connected thereto.

FIG. 4 is an enlarged plan, view showing a fragmentary portion of the circuit breaker operating mechanisms including elements of the interpole trip system, the system to. prevent contact closing prior to latching of all operating mechanisms and the auxiliary trip unit and switch subassembly of the instant invention.

, FIG. 5 is a side elevation of the subassembly of FIG. 4 looking in the direction of arrows 5-5 of FIG. 4.

FIG. 6 is an end view of the subassembly looking in the direction of arrows 66 of FIG. 5.

FIG. 7 is an exploded perspective of the auxiliary switch and shunt trip subassembly.

FIG. 8 is a front perspective of the insulating barrier that supports the subassembly of FIG. 7.

Now referring most particularly to FIGS. 1-4. Three phase molded case circuit breaker 25 of FIGS. I and 2 includes an individual overcenter spring-powered toggle operating mechanism. Other examples of circuit breakers having more than a single spring-powered operating-mechanism are disclosed inU. S. patents Nos. 2,067,935 and 3,125,653.

Circuit breaker 25 includes a molded housing constructed of base 26 and removable cover 27- joined along line 28 and provided with longitudinal internal partitions 31, 32 which divide

housing

26, 27 into three side-by-side longitudinally extending elongated compartments, one for each phase or pole of circuit breaker 25. Cover 27 is provided with aperture 29 through which stubby bifurcated extension 33 of operating handle means 30 extends. Each section of handle extension 33 receives an individual pin 34 extending upwardly from the web portion of inverted generally U-shaped operating yoke member 35 of the center phase. Operating members 35 of the outer phases are each secured to handle means 30 by a pair of screws 152.

Member 35 is pivoted to the spaced arms of generally U-shaped operating mechanism frame 36 at outwardly extending lugs 37. Bolts 48, received by threaded apertures of inturned edges 360 at the bottom of frame 36, fixedly secure the latter to base 26. Transverse tie member 49 is riveted to the arms of frame 36 to maintain spacing therebetween and to stabilize the frame structure.

Four tensioned coil springs 38, each connected at one end thereof to the web of operating member 35, combine to constitute the main operating spring means for the overcenter toggle-type contact operating mechanism. The other ends of springs 38 are connected to spaced

plates

39, 39 that are pivotally mounted to toggle knee pin 41 connecting upper 42 and lower 43 toggle links. The upper ends of upper toggle links 42 are pivotally connected to the spaced arms of latchable cradle 40 at pins 44, and the lower ends of lower toggle links 43 are pivotally connected to contact carrier 45 by rod 46 that extends between the spaced arms of contact carrier 45. The spaced arms of cradle 40 are positioned adjacent the inner surfaces of the spaced arms of frame 36 and are pivotally connected thereto by pins 47 that are secured to frame 36.

Under normal operating conditions plate 51, secured to web 40a of cradle 40, is in engagement with forward latching surface 52 of auxiliary latch 53. The latter is loosely mounted to pivot rod 55 extending between the spaced arms of mechanism frame 36 and slightly outboard thereof. The coiled end sections of torsion spring member 56 are wound about pivot rod 55, with the ends of these sections bearing against rod 57 and auxiliary latch 53 to bias the latter counterclockwise against stop rod 58. The ends of

rods

57 and 58 are supported by the arms of frame 36. Leaf spring 73 secured to auxiliary latch 53 bears against pivot rod 55 biasing latch 53, so that rod 55 will normally lie at the central por- I tion of V-shaped 74 of auxiliary latch 53.

The ends of rod55 projecting outboard of mechanism frame 36 are engaged by the hooked portions at the forward extension 59 of the arms for U-shaped trip unit frame 60, whose web portion is seated on a forwardsurface of load strap 61, being secured thereto by bolts 62 that extend through clearance apertures in strap 61 and are received by threaded inserts molded in base 26.

Rear latch tip 54 engages latch tip 63 at the U-shaped forward arm of primary latch 65, whose rear latch'tip 64 is engaged by latch plate 67 mounted on one leg of L-shaped carrier 66. Primary latch 65 is pivotally mounted to trip unit frame 60 at stub shaft 69, and the carrier is pivoted on rod 68 to frame 60. Tension spring .75 biases primary latch 65 in a clockwise direction about pivot 69. The other leg of carrier 66 is provided with transversely extending pin 71 that projects into triangular window 72 of primary latch '65 at a portion thereof near rear latch tip 64, for a reason to be hereinafter explained. Tension spring 76, connected between frame 60 and carrier extension 66a, biases carrier 66 in a counterclockwise direction about its pivot 68 toward latching position.

When automatic tripping occurs because of a fault current condition, carrier 66 in the faulted pole is moved clockwise either by the deflection of bimetal 77 or movement of magnetic armature 78, causing latch plate 67 to releaseprimary latch 65, which in turn releases secondary latch 53 and permits main operating springs 38 to rotate cradle 40 in a counterclockwise direction to break toggle 42, 43. The force from main spring 38 acts through cradle 40, primary latch 53, and

secondary latch 65 to drive cam surface 78, bounding opening 72, against extension 71 to rotate carrier 66 clockwise, with surface 79 thereof engaging ear 81 of extension82 on tripper bar 80 which extends between all three phases. This causes tripper bar 80 to rotate in a counterclockwise direction, so that extensions 82 in the non-faulted phases rotate counterclockwise with cam surfaces 83 thereof engaging transversely extending pin 84 of carriers 66 in the non-faulted phases, rotating them clockwise or in the trippingdirection, to release the cradle latching systems in the non-faulted phases, so that the contacts of all three phases are open.

In order to prevent closing of the contacts of any one phase before the operating mechanisms of all phases are latched, circuit breaker is provided with a defeater. latching system including defeater latch 80 and defeater lever 90. Latch 80' is pivotally mounted upon rod 55 and includes protrusion8l' extending over the rear of cradle 40 when the latter is in latched position. Latch 80' further includes protrusion 82 extending over the forward end of defeater lever 90 in slot 91 thereof. Coiled tension spring 83 is connected between stop rod 57 and latch 80', passing partially around rod 55, to bias latch 80' in a counterclockwise direction about its pivot 55 and maintaining this pivot in the basic position at the right end of slot 84' in latch 80'. This basic position is established through the engagement of latch stop surface 86 and stop rod 57.

Slot 91 is in the web of the U-shaped forward portion of latch lever 90, with the U arms having pivot pin 69 for lever 90 extending therethrough. Rear portion 89 of lever 90 is positioned below and in interfering relationship with transverse pin 71 mounted to latch plate carrier 66.

During normal relatching of circuit breaker 25, inwardly protruding portions of the operating member arms engage outboard portions of pin 44 to pivot cradle v clockwise, whereby the latter cams defeater latch 80' away and moves below auxiliary latch 53. Upon release of the circuit breaker operating handle 30, the elreleasing direction. During this releasing movement of carrier 66, surface 79 thereof engages nose 81 of one trip bar extension 82 to rotate common tripper bar 80 in a counterclockwise direction, with the other extensions 82 on bar '80 engaging pins 84 on the latch plate carriers 66 of the other poles, thereby causing the latch systems of all other phases to be released.

The lower end of bimetal 77 is fixedly secured to shading coil 99, and these elements are fixedly secured to transverse molded insulating barrier member 95 secured to trip unit frame 60. The horizontal leg of inverted U-shaped stationary magnetic frame member 98 passes through the center of coil 99. Member'98 is secured tothe rear of frame 60, with the vertical legs of member 98 being on opposite sides of load strap 61. The other U-shaped magnetic frame member 96 is secured directly to load strap 6l,'with the ends of the arms for frame members 96 and 98 confronting one anotherin spaced relationship. Thus, current flowing in load strap 61 generates flux in magnetic frame 96, 98 which induces current flow in shading coil 99 and thereby generates heat that is conducted to bimetal 77 forheating thereof. Coiled tension spring 97, connected between armature 78 and an element mounted to the rear transverse part a of frame 60, biases the former away from two spaced legs 98a extending upward from the horizontal leg of member 98, and is drawn downward toward legs 98a when overload currents generate sufficient magnetic flux in

magnetic frame

78, 96, 98.

With particular reference to F 16. 2, it isseen that the movable contact structure forea'ch phase of circuit breaker 25 includes ei ght'main contacts, only two of which 103 and 107 being illustrated, and a single arcing contact 101. The latter contact 101 is mounted at the forward end of arm 112, which is pivotally mounted to carrier 45 at toggle connecting rod 46. The main contacts are arranged in two parallel rows, each containing four contacts and positioned to the rear of arcing contact 101 and disposed at right angles to the plane of movement of arcing contact arm 112.

The main contacts, including contact 103, in the forward row are mounted to individual contact arms 113-116, all pivotally mounted to carrier 45 on rod 46. The four remaining main contacts are in the rear row, including contact 107, and are mounted to the forward ends of four additional contact arms all pivotally mounted to carrier 45 on rod 102. In particular, contact 107 is mounted to arm 117. All of the movable contact arms are connected to load strap 61 by means of individual stacks 121 of flexible sheet conductors. The movable contacts are aligned with and engage stationary contact portions on the upper surface of line strap 136 when circuit breaker 25 is closed. For a more detailed description of the contact structure, reference is made to copending U. S. patent application Ser. No. 275,568, filed July 27, 1972, and assigned to the assignee of the instant invention.

The spaced arms of contact carrier 45 are provided with rearward extensions 45a, 45b that are spaced by and secured to shouldered cylindrical tube 146. Extensions 45a, 45b are provided with aligned bushings 142 that receive stub shafts 144 extending inward from the sides of frame 36 to pivotally mount contact carrier 45 to frame 36. After all contact structures, operating mechanisms, latchingdevices, and automatic trip units are mounted to base 26, and all adjustments to these mechanisms have been made, the contact structures of all phases are operated to the closed circuit position, so that the tubular members 146 of all phases are axially aligned and are positioned above barriers 31, 32 and the longitudinal sides of base 26. Thereafter, cylindrical tie bar 147 is driven longitudinally into the members 146 of all phases to constitute a rigid mechanical connection between the movable contact structures of all phases. The fit between tie rod 147 and tubular members 146 is tight enough to prevent unintentional axial movement of tie rod 147, yet permit tie rod 147 to be removed for convenient servicing and replacement of parts. Mechanism frame 36 is provided with aligned elongated slots 148 to provide clearances for movement of rod 147 during opening and closing of the movable contact structures.

Platelike transverse insulating barrier 98 of FIG. 8 supports the subassembly of FIG. 7, with the latter being secured to the former by

screws

201, 202 that are received by the respective threaded

inserts

203, 204 in

bosses

205, 206, respectively, on the forward surface of barrier 95. The subassembly of FIG. 7 includes normally closed auxiliary switch 207, mounted within generally rectangular insulating housing 208 and connected in electrical series with shunt trip energizing coil 210'by insulated wire lead 209. Coil 210 is wound on bobbin 211 and surrounds lower leg 212 of C-shaped laminated magnetic yoke 213 that forms the stationary portion of a magnetic frame also including laminated movable armature 214.

Rivets 215 extend across armature 214 and secure spaced

side members

216, 217 thereto. Rivets 218 extend through yoke 213 and secure

metal frame members

221, 222 to opposite sides of yoke 213. Mounting

screws

201, 202 pass through

clearance apertures

223, 224 in

frame members

221, 222 respectively to fixedly secure yoke 213 to insulating barrier 95. Forwardly extending formations 219 of barrier 95 seat outwardly extending

ears

225, 226 of the respective members 221,

222. Pin 227 extends through aligned

apertures

228, 229 in

respective members

221, 222 and also extends through aligned

apertures

232, 233 in

members

216, 217 to pivotally mount armature 214 with respect to yoke 213. Speed nut 231 at the free end of pin 227 maintains the latter in its operative position. Coiled tension spring 234 extends between ear 226 and outturned car 235 of member 217 to bias the lower end of armature 214 clockwise with respect to FIG. 5, away from yoke 213. Another tension coil spring 236 extends between ear 225 and outtumed ear 237 of member 216 to provide an additional biasing force urging the lower end of armature 214 away from yoke 213. Intumed ears 238, 239 of the

respective members

216, 217 support insulating block 240 that is secured in place by a pair of rivets 291. Block 240 is provided with a front-to-back threaded bore 241 which receives the threaded forward portion of actuating pin 242. The portion of pin 242 extending forward of block 240 threadably receives lock nut 243, with lock washer 244 interposed between nut 243 and the forward surface of block 240.

When operating coil 210 is energized, magnetic flux generated in

magnetic frames

213, 214 attracts the lower end of armature 214 to yoke 213,50 that armature 2'14 pivots counterclockwise with respect to FIG. 5, moving rear end 245 of actuating pin 242 upward. Pin end 245 extends through aperture 289 in barrier and engages extension 79 of latch plate carrier 66, pivoting the latter clockwise with respect to FIG. 5, to cause tripping of circuit breaker 25 in accordance with overload tripping operations previously described.

Screws 25] extend from the rear of switch 207 through clearance apertures 252 in housing 208 and clearance apertures 253 in downwardly extending forwardly offset leg 254 of auxiliaryframe member 286 and are secured by nuts 255. Screws 285

secure frame members

222 and 286 together. Forwardly extending spaced ears 256 of leg 254 are provided with aligned apertures 257 that receive rivets 258. The latter also extends through aligned apertures 259 in upstanding ears'261 along opposite edges of L-shaped actuator and are disposed at the portion of actuator leg 262 adjacent its junction with actuator leg 263. Actuator leg 262 is operatively positioned to engage depressible switch actuator button 264. that normally extends out the bottom of housing 208. Actuator leg 263 is operatively positioned for engagement by tubular bushing 146 mounted to the rear of contact carrier 45. When contact carrier 45 pivots clockwise with respect to FIG. 5 to the open circuit position, bushing 146 engages actuator leg 263, pivoting the latter counterclockwise, so that actuator leg 262 depresses operating button 264 to open auxiliary switch 207 thereby opening the energizing circuit for coil 210.

Insulated wires

271, 272 from switch 207 and coil 210 extend through strain relief grommet 273 from rear to front and on the forward side of grommet 273 extend through insulating sleeve 274. The latter extends through plastic wire retaining loop 275 and then extends outside of

breaker housing

26, 27 through a single aperture in the side thereof at the location indicated by reference numeral 280 in FIG. 6.

Apertures

281, 282 in the

respective frame members

286, 222 are provided for the mounting of grommet 273 and retainer 275, respectively.

Thus, it is seen that the subassembly of FIG. 7, including auxiliary switch 207 and auxiliary trip means 210, 213, 214, 242, is mounted entirely within the longitudinal housing compartment provided for one pole of circuit breaker 25, the series circuit connection 209 between auxiliary trip coil 210 and auxiliary switch 207 is disposed inside this same housing compartment, and the other leads 271, 272 from coil 210 and switch 207 extend through common aperture 280 in

circuit breaker housing

26, 27.

It is noted that because of high magnitude current flow in circuit breaker 25, the magnetic fields generated are very strong. In order to reduce adverse effects of these magnetic fields, many of the frame parts and operating mechanism parts are constructed of nonmagnetic stainless steel.

For those features of construction in circuit breaker that have not been described in detail herein, reference is made to one or more of the copending U. S. patent applications Ser. Nos. 275,446, 275,454, 275,507, 275,508, 275,521, 275,522, 275,523, 275,568, 275,569, 275,577, 275,578, 275,621 .and 275,622, all filed on July 27, 1972, and all assigned to the assignee of the instant invention.

Although there has been described a preferred embodiment of this novel invention, many variations and modifications will now become apparent to those skilled in the art. Therefore, this invention is to be limited not by the specific disclosure herein but only by the appending claims.

The embodiments of the invention in which an exclusive privilege or property is claimed are defined as follows:

l. A multipole circuit breaker including a housing having an individual compartment for each pole of said circuit breaker; said compartments being elongated and positioned side by side; an individual set of cooperating contacts within each of said compartments; operating means connected to said cooperating contacts for opening and closing thereof; fault responsive trip means for each of said poles operatively connected to said operating means for automatically opening the cooperating contacts of all poles responsive to predetermined overload conditions at any of said poles; a first of said poles including an auxiliary trip device and an auxiliary switch; said contacts of said first pole, said auxiliary trip device and said auxiliary switch being disposed within a first of said compartments; said auxiliary trip device being operatively positioned so that upon operation thereof a portion of said device operates the fault responsive means of said first pole to open said circuit breaker; said auxiliary switch being operatively positioned for operation by said contacts of said first pole.

2. A multipole circuit breaker as set forth in claim 1 in which the auxiliary trip device includes an electromagnet having an operating coil; saidauxiliary switch 8 being connected in circuit with said coil. 7 3. A multipole circuit breaker as set forth in claim 2 in which there are electrical leads extending from said coil and said auxiliary switch external of said housing through a common opening therein.

4. A multipole circuit breaker as set forth in claim 1 in which there is a transverse insulating barrier within said first compartment; said fault responsive trip means for said first pole positioned on one side of said barrier; both said auxiliary trip device and said auxiliary switch positioned on the other side of said barrier.

5. A multipole circuit breaker as set forth in claim 4 in which there is a metal frame supporting both said auxiliary trip device and said auxiliary switch to form a subassembly that is mounted to said barrier by fastening means engaging said metal frame.

6. A multipole circuit breaker as set forth in claim 5 in which the auxiliary trip device includes an electromagnet having an operating coil; said auxiliary switch being connected in series circuit with said coil; said auxiliary switch being normally closed and being operated to its open position by said contacts of said first pole when these contacts are in their open position.

7. A multipole circuit breaker as set forth in claim 6 in which there are electrical leads extending from said coil and said auxiliary switch external of said housing through a common opening therein. I

8. A multipole circuit breaker as set forth in claim 4 in which the portion of the auxiliary trip device that operates the fault responsive means extends through said barrier.

9. A multipole circuit breaker as set forth in claim 8 in which the auxiliary trip device includes an electromagnet having an operating coil; said auxiliary switch being connected in circuit with said coil; said electromagnet also including a movable armature; means connecting said portion to said armature, whereby upon movement of said armature resulting from energization of said coil said portion operates said fault responsive trip means of said first pole to bring about opening of said circuit breaker.

10. A multipole circuit breaker as set forth in claim 9 in which there are electrical leads extending from said coil and said auxiliary switch external of said housing through a common opening therein.

Claims

1. A multipole circuit breaker including a housing having an individual compartment for each pole of said circuit breaker; said compartments being elongated and positioned side by side; an individual set of cooperating contacts within each of said compartments; operating means connected to said cooperating contacts for opening and closing thereof; fault responsive trip means for each of said poles operatively connected to said operating means for automatically opening the cooperating contacts of all poles responsive to predetermined overload conditions at any of said poles; a first of said poles including an auxiliary trip device and an auxiliary switch; said contacts of said first pole, said auxiliary trip device and said auxiliary switch being disposed within a first of said compartments; said auxiliary trip device being operatively positioned so that upon operation thereof a portion of said device operates the fault responsive means of said first pole to open said circuit breaker; said auxiliary switch being operatively positioned for operation by said contacts of said first pole.

2. A multipole circuit breaker as set forth in claim 1 in which the auxiliary trip device includes an electromagnet having an operating coil; said auxiliary switch being connected in circuit with said coil.

3. A multipole circuit breaker as set forth in claim 2 in which there are electrical leads extending from said coil and said auxiliary switch external of said housing through a common opening therein.

7. A multipole circuit breaker as set forth in claim 6 in which there are electrical leads extending from said coil and said auxiliary switch external of said housing through a common opening therein.