US3718878A

US3718878A - Fused circuit breaker

Info

Publication number: US3718878A
Application number: US00232794A
Authority: US
Inventors: J Wilson
Original assignee: Matsushita Electronics Corp
Current assignee: Panasonic Holdings Corp
Priority date: 1972-03-08
Filing date: 1972-03-08
Publication date: 1973-02-27
Anticipated expiration: 1990-02-27
Also published as: CA967203A; ZA731151B; JPS5340669Y2; BR7301676D0; JPS491855U; GB1414072A; AU5246173A

Abstract

A multi-pole fused circuit breaker, of the type comprising current limiting fuses and a removable enclosed multi-pole trip device, comprises improved coordinating means for tripping the breaker when any of the fuses is actuated.

Description

United States Patent 1 Wilson 11 3,718,878 1 Feb. 27, 1973 [s41 FUSED CIRCUIT BREAKER [75] Inventor: James C. Wilson, Beaver, Pa.

[73] Assignee: Matsushita Electronics Corporation,

Osaka, Japan 22 Filed: March 8, 1972 [21] Appl. No.: 232,794

[52] US. Cl. ..337/7, 337/146, 337/186 [51] 1nt. C1....., ..H0lh 85/50 [58] Field of Search ..337/6, 7, 48, 49, 50, 146,

[56] References Cited UNITED STATES PATENTS 3,538,475 11/1970 Cellerini ..337/7 2,939,936 6/1960 3,638,157 1/1972 Kruzic ..337/6 Primary Examiner-Bemard A. Gilheany Assistant Examiner-A. T. Grimley AttorneyA. T. Stratton et a1.

[57] ABSTRACT A multi-pole fused circuit breaker, of the type comprising current limiting fuses and a removable enclosed multi-pole trip device, comprises improved coordinating means for tripping the breaker when any of the fuses is actuated.

10 Claims, 6 Drawing Figures FUSED CIRCUIT BREAKER BACKGROUND OF THE INVENTION 1. Field of the Invention Fused circuit breakers of the type comprising current limiting fuses, an enclosed trip device, and means operable to trip the breaker when any of the fuses blows.

2. Description of the Prior Art In the patent to Cellerini, US. Pat. No.-3,538,475, there is disclosed a multi-pole fused circuit breaker of the general type herein disclosed. Each current limiting fuse, however, comprises an" extension that extends through a separate opening in the housing'of the trip device to position the plunger of the fuse'such that the plunger will directly engage and'actuate thetrip bar of the trip device when the fuse blows. When the circuit breaker cover is removed and the removable trip device, or any of the fuses, is removed from the breaker a worker can tamper with the internal partsofthetrip' device through the openingsin the housing of thetrip device. The subject'invention provides'a-more totally enclosed trip device housingin that intermediate members, that are mounted on the trip device housing, slidably fit into relatively small openings in the. trip device housing to provide operative connections between the plungers of the fuses and the enclosed trip bar of the trip device. This invention distinguishes over prior art of the type disclosed in thepatent to Cellerini et al., US. Pat. No. 3,248,500 in that a common protrude through the trip device housing, are spaced from the internal tripbar so that if a-worker, either accidentally or intentionally, were to tamper with any of the intermediate members-to preventoperation of any of the intermediate members, the trip bar would still be operable to trip the breaker on overloads by operation of any other of the intermediate members or'by operation of any of the trip means of thetrip device.

SUMMARY OF THE INVENTION An improved multi-pole circuit breaker is provided comprising an'insulating circuit breaker housing and a circuit breaker mechanism supported withinthe insulating circuit breaker housing. The circuit breaker mechanism comprises a pair of contacts for each pole, a releasable member releasable to effect automatic opening of all of the pairs of contacts, and a multi-pole trip device. The muIti-pole trip device comprises an insulating trip unit housing, a common trip barmovably mounted in the insulated trip unit housing and trip means for each pole unit operable upon the occurrence of certain overloads to automatically move the trip bar to a tripped position to effect release of the releasable member. The trip device housing is provided with an opening therein for each of the poles.- For each pole an intermediate member, that is supported on the trip device housing, extends from outside of the trip device housing into the trip device housing. Each of the intermediate members is biased to an unactuated position spaced from the trip bar inside of the trip device housing. A separate current limiting fuse is provided for each pole with each of the current limiting fuses being supported inside of the circuit breaker housing and outside of the trip unit. housing. Each of the fuses is connected in electrical series with the contacts of the associated pole. Each of the fuses comprises biased plunger means automatically movable to an extended actuating position when the fuse blows, and each of the fuses is constructed to blow upon theoccurrence of a severe overload over a predetermined value to interrupt the overload. Upon the occurrence of an overload over a predetermined value in any of the poles, the associated fuse blows and the associated plunger means moves to an extended actuating position to move the associated intermediate member against the common ,trip bar to thereby move the common trip bar to the tripped position. The intermediate members are mounted on the trip device housing and they slidably fit into relatively small openings inthe trip device housing thereby making it difficult to tamper'with the internal parts of the trip device housing whenthe cover of the insulating circuit breaker housing is removed and when BRIEF DESCRIPTION OF. TIIE DRAWINGS FIG. I is a sidesectional view illustrating the center compartment of a three-pole circuit breaker with part ofthetrip device being shown in broken lines for clarity, and with certain parts being broken away;

FIG. 2' is a side sectional view of part of the circuit breaker illustrated in FIG. 1; 7

FIG. 3 is'a view of the three-pole tripdevice seen in F IG. 2 with the cover of the insulating trip device housing removed and with. three main conductors of the three-pole units being shown in section;

FIG. 4 is a front elevational view of the removabletrip device seen in FIG. 2;

FIG. 5 is top view, with parts broken away, of the removable trip device seen inFIG. 4', and

FIG. 6 is a perspective view of one of the current limiting fuses.

DESCRIPTION OF THE, PREFERRED EMBODIMENT Referring to the drawings, there is shown in FIG. 1 a circuit breaker 3 comprising an insulating circuit breaker housing 5. The circuit breaker 3 is of the type more specifically described in the patent to Cellerini,, US. Pat. No. 3,538,475. The insulating housing 5 comprises a molded insulating base 7, that is molded as an integral unit, and a molded insulating cover'9, that is molded as an integral unit, secured to the base 7. An operating mechanism 11, a trip unit or trip device 13, fuse means 15 and an arc-extinguishing unit 17 are all supported in the housing 5 on the base 7. The circuit breaker 3 is a three-pole circuit breaker comprising three compartments'disposed in a side-by-side relationship. The center compartment or pole unit (shown in FIG. 1) is separated from the two outer pole units by cooperating

insulating barriers

18 and 19 that are molded integrally with the housing cover 9 and base 7 respectively. The operating mechanism 11 is disposed in the center pole unit.

Each pole unit comprises a stationary contact 21 that is fixedly secured to a rigid conductor 23 that is secured to the base 7 by means of bolts 25. In each pole unit, a movable contact 27 is secured to a contact am 29 that is pivotally mounted on a switch arm 31 by means of a pivot pin 33. Each of the switch arms 31 is pivotally supported at one end thereof on a support bracket 34 by means of a separate pivot pin 35. The switch arms 31 for all three of the pole units are connected to move in unison by means of an insulating common tie bar 37 that is fixedly connected to all three of the switch arms. Each of the contact arms 29 is biased about the associated pivot 33 by means of a spring 39 to provide contact pressure in the closed position.

The switch arms 31 are operated to the opened and closed positions by means of the operating mechanism 11. The operating mechanism 11 comprises a toggle link 41 that is pivotally connected to an extension 43 of the center-pole switch arm 31 by means of a pivot pin 45. The toggle link 41 is pivotally connected to another toggle link 47 by means of a pivot pin 53. The upper end of the toggle link 47 is pivotally connected to a trip member or releasable member 51 by means of a pivot pin 53. The trip member 51 is pivotally supported at one end thereof on the supporting bracket 34 by means of a pivot pin 57. The other end 59 of the trip member 51 is held in a latched position by means of a latch structure 61. The latch structure 61 is of the type more specifically described in the patent to G. G. Grissinger et..al., US. Pat. No. 2,586,326, issued 'Feb. 19, 1952 and assigned to the assignee of the instant case. The operating mechanism 11 also comprises an inverted U- shaped operating lever 63 that is pivotally supported on the bracket 34 by means of pins 65 that engage the inner ends of the legs of the U-shaped operating lever 63. An insulating shield 67, for substantially closing an opening 69 in the front of the cover 9, is secured to the upper end of the operating lever 63. An insulating handle portion 71, formed integral with the insulating shield 67, extends out through the opening 69 in the front of the cover 9 to permit manual operation of the breaker. Two overcenter springs 75 (only one being shown in FIG. 1) are connected under tension between the knee pivot pin 53 of the toggle 41 47 and the upper end of the operating lever 63.

In each pole unit, an arc-extinguishing unit 81 is provided to extinguish the arcs drawn between the associated

contacts

21, 27. Each arc-extinguishing unit 81 comprises an insulating housing 83 and a plurality of stacked magnetic steel plates 85 supported within the housing 83. The moving contact 27 moves within a generally V-shaped opening in the stacked plates 85, and the are drawn between the contacts is magnetically moved to the right (FIG. 1) into the plates 85 to be extinguished during circuit interruption. Each of the arc-extinguishing units 81 is secured to the associated rigid conductor 23 by means of four bolts 89 (only two of which are seen in FIG. 1) that are threaded into tapped openings in the associated conductor 23.

The circuit breaker contacts are manually operated between the closed and opened positions by movement of the handle 71. Movement of the handle 71 in a counterclockwise direction from the on to the off position moves the line of action of the spring means to the left to an overcenter position to effect a collapse of the toggle 41, 47 to pivot the switch arm 31 for the center-pole unit in a counterclockwise direction about the associated pivot 35 to an open position in a well known manner. This movement, because of the connection of all of the switch arms 31 by means of the common tie bar 37, simultaneously moves all of the three switch arms 31 to the open position.

The contacts are manually closed by reverse movement of the handle 71 to the on position. This movement moves the operating lever 63 to move the line of action of the overcenter spring means 75 to the right to thereby reset or erect the toggle 41, 47 to move all three of the switch arms 31 simultaneously to the closed position in a well-known manner.

Referring to FIGS. 2 and 3, the trip device 13 com'-' prises an insulating trip device housing 1 10 comprising a molded insulating base 113 and a molded insulating cover 115 that is secured to the base 113 by suitable securing means. Three thermaland-magnetic tripping means 116 are supported in three compartments in the

trip device enclosure

113, 115, which compartments are separated by means of insulating barriers 117. The trip device 15 comprises a molded insulating trip bar 119 that passes through suitable openings in the barriers 117 and is common to all three of the pole units. The trip bar 119 is pivotally supported on a pair of brackets 121 by pivot pins 122. The brackets extend out of the base 1 l3 and are supported on a suitable supporting bracket 123 that is secured to a rigid main conductor 125. A separate laminated U-shaped magnetic member 126, for each pole unit, is suitable mounted in the associated compartment of the trip device by means of bolts 127 that secure the magnetic member to the trip-unit base 113. Each of the main conductors 125 passes through the opening inthe associated U- shaped magnetic member 126 and is held in place by means of a bolt 129 that extends into a suitable opening in the conductor 125. A separate movable armature 131 is pivotally supported on one leg of each of the I magnetic members 126 and is biased to an open position by means of a spring 133. A separate rod l35 is pivotally connected to each armature 131, and each of the rods 135 has a head portion 137 for engaging and operating the trip bar 119 upon sufficient energization of the

electromagnet

126, 131. The tripping electromagnet is energized by current flowing through the associated main conductor 125.

The circuit breaker contacts are tripped open upon the occurrence of an overload current above a first predetermined value-and below a second predeter-. mined value by operation of any one of the tripping electromagnets. When one of the tripping electromagnets is energized sufficiently by an overload current through the associated main conductor 25, the magnetic armature 131 is attracted toward the magnetic yoke 126, and the armature pivots on the one leg of the yoke 126 and moves into engagement with the other leg of the yoke 126. During this movement, the associated rod 135 is pulled down, whereupon the head 137 thereof engages the trip bar 119 causing the trip bar 119 to rotate in a counterclockwise (FIG. 2)

direction. This movement effects a releasing movement of the latch structure 61 to disengage the latch structure 61 from the trip member 51 (FIG. 1) in a wellknown manner.- Upon release of the trip member. 51, the springs 75 act to rotate the trip member 51 in a clockwise (FIG. 1) direction about the pivot 57 and to collapse the toggle 41, 47 to thereby pivotally move the three switch arms 31 in a counterclockwise direction to the open position. During the automatic tripping operation the line of fore of the spring means 75 operates to move the operating lever 63 and handle 71 to an intermediate position between the on" and off positions in a well-known manner to provide a visual indication that the circuit breaker has been automatically tripped.

Following an automatic tripping operation, it is necessary to reset and relatch the circuit-breaker mechanism before the contacts can be closed. This is effected by moving the handle 71 to the full off position. During this movement, a pin 137, that is supported on the operating lever 63, engages a shoulder 139 on the trip member 51 to move the trip member 51 in a counterclockwise direction about the pivot 57. Near the end of this movement, the free or latching end 59 of the trip member 51 cams the latch structure 61 to the left against the bias of spring means (not shown) and moves below the latching end of the latch structure 61 whereupon the latch structure 61 is biased back to the latching position seen in FIG. 1 to relatch the trip member 51 in a well-known manner. The breaker con tacts can then be operated in the previously described manner by movement of the handle 71.

Three adjusting mechanisms 141 are provided for adjusting the positions of the armatures to thereby permit selection of the overload current that will be required to magnetically trip the circuit breaker. The armatures are adjusted by rotation of knobs 143 that extend through openings 145 in the trip device housing 110. The adjusting mechanisms are specifically described in the patent to'G. F. Thomas et al., U.S. Pat. No. 3,073,92 5,issued Jan. 15, 1963.

' Thermal tripping means is provided in each pole to effect automatic tripping of the circuit breaker with a time delay upon the occurrence of certain overload currents below said first predetermined value. Each thermal tripping means comprises a bimetal a that deflects when heated in response to overloads in a wellknown manner. Upon the occurrence of certain overload currents below said first predetermined value in any of the poles the associated bimetal 159 will bend to the left (FIG. 2) to engage an associated adjusting screw 165 supported on the trip bar 119 to thereby rotate the trip bar 119 counterclockwise after a time delay to effect a tripping operation of the circuit breaker in the same manner as was hereinbefore described with regard to the electromagnetic tripping operation.

Each main conductor 125 is a rigid generally L- shaped conducting member that is cast as an integral unit. The main conductor 125 comprises a horizontal leg 171 and a vertical leg 173 that extends generally normal to the direction of extension of the horizontal leg 171. An opening is provided at the back of the horizontal leg 171 for receiving the bolt 129 (FIG. 3). The horizontal leg 171 is provided with two openings therein for receiving mounting bolts that will be hereinafter described. The vertical leg 173 is provided with two tapped openings at the front thereof. Two bolts 175 pass through suitable openings in part of the support 123, through the openings in the horizontal leg 171 of the conductor 125, through suitable openings in a conductor 177, and they are threaded into two tapped inserts 179 (only one of which is seen in FIG. 1) in the base 7 to secure the bracket 123, conductor 125 and conductor 177 in position on the base 7. As can be seen in FIG. 1, a laminated flexible conductor 181 is connected at one end thereof to the conductor 177 and at the other end thereof to the associated contact arm 29.

In each pole unit, a generally L-shaped rigid main conductor 185 is secured to the insulating base 7 by bolt means 187. Each main conductor 185 comprises a horizontal leg 189 (FIG. 2) and a vertical leg 191. The vertical leg 191 is provided with a pair of tapped openings for receiving a pair of bolts 193.

Referring to FIGS. 2 and 6, a separate current limiting fuse 195 is mounted in each compartment or pole unit of the circuit breaker. Each of the fuses 195 com prises a fuse body 197 and two

fuse terminals

199, 201 at opposite ends of the fuse body. The fuse terminal 199 is provided with a pair of openings for receiving bolts 193 and the fuse terminal 201 is provided with a pair of openings for receiving bolts 203 (FIG. 2). The fuse terminal 201 is formed with a slot 205 (FIG. 6) therein..A plunger 207, which is spring biased toward an extended outer actuating position and maintained in the unactuated position seen in FIGS. 2 and 6 under normal conditions, extends from the fuse body 195 and is disposed in the slot 205. An actuator 209, secured to move with the plunger 207, extends through the slot, 205 above and below the terminal 201. A stop 213, is screwed in the outer end of the slot 205 to limit movement of the plunger 207 and actuator 209 in the extended or actuated position thereof. When the fuse blows to interrupt the current, a restraining means, which normally holds the plunger 207 in the unactu ated position, releases the plunger 207, and spring biasing means (not shown) will force the plunger 207 and actuator 209 outward (to the right as seen in FIG. 2) to an extended actuating position, which position is limited by engagement of the plunger 207 with the stop 213. The means for operating the plunger 207 may be of the type described in the patent to Rawlins et al., US. Pat. No. 2,435,844, or other well-known means may be used.

As is best illustrated in FIGS. 4 and 5, the tripdevice 13 comprises a separate elongated intermediate member 217 for each of the three poles. Each of the intermediate members 217 is supported on the trip device housing 110 by means of a separate bracket 219. Each of the intermediate members 217 slidably fits in a relatively small opening 221 (FIG. 5) in the trip device housing 1 10, and is spring biased outward to the unactuated position seen in FIG. 5 by means of a spring 223. A shoulder 227 on each of the intermediate members 217 engages the associated bracket 219 to limit outward movement of the member 217. As can be understood with reference to FIGS. 2 and 5, each of the intermediate members 217 is spaced from the trip bar 1 19 in the unactuated position thereof.

In each pole unit, an external terminal conductor 229 (FIG. 1) extends into a suitable opening in the housing base 7 and is bolted to the internal main conductor 185 by bolt means 231. In each pole unit an extemal terminal conductor 233 extends into a suitable opening in the insulating base 7 and is bolted to the internal main conductor 23 by bolt means 235. The

conductors

229, 233 are of the type more specifically described in the patent to Cellerini et al., U.S. Pat. No. 3,287,534. r

In each pole unit, the circuit extends from the external terminal conductor 229, through the internal conductor 185, the current limiting fuse 195, the terminal conductor 125, the conductor 177, the flexible conductor 181, the contact arm 29, the

contacts

27, 21, the conductor 23 to the other external terminal conductor 233. Upon occurrence of an overload above a first predetermined value in any of the three-pole units of the circuit breaker, the previously described thermal tripping operation will occur with a time delay releasing the trip member 51 to simultaneously open the contacts of all three pole units. Upon the occurrence of an overload above a second predetermined value in any of the pole units of the circuit breaker, the previously described electromagnetic tripping operation will occur to release the trip member 51 and open the contacts of all three pole units. Upon the occurrence of a severe overload above a third predetermined value in any of the pole unites, the fuse 195 in that pole unit will blow instantaneously to limit the amount of current that will pass through the circuit breaker and to interrupt the circuit, and when the fuse blows, the plunger 207 of the blown fuse will be released. Upon release of the plunger 207, the plunger biasing means will force the plunger 207 and actuator 209 from the unactuated position shown in full lines in FIG. 6 to the extended actuating position shown in broken lines, with the plunger 207 engaging the stop 213 to limit movement of the plunger 207 and actuator 209 in the extended actuated position. During this movement, the actuator 209 of the blown fuse will move the associated intermediate member 217 (FIGS. 1 and 2) inward against the bias of the spring 223. During this movement, the inner end of the intermediate member 217 will engage the trip bar 119 to rotate the trip bar in a counterclockwise (FIGS. 1 and 2) direction to release the latch structure 61 to thereby release the releasable member 51 (FIG. 1). Upon release of the releasable member 51, the circuit breaker will be automatically operated to the tripped open position in the same manner as was hereinbefore described. The plunger 207 and actuator 209 will remain in the extended position to hold the trip bar 1 19 in the tripped position to thereby prevent a resetting operation ofthe circuit breaker mechanism so that the circuit breaker contacts will remain in the open position until the blown fuse is replaced and until the circuit breaker mechanism is thereafter reset and relatched in the same manner as was hereinbefore described. The cover 9 of the insulating housing 50f the insulating circuit breaker housing 5 is secured to the base 7 by bolt means (not shown). In order to remove the cover 9, the bolt means is removed and the cover is lifted off of the base. A suitable cover interlock means maybe provided to maintain the trip bar in the tripped position so long as the cover 9 is removed. The

bolts

193, 203 of the blown fuse can be removed and the blown fuse 195 can be removed and replaced with an unactuated fuse. The circuit breaker cover 9 can then be replaced. Thereafter, the handle 71 of the circuit breaker can be moved to the full off position to reset and relatch the releasable member 51 in the same manner as was hereinbefore described. With the cover 9 removed, it can be appreciated that the openings in the trip device housing, through which the knobs 143, terminal main conductors 125, and intermediate members 217 extend, are substantially filled by these members so that a worker cannot easily tamper with the internal parts of the removable trip device. The trip device 13 is removable and can be replaced if desired by a difierent drip device 13. When the cover 9 of the circuit breaker housing is removed, a worker cannot easily tamper with the internal parts of the trip device 13, and when the trip device 13 is removed a worker cannot easily tamper with the internal working parts of the trip device 13. It is also to be noted that the intermediate members 217 are spaced from the trip bar 119 in the unactuated position thereof. Thus, if a worker were to accidentally or intentionally lodge a part in a position to prevent movement of one of the intermediate members 217 to the actuated position, the trip bar 1 19 would still be operable to the tripped position by operation of any of the other intermediate members 217, or by operation of the thermal or electromagnetic trip means of any of the three poles. I

I claim:

1. A multi-pole circuit breaker comprising an insulating circuit breaker housing, a circuit breaker mechanism supported within said insulating circuit breaker housing, said circuit breaker mechanism comprising a pair of contacts for each pole, a releasable member releasable to effect automatic opening of all of said pairs of contacts,

said circuit breaker mechanism comprising a multipole trip devicesupported in said insulating circuit breaker housing, said multi-pole trip device comprising an insulating trip device housing, a common trip bar movably mounted in said insulating trip device housing and movable to a tripped position to effect release of said releasable member, said insulating trip device housing having an opening therein for each of said poles, an intermediate member for each pole extending from outside of said trip device housing through the associated opening into the inside of said trip device housing, each of said intermediate members being spaced from said trip bar inside of said trip device housing,

a separate fuse for each pole, each of said fuses being supported inside of said circuit breaker housing and outside of said trip unit housing, eachof said fuses being in electrical series with the contacts of the associated pole, each of said fuses comprising biased plunger means automatically movable to an extended actuating position when the fuse blows, each of said fuses being constructed to blow upon the occurrence of an overload above a'predetermined value to effect interruption of the overload, upon the occurrence of 1 an overload over said predetermined value in any of said poles the associated fuse blowing and the associated plunger means moving to the extended actuating position to engage the associated intermediate member to move the associated intermediate member against said trip bar to thereby move said trip bar to said tripped position.

2. A multi-pole circuit breaker according to claim 1, each of said intermediate members being an elongated member supported on said trip unit housing for rectilinear movement in the associated opening.

3. A multi-pole circuit breaker according to claim 2, spring means for each of said intermediate members biasing the associated intermediate member to the nonactuated position spaced from said trip bar, upon the occurrence of said overload over said predetermined value in any of said poles the associated fuse blowing and the associated plunger means moving to engage the associated elongated intermediate member to move the associated elongated intermediate member against the bias of the associated spring means to thereby move the associated elongated intermediate member against said trip bar to thereby move said trip bar to said tripped position.

4. A multi-pole circuit breaker according to claim 1, said multi-pole trip device comprising a separate trip means in said trip unit housing for each pole operable upon the occurrence of overload current conditions below said predetermined value in the associated pole to automatically move said trip bar to said tripped position independent of said intermediate members.

5. A multi-pole circuit breaker according to claim 4, each of said intermediate members being an elongated member supported on said trip unit housing for slidable rectilinear movement in the associated opening.

6. A multi-pole circuit breaker according to claim 5, spring means for each of said elongated intermediate members biasing the associated elongated intermediate member to the non-actuated position spaced from said trip bar.

7. A multi-pole circuit breaker according to claim 1, and each of said fuses comprising stop means limiting the movement of the associated plunger means in the extended actuating position of the associated plunger.

8. A multi-pole circuit breaker according to claim 1, each of said fuses comprising a terminal having a slot therein, each of said fuse plunger means comprising-an actuator extending vertically through the .associated slot and moving in the associated slot, and upon movement of each of said fuse plunger means to the extended position the associated actuator engaging the associated intermediate member to move the associated intermediate member against said trip bar to thereby move said trip bar to said tripped position.

9. A multi-pole circuit breaker according to claim 8, said multi-pole circuit breaker being a three-pole circuit breaker, in each of said current limiting fuses the said slot means in the associated terminal being offcenter widthwise across the associated terminal, for two of said poles the current limiting fuses being in the same orientation with the actuator on one side of the associated slot engaging the associated intermediate member to move the associated intermediate member, for the third of said poles the fuse being turned over with the actuator on the opposite side of the associated slot engaging the associated intermediate member to move the associated intermediate member.

10. A three-pole circuit breaker according to claim 9, each of said intermediate members comprising an elongated member supported on said trip unit housing for rectilinear sliding movement in the associated opening, spring means for each of said intermediate members biasing the associated intermediate member to the non-actuated position spaced from said trip bar, and upon movement of any of said fuse plunger means to the extended actuating position the associated actuator engaging the associated elongated intermediate member to move the associated elongated intermediate member against the bias of the associated spring means to move the associated intermediate member against said trip bar to thereby move said trip bar to said tripped position.

V UNITEDiST ATES PATENT. OFFICE. I ACERTIFICATE OF CORRECTION Patent No. 3 718 387-8v Dated February. 7 P 1973 I .c,., 7 James C Wils on it: is certified that error appears in theabove-id'entified patent and that said Letters, Patent are hereby corrected as shown below:

The assignee is incorrect. Cancel "Matsushita' Electronics 1 Corporation, Osaka, Japan" and substitute Westinghouse Electric Corporation, Pittsburgh Pennsylvania Signed and' sealed this 29th day" of January 19%..

(SEAL) Attest:

. EDWARD M. FLETCHER, JR. v RENE D. TEGTP IEYER v Attesting Officer Acting Commissioner of Patents romd po-wso (yo-6 4 j p]. counumbv muignl emu um o-au-au UNITED; STATES PATENT. OFFICE- CERTIFICATE OF CORRECTION Patent No. Dated February 7; 973

Inventr'(8) James C. Wilson It is certified that error appears in the above-identified patent and vthat said Letters Patent are hereby corrected as shown below:

Theassignee is incorrect. Cancel "Matsushita Electronics Corporation, Osaka, Japan" and substitute Westinghouse Electric Corporation, Pittsburgh, Pennsylvania Signed and sealed this 29th dayof January l97L (SEAL) Attest:

. EDWARD M.FLETCHER,JR. RENE D. TEGTMEYER Attesting Officer Acting Commissioner of Patents FORM Po-1050 (1M9)

Claims

1. A multi-pole circuit breaker comprising an insulating circuit breaker housing, a circuit breaker mechanism supported within said insulating circuit breaker housing, said circuit breaker mechanism comprising a pair of contacts for each pole, a releasable member releasable to effect automatic opening of all of said pairs of contacts, said circuit breaker mechanism comprising a multi-pole trip device supported in said insulating circuit breaker housing, said multi-pole trip device comprising an insulating trip device housing, a common trip bar movably mounted in said insulating trip device housing and movable to a tripped position to effect release of said releasable member, said insulating trip device housing having an opening therein for each of said poles, an intermediate member for each pole extending from outside of said trip device housing through the associated opening into the inside of said trip device housing, each of said intermediate members being spaced from said trip bar inside of said trip device housing, a separate fuse for each pole, each of said fuses being supported inside of said circuit breaker housing and outside of said trip unit housing, each of said fuses being in electrical series with the contacts of the associated pole, each of said fuses comprising biased plunger means automatically movable to an extended actuating position when the fuse blows, each of said fuses being constructed to blow upon the occurrence of an overload above a predetermined value to effect interruption of the overload, upon the occurrence of an overload over said predetermined value in any of said poles the associated fuse blowing and the associated plunger means moving to the extended actuating position to engage the associated intermediate member to move the associated intermediate member against said trip bar to thereby move said trip bar to said tripped position.

3. A multi-pole circuit breaker according to claim 2, spring means for each of said intermediate members biasing the associated intermediate member to the non-actuated position spaced from said trip bar, upon the occurrence of said overload over said predetermined value in any of said poles the associated fuse blowing and the associated plunger means moving to engage the associated elongated intermediate member to move the associated elongated intermediate member against the bias of the associated spring means to thereby move the associated elongated intermediate member against said trip bar to thereby move said trip bar to said tripped position.

8. A multi-pole circuit breaker according to claim 1, each of said fuses comprising a terminal having a slot therein, each of said fuse plunger means comprising an actuator extending vertically through the associated slot and moving in the associated slot, and upon movement of each of said fuse plunger means to the extended position the associated actuator engaging the associated intermediate member to move the associated intermediate member against said trip bar to thereby move said trip bar to said tripped position.

9. A multi-pole circuit breaker according to claim 8, said multi-pole circuit breaker being a three-pole circuit breaker, in each of said current limiting fuses the said slot means in the associated terminal being off-center widthwise across the associated terminal, for two of said poles the current limiting fuses being in the same orientation with the actuator on one side of the associated slot engaging the associated intermediate member to move the associated intermediate member, for the third of said poles the fuse being turned over with the actuator on the opposite side of the associated slot engaging the associated intermediate member to move the associated intermediate member.