US3652961A

US3652961A - Circuit breaker with electromagnetic trip means

Info

Publication number: US3652961A
Application number: US75200A
Authority: US
Inventors: John G Salvati; Eugene J Walker
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1970-09-24
Filing date: 1970-09-24
Publication date: 1972-03-28
Anticipated expiration: 1989-03-28
Also published as: AU3328771A; CA929565A; JPS477027A; AU468325B2

Abstract

A circuit breaker with electromagnetic trip means comprises a stationary magnetic part and pole-piece means adjustably mounted on the stationary magnetic part to provide adjustment of the air gap between a stationary magnetic structure and a movable armature. The circuit breaker is a multi-pole circuit breaker with the armatures being mounted on a common trip bar.

Description

United States Patent Saivati et ai.

151 3,652,961 [451 Mar. 28, 1972 [54] CIRCUIT BREAKER WITH 2,843,807 7/1958 Lewus ..335/273 ELECTROMAGNETIC TRIP MEANS Primary Examiner-Harold Broome [72] inventors: John G. Salvati, Beaver Falls; Eugene J. A yw m -L and i hik Walker, Beaver, both of Pa.

[57] ABSTRACT [73] Assignee: Westinghouse Electric Corporation, Pittsburgh, A circuit breaker with electromagnetic trip means comprises a stationary magnetic part and pole-piece means adjustably Filedi p 1970 .mounted on the stationary magnetic part to provide adjust- :ment of the air gap between a stationary magnetic'structure [21] Appl' 75200 and a movable armature. The circuit breaker is a multi-pole circuit breaker with the armatures being mounted on a com- 52 U.S. Cl ..335/176 mnltia et- [51] Int.Cl. ..H01h 69/01 [58] Field ofSearch ..335/l76, 42, 23,36,37,273

1 References C te .v r W2.E'simsiPmfissEsuss.

UNITED STATES PATENTS 2,673,264 3/1954 Coie iilfli 75 i 15 9 b Z "inf I0 ma 95 57 */l- 2 n3 51 8| /1 59 |4| rm: fi |3| 97 65 TI 53 t 49 I 9 9 {by 65 70 l l :5 33 27 29 [9 Q 24 PATENTEDMAR28 m2 3,652,961

same or z 47 FIG. 5

CIRCUIT BREAKER WITH ELECTROMAGNETIC TRIP MEANS CROSS-REFERENCE TO RELATED APPLICATION The electromagnetic trip means of this invention is utilized in a multi-pole molded case circuit breaker of the type dis closed in the patent application of Eugene J. Walker, Ser. No. 858,614 filed Sept. I7, 1969.

BACKGROUND OF THE INVENTION 1. Field of the Invention Circuit breakers of the type comprising electromagnetic trip means.

2. Description of the Prior Art The U.S. Pat. to Cole No. 2,673,264 issued Mar. 23, 1954 discloses a multi-pole circuit breaker with a separate electromagnetic trip device in each pole. Each of the electromagnetic trip devices comprises a stationary magnetic structure and a movable magnetic armature. The armatures are adjustably mounted on a common trip bar that moves to a tripping position to trip the breaker upon electromagnetic attraction of any of the armatures.

SUMMARY OF THE INVENTION A circuit breaker comprisesa releasable member releasable by operation of an improved electromagnetic trip device to effect automatic opening of the breaker contacts. The electromagnetic trip device comprises a stationary magnetic structure and a movable armature supported for movement toward and away from the stationary magnetic structure. The stationary magnetic structure comprises a first magnetic part and pole-piece means adjustably mounted on the first magnetic part. The mounted position of the pole piece means on the first magnetic part can be adjusted to thereby adjust-the air gap between the stationary magnetic structure and the armature. The circuit breaker is a multi-pole circuit breaker and the armatures of all of the pole units are mounted on a common trip bar that is movable to effect release of the releasable member upon attraction of any of the armatures.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a side sectional view, through the center pole unit, of a three-pole circuit breaker constructed in accordance with principles of this invention;

FIG. 2 is an enlarged view relative to FIG. 1 illustrating the latch mechanism and trip device seen in FIG. 1;

FIG. 3 is a top plan view, with parts broken away, of the parts illustrated in FIG. 2;

FIG. 4 is a sectional view with parts broken away, taken along the line IV-IV in FIG. 3;

FIG. 5 is an end view of the latch member seen in FIG. 3 looking in the direction of the VV arrows in FIG. 3; and

FIG. 6 is an end view of the trip bar with the three armatures mounted thereon.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, there is shown, in FIG. I, a threepole molded-case type circuit breaker 5 comprising an insulating housing 7 and a circuit breaker structure 9 supported in the housing 7. Except for the trip means, the circuit breaker structure 9 is of the type described in the patent application of Eugene J. Walker et al. Ser. No. 858,614 filed Sept. 17, 1969.

The insulating housing 7 is a two-part housing comprising a molded insulating base 11 and a molded insulating cover 13 secured to the base 11. A pair of insulating barriers 15 (only one being shown in FIG. 1) molded integral with the insulating cover 13 cooperate with a pair of insulating barriers 17, that are molded integral with the insulating base 1 l, to separate the housing into three adjacent pole-unit compartments for husing the three-pole units of the circuit breaker.

Each pole of the circuit breaker includes a stationary contact l9 and a movable contact 23. The stationary contact 19 is mounted on the inner end of a-conductor 24 that extends into an open cavity in the one end of the housing where a solderless terminal connector 27 is secured to the conductor 24 to enable connection of the pole unit in an electric circuit. The movable contact 23 is part of a movable contact structure 25 that includes a switch arm 27 and a contact arm 29 having the contact 23 secured thereto. The switch arm 27 is fixedly secured to a common tie bar 33. The contact arm 29 is pivotally supported on the switch arm 27 and biased about the pivot to provide contact pressure in the manner disclosed in the above-mentioned application Ser. No. 858,614. In each pole unit, a flexible conductor 41 is connected at one end thereof to the associated contact arm 29 and at the other end thereof to a conductor 43 that is in turn secured to a looped conductor 45 that is in turn secured to a conductor 47 that extends into a cavity at the end of the circuit breaker where a solderless terminal connector 49 is secured to the conductor 47 in order to pennit connection of the pole unit in an electric circuit. The circuit through each pole unit extends from the terminal connector 49 through the conductor 47, conductor 45, conductor 43, flexible conductor 41, contact arm 29, movable contact 23, stationary contact 19, conductor 24 to the other solderless terminal connector 27.

The contact arm structures 25 for the three-pole units are simultaneously operated between the open and closed positions by operation of a single operating mechanism SI that is located in the center pole unit compartment. The operating mechanism 51 is supported on a pair of supporting plates 53 (only one being shown in FIG. 3) that are supported in the center pole unit compartment. An inverted generally U- shaped operating member 55 is pivotally supported at the inner ends of the legs thereof in U-shaped notches in the plates 53. A releasable trip member 57 is pivotally supported on the plates 53 by means of a pin 59. One end of the releasable trip member 57 is latched in the operating position seen in FIG. I by means of a latch mechanism 61. A pair of

toggle links

63 and 65 are pivotally connected together by means of a knee pivot 67. The upper toggle link 63 is pivotally connected to the releasable trip member 57 by means of a pivot pin 69. The lower toggle link 65 is pivotally connected to the switch arm 27 of the center pole unit by means of a pivot pin thatalso serves to pivotally mount the contact arm 29 on the switch arm 27. A pair of tension springs 73 (only one being seen in FIG. 1) are supported under tension between the knee pivot 67 and the bight portion of the operating member 55. An insulating member 75, which is connected to the front portion of the operating member 55, comprises a handle part 77 that protrudes out through an opening 79 in the housing cover 13 to permit manual operation of the circuit breaker.

The tie bar 33 is supported for pivotal movement about the elongated axis thereof that extends normal to the plane of the paper as seen in FIG. 1. In order to manually open the circuit breaker, the handle 77 is moved from the closed position seen in FIG. I, in a counterclockwise direction about the pivot of the operating member 55, to the open position. During this movement, the line of action of the overcenter springs 73 is moved to the left to collapse the

toggle

63, 65 to thereby move the contact arm structure 25 of the center pole unit to the open position. This movement, because all three of the contact arm structures 25 are fixed to the tie bar 33, pivots the tie bar 33 to simultaneously move all three contact arm structures 25 to the open position. The circuit breaker is manually closed by moving the handle 77 to move the operating member 55 in a clockwise direction to the closed position seen in FIG. I. This moves the line of action of the springs 73 to the right to erect the

toggle

63, 65 to thereby move the contact arm structure 25 for the center pole unit to the closed position. Because all three of the contact arm structures 25 are fixedly secured to the common tie bar 33, this movement pivots the tie bar 33 to simultaneously move all three contact arm structures 25 to the closed position.

The latch structure 61 (FIGS. l-3) comprises a latch member 81 formed with two downwardly extending leg portions 83 having elongated slots 85 (FIG. 2) therein for receiving a pin 87 that passes through the slots 85 and is connected to the supporting plates 53 to support the latch member 81 for pivotal and sliding movement on the pin 87. A spring 91 biases the latch 81 in a counterclockwise direction as seen in FIGS. 1 and 2. The free end of the releasable trip member 57 is disposed in a window opening 93 (FIG. engaging the latch 81 at the upper end of the opening 93 in the latched position seen in FIGS. 1 and 2. A latch part 95 extends from the latch 83 to rest on a latch part 97 that is a surface molded integral with an insulating trip bar 99. The trip bar 99 extends across all threepole units of the circuit breaker, and a pair of pins 101 (FIG. 6) are supported on the side walls of the circuit breaker to support the trip bar 99 for pivotal movement about the elongated axis of the trip bar 99 which axis is normal to the plane of the paper as seen in FIG. 1. The trip bar 99 is provided with three upwardly extending projections 103 (FIG. 6) for the three-pole units of the circuit breaker. As can be understood with reference to FIG. 1, the latch 81 is prevented from moving counterclockwise about the pin 87 by engagement of the latch part 85 of the latch 81 with the latch part 97 of the trip bar 99 so that the latch 81 prevents clockwise tripping movement of the releasable trip member 57.

In each pole unit, an elongated bimetal 107 is connected to one leg of the looped conductor 45 at the lower end thereof, and an actuating screw 109 is mounted on the upper free end of the bimetal 1117. Upon the occurrence of a lesser overload current above a first predetermined value in any of the pole units, the bimetal 107 of the overloaded pole unit will flex to the right with a time delay and the actuating screw 109 will move the projection 103 to rotate the trip bar 99 in a clockwise (FIG. 1) direction to trip the circuit breaker open. Upon clockwise movement of the trip bar 99, the latch part 97 of the trip bar 99 will release the latch part 95 of the latch member 81 permitting the latch member 81 to move in a counterclockwise (FIG. l)-direction to thereby release the releasable member 57. Upon release of the releasable member 57 the spring 73, operating through the toggle link 63, will pivot the releasable member 57 in a clockwise (FIG. 1) direction about the pin 59 to change the line of action of the spring 73 which will operate to collapse the

toggle

63, 65 opening the contacts 23, 25 in a well known manner. Following a tripping operation, the circuit breaker is reset by movement of the handle 77 to a position slightly past the full off" position. Turning this movement, a part 113 (FIG. 1) on the member 55 engages a shoulder portion 115 on the releasable trip member 57 to rotate the trip member 57 in a counterclockwise direction. As the releasable trip member 57 moves in a counterclockwise direction it engages the latch 81 wiping past the latch 81 which movement is permitted by the elongated slots 85 (FIG. 2) in the latch 81 which receive the supporting pin 87. As the trip member 57 wipes by the upper part of the latch 81, the free end of the trip member 57 engages the ledge as the lower end of the opening 93 (FIG. 5 to pivot the latch member 81 in a clockwise (FIGS. 1 and 2) direction to the latching position seen in FIG. 1 whereupon the torsion spring 91, which engages the trip bar 99 at one end thereof, biases the trip bar 99 to the latched initial position seen in FIG. 1. Thereafter upon release of the handle 77 the trip member 57 will be again latched at the upper end of the window opening 93 (FIG. 5) of the latch member 31 in the latched position in the same manner as was hereinbefore described.

There is an improved electromagnetic trip device 121 in each pole unit of the circuit breaker. Each of the electromagnetic trip devices 121 comprise a stationary magnetic structure 123 and a movable magnetic armature 125. Each of the armatures 125 is fixedly secured to the insulating trip bar 99 by means of a rivet 1.27. Each of the stationary magnetic structures 123 comprises a stationary magnetic part 131 (FIGS. 2-4) that is a generally flat plate of magnetic material having a pair of elongated vertical slots 133 (FIG. 4) therein. Each of the magnetic parts 131 is mounted in the pole unit by being dropped into a pair of slots (FIG. 3) in the opposite sides of the insulating housing part of the pole unit with the ends of the magnetic part 131 fitting within the slots to support the magnetic part 131 in the pole unit. In addition to the magnetic part 131, each of the stationary magnetic structures 123 comprise two magnetic pole pieces 137 that are rod shaped or generally circular in cross section. Each of the pole pieces 137 is provided with a tapped opening at one end thereof, and a separate mounting screw 139 passes through the associated slot 133 (FIG. 41) in the magnetic part 131 and is threaded into the tapped opening of the associated pole piece 137 to mount the pole piece 137 on the magnetic part 131. As can be understood with reference to FIGS. 1 and 2, each of the armatures extends at an angle relative to the pole pieces 137 so that vertical adjustment of the pole pieces 137 on the magnetic part 131 will vary the working air gap between the annature 125 and the stationary magnetic structure 123. When it is desired to lessen the air gap, the screws 139 are loosened and the pole pieces 137 are moved upward, for example to the position shown in broken lines in FIG. 2, whereupon the screws 139 are tightened to fixedly secure the pole pieces 137 in the new adjusted position on the magnetic part 131. The adjustability of the magnetic air gap permits the manufacturer of the circuit breaker to adjust the electromagnetic trip in order to provide electromagnetic tripping action responsive to a predetermined overload current. Upward adjustment of the pole pieces 137 decreases the air gap to provide that the electromagnetic trip device will trip the breaker upon the occurrence of a lesser overload current, and downward adjustment of the pole pieces 137 enlarges the air gap to provide that the electromagnetic trip device will trip the breaker upon the occurrence of a higher overload current. There is an insulating barrier 141 (FIG. 1) in each pole unit which is supported in slots in the side walls of the pole unit. During assembly of the circuit breaker, with the cover 13 removed, the insulating barrier 141 is removed and the solderless connector 49 is removed. This provides access to an operator who can work the screws 139 from the end of the circuit breaker. Current is passed through the circuit breaker and the air gap is adjusted to provide the desired tripping characteristics whereupon the screws 139 are tightened to secure the pole pieces 137. Thereafter, the solderless terminal connectors 49 are put into place and the barriers 141 are mounted in the base 11 after which the cover 13 is secured to the base 11 to thereby complete assembly of the circuit breaker. In addition to the advantage of adjustability and simplified construction, an additional advantage of the electromagnetic device of this invention is that the armatures 125 are all secured to the trip bar 99 so that the reset spring 91, which operates to reset the trip bar 99 following tripping operations, also serves to return the three armatures 125, which are secured to the trip bar, to the initial position seen in FIG. 1 following a tripping operation in any of the pole units.

As can be understood with reference to FIGS. 1-41, the looped conductor 45 passes between the pole pieces 137 and over the magnetic part 131. Thus, the current through the conductor 45 magnetically energizes the electromagnetic trip device 123. Upon the occurrence of an overload above a second predetermined value higher than the first predetermined value in any of the pole units, the armature 125 in the overloaded pole unit is instantaneously attracted to the pole pieces 137 to rotate the trip bar 99 in a clockwise (FIG. 1) direction to effect a tripping operation in the same manner as was hereinbefore described. Following an electromagnetic tripping operation, the circuit breaker is reset and relatched in the same manner as was hereinbefore described.

From the foregoing, it can be understood that there is provided by this invention a circuit breaker with an improved adjustable electromagnetic trip device. The electromagnetic trip device comprises a stationary magnetic structure that comprises a stationary magnetic part and a pair of pole pieces adjustably mounted on the stationary magnetic part to provide adjustment of the air gap between the stationary magnetic structure and the associated movable armature that is fixedly secured to the common trip bar of the circuit breaker. There is a separate electromagnetic trip device in each pole unit, and all of the armatures are fixedly mounted on the trip bar that is common to all of the pole units. An advantage of mounting the armatures on the trip bar is that the one recess spring, which resets the trip bar following tripping operations, serves also to reset all of the armatures.

We claim:

1. A circuit breaker comprising a pair of contacts, a releasable trip member releasable to effect automatic opening of said contacts, an electromagnetic trip device comprising a stationary magnetic structure, a movable magnetic armature supported for movement toward and away from said stationary magnetic structure, said stationary magnetic structure comprising a stationary magnetic part and magnetic pole-piece means, said stationary magnetic part being a generally flat plate, adjustable mounting means adjustably mounting said pole-piece means on said generally flat plate such that said pole-piece means is movable rectilinearly on said generally flat plate to the adjusted positions thereof, said armature being slanted relative to the plane of rectilinear movement of said pole-piece means whereby rectilinear adjustable movement of said pole-piece means will vary the air gap between said polepiece means and said armature, and conducting means energizing said electromagnetic trip device such that upon the occurrence of overload current conditions above a predetermined value said armature will be attracted to said stationary magnetic structure to effect release of said releasable trip member.

2. A circuit breaker according to claim 1, said pole-piece means comprising a pair of pole pieces, a separate adjustable mounting means for each of said pole pieces adjustably mounting the associated pole pieces on said generally flat plate.

3. A circuit breaker according to claim 2, said generally flat plate having a pair of slots therein, each of said pole pieces having a tapped opening therein, a separate mounting bolt for each of said pole pieces extending through a separate one of said slots and being threaded into the tapped opening of the associated pole piece to adjustably mount the associate pole piece on said generally flat plate.

4. A circuit breaker according to claim 2, said conducting means being a looped conductor extending up along one side of said generally flat plate and down between said pole pieces on the other side of said generally flat plate.

5. A circuit breaker according to claim 3, each of said pole pieces being a member generally circular in cross section with the tapped opening extending axially in the member, and each of said mounting bolts being threaded into the tapped opening of the associated pole piece to secure the pole piece in the ad justed position on said generally flat plate.

6. A circuit breaker according to claim 1, said circuit breaker being a multi-pole circuit breaker comprising a pair of contacts for each pole, said releasable trip member being releasable to effect automatic opening of all of said pairs of contacts, a separate one of said electromagnetic trip devices for each pole, a common trip bar common to all of said poles and being movable to a tripping position to effect release of said releasable member, and each of said armatures being mounted on said common trip bar whereby when any one of said armatures is attracted to the associated stationary magnetic structure the attracted armature will move said common trip bar to the tripping position.

7. A circuit breaker according to claim 6, each of said polepiece means comprising a pair of pole pieces, and a separate mounting means for each of said pole pieces adjustably mounting the associated pole piece on the associated generally flat plate.

8. A circuit breaker according to claim 7, each of said generally flat plates having a pair of slots therein, each of said pole pieces having a tapped opening therein, a separate mounting bolt for each of said ole pieces extending through a separate one of said slots and eing threaded mto the tapped opening of the associated pole piece to adjustably mount the associated pole piece on the associated generally flat plate.

9. A circuit breaker according to claim 8, and each of pole pieces being generally circular in cross section with the associated tapped opening extending axially in the pole piece.

Claims

1. A circuit breaker comprising a pair of contacts, a releasable trip member releasable to effect automatic opening of said contacts, an electromagnetic trip device comprising a stationary magnetic structure, a movable magnetic armature supported for movement toward and away from said stationary magnetic structure, said stationary magnetic structure comprising a stationary magnetic part and magnetic pole-piece means, said stationary magnetic part being a generally flat plate, adjustable mounting means adjustably mounting said pole-piece means on said generally flat plate such that said pole-piece means is movable rectilinearly on said generally flat plate to the adjusted positions thereof, said armature being slanted relative to the plane of rectilinear movement of said pole-piece means whereby rectilinear adjustable movement of said pole-piece means will vary the air gap between said pole-piece means and said armature, and conducting means energizing said electromagnetic trip device such that upon the occurrence of overload current conditions above a predetermined value said armature will be attracted to said stationary magnetic structure to effect release of said releasable trip member.

5. A circuit breaker according to claim 3, each of said pole pieces being a member generally circular in cross section with the tapped opening extending axially in the member, and each of said mounting bolts being threaded into the tapped opening of the associated pole piece to secure the pole piece in the adjusted position on said generally flat plate.

7. A circuit breaker according to claim 6, each of said pole-piece means comprising a pair of pole pieces, and a separate mounting means for each of said pole pieces adjustably mounting the associated pole piece on the associated generally flat plate.

8. A circuit breaker according to claim 7, each of said generally flat plates having a pair of slots therein, each of said pole pieces having a tapped opening therein, a separate mounting bolt for each of said pole pieces extending through a separate one of said slots and being threaded into the tapped opening of the associated pole piece to adjustably mount the associated pole piece on the associated generally flat plate.