US3562733A

US3562733A - Electric circuit breaker with improved trip alarm

Info

Publication number: US3562733A
Application number: US691042A
Authority: US
Inventors: Frank H Murphy; Henry E S Owen
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1967-12-15
Filing date: 1967-12-15
Publication date: 1971-02-09
Anticipated expiration: 1988-02-09

Abstract

A TRIP ALARM FOR SIGNALLING ONLY WHEN THE CIRCUIT BREAKER TRIPS DUE TO OVERLOAD CURRENTS, INCLUDING A FIRST SET OF CONTACTS CLOSED BY THE TRIPPING ACTION OF A TRIP UNIT AND A SECOND SET OF CONTACTS CLOSED BY THE TRIPPING MOVEMENT OF THE BREAKER MECHANISM, THE CLOSING OF THESE CONTACTS COMPLETES THE CIRCUIT TO A RELAY WHICH ACTUATES THE TRIP ALARM AND ALSO CLOSES CONTACTS BY-PASSING THE FIRST SET OF CONTACTS TO MAINTAIN THE CIRCUIT THROUGH THE TRIP ALARM EVEN THOUGH THE TRIP ALARM RETURNS TO THE UNTRIPPED CONDITION.

Description

ELECTRIC CIRCUIT BREAKER WITH IMPROVED TRIP ALARM Filed Dec. 15, 1967 Feb. 9, 1971 H MURPHY E'AL 2 Sheets-Sheet 1 INVENTORS I kAIVK MURPHY, HENRY E. 5: Owe

6) m a 1M y.

. Feb. 9, 1971 M RPHY ET'AL 3,562,733

ELECTRIC CIRCUIT BREAKER WITH IMPROVED TRIP ALARM Filed Dec. 15, 1967 2 Sheets-Sheet z.

POWER Sol/E615 13 LEL fie/P INVENTORS HMNK H. MURPHY, A 4 74 HENRY E. SO

United States Patent Oflice Patented Feb. 9, 1971 U.S. Cl. 340253 4 Claims ABSTRACT OF THE DISCLOSURE A trip alarm for signalling only when the circuit breaker trips due to overload currents, including a first set of contacts closed by the tripping action of a trip unit and a second set of contacts closed by the tripping movement of the breaker mechanism; the closing of these contacts completes the circuit to a relay which actuates the trip alarm and also closes contacts bypassing the first set of contacts to maintain the circuit through the trip alarm even though the trip alarm returns to the untripped condition.

BACKGROUND OF THE INVENTION (1) Field of the invention Our invention relates to electric circuit breakers and more particularly to circuit breakers including an auxiliary device for the purpose of providing remote indication of the tripped condition of the circuit breaker mechanism.

(2) Description of the prior art In accordance with the prior art, auxiliary devices have been provided for use with electric circuit breakers for the purpose of giving a remote indication of the tripped condition of the circuit breaker. Such signal means are commonly operated by a part of the circuit breaker which moves only when the circuit breaker is tripped. Thus the signal means is not actuated when the breaker is manually opened by operation of the circuit breaker handle.

In certain types of circuit breakers, however, manual operation of the breaker is achieved by manually tripping the breaker, thus performing manually the same operation which the automatic trip device performs in response to an overload or other abnormal condition. It is therefore not possible to utilize prior art forms of signal means in this type of breaker to indicate whether the breaker has been opened by automatic tripping means as distinguished from manually operated trip means. This is because as noted previously movement of the circuit breaker mechanism resulting from the tripping of the breaker will cause the actuation of these prior art forms of signal means irrespective of whether the tripping of the breaker is done manually, or automatically as a result of the sensing of abnormal current conditions.

OBJECTS OF THE INVENTION It is an object of the present invention to provide a trip alarm system for an electric circuit breaker wherein the alarm system is capable of indicating the fact that the breaker has been opened by automatic tripping means as distinguished from manually operated trip means.

It is another object of the present invention to provide a trip alarm system for an electric circuit breaker wherein the alarm system is triggered only when the breaker has been opened by automatic tripping means.

A still further object of the present invention is to provide a trip alarm system for an electric circuit breaker wherein the trip alarm system once actuated will continue to signal as long as the breaker remains in the open circuit position.

Another object of the present invention is to provide a trip alarm system for an electric circuit breaker wherein the trip alarm system is reliable in operation, simple in construction, and relatively inexpensive to manufacture.

Yet another object of the present invention is to provide a trip alarm system for an electric circuit breaker wherein the trip alarm system may be readily incorporated in electric circuit breakers having manually operated trip means without requiring any substantial modifications in the breaker.

SUMMARY OF THE INVENTION In accordance with the present invention there is provided an electric circuit breaker including an insulating casing having a pair of relatively movable contacts supported therein. The contacts are movable between open and closed circuit positions. Releasable means are provided to cause movement of the contacts to the open circuit position. Latch means are supported in the casing and releasably engage the releasable means. A current responsive trip means is suitably mounted in the casing for engagement with the latch means. The current responsive trip means causes release of the releasable means from the latch means upon the occurrence of predetermined current conditions to thereby cause opening of the contacts. A manually operated trip means is also provided suitably mounted in the casing for engagement with the latch means. Operation of the manually operated trip means also causes release of the releasable means from the latch means to thereby cause opening of the contacts. A trip alarm means is mounted in the casing for providing indication of movement of the contacts to the open circuit position. The trip alarm means includes a first switch which is actuated by the trip lever of the tripping unit when an overload occurs, and a second switch which is actuated by the cradle of the breaker as the breaker trips as a result of the overload. The actuation of both of these switches completes the circuit through the trip alarm. When the breaker is manually tripped, the aforesaid first switch is not actuated and thus the circuit through the trip alarm is not completed and no indication of tripping is given by the trip alarm. In this manner the trip alarm means is capable of ditferentiating between opening of the contacts caused by operation of the current responsive means as distinguished from the manually operated means, such that the trip alarm means provides this indication only when the contacts are opened as a result of operation of the current responsive means.

The invention will be more fully understood from the following detailed description and its scope will be pointed out in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings,

FIG. 1 is a perspective view of an electric circuit breaker incorporating the present invention;

FIG. 2 is a side elevational View of the electric circuit breaker of FIG. 1 with a portion of the side wall of the insulating casing thereof being broken away for clarity of illustration, and showing the circuit breaker operating elements in the closed position;

FIG. 3 is a perspective view of a portion of the circuit breaker of FIG. 2 illustrating on an enlarged scale the trip alarm assembly thereof in accordance with the present invention;

FIG. 4 is a perspective view of a portion of the circuit breaker of FIG. 2 illustrating on an enlarged scale the trip alarm assembly in conjunction with the manually operated trip means in accordance with the present invention;

FIG. 5 is a side elevational view of the circuit breaker trip alarm assembly in accordance with the present invention illustrating the position of the operative parts thereof after the circuit breaker has been tripped by operation of manually operable trip means;

FIG. 6 is a fragmentary side view similar to that of FIG. illustrating the position of the operative parts thereof after the circuit breaker has been tripped due to the operation of current responsive trip means; and

FIG. 7 is a schematic representation of the electric circuitry of the circuit breaker trip alarm assembly in accordance with the present invention.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring now to the drawings, and more particularly to FIGS. 1 and 2 thereof, the invention is shown embodied in a circuit breaker designated by the numeral 10 which has a generally rectangular insulating casing with a base portion 11 and a removable cover portion 12. For convenience, the construction of a single pole chamber of the circuit breaker 10 is shown and will be described in detail although it will be understood that the circuit breaker 10 generally includes three pole chambers, all substantially identical except that the center pole chamber contains the major portion of the operating mechanism.

A line terminal (not shown) is supported at one end of the base portion 11 and is electrically connected to one end of a conductive strap 13, the latter having a relative- 1y stationary contact 14 supported at the other end thereof. A load terminal (not shown) is supported at the other end of the base portion 11 of the circuit breaker, and is electrically connected to a conventional circuit breaker trip unit 15, the latter being supported in close proximity to the load terminal.

A pivoted contact arm assembly indicated generally by the reference numeral 16 is supported in the base portion 11 of the circuit breaker between the trip unit 15 and the stationary contact 14. The pivoted contact arm assembly 16 includes a current carrying support block 17 which is fastened by means of bolts 18 (only one shown) to the base portion 11 of the circuit breaker, and an elongated contact arm segment 19 supported on the block 17 by means of the pivot pin 20. The contact arm segment 19 carries at its free end a movable contact 21. The contact arm pivot assembly 16 also includes a U- shaped bracket member 22 which overlies the contact arm segment 19, and is also pivotally supported on the pivot pin 20. Any suitable restraining means which will not interfere with the pivoting of the U-shaped bracket member 22 may be utilized to hold the latter on the pivot pin 20. Suitable biasing means 23 are provided between the bracket member 22 and the contact arm segment 19 resiliently limiting movement of the arm segment 19 to ward the back of the contact arm assembly 16.

A contact cross arm 24 extends across the plurality of poles of the multipole circuit breaker 10 and is rigidly affixed by suitable means such as by screws 25 and nuts 26 (only one of each shown) to a number of contact arm pivot assemblies similar to that shown at 16. As best seen in FIG. 2, the frame member 27 is provided with a cutaway portion 28 for the purpose of providing clearance for the cross arm 24 as the latter moves upwardly with the contact arm segment 19 to the open contact position illustrated in phantom therein.

Pivotally mounted on the frame member 27 by the pivot pin 29 is the pivoted end portion 30 of the releasable member or cradle generally designated by the numeral 31. The opposite end of the releasable member 31 carries a roller 32 which is rotatably mounted thereon by means of the pin 33. The roller 32 engages the end portion 34a of the primary latch 34 of the intermediate latch mechanism, generally designated by the reference numeral *35, in a manner to be more fully described hereinafter. The cradle 31 and the contact arm pivot assembly 16 are connected intermediate their ends by the pivot pins 36, 37 to the toggle linkage provided by the

toggle links

38, 39 which are pivotally connected to each other by the knee pin 40. The toggle linkage is biased toward straightened condition by a pair of tension springs 41 (the second spring is behind the cradle 31) which are engaged by the knee pin 40 at one end and attached to the pin 42 fixedly carried by the frame member 27, at the other end.

The fixed ends of the tension springs 41 are thus spaced toward the stationary contact 14 to the side of the line drawn between the pivot pins 36, 37 for the

toggle links

38, 39 in the latched position of the cradle 31. Thus, the springs bias the

toggle links

38, 39 toward the stationary contact 14 to hold the moveable contact 21 in firm contact with the stationary contact 14 in the latched position of the cradle 31 as shown in FIG. 2. At the same time the springs 41 tend to rotate the cradle 31 in a clockwise direction about the pivot pin 29 to hold the roller 32 against the end portion 34a of the primary latch 34.

The primary latch 34 of the intermediate latch mechanism 35 is pivotally mounted by means of pivot pin 43 on the supporting frame 44 of the latch mechanism 35 while the entire mechanism 35 is supported within the circuit breaker housing by suitable means (not shown). Primary latch 34 has a radius on the end portion 34a which has a center slightly to the back of the pivot point of the latch 34 itself. This causes the primary latch 34 to be biased backwardly due to the breaker mechanism force being exerted on the end portion 34a of the latch 34. The primary latch bias force is then transmitted to an intermediate latch 45 which further reduces the force components, so that the final tripping force required on the tripping latch lever 46 is very low compared to the initial breaker force. The tripping latch lever 46 is spring biased upwardly by the latch reset spring 47. A similar latch reset spring (hidden by the supporting frame 44) interconnects the intermediate latch 45 and the primary latch 34. As best seen in FIG. 4, the latch lever 46 is suitably provided with a slot 46a which engages the hook portion 45a of the intermediate latch 45 when the latter are in the latched position.

As seen in FIG. 2, the trip 'unit 15 is supported within the base portion 11 of the circuit breaker closely adjacent the contact arm pivot assembly 16 and the inter mediate latch mechanism 35, and is electrically connected to the current carrying support block 17 of the contact arm pivot assembly 16 by means of the connector 48 which fixedly secures the terminal 49 of the trip unit 15 to the block 17. In order to complete the current carrying path through the circuit breaker 10, the trip unit 15 as was noted earlier is provided with another terminal (not shown) which is connected in the conventional manner to the load terminal (not shown) of the circuit breaker.

Housed in the trip unit 15 is a conventional thermal sensitive device (not shown) and a conventional magnetic sensitive device (also not shown). Upon the occurrence of overload conditions of current flow through the circuit breaker one or the other of these devices operates automatically to cause the trip bar 50 to move in a clockwise direction as viewed in FIG. 2. During the course of this clockwise or downward movement, the trip bar 50 engages the calibrating screw 51 supported on the tripping latch lever 46 of the intermediate latch mechanism 35 causing the latch lever 46 to also pivot downwardly, about pivot pin 52 and against the bias of reset latch spring 47. This tripping movement of the latch lever 46 is transmitted to the primary latch 34 by means of the intermediate latch 45 whereby movement of the primary latch 34 releases the cradle 31 of the circuit breaker 10 to thereby cause opening of the

contacts

14 and 21 in the conventional manner.

The circuit breaker 10 is also provided with a manually operable trip mechanism, generally designated by the reference numeral 53. As best seen in FIG. 4, the mechanism 53 includes an elongated member 54 slidably mounted on frame member 55 by means of a pair of shouldered pins 56 carried by the frame member 55 and received in the slots 57 suitably provided in the elongated member 54. Spring 58 interposed between the frame member 55 and the flange portion 54a of elongated member 54 biases the latter in an upward direction such that the button 59 attached to the flange portion 54a by suitable means such as by a screw (not shown) is readily accessible through the opening 60 provided for this purpose in the removable cover portion 12 of the circuit breaker shown in FIG. 1.

To manually trip the circuit breaker 10, the button 59 is depressed thereby causing the elongated member 54 to slide downwardly along the side wall of the frame member 55 such that the integrally formed L-shaped portion 54b of member 54 engages the tripping latch lever 46 of the intermediate latch mechanism 35. The downward movement of latch lever 46 releases the intermediate latch 45 and thereby causes the primary latch 34 to release the cradle 31 whereby the

contacts

14 and 21 are opened. It is thus seen that the manually operable trip mechanism 53 causes the

contacts

14 and 21 to open in a manner similar to that previously described in connection with the automatic tripping of the circuit breaker resulting from the sensing of overload currents by the current sensitive devices housed in the trip unit 15.

Referring now to FIG. 3, a trip alarm assembly, generally designated by the numeral 61, is provided in the circuit breaker 10 as a means of giving a remote indication that the circuit breaker has been tripped automatically by operation of either of the devices housing in the trip unit 15. The trip alarm assembly 61 which is mounted on the frame 55 by means of screws 80 includes a pair of switches A and B secured by screws 62 to the frame member 79. Associated with switch A is an actuating lever 63 which is pivotally mounted on pin 64, the latter being fastened to the frame member 79. Switch B is similarly provided with an actuating lever 65 which is 'pivotally mounted on pin 66 secured to the frame member 79. The operating

members

67 and 68 of the switches A and B, respectively, are normally held depressed which corresponds to the open circuit position of each of these switches by the actuating levers 63 and 65, respectively. Actuating lever 63 is biased downwardly by spring 69 which has one end secured to the lever 63 and the other to the pin 66 whereas actuating lever 65 is biased upwardly by spring 70 which has one end secured to the lever 65 and the other to the pin 64. The trip alarm assembly 61 also includes a relay 71 which is suitably mounted on frame member 79 and which is electrically connected to switches A and B by wires indicated generally by reference numeral 72. The relay 71 is provided with a pair of

contacts

73 and 74, as indicated in FIG. 7, for a purpose to be more fully described hereinafter.

Referring now to FIGS. 2 and 6, when the circuit breaker 10 is tripped automatically by virtue of the operation of the devices housed in the trip unit 15, the cradle 31 after its release by primary latch 34 moves in an upward or clockwise direction about pivot pin 29. In doing so, pin 75 carried by the cradle 31 closely adjacent the roller 32 engages the actuating lever 63 to cause the latter to pivot about pin 64 against the bias of spring 69.

This movement of the actuating lever 63 permits the operating member 67 of switch A to move outwardly thereby closing the electric circuit through switch A. Meanwhile, the trip bar 50 in moving downwardly to engage the tripping latch lever 46 has at the same time engaged the actuating lever 65 causing the latter to pivot about pin 66 against the bias of spring 70 to thereby allow the operating member 68 of switch B to move outwardly whereby switch B is now in a closed circuit position.

Referring to the schematic representation of the electric circuitry of the trip alarm assembly as shown in FIG. 7, with the operating

members

67 and 68 of switches A and B, respectively, being released in the manner previously described, the circuit L L is completed through switches A and B thereby causing the relay 71 to be energized. A conventional power source 69 is connected to the terminals L L and it is this power that is switched by

members

67 and 68 to operate relay 71. When the circuit breaker 10 clears the circuit, the current responsive means housed in the trip unit 15 which initiated the tripping of the breaker will become de-activated with the result that the trip lever 50 of the trip unit 15 will return to its normal position thereby allowing switch B to open since the actuating lever is moved upwardly under the influence of spring 70 to once again depress the operating member 68. To prevent the relay 71 from opening as the trip lever 60 returns to its normal position, the relay 71 is provided with a set of contacts 73 which are electrically connected in parallel with switch B for the purpose of keeping the relay 71 energized even though the switch B has been opened. With the relay 71 energized the contacts 74 are closed completing the signal circuit L L as long as the actuating lever 63 remains engaged by the pin 75 carried by the cradle 31, that is, as long as the cradle 31 remains in the trip position. It is to be understood that the signal circuit L L would be electrically connected in a conventional manner to either a visual or an audible signal indicator shown symbolically by rectangle 74 which is labeled trip alarm means. When the circuit breaker 10 is re-latched, thereby causing the

contacts

14 and 21 to return to their closed circuit position, the cradle pin 75 moves out of engagement with the actuating lever 63 thereby permitting the latter to move downwardly under the influence of spring 69 whereby operating member 67 is depressed causing the circuit through switch A to open. With the circuit through switch A open, the relay 71 is de-energized thereby causing

contacts

73 and 74 to open which stops the signal.

Referring to FIGS. 4 and 5, when the circuit breaker 10 is manually tripped by operation of the manually operable trip mechanism 53 in the manner previously described, the cradle 31 is released by the primary latch 34 and pin 75 calried by the cradle 31 moves into engagement with the actuating lever 63 of switch A, thereby closing the circuit through switch A in the manner set forth hereinabove. The manually operable trip mechanism 53 does not, however, engage the actuatinglever 65 of switch B. Thus, switch B remains in its open circuit position by virtue of the fact that actuating lever 65 continues to depress operating member 68. With switch B in the open circuit position, circuit L L is not completed and relay 71 does not become energized.

Contacts

73 and 74 therefore remain open and the signal circuit L -L will not operate so as to provide either a visual or an audible signal. The trip alarm assembly 61 is thus capable of differentiating between a manual tripping of the circuit breaker 10 and the automatic tripping thereof. The purpose of utilizing two circuits and four leads, i.e., power circuit L -L and signal circuit L L is that this allows the power to be DC current and the signal AC current or vice versa, if desired.

In the preferred embodiment, an indicator 76 bearing the legends OPEN and CLOSED thereon is provided as shown in FIG. 1 for the purpose of indicating whether the

contacts

14 and 21 are in the open or closed circuit position. One or the other of the legends carried by the indicator 76 is at all times visible in the window 77 suitably provided for this purpose in the removable cover portion of the circuit breaker 10.

Also in accordance with the preferred embodiment, after the circuit breaker 10 has been tripped, the

contacts

14 and 21 may be re-closed by operation of the handle 78 and the yoke 79 in the manner described and claimed in the copending application of C. L. Iencks and G. W.

Kiesel, Ser. No. 597,946, filed Nov. 30, 1966, and assigned to the same assignee as the present application. As set forth more fully in the aforesaid application, the

contacts

14 and 21 of the circuit breaker 10 cannot be opened by operation of the handle 78, the latter being operable solely for the purpose of closing the contacts. The

contacts

14 and 21 are opened by operation of either the manually operable trip mechanism 53 or the automatic operation of the devices housed in the trip unit 15. With such a circuit breaker, it is desirable to provide some means whereby it is possible to readily determine whether the circuit breaker 10 has been tripped manually or automatically. The trip alarm assembly 61 in conjunction with the indicator 76 has been provided for the purpose of performing this funtcion. Thus, by virtue of the indicator 76 it is possible to determine whether the

contacts

14 and 21 are open or closed. If the contacts have been opened by automatic operation of the devices housed in the trip unit 15, the visual or audible signal indictaor connected to the signal circuit L -L will indicate this fact.

While the invention has been shown in only one particular embodiment, it will be apparent that many modifications thereof may be made, and we therefore intend by the appended claims to cover all such modifications as fall within the true spirit and scope of the invention.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. An electric circuit breaker comprising:

(a) an insulated casing;

(b) a pair of relatively movable contacts supported in said casing, said contacts being movable between open and closed circuit positions;

() means including a releasable member to cause movement of said contacts to said open circuit position;

(d) latch means supported in said casing, said latch means including a latch member releasably engaging said releasable member;

(e) current responsive trip means mounted in said casing for engagement with said latch member, said current responsive trip means causing release of said releasable member from said latch member upon the occurrence of predetermined current conditions to thereby cause tripping of said circuit breaker and opening of said contacts;

'(f) manually operable means mounted in said casing, operation of said manually operable means causing release of said releasable member from said latch member to thereby cause tripping of said circuit breaker and opening of said contacts;

(g) trip alarm means mounted in said casing for providing indication of tripping of said circuit breaker, said trip alarm means being capable of differentiating between tripping of said circuit breaker caused by operation of said current responsive trip means as distinguished from said manually operable means;

(h) said trip alarm means providing said indication only When said circuit breaker is tripped as a result of operation of said current responsive trip means;

(i) said trip alarm means comprising a first and a second switch each having an open and a closed position, and means electrically connecting said first and second switches in circuit to a signal indicator (c) contact moving means comprising releasable means to cause movement of said contacts to said open circuit position;

(d) said contact moving means further comprising latch means supported in said casing, said latch means releasably engaging said releasable means;

(e) first trip means mounted in said casing for engagement with said latch means, said first trip means causing release of said releasable means from said latch means automatically upon the occurrence of predetermined current conditions to thereby cause tripping of said circuit breaker and opening of said contacts;

(f) second trip means mounted in said casing for engagement with said latch means, said second trip means being manually operable to cause release of said releasable means from said latch means to thereby cause tripping of said circuit breaker and opening of said contacts;

(g) trip alarm means mounted in said casing for providing an external indication when said circuit breaker trips;

(h) said trip alarm means being operatively responsive to said contact moving means and being capable of differentiating between tripping of said circuit breaker caused by operation of said first trip means as distinguished from said second trip means whereby said indication of tripping of said circuit breaker is provided only when said circuit breaker is tripped as a result of the operation of a particular one of said trip means;

(i) a first switch means having an open and closed position, said first switch means being actuated by said releasable means;

(j) a second switch means having an open and a closed position, said second switch means being actuated by 'said particular one of said trip means;

(k) a relay having at least a first set of contacts, said first set of contacts being connectable to a signal indicator; and

(1) means electrically connecting said first and said second switch means and said relay in series whereby when said first and said second switch means are each in said closed position said relay is energized to thereby cause closing of said first set of relay contacts and operation of said signal indicator.

3. An electric circuit breaker as set forth in claim 2 wherein:

(a) said relay further includes a second set of contacts, said second set of contacts also being closed upon energization of said relay; and

(b)a pair of relatively movable contacts supported in trically connecting said second set of relay contacts in parallel with said second switch means whereby said second switch means once closed can move to its open position without interrupting the operation of said signal indicator.

4. An electric circuit breaker comprising:

(a) an insulated casing;

(c) means including a releasable member to cause movement of said contacts to said open circuit position;

(f) manually operable means mounted in said casing, operation of said manually operable means causing release of said releasable member from said latch member to thereby cause tripping of said circuit breaker and opening of said contacts;

(h) said trip alarm means providing said indication only when said circuit breaker is tripped as a result of operation of said current responsive trip means; and

(i) said trip alarm means comprising first means 0perated in response to movement of said current re- 10 sponsive trip means and second means operated in response to movement of said releasable member and means connecting said first and second means to a signal indicator whereby when said first and second means are each in operated condition said signal in- DONALD J. YUSKO, Primary Examiner D. MYER, Assistant Examiner U. S. Cl. X.R. 2005, 153