US3204063A - Thermal current responsive circuit breaker - Google Patents

Description

Aug 31, 1965` w. H. NASH ETAL 3,204,063

THERMAL CURRENT RESPONSIVE CIRCUIT BREAKER Filed Sept. 19, 1962 4 Sheets-Sheet l 7f3 7 /zz 22d/4M 2224/4470 lesa/440 Z a3 Il" IZ, f I;

I ray mvENToRs. m4/.MM H. NASH EEZ/5WD Z//. K/Q/V//VSKY n m f, jai/w( MM @rfa/@Nay Aug. 31, 1965 w. H. NASH ETAL 3,204,063

THERMAL CURRENT RESPONSIVE CIRCUIT BREAKER Filed Sept. 19, 1962 4 Sheets-Sheet 2 INVENTORS. Zl//LL//V/ H. NAF/'f Aug. 31, 1965 w. H. NASH ETAL 3,204,063

THERMAL CURRENT RESPONSIVE CIRCUIT BREAKER 4 Sheets-Sheet 3 Filed Sept. 19, 1962 Aug. 31, 1965 W. H. NASH ETAL THERMAL CURRENT RESPONSIVE CIRCUIT BREAKER Filed Sept. 19, 1962 4 Sheets-Sheet 4 f/Z INVENTORS, Y@ w/L/Aw H, N45# LM LUM United States Patent() 3,204,063 THERMAL CURRENT RESPONSIVE CIRCUIT BREAKER William H. Nash and Edward W. Kaminsky, South Milwaukee, Wis., assignors to McGraw-Edison Company,

Milwaukee, Wis., a corporation of Delaware Filed Sept. 19, 1962, Ser. No. 224,636 8 Claims. (Cl. 200-116) This invention relates to circuit breakers and more particularly to circuit breakers which have particular but not exclusive application to the protection of electrical apparatus such as traansformers.

Distribution class transformers are often provided with circuit breakers which open the secondary circuit upon thev occurrence of a short circuit across the secondary leads or when prolonged overloads heat the transformer to a point Where the secondary circuit must be opened to prevent insulation damage. For this purpose circuit breakers are provided with thermal and overcurrent responsive elements adapted to open the circuit breaker contacts upon the occurrence of such overloads. In addition, such devices may also include a signal light assembly for giving an external indication that the device being protected has been subjected to an overload.

It is an object of the invention to provide a new and improved three pole circuit breaker for use -in three phase transformers and which are responsive both to the temperature of the transformer dielectric fluid and to overload currents in the secondary leads.

Another object of the invention is to provide a three pole circuit breaker having a single operating mechanism and which is operative to interrupt current simultaneously in each phase upon the occurrence of an overload in any one of the phases.

These and other objects and advantages of the instant invention will become apparent from the detailed description thereof taken in view of the accompanying drawings in which:

FIG. l is a front elevational view of the circuit breaker according to the instant invention;

FIG. 2 is an exploded perspective View of the operating mechanism of the circuit breaker shown in FIG. l;

FIG. 3 is a view taken along lines 3-3 of FIG. l except that the circuit breaker contacts are shown in open position;

FIG. 4 shows the circuit breaker operating mechanism in an unlatched position with the main contacts open;

FIG. 5 shows the circuit breaker operating mechanism when it is latched and the main contacts are open;

FIG. 6 shows the circuit breaker operating mechanism when it is latched and the main contacts are closed and is taken along lines 6-6 of FIG. 1;

FIG. 7 is a View taken along lines 7-7 of FIG. l; and

FIG. 8 is a View taken along lines 8 8 of FIG. 7.

Referring now specifically to FIGS. 1 and 2, the invention is shown to comprise a three pole automatic trip free circuit breaker 9 mounted on a suitable base 10. Each pole is identical .and includes a contact assembly 12 and an over-current responsive assembly 14. A common operating and latch assembly 16 holds each of the contact assemblies 12 in closed position and is operable to simultaneously release 'all of said Contact assemblies upon the actuati-on of any one of the overcurrent assemblies 14. Prior to the release of the operating mechanism 16 and the consequent opening of the contact assemblies 12, each of the overcurrent responsive ice assemblies 14 is operable to actuate a signal light mechanism 18 so that an external signal is given to -indicate that the system or device being protected has been subjected to 'an overload.

The base 10 includes a base plate 11 and a pair of panels 19 and 19a extending normally from the plate 11 to support the operating mechanism 16 and the signal light mechanism 18 adjacent one side of said assembly as seen in FIG. l. A third support panel 20 is aixed to the base 10 and disposed adjacent the opposite side and is interconnected with the panels 19 by crosspins 21. The base plate 11, panels 19, 19a and 20 and the crosspins 21 provide a relatively rigid supporting structure for the contact assemblies 12, the overcurrent assemblies 14, and the operating mechanism 16.

A plurality of insulating panels 22 separate the poles 11 from each other and from the support panels 19 and 20. As seen in FIGS. 1 and 3, the insulating panels 22 are substantially co-extensive with the support panels 19 and 20 and are rigidly secured thereto by the crosspins 21. As seen in FIGS. 2 and 3v each phase is also provided with a rst insulating member 23 for supporting its contact assembly 12 and a second insulating member 24 for supporting its overcurrent assembly 14. Crosspins 25 extending through the side panel 20 in each of the insulating panels 22, rigidly afx the insulating members 23 to the base 10 while the insulating members 24 are ailixed thereto by one of the crosspins 21 and a second crosspin 26 extending through the panels 20 and 22.

Each of the contact assemblies 12 is shown in FIGS. 2 and 3 to include a movable contact member 27 and a cooperating fixed contact 28 which is mounted on the insulating member 23. The movable Contact 27 is carried at one end of a contact carrier arm 29 which is pivotally connected at its other end by means of a pin 30 extending through the legs of a Ueshaped bracket member 31 aflixed to the upper end of the insulating member 23.

The overcurrent responsive assemblies 14 each includes a bimetallic element 32 which is affixed at one end to the insulating member 24 and which has an insulating bar 34 longitudinally afxed to its oppoiste ends by means of a rivet 35. An adjustable trip pin 40 is threadably received in the free end of each of the trip members 34 and each engages the upper surface of one of the trip fingers 41 associated with each pole and each of which is carried by a common trip bar 42 pivotally mounted by pins 43 on the support panel 20 and on the right-hand most insulating panel 22 as viewed in FIG. 1. A pair of insulating skirts 44 are disposed on each of the insulating trip members 34 between the trip pin 40 and the rivet 35 so as to increase the leakage path between the current carrying bimetallic element 32 and the metallic trip pin 40 and trip bar 42.

Referring now in particular to FIGS. 2, 4, 5 and 6, the operating and latch assembly 16 is shown to include a generally U-shaped operating member 50 having a transverse operating rod 51 extending between its legs 52 and 53 and through guide slots 51a in the panels 19 and 19a. Legs 52 and 53 are pivotally mounted at their ends at 54 on the support panels 19, 19a.

A latching mechanism 55 is disposed between the support panels 19, 19a and includes a latch arm 57 which carries a latch tip 58 at one end and which is pivoted at its other end on a lixed axis by means of a transverse pin 60 extending between the support panels 19, 19a.

An operating shaft 45 is pivotally mounted at its opposite ends between the support panels 19a and 2G and has three U-shaped crank members 46 affixed thereto. Each of the crank members 46 is adjacent one of the poles and the free ends thereof are each pinned to an insulating link 47 at 48. The other end of each insulating link 47 is pivotally connected to its contact arm 29 at 49 so that clockwise rotation of operating shaft 45 as viewed in FIG. 3, will simultaneously rotate each of the contact arms 29 counterclockwise and thereby force the movable contacts 27 into engagement with the fixed contacts 28.

The latch arm 57 is coupled at a point intermediate its ends to the operating shaft 4S by an overcenter assembly 61 having a rst toggle link 62 which is pivotally connected at 63 to the mid point of latch arm 57 and a second toggle link 65 pivotally connected at 66 between the arms of a U-shaped crank element 67 affixed to the operating shaft 45. The other ends of the toggle links 62 and 65 are pivotally connected together by a knee pin 68. The overcenter assembly also includes a pair of parallel overcenter springs 70 which are connected at one end to the knee pin 68 and at their other ends to the transverse operating rod 51.

The latching mechanism S also includes a latch shaft 72 pivotally mounted between the support panels 19, 19a and having a half moon latch recess 74 intermediate its ends. A reset arm 75 is aiixed to the shaft 72 and both are urged toward counterclockwise rotation by a seer spring 76 which engages the arm 75 at one end and is anchored to the support panel 19 at its other. A pin 78 extends transversely from the free end of the resetting arm 75 and engages the upper edge of a latch member 80 which is pivotally mounted at 81 on an adjusting lever 83 which, in turn, is pivotally mounted intermediate its ends by a pin 84 extending between the support panels 19, 19a. i

The latch member 80 has a generally inverted U-shaped configuration with one leg 86 depending from its pivoted end and comprising a latch finger for engaging the upwardly extending latch lip 87 of a latch plate 88 which is affixed to a pivot pin 89 extending between the support panels 19, 19a. A reset pin 91 extends transversely from the other leg of the latch member 80 for cooperative engagement with a reset linger 92 integral with the operating member 50 and extending generally upwardly therefrom.

As seen in FIGS. l and 2, a crank 94 integral with the pivot pin 89, extends through support panel 19 and is disposed adjacent a trip pin 95 extending laterally from the trip bar 42.

Operation of the latching mechanism will now be discussed in relation to FIGS. 2, 4, 5, and 6. As shown in FIG. 2, the operating member 5t) is adapted to be rotated by pivotal movement of an operating handle (not shown) disposed on the exterior of the apparatus being protected. A connecting rod 97 and a link 98, which threadably receives one end of the rod 97, connect the external operating handle (not shown) to the operating member 50. Pivotal movement of the operating member 50, in order to latch the mechanism 55 and to close and to reopen the contact assemblies 12, is accomplished by moving the operating rod 97 in a generally upward and downward direction as viewed in FIG. 2.

Referring now to FIG. 4 which shows the operating mechanism 16 in its unlatched position with the contact assemblies 12 open, it can be seen that the transverse rod 51 engages the lower edge of the latch arm 57. In order to operate the mechanism 16 to the latched position shown in FIG. 5, operating member 5l) is pivoted clockwise whereby transverse pin 51 forces counterclockwise rotation of the latch arm 57. In addition, counterclockwise pivotal movement of operating member 50 will bring the integral reset inger 92 into engagement with the transverse pin 91 on the latch member 80 thereby rotating the latter clockwise about pin 81, and against the action of a spring 100 which is anchored to the panel member 19.

As operating member 50 continues to rotate counterthemselves.

clockwise, the clockwise rotation of latch 99 will continue as the pin 91 rides on the curved surface 181 of the reset nger 92 until the latch finger 86 on member 80 moves past the latch lip 87 of the latch plate 88. After the latch finger 80 has moved free of the latch lip 87, as shown in FIG. 5, a spring 102, extending between an eyelet 184 in the upper surface of the latch plate 88 and the panel member 19, rotates the latch plate 88 through a slight clockwise angle until the lip 87 is disposed in the path of the latch finger 86 whereupon further rotation of latch plate 88 is prevented by the engagement of the trip pin 95 by the crank 94, see FIG. 2.

As stated hereinabove, counterclockwise rotation of operating member 50 also pivots the latch finger 57 connterclockwise to move its latch tip 58 toward the half moon latch 74. Simultaneous with this action, the rotation of the latch member 80 by the reset finger 92 allows counterclockwise rotation of the shaft 72 by the seer spring 76 as the pin 7 8 on the arm 75 follows the movement of member 80. The half moon latch 74 is therefore in its position shown in FIG. S as the latch tip 58 approaches. Engagement of the latch tip 58 with the fiat portion of the half moon latch 74, will rotate the shaft 72 through a slight clockwise angle until the latch tip 58 has moved past, whereupon shaft 72 will return to its position shown in FIG. 5 by the -spring 76 to latch the arm 57 in its position shown in FIG. 5.

It can be seen that as the latch arm 57 was moved from its position shown in FIG. 4 to its position shown in FIG. 5, the toggle link 62 moves the knee pin upward and to the left as viewed in FIG. 4 until it assumed the position shown in FIG. 5. Because the position of the knee pin 68 in FIG. 5 is not at the center of curvature of the guide slots 51a, the end of the overcenter spring 70 attached to pin 51 will be rotated through an arc whose radius is longer than the relaxed length of the springs As a result the springs 7th Will be extended so that energy will be available to rapidly close the contacts 12 and to separate them rapidly upon tripping.

When the operating mechanism 16 is in its latched position shown in FIG. 5, the Contact assemblies 12 may be closed by rotating the operating member 5t) clockwise to its position shown in FIG. 6. As the operating member 50 pivots, the ends of the overcenter springs 70 that engage the transverse pin 51 are moved downwardly as Viewed in FIG. 5 while the other ends thereof momentarily rernain stationary. When the line of action of the springs 70 passes the pivot point 63 of toggle link 62 as the operating member 50 moves clockwise, the toggle assembly will become overcentered causing knee pin 68 to snap from its position shown in FIG. 5 to its position shown in FIG. 6. This brings the link into toggle with the link 62 to snap the crank 67 and the operating shaft 4S clockwise. It can be seen with reference to FIG. 3 that clockwise rotation of the crank shaft 45 will move the contact arms 29 counterclockwise and the movable contacts 27 into engagement with stationary contacts 28. It will be appreciated also that because of the downward movement of the knee pin 68 during the closing of the contact assembly 12, the overcenter springs are somewhat shortened so that a portion of their .stored energy is utilized in the closing of the contact assembly 12.

The operating sequence during manual opening of the main contacts is substantially opposite to that of the closmg operation just explained. Here the operating member 50 is rotated counterclockwise from its position shown in FIG. 6 to its position shown in FIG. 5. When the line of action of the overcenter springs 70 pass the pivot point 63, the toggle will be broken and pin 68 will snap upwardly from its position shown in FIG. 6 to its position shown in FIG. 5. This rotates the operating shaft. 45 counterclockwise to open the Contact assemblies 12.. Latch arm 57 and latch member 80 will, however, remainl latched as shown in FIG. 5.

Referring now specifically to FIGS. 2 and 3,.,t`he elec trical current path through each pole of the device when the contact assemblies 12 are closed, is from a first conductive terminal member 106 affixed to the insulating member 23 and electrically connected to the stationary contact 28; through the lixed and movable contacts 28 and 27 respectively; through a iiexible conductive member 107 attached at one end to the movable contact 27 and at its other end to a rigid conductive member 109 which is held in electrical engagement with the bimetallic element 32 by the rivet 35; through the bimetallic element 32; and out a second terminal 110 in electrical engagement with the bimetallic element 32 and mounted on insulating member 24. If the device is used to protect an oil-immersed transformer, the base is normally mounted below the oil level by means of bracket members (not shown). As a result, the bimetallic element 32 in each pole is subjected to heating as a result of the flow of load current therethrough and due to the temperature of the ambient oil. Should the 12R lost due to a high magnitude overcurrent heat any of the bimetallic elements or should the elements be heated by a low magnitude overcurrent in the transformer windings which heats the surrounding oil, or should a combination of both cause downward deflection of the left end of any of the bimetallic elements 32, as viewed in FIGS. 2 and 3, the consequent downward movement of the trip pin 40 will rotate the trip bar 42 clockwise. As a result, the trip pin 95 will move downwardly to rotate the latch plate 88 counterclockwise through the agency of the crank 94. If such rotation of latch plate 88 be sufficient to move the latch lip 87 out of latching engagement with the latch finger 86, latch member 80 will be free to rotate counterclockwise under the influence of spring 100 from its position shown in FIG. 6 to its position shown in FIG. 4. As a result of the engagement between the upper edge of latch member 80 and the transverse pin 78 on the arm 75, the latch shaft 72 and the half moon latch 74 will rotate clockwise as the spring 100 overcomes the seer spring 76. The latter action releases the latch arm 57 for rapid clockwise movement as the overcenter springs 70 contract. This moves the knee pin 68 from its position shown in FIG. 6 to its position shown in FIG. 4 to thereby break the toggle linkage 62, 65. The operating shaft 45 is thereby rotated counterclockwise to simultaneously open the contact assemblies 12 and interrupt the circuit through each. The energy of the latch arm 57 impacting the transverse rod 51 is taken by a shock absorbing spring 112 mounted below rod 51 and aixed to the frame 10.

The amount of downward deflection of the bimetallic elements 32 and hence, the magnitude of the overcurrent necessary to trip the device may be adjusted by varying the amount of overlap between the latch iinger 86 and the latch lip 87 through the agency of the adjusting link 83 or the adjustable trip pins 40. Rotation of the trip pins 40 allows the amount of deflection required of each bimetallic element 32 to trip the device to be individually adjusted. For simultaneous adjustment of all the phases an adjusting screw 113 extending through panel member. 19 and engaging the link 83 produces rotation of said link about pivot 84 so as to move the latch linger 86 upwardly and downwardly relative to the latch lip 87.

The signal light assembly 18, shown in FIGS. 1, 2 and 7, is provided to give an external indication that the device being protected has been overloaded and includes a movable Contact latch member 115, and a stationary contact member 116 and is normally adapted to be tripped upon the occurrence of an overload current less than that necessary to cause tripping of the circuit breaker itself. Suitable insulation 117 electrically insulates the stationary contact member 116 from the metallic panel member 19a. Movable contact latch member 115 is rotably mounted at 118 on an L-shaped adjusting bar 120 and includes a latch tip 121 adapted to engage the latch lip 87 of the latch plate 88. Adjusting bar 120 is slidably mounted on the panel 19a by means of a slot 126 formed in said panel and which receives the pivot pin 118. Upward and downward movement of the pivot pin 118, in order to vary the overlap between latch tip 121 and latch lip 87, is accomplished by means of an adjusting screw 122 which engages the adjusting bar and the panel 19a.

When any of the bimetallic elements 432 are heated to the point where latch plate 88 is sutiiciently rotated to release the latch tip 121, the contact member 115 will be rotated clockwise as viewed in FIG. 7, under the influence of a seer spring 123, until a contact ear 124 engages the stationary contact 116 thereby grounding stationary contact 116 to the frame to complete the circuit through a current transformer 125, inductively coupled to one of the leads of the protected device, and a signal light 127, whereby the latter is energized.

The signal light assembly 18 is also provided with a resetting crank 128 pivotally mounted at 129 on panel 19a. A leaf spring 130 is affixed to the lower end of the reset crank 128 and its free end is disposed below the transverse rod 51. It can be seen in FIG. 7 that counterclockwise rotation of operating member 50 will rotate the reset crank 128 counterclockwise from its full position to its phantom position whereupon a transverse pin 132 will engage a reset ear on the movable contact latch member 115 to rotate the latter counterclockwise to its phantom position whereupon latch tip 121 will re-engage the latch lip 87.

The signal light assembly will normally be set to trip upon the occurrence of a smaller overload current and that necessary to trip the circuit breaker itself. This is accomplished by providing a .smaller overlap between the latch tip 121 and the latch lip 87, then between the latch finger 86 and said latch lip. In operation, therefore, a predetermined overload current in one of the poles will rotate the latch bar 88 sufficiently to trip the signal light assembly, thereby energizing the signal light 127 while the main contacts remain closed. Should the overload current thereafter increase a suflicient amount, the main contacts will then be tripped open.

Because the signal light assembly 18 is tripped by an overload current which is insufficient to trip the circuit breaker itself, assembly 18 should be reset without tripping the circuit breakers main contacts. This is accomplished by counterclockwise rotation of operating member 50 is viewed in FIG. 7 in a manner described above. It can be seen that in the resetting of the signal light assembly 18 operating member 50 is moved in the opposite direction from that during the manual tripping operation, previously described, so that resetting of the signal light assembly cannot cause accidental tripping of the device. In the event that the signal light assembly has been tripped by an overload current which is also suiiicient to trip the circuit breaker itself, the signal light assembly will be reset when the main contact assemblies 12 are closed by the action of the operating member 50 in moving the latching mechanism 55 from the position shown in FIG. 5 to its `position shown in FIG. 6.

The signal light resetting crank 128 performs the additional function of testing the signal light without tripping the latch tip 121 or the main contacts 12. In order t0 determine whether the signal light 127 is operable, the operating member 50 is rotated counterclockwise in FIG. 7 to rotate the reset crank 128 counterclockwise until the pin 132 engages the reset arm 133. Further, rotation of the operating member 50 will cause rotation of the contact member 115 in opposition to the spring 123 until a second contact iinger 135 is moved into engagement with the stationary contact 116 to co-mplete the circuit through the signal light 127, and if operating it will light. It will be appreciated that the latter operation is accomplished without tripping the signal light latch 121 and without moving the operating member 50 in a direction which would result in opening of the main contacts 32.

While only a single embodiment of the invention is shown and described, it is intended to cover in the 7 appended claims all modifications which fall within the true scope and spirit thereof.

We claim:

1. A three pole circuit breaker including a base, each pole including a bimetallic element and fixed and movable contact means, a single latching assembly common to all of said poles, said latching assembly including first and second independent pivotal latching members and first and second independent pivotal holding members for respectively maintaining said first and second latching members in a latch position, spring means resiliently urging said second latching member into engagement with said first holding member for resiliently urging said first holdingl member toward pivotal movement in a latch releasing direction when said second latch member is released from its latched position and allowing said first holding member to return to its holding position when said second latch member is in its latched position, an overcenter assembly coupled to said first latching member and to each of said movable contacts for simultaneously moving said contacts between open and closed positions, an operating member movable from a first position to a second position to latch each of said latching members on its associated holding member, movement of said operating member from its second position to said first position placing said overcenter means in a rigid condition to close said movable contacts, a common trip bar coupled to said second holding member and rotatably mounted on said base, said trip bar having a trip finger adjacent each of said bimetallic elements so that the deflection of any of said elements as a result of an overiload current through its pole will rotate said trip bar and said second holding member to release said second latching member for rotation by said spring means to pivot said first holding member out of latching engagement with said iirst latching member and to release said overcenter means for the simultaneous opening of each of .said movable contacts.

2. A three pole circuit breaker including, a base, each pole including a bimetallic element fiXedly mounted adjacent one end on said base and a fixed and movable contact, a single latching assembly common to all of said poles, said latching assembly including first and second independent pivotal latch members and first and second independent pivotal holding members for respectively maintaining said first and second latch members in a latched position, said first holding member and said second latch member being elongate and pivotally mounted adjacent one end, first spring means resiliently urging said second latch member away from its holding element, second spring means resiliently urging the other end of said first holding member into engagement with the other end of said second latch member the spring force of said first spring means being substantially larger than that of said second spring means so that said first holding member is pivoted in a latch releasing direction When said second latch member is out of its latched position and allowed to return to its latching position when said second latch member is in its latched position, an overcenter assembly coupled to said first latch member and to each of said movable contacts, an operating member movable in a first direction to engage each of said latch members for movement toward their associated holding members, movement of said operating member in a second direction after said latch members are in a latched position placing said overcenter assembly in a rigid condition to simultaneously close each of said movable contacts, a common trip bar engageable with said second holding member and rotatably mounted on said base, said trip bar having a trip means adjacent each of said bimetallic elements so that the defiection of any of said elements as a result of an overload current through its pole will rotate said trip bar and said second holding member to release said second latch member and pivot said first holding member out of latching engagement with said first latch member and to release said overcenter means for the simultaneous opening of each of said movable contacts.

3. A three pole circiut breaker including, a base, each pole including a bimetallic element fixedly mounted adjacent one end of said base and a fixed and movable contact, each of said movable contacts being mounted on a contact carrier pivotally mounted on said base, a single latching assembly common to all of said poles, said latching assembly including first and second independent pivotal latching members and first and second independent pivotal holding members for maintaining said first and second latching members in a latched position, said first holding member and said second latching member being elongate and pivotally mounted adjacent one end, the other end of said second latching member engaging the other end of said first holding member, spring means resiliently urging said second latching member toward pivotal movement against said first holding member to pivot the latter in a latch releasing direction when said second latching member is out of its latched position, said first holding member being biased for return to its holding position when said second latching member is in its latched position, an operating shaft rotatably mounted on said base and coupled Vto said contact carriers for simultaneously moving said movable contacts between open and closed positions, an overcenter assembly coupled to said first latching member and to said operating shaft, an operating member movable from a first position to a second position to latch Ieach of said latching members on its associated holding members, movement of said operating member from its second position to said first position placing said overcenter means in a rigid condition torotate said operating shaft into a switch closed position, a common trip bar coupled to said second holding member and rotatably mounted on said base, said trip bar having a trip means adjacent each of said bimetallic elements so that the deiiection of any of said elements as a result of an overload current through its pole will rotate said trip bar and said second holding member to release said second latching member and pivot said first holding member out of latching engagement with said first latching member and to release said overcenter means for the simultaneous opening of each of said movable contacts.

4. A three pole circuit breaker comprising, a base, each pole including a bimetallic element and a main fixed and a main movable Contact, a collapsible linkage assembly for opening said main movable contacts, a latching assembly for holding said main movable contact closed, an operating member movable in a first direction to place latching assembly in a latched condition, subsequent movement of said operating member in an opposite direction placing said linkage assembly in a rigid condition to close said main movable contacts, trip bar means coupled to said latching assembly and rotatably mounted on said base, said trip means being engageable by each of said bimetallic elements so that the deflection of any of said elements as a result of an overload current through its pole will rotate said trip bar means to trip said latching assembly and release said linkage assembly for the simultaneous opening of each of said main movable contacts, a signal light assembly including a signal light and a first contact member rotatably mounted on said frame and a second contact member iixedly mounted on frame, said first contact member having a latch portion and a pair of contact portions engageable with said second contact member upon rotation in either direction, spring means resiliently urging one of said contact portions into engagement with said stationary contact, said latch portion being engageable with said latching assembly to normally prevent rotation of said first contact member, deflection of any one of said bimetallic elements unlatcliing said first contact member for rotation of one of said contact portions into engagement with said second contact member to complete an energizing circuit through said signal light, relatching means engageable by said operating member upon movement of the later in said opposite direction after said movable contact has been closed being operative to relatch said first contact member, movement of said operating member in said opposite direction after said first contact member has been latched being operative to move said other contact portion into engagement with said second contact member to test said signal light without tripping said main movable contacts.

5. A three pole circuit breaker comprising, a base, each pole including a bimetallic element and a main fixed and a main movable contact, a single latching assembly common to all of said poles, said latching assembly including a pivotal latch member and a pivotal holding member for maintaining said latch member in a latched position, an overcenter assembly coupled to said latch member and to each of said main movable contacts for simultaneously moving said contacts between open and closed positions, an operating member movable in a first direction to move said latch member into latching engagement with said holding member, subsequent movement of said operating member in an opposite direction placing said overcenter means in a rigid condition to close said main movable contacts, a common trip bar coupled to said holding member and rotatably mounted on said base, said trip bar having a trip portion adjacent each of said bimetallic elements so that the deflection of any of said elements as a result of an overload current through its pole will rotate said trip bar to trip said latching assembly and release said overcenter means for the simultaneous opening of each of said movable contacts, a signal light assembly including a signal light and a first contact member rotatably mounted on said frame and a second contact member fixedly mounted on said frame, said first contact member having a pair of circumferentially spaced apart contact fingers straddling said second contact member and a latch finger, spring means resiliently urging one of said Contact fingers toward rotation into engagement with said stationary contact, said latch finger engageable with said holding member to normally prevent engagement of said one contact finger and said stationary contact, deflection of any one of said bimetallic elements unlatching said first contact member to complete an energizing circuit through said signal light, relatching means engageable by said operating member upon movement of the latter in said opposite direction after said movable contact has been closed being operative to relatch said first contact member, movement of said operating member in said opposite direction after said first contact member has been latched being operative to move said second contact finger into engagement with said second contact member to test said signal light without tripping `said main movable contacts.

6. A three-pole circuit breaker, each pole including overcurrent responsive means and fixed and movable contact means, a single latching assembly common to all of said poles, said latching assembly including first and second independent pivotal latching members, first and second independent pivotal holding members for respectively maintaining said first and second latching members in a latched position, biasing means resiliently urging said second latching member into resilient engagement with said first holding member for resiliently urging said first holding member toward pivotal movement in a latch releasing direction when said second latch member is released from its latched position and allowing said first holding member to return to its holding position when said second latching member is in its latched position, an overcenter assembly coupled to said first latching member and to each of said movable contacts for simultaneously moving said contacts between open and closed positions, an operating member movable from a first position to a second position to latch each of said latching members on its associated holding member, movement of said operating member from said second position to its first position placing said overcenter means in a rigid condition to close said movable contacts, common trip means coupled to said second holding member and to each of said overcurrent responsive means so that the occurrence of an overload current through any of said poles will pivot said second holding member to release said second latching member for rotation by said biasing means to rotate said first holding member out of latching engagement with said first latching member whereby said overcenter means is released for simultaneous opening of said movable contacts.

7. A three-pole circuit break-er, each pole including overcurrent responsive means and fixed and movable contact means, a single latching assembly common to all of said pol-es, said latching assembly including first and second independent pivotal latching members, first and second independent pivotal holding members for respectively maintaining said first and second latching members in a latched position, said first holding member and said first latching mem-ber being elongate and pivotally mounted adjacent one end, 'biasing means resiliently urging the other end of said second latching member .into resilient engagement with the other end of said first 'holding member for resiliently urging said first holding member toward pivotal movement in a latch releasing direction when Isaid second latch member is rel-eased from its latched position and allowing said first holding member to return to its holding position when said second latching member is in its latched position, a collapsible overcenter assembly coupled to said first latching member and to each of said movable contacts for simultaneously moving said contacts between open and closed positions, an operating member movable from a first position to a second position to latch each of said latching members in its associated holding member, movement of said operating members from said second position to its first position placing said overcenter means in a rigid condition to close said movable contacts, common trip means coupled to said second holding member and to each of said overcurrent responsive means so that the occurrence 1of an overload current through any of said poles will pivot said second holding member to release said second latching member for rotation by said biasing means to rotate said first holding member out of latching engagement with said first latching member whereby said overcenter means is released for simultaneous opening of said movable contacts.

8. A circuit breaker comprising main fixed and main movable contact means and overcurrent responsive means in circuit with said main contact means, a collapsible linkage assembly coupled to said main movable contact means, a latching assembly for holding said collapsible linkage means in `a rigid condition so that said main movable contact means is closed, an operating member movable in a first direction t-o place said latching assembly in a latched condition, subsequent movement of said operating member in an opposite direction placing said linkage assembly in a rigid condition to close said main movable contact means, overcurrent responsive means, trip means coupled to said latching assembly and to said overcurrent responsive means, said over-current responsive means -operable upon th-e occurrence of an overcurrent to operate said trip means for releasing said latching assembly so that said main contact means is opened, a signal light assembly including a signal light and a rotatable auxiliary contact member and a fixed c-ontact member, said auxiliary contact member having a lat-ch portion and a pair of contact portions engageabl-e with said fixed contact member upon rotation in either direction, spring means resiliently urging one of said contact portions into engagement with said station-ary contact, said latch portion being engageable with said latching assembly to normally prevent rotation of said auxiliary contact member, operation of said overcurrent responsive means 'being -operable to unlatch said auxiliary contact member for rotation of said one contact portion into er1- References Cited bythe Examiner UNITED STATES PATENTS Dorfman 200-116 S-andin 200-116 Runke 20G-116 Bennett 200-109 Case 20D-116 Cellerini et al 20G-88 Walker et al 200-88 Steven et al. 20G-88 BERNARD A. GILHEANY, Primary Examiner.

Claims (1)

1. 6. A THREE-POLE CIRCUIT BREAKER, EACH POLE INCLUDING OVERCURRENT RESPONSIVE MEANS AND FIXED AND MOVABLE CONTACT MEANS, A SINGLE LATCHING ASSEMBLY COMMON TO ALL OF SAID POLES, SAID LATCHING ASSEMBLY INCLUDING FIRST AND SECOND INDEPENDENT PIVOTAL LATCHING MEMBERS, FIRST AND SECONG INDEPENDENTLY PIVOTAL HOLDING MEMBERS FOR RESPECTIVELY MAINTAINING SAID FIRST AND SECOND LATCHING MEMBERS IN A LATCHED POSITION, BIASING MEANS RESILIENTLY URGING SAID SECOND LATCHING MEMBER INTO RESILIENT ENGAGEMENT WITH SAID FIRST HOLDING MEMBER FOR RESILIENTLY URGING SAID FIRST HOLDING MEMBER TOWARD PIVOTAL MOVEMENT IN A LATCH RELEASING DIRECTION WHEN SAID SECOND LATCH MEMBER IS RELEASED FROM ITS LATCHED POSITION AND ALLOWING SAID FIRST HOLDING MEMBER TO RETURN TO ITS HOLDING POSITION WHEN SAID SECOND LATCHING MEMBER IS IN ITS LATCHED POSITION, AN OVERCENTER ASSEMBLY COUPLED TO SAID FIRST LATCHING MEMBER AND TO EACH OF SAID MOVABLE CONTACTS FOR SIMULTANEOUSLY MOVING SAID CONTACTS BETWEEN OPEN AND CLOSED POSITIONS, AN OPERATING MEMBER MOVABLE FROM A FIRST POSITON TO A SECOND POSITION TO LATCH EACH OF SAID LATCHING MEMBERS ON ITS ASSOCIATED HOLDING MEMBER, MOVEMENT OF SAID OPERATING MEMBER FROM SAID SECOND POSITION TO ITS FIRST POSITION PLACING SAID OVERCENTER MEANS IN A RIGID CONDITION TO CLOSE SAID MOVABLE CONTACTS, COMMON TRIP MEANS COUPLED TO SAID SECOND HOLDING MEMBER AND TO EACH OF SAID OVERCURRENT RESPONSIVE MEANS SO THAT THE OCCURRENCE OF AN OVERLOAD CURRENT THROUGH ANY OF SAID POLES WILL PIVOT SAID SECOND HOLDING MEMBER TO RELEASE SAID SECOND LATCHING MEMBER FOR ROTATION BY SAID BIASING MEANS TO ROTATE SAID FIRST HOLDING MEMBER OUT OF LATCHING ENGAGEMENT WITH SAID FIRST LATCHING MEMBER WHEREBY SAID OVERCENTER MEANS IS RELEASED FOR SIMULTANEOUS OPENING OF SAID MOVABLE CONTACTS.

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