US2318085A - Circuit breaker - Google Patents

Description

May 4, 1943- M. G. LEONARD 2,318,085

CIRCUIT BREAKER Filed Sept. 19, 1940 Y 3 Sheets-Sheet l May 4, 1943, M. G. LEoNARD CIRCUIT BREAKER Filed Sept. 19, 1940 5 Sheets-Sheet 2 INVENTOR /Verr/V/ 6 e0/fara."

BY q (\TTORN% WITNESSES: l

May 4, 1943. M. G. I EoNARD 2,318,085

C IRCUI T BREAKER Patented May 4, 1943 CIRCUIT naman Merrill G. Leonard, Sharon, Pa., .assigner to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application September 19, 1940, Serial No. 357,391

(Cl. V200-116) 12 lClaims.

The invention relates to circuit interrupters and more particularly to multipole circuit breakers of the type which are manually operable andalso automatically operable in response to predetermined abnormal conditions.

The present invention in certain respects constitutes a further development and improvement of the circuit breaker disclosed in my copendingy application Serial No. 163,202, illed September 10. 1937, assigned to the assignee of this invention, and now Patent No. 2,227,506, issued January 7, 1941.

An object of the present invention is the provision of an improved multipole circuit breaker that is simple, compact, and inexpensive to manufacture.

Another object of the invention is the provision of a multipole circuit breaker embodying an individual actuating mechanism and trip means for the contacts of each pole, with means which utilize the energy released during or after tripping of any one poleto automatically trip the other poles.

Another object ofthe invention is the provision oi' an improved multipole circuit breaker having an individual actuating means and trip means for the contacts of each pole, and a novel interlocking means operable when any pole of the breaker trips to automatically effect tripping of the other poles. 4

Another object of the invention is the provision of a multipole circuit breaker having an individual actuating means and trip means for the contacts of each pole, and an interlock which utilizes the kinetic energy oi' the moving contact arm of whichever pole is tripped at the end of its opening motion to automatically trip theother pole or poles.

Another object of the invention is the provision of an improved multipole circuit breaker mechanism in which the opening movement oi the contact arm of any pole upon tripping there- 'of is utilized to move-the electroresponsive trip element of the other pole to automaticallytrip the other pole.

Another object of'the'invention is the provision of a circuit breaker with a novel self-aligning 'contact means of simplefand inexpensive construction.

The novel features that are considered chal'-l acterlstic of the invention are set forth in particular in the appended claims. The invention itself, however, both as to construction and opthe parts being shown in the closed circuit position;

Fig. 3 is a fragmentary perspective view of the circuit breaker mechanism:

Fig. 4 is an enlarged view, partly in section, of the contact means and switch arm of the breaker; and v Fig. 5 is a sectional view similar to Fig. 1 showing the position of the parts when one pole of the breaker has been tripped.

Referring to the drawings, the circuit breaker illustrated isof the two-pole type and includes a housing 9 of molded insulating material which serves to support and enclose the various parts of the circuit breaker mechanism. The housing is divided into two compartments by a longitudinal partition formed integral with the housing to provide chambers for the mechanisms of the two poles of the breaker. The two poles of the circuit breaker are substantially identical in construction, and hence a detailed description of only one pole will be given, since it is believed that it will be suillcient for a clear understanding of the invention.

Each pole of the circuit breaker comprises in general a stationary contact Il, a cooperating movable contact i3 carried by a movable switch arm'i5, actuating means indicated generally at I1 for moving the switch arm to open and closed circuit position. and a trip device indicated generally at. I9 which is operable in response to predetermined current conditions vin the circuit of its pole to cause the actuating means to automatically open the contacts.

I'he stationary contact il is secured tothe inner angularly'bent end oi' a terminal conducting strip 2i, which is secured to the end wall of the housing by suitable rivet fastening means 23. The opposite end of the terminal conducting strip 2l is angularly bent, andextends outside of the housingl 9 for connecting the breaker tc an external electrical circuit.

The movable contact i3 is carried by the switch arm i5 which is generally U-shaped, as best shown in Fig. 3. The switch arm l5 is stamped "from sheet metal, and is bent to provide a pair of parallel legs 25 (Fig. 3) and -a bight portion 2l. The movable contact i3 is mounted on a projection 23 which is formed integral with the switch arm i5. The bight portion 2l of the switch arm I5 is provided with an extension 3l which has a'par of lugs 33 extending -laterally from the sides/thereof and formed integral therewith for a purpose which will be hereinafter described.

The actuating means for the movable contact I3 comprises in general a pivoted releasable member 35 to which the switch arm i5 is pivoted, a

Fig. 2 is a front elevational view oi' the circuit movable operating member 31, and an overcenter sprirg 39 connecting the operating member and the bight portion 21 of the switch arm I5.

'Ihe pivoted releasable member 35 is stamped from sheet metal plate and formed to provide a pair of spaced parallel legs 4I (Fig. 3) which are joined by a 'bridge portion 45 at the inner end. The releasable member 35 is pivotally supported by means of a pivot pin 41, the ends of which are removably engaged in suitable bearing recesses 49 (Fig. 1) formed in the insulating material of the housing. The switch arm I5 is nested within the legs 4I of the releasable member 35, and is pivoted to the releasable member by a pair of vshort pivot pins 53. It will thus be seen that the releasable member 35 and the switch arm I5 connected thereto are removably mounted in the housing 9, and these elements are adapted'to be retained in mounted position by means of the overcenter spring 39.

`|The operating member 31 is also stamped from sheet metal plate and formed to provide a pair of outstanding legs 55 (Fig. 2) which are provided with openings for engaging a common operating member which will be hereinafter described. The operating member 31 is provided the releasable member 35 to its latched position when the operating member is manually moved upwardly beyond its normal open position following a tripping operation.

The trip device I9 comprises a U-shaped bimetallic trip element 69 which has its bight portion 1I (Fig. 3) secured to a pivoted adjusting arm 13 by means of a plurality of rivets 15. The lower ends of the legs of the trip element 69 have an insulating block 11 secured thereto by pivotally mounted in the housing 9, and it will at each end with a pair of lateral projections 59 (Fig. 2) which are adapted to slide on spaced parallel arcuate surfaces 6| formed on the molded housing. Suitable ribs 62 (Fig. 2) are provided on the housing adjacent the arcuate guide surfaces 6| for guiding the operating member 31 land preventing lateral displacement thereof.

The operating member 31 and the bight portion 21 of the switch arm l5 are perforated to receive the hook ends of the overcenter spring 39. The overcenter spring 39 is held in tension between the switch arm I5 and the operating member 31, and thus serves to maintain the pivoted releasable member 35 and the operating member 31 in mounted position in the molded housing.

'I'he spring 39 is disposed between the legs of the switch arm l5 and the legs of the pivoted releasable member 35, and in the closed circuit position of the breaker the line of action of the spring 39 is so disposed relative to the pivot axis 41 of the releasable member 35 that it tends to bias the releasable member in an upward or clockwise direction about the pivot axis 41. The releasable member 35 is normally held in the latched position shown in Fig. 1 by means of the current-responsive trip device I9, the bridging portion 45 of the releasable member 35 being provided with a latch projection 63 which normally engages a latch 65 carried by the trip device.

The downward' movement of the operating member 31 is limited by a pair of stops 66 (Fig. 2) adjacent the arcuate surfaces 6I. The stops 66 are adapted to be engaged by the upper lateral projections 59 of the operating member 31 in the closed circuit position of the operating member, as shown in Fig. 2. Upward movement of the operating member 31 is limited by the engagement of the lower lateral projections 59 of the operating member with a pair of projections 61 formed on the legs 4| of the pivoted releasable member 35. The projections 61 extend through the opening in the housing between the sides of the operating member 31 and the arcuate surfaces 6| as best shown in Fig. 2.

The projections 61 of the releasable member 35 and the lower lateral projections 59 of the operating member 31 form a means for resetting be seen that rotative movement of the adjusting arm 13 about the pivot 85 will change the position of the latch 65 with respect to the latch projection 63 of the pivoted releasable member 35.

The right-hand end of the adjusting arm 13 is notched to receive an adjusting screw 89 which passes through a transverse partition wall 9| formed in the housing 9. 'Ifhe screw 89 is held in mounted position on the partition wall 9| by means of a nut 93. A tubular adjusting nut 95 is threaded on the end of the screw 89, and this nut engages the notched end of the adjusting arm 13. The tubular nut 95 is provided with a knurled portion 91 which extends through an opening 96 provided therefor in the upper end wall 99 of the housing to provide for manual adjustment of the nut 95.

A coil compression spring |03 encircles the screw 89 and engages the notched end of the. adjusting arm 13 at one end and the transverse partition wall 9| at its other end. The spring |03 serves to maintain the notched end of the adjusting arm 13 in engagement with the tubular adjusting nut 95.

From the foregoing description of the trip device, it will be apparent that when the nut 95 is screwed down it will move the adjusting arm 13 and bimetal trip element 69 in a clockwise direction about the pivot 85, and thereby decrease the amount of overlap between the latch carried by the bimetal trip element 69 and the latch projection 63 of the releasable member 35. This will cause thel breaker to be tripped in response.

to a lower magnitude overload. Conversely, when the nut 95 is screwed out, that is, backed off, the

'effect tripping of the breaker.

As has previously been mentioned, the structures of the two poles ofthe breaker are identical, and are insulated from lone another by a centrally disposed longitudinal partition wall I 0 formed in the housing 9. The operating members 31 for the two poles are connected for simultaneous movement together by a common operating member I of insulating material. The common operating member I Il is in the form of a yoke. rand the opposite arms thereof extend through the openings provided therefor in the two operating members 31. An operating rod (not shown) is adapted to be connected to the central portion' of lthe common operating member III.

A cover I|1 of molded insulating material is removably secured to the housing 9 for the purpose of enclosing and protecting the currentresponsive trip devices I9. The cover II1 is provided with a central longitudinal partition |I9 which aligns with the partition III) formed in the housing 9 so as to completely isolate the two poles of the breaker from one another.

The circuit for each pole of' the breaker is the same and extends from the lower terminal strip 2|'through the stationary contact II, the movable contact I3, and a flexible shunt conductor |23 connected to the movable contact, to one leg of the bimetal trip element 69, and through the bimetal trip element 69 and a flexible shunt conductor |25 to an upper terminal strip |21 (Fig. 2), the end of which extends outside of the casing on the side thereof.

Referring to Fig. 4, the movable contact I3 is mounted on the switch arm I5 for limited tilting f or swiveling movement relative thereto, so as to permit the contact to seat flat against the stationary contact II. .For this purpose, the movable contact I3 is provided with a reduced cylindrical portion |29 between the front and back thereof, and is formed to provide substantially spherical shoulders |3| adjoining the reduced portion. The movable contact is loosely retained in a C-shaped notch |33 provided therefor in the lower projection 29 of the switch arm I5. The

extending fingers |35 forming the notch are bent toward each other slightly to retain thecontact I3 in the notch. The fingers, however, are not bent far enough to bind the contact. The flexible shunt conductor |23, which connects the movable contact to one end of the bimetal trip element 69, is rigidly attached at its other end to the back of the movable contact I3, and extends through and is firmly held in a bushing |31 which is mounted in a notch provided in the bight portion 21 of the switch arm I5.

The spherical shoulders |3I permit the movable contact I3 to tilt or swivel a slight amount, so as to seat fiat against the stationary contact when it is moved to closed circuit position.

The circuit breaker is provided with an interlock mechanism designed so that when either pole of the breaker trips the other pole will also trip. The interlock mechanism utilizes the kinetic energy of either of the switch arms I5 i,

of insulating material which is transversely disposed in the upper portion of the housing 9 between the partitionwall 9| and the upper end wall 99 of the housing. The bar |39 is pivotally mounted intermediate its ends on a rod I4| which is mounted in the housing 9. The rod |4| has its inner end engaged in a bearing provided therefor in the mid portion of the bar |39, and the other end is bent upwardly at a right angle and extends through a notch |43 (Fig. 2) provided therefor in the upper end wall 99 of the housing. The angularly bent end of the pivot rod |4I is securely retained in the notch |43 by a pair of nuts |45 which are threaded on the rod and engage the opposite sides of the end wall 99, as shown in Fig. 2. y

The opposite ends of the insulating bar |39 are disposed directly above the notched ends of the adjusting arms 13 on'the side thereof opposite the coil springs |03. The opposite ends of the bar |39 engage the heads of a pair of pins y 63, andthe corresponding switch arm I5 is causedv y causes the insulating bar |39 justing arm |41 which are slidably mounted in openings provided therefor in the partition wall 9|. The pins |41 extend through the notches in the ends of the adjusting arm 13, and the heads of the pins are disposed ybetween the adjusting arm 13 and the insulating Ibar |39. The lower ends of the pins |41 project through the transverse partition wall 9|, and are disposed to be engaged and moved by angularly bent projections |49 of the switch arms I5 as the switch arms approach the tripped open position.

When either pole of the circuit breaker is tripped in response to predetermined overload conditions, the releasabie member 35 of the affected pole is released by the tripping of the latch to move to a tripped open circuit position, as shown in Fig. 5. As the switch arm I5 approaches the tripped open position, the projection I 49 thereof strikes the pin |41 and the impact to rotate on the pivot |4I, thus pushing the adjusting arm 'I3 of the other pole. This causes rotation o1' the ad` 13 of the other pole aboutits pivot 85, moving the bimetal trip element 69 and latch 65 to release the releasabie member 35 of the other pole to cause tripping thereof. When the circuit breaker is manually operated to the opencircuit position, the projections |49, as shown dotted in Fig. I, do not engage the pins |41, and hence the interlock bar |39 is not affected by manual opening of the circuit breaker.

The operation of the circuit breaker is briefly as follows: To manually open the circuit breaker, the common operating member III is moved in an upward direction to effect simultaneous upward movement of the two operating members 31 which are connected thereto. The upward movement of the operating members 31 moves the line of action o1' the overcenter springs 39 across and above the pivot axis 53 of the switch arms I5. As soon as the line of action of the overcenter springs crosses above the pivot axis 53, the springs act to move the twoswitch arms I5 simultaneously to the open circuit position, indicated by the dotted lines in Fig. 1. This movement of the switch arms takes place with a snap action.

To manually close the circuit breaker, the common operating member I I is moved downwardly to effect simultaneous downward movement of the two operating members 31. The downward movement of the operating members 31 moves the line of action of the overcenter springs 39 across and below the pivot axis 53 of the switch arms I5. As soon as the line of action of the overcenter springs 39 crosses below the pivot axis 53,

the springs act to move the switch arms I5 to the closed circuit position shown in Fig. 1 with a snap action.

When an overload of predetermined magnitude and duration occurs in the circuit through either pole of the circuit breaker, the bimetal trip element 69 of' the affected pole is heated thereby a sufficient amount to deflect in a direction away from the actuating means. This deflection of the trip element causes the latch 65 to disengage the latch projection 63`of the releasabie member 35, effecting release of the releasabie member. The overcenter spring 39 of the affected pole then moves the pivoted releasabie member 35 in a clockwise direction about its pivot -axis 41 from the position shown in Fig. 1 to the position shown in Fig. 5. During this movement, the legs 4I of the pivoted releasable member 35 engagethe lateral projections theswitch arm tion, as shown in Fig. contacts.

As has previously been described, the tripping of either pole of the'circuit breaker will operate through the interlock bar |39 to also eiect tripping of the other pole of the breaker. v As the switch arm 5 of the pole on which initial tripping occurs approaches its tripped open circuit position, the projection |49 thereof strikes the pin l|4`| on thatpole and the impact causes rotation of the interlock bar |38 about its pivot |4|. The oppositeend of the bar |39 pushes the'adjusting arm 13 of the trip element of the other pole inwardly,'causing rotation ofthe adjusting arm T3 andl thel bimetal trip element 69 about thepivot 85 to effect/'release of the releasable member 35, thereby tripping the other pole of the circuit breaker. v

Before the circuit breaker can be reclosed following a tripping operation, it is necessary to reset the pivote'd releasable members 35 to their 33 of the switch arm l5 yand move to the tripped open circuit posi- 5, to effect opening o f the latched position. To yreset the circuit breaker,

the common operating member is moved in anupward direction slightly beyond thenormal open positionV thereof.A During this movement, the lower lateral projections 59 of the operating members '31 engage the projections B1 of the pivoted releasable members 35, and effect movement of the releasable members in acounterclockwise direction about their pivot axes 41 to return the releasable members `to their latched position. After the pivoted releasable members have thus been returned to latched'position, the breaker may beA manually closed in the manner previously described. j l

While the invention has been disclosed in accordance with the provisions of the patent statutes, it is to be understood that various changes in the structural details thereof maybe made without departing from' some of the `essential features of the invention. It isl desired, therefore, that the language of the appended claims be .given the broadest reasonable construction permissible inthe light of the prior art. I claim as my invention:

1. A multiple circuit breaker comprising a movable contact arm for each pole, actuating means for each contact arm comprising an overcenter spring for moving the contact arm toopen and to closed circuit position with a snap action and a current-'responsivetrip element operable to cause movement of the contact arm to open circuit position, means operable by the opening movement of the contact arm of any pole when tripped for causing movement of the currentresponsive trip element of theother of the poles to trip the other of the poles. y

2. A multipole circuit breaker comprising a set of separable contacts for each pole, an actuating means for the contacts of each pole including a current-responsive tripping means operable to cause automatic opening of the contacts of its pole, and means comprising an interlock bar pivoted intermediate its ends for movement in a plane at right angles to thez plane of movement of the movable contacts and disposed to be moved by the opening movement of the actuating means ofany pole upon tripping thereof to cause tripping of the other of the poles.

3. A multipole circuit breaker comprising a set of contacts and a movablecontactarm for each pole, an actuating means for each contact arm includingv a member releasable to cause automatic'circuit opening operation of said contact arm and a. pivotally mounted current-responsive trip element operable in response to predetermined current conditions in the circuit through its pole to effect release of said releasable member; and means comprising an interlock bar pivoted intermediate its ends disposed to be moved by the opening movement of the contact arm of any pole upon tripping thereof to move the trip element of the other of the poles about its pivot to effect trippingof the other of the poles.

4. A multipole circuit breaker comprising a` set of separable contacts for each pole, an actuating means for each set of contacts for. opening and closing the same and a pivotally mounted current-responsive bimetal trip element for each of a plurality of the poles deectable in response to predetermined current conditions in the circuit of its pole to cause automatic opening of the contacts of its pole, a separate adjusting means for each bimetal trip element for moving the bimetal element about its pivot to adjust the trip characteristic of the corresponding pole of the breaker, and means operable by the opening movement of the actuating means of any pole Whentripped to move the bimetal trip element of other of the poles about its pivot to eiect tripping of other of the poles.

5.` A multipole circuit breaker comprising a set of separable contacts and a movable'contact arm therefor for each pole, an actuating means for each contact arm comprising an overcenter spring operable to move said contact arm to open and to closed circuit position, a member releasable to cause movement of said contact arm to open circuit position, and a current-responsive trip element for each of a plurality of the poles operable in response to predetermined current conditions in the circuit of its pole to effect release of said releasable member vand thereby cause movement of thecontact arm of its pole to open circuit position, manually operable means for moving said overcenter springs to manually actuate said Contact arms, and means operable by the opening movement of the v contact arm of any pole when tripped to cause the current responsive trip element -of other of said poles to release its corresponding releasable member and thereby trip the other of said poles.

6. A multipole circuit breaker comprising a set of separable contacts and a movable contact arm therefor for-each pole, an actuating means for each contact arm comprising an overcenter spring operable to move said contact arm to open and to closed circuit position, va member 4releasable to cause movement o f said contact arm to open circuit position, and a currentresponsive trip element operable in response to predetermined current'conditions in the circuit of its pole to eiect release of said releasable member and thereby cause movement of the contact arm of its pole to open circuit position, manually operable means for moving said overcenter springs to manually actuate said contact arms, and means comprising an interlock bar disposed to be moved by the contact arm of any pole when tripped to move the current-responsive trip element of other of the poles to tripA said other of the poles.

7. A multipole circuit breaker comprising a'set of separable contacts and a movable.contact arm therefor for each pole, an actuating means for each contact arm comprising an overcenter spring operable to move said Contact arm to open and to closed circuit position, a member releasable to cause movement of said contact arm to open circuit position, and a pivoted currentresponsive trip element for each of a plurality of the poles operable in response to predetermined current conditions in the circuit of its pole to effect release of said releasable member and thereby cause movement of the contact arm of its pole to open circuit position, manually operable means for moving said overcenter springs to manually actuate said contact arms, and means comprising an interlock bar pivoted intermediate its ends disposed to be moved by the opening movement of the contact arm of any pole when tripped to cause release of the releasable member of other of the poles to thereby eiect tripping of other of the poles.

8. A multipole circuit breaker comprising a set of separable contacts and a movable contact arm therefor for each pole, an actuating means for the contact arm of each pole comprising a releasable member pivoted on a stationary support, said contact arm being pivotally supported on said releasable member, an overcenter spring connected to the contact arm operable to move the contact arm to open and to closed circuit position while said releasable member remains stationary, said pivoted releasable member being normally restrained and being moved by said spring when released to cause automatic movement of the contact arm to open circuit position, and a current-responsive trip element operable in response to predetermined current conditions in the circuit through its pole to effect release of the releasable member of its pole, and means comprising a bar which is moved during the opening movement ofthe contact arm of either pole upon tripping thereof to eiect tripping of the other pole.

9. A multipole circuit breaker comprising a set of separable contacts and a movable contact arm therefor for each pole, an actuating means for the contact arm of each pole comprising a pivoted releasable member to which the contact arm is pivoted, an overcenter spring connected to the contact arm operable to move the contact arm to open and to closed circuit position, said pivoted releasable member being normally restrained and being moved by the spring -when released to cause automatic movement of the contact arm to open circuit position, and a pivoted current-responsive bimetal trip element.

carrying a. latch for normally restraining said releasable member, said bimetal trip element being operable in response to predetermined current conditions in the circuit of its pole to flex without pivoting and eiect release of the releasable member of its'pole, the contact arms and actuating means of the several poles being disposed side by side, manually operable means for moving said overcenter springs to actuate said contact arms, and means comprising an interlock bar disposed to be moved by the opening movement of the contact arm of either pole when tripped to move the bimetal trip element of the other pole about its pivot to effect tripping of the other pole.

10. In a multipole circuit breaker, relatively movable contacts for each pole comprising a stationary contact and a cooperating movable contact carried by a movable contact arm, an actuating means for each contactarm for moving able in response to predetermined current conditions in the circuit of its pole to ex Without pivoting and effect release o the releasable member of its pole, the contact means and actuating means of the several poles being disposed side by side, and means comprising a transversely disposed bar pivoted intermediate its ends about an axis parallel to the plane of movement of the contact arms and movable by the opening movement of the contact arm of either pole when tripped to move the bimetal trip element of the other pole about its pivot to effect tripping of the other pole.

l1. A multipole circuit breaker comprising a set of separable contacts and a movable contact arm therefor for each pole, an actuating means for each contact arm for moving the contact arm to open and to closed circuit position, the actuating means of each of a plurality of the poles including a member releasable to cause movement of the contact arm to open circuit position and a pivoted current-responsive bimetal trip element carrying a latch for normally restraining the actuating member and having an arm held in engagement with an adjusting element by a spring, said bimetal trip element being operable in response to predetermined current conditions in thev circuit of its pole to ex Without pivoting and eiect release of the releasable member of its pole, the contact means and actuating means of the several poles being disposed side by side, and means comprising a transversely disposed interlock bar movable by the opening movement of the contact arm of any pole when tripped to move the bimetal trip element of other of the poles about its pivot to effect tripping cf other of the poles, said interlock bar being pivoted intermediate its ends about an axis parallel to the plane of movement of the contact arms and engageable with the arms of said bimetal trip elements on the side opposite the springs.

12. A multipole circuit breaker comprising a movable contact arm for each pole, an actuating means for each contact arm for moving the contact arm to open circuit position, each actuating means including a spring biased member mounted for movement independently of and relative to said contact arm and releasable to cause automatic operation of the contact arm to open circuit position, a spring for actuating said releasable member and said contact arm, a latch for normally restraining the releasable member, and a 'current-responsive trip element operable in response to predetermined current conditions in the circuit of its pole to operate the latch and effect release of the releasable member of its pole, means operable by the kinetic energy of either contact arm at the end of its opening movement following tripping thereof for operating the latch of the other pole to disengage the releasable member of said other polesand thereby eiect tripping of said other pole.

MERRILL G. LEONARD.

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