US2192059A - Circuit breaker - Google Patents

Description

Feng-1, 1940.

H. H. WILL-MANN CIRCUIT BRAKER Filed Aug. 2, 1937 2 sheets-sheet x mlm.

WITNESSES:` may? l,

Patented Feb. 27, 1940 CIRCUIT BREAKER Hans H. Willmann, Berlin-Charlottenburg, Germany, assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application August 2, 1937, Serial No. 157,027 l In Germany 6 Claims.,

The invention relates to circuit breakers in general and more particularly to moderate power circuit breakers of the type usedfor controlling lighting and moderate power industrial distribu- 3 tion circuits.

An object of the invention is the provision of an improved circuit breaker of the above type that is simple, safe and reliable in operation, extremely compact, and which can be manufactured at a relatively low cost.

Another object of the invention is the provision of an improved circuit breaker embodying an electromagnetic means for opening the breaker in response to heavy overloads and short circuit conditions, anda thermal means for opening the breaker in response to moderate overloads of predetermined duration; the electromagnetic means also serving.v to move and extinguish the arc formed during circuit interruption.

Another object of the invention is the provision of a circuit breaker with an improved electromagnetic means which serves both as a blowout means for moving and extinguishing the arc during circuit interruption and also as a trip means for opening the breaker in response to heavy overloads and short circuit conditions.

Another object of the invention is the provision of a, circuit breaker with an improved electromagnetic blowout means for producing a-very strong blowout eld capable of rapidly moving and extinguishing large arcs in an extremely short period of time, yet which is so arranged together with the other parts of the breaker that the breaker occupies a relatively small amount of space.

Another object of the invention is the provision of a circuit breaker as described in the preceding paragraphs in wl'fich the electromagnetic means and other parts of the breaker are arranged in a novel cooperative manner so that the breaker as a whoie occupies a much smaller space for a given switching power or provides a greater switching power for a given amount of space occupied by the breaker than has heretofore been considered possible. l

The novel features that are considered characterist'c of the invention are set forth in particular in the appended claims. The .invention itself, however, both as to structure and operation together with additional objects and advantages thereof will best be understood from the following detailed description of one embodiment therepf when read in connection with the accompanying drawings, in which:

Figure l is a vertical sectional view of a circuit August 3, 1936 (Cl. 20o- 106) breaker constructed in accordance with the invention, the breaker being shown in the open circuit n position Fig. 2 is a sectional view of the circuit breaker taken at right angles to Fig. 1 on the line IIC- II thereof;

Fig. 3 is a sectional view similar to Fig. 1 showing the position of the various parts when the circuit breaker is in the closed circuit position;

Fig. 4 is a plan view of the stationary contact and the means for connecting the same to the windings of the electromagnet;

Fig. 5 is a view taken at right angles to Fig. 4;

Fig. 6 is a side elevational view of the movable contact and switch member; and

Fig. 7 is a horizontal sectional view of the mov- A main frame, comprising a base portion I9 and a pair of spaced parallel side'plates 2l, is mounted within the casing on the base 9. 'I'he main frame serves to support a movable switch member indicated generally at 23, and actuating means indicated generally at 25.

The switch member 23 (Figs. 6 and 7) comprises a block 21 oi insulating material, a movable contact 29 secured to the upper end of the block by suitable fastening means 3|, and a yokeshaped switch lever 33. The ends of the legs of the yoke-shaped switch lever 33 are rounded as indicated at 35 so as to fit in circular recesses provided in the opposite sides of the insulating block 2li. li'he block 2'! is slotted as indicated at 3i at the end opposite that carrying the contact 29, so as 'to permit the block and contact 29 carried thereby to have a limited rotational movement about the rounded ends 35 of the yokeshaped switch lever 33. A coil compression spring 39 is disposed between the upper portion of the slotted end of the block 21 and a cross piece QI which bridges the legs of the yoke-shaped switch lever 33. The spring 39 biases the block 21 in a counter-clockwise direction about its pivot axis formed by the rounded ends 35 of the yokeshaped switch lever 33, so as to kmaintain a pre- 5 determined high contact pressure between the movable contact 29 and the stationary Contact I1 when the circuit breaker is in the closed circuit position.

The switch member 23 is pivotally mounted upon the main frame for movement in a plane perpendicular to the base 9 between yopen and closed circuit position by means of a transverse pivot pin 43 which extends through the side walls 2| of the frame and through an opening 45 provided therefor in the yoke-shaped switch lever 33, the axis of the pivot pin 43 being disposed parallel to the base 9 of the breaker. The pivot mounting of the switch member 23 is such that the path of movement of the movable contact 29 carried thereby is located between the side walls of the arc chute I3 within the interrupting chamber. A iiexible shunt conductor 41 consisting of a flat resilient strip of conducting material is secured at one end to the movable contact 29 and serves to conduct current thereto.

The actuating means for the circuit breaker comprises in general a pair of toggle links 49 and 5|, a carrier lever 53, a latching or blocking `lever 55 for the carrier lever, a closing push button 51 and a releasing push button 59. The upper end of the toggle link 49' is pivotally connected to a projecting portion of the yoke-shaped switch lever 33 by means of a pivot pin 6|, while the lower end of the toggle link is pivotally con- ;,nected to the upper end of the toggle link 5| by that it is desired to close the breaker.

means of a knee pivot pin 63. of the toggle formed by the links 49 and 5| is pivotally connected to the carrier 53 by means of a pivot pin 65, the carrier itself being pivotally supported on the main frame by means of a transverse pivot pin G1. The inner end of the closing push button 51 is provided with a pair of projecting studs 69 which pass through openings provided in lugs 1| carried by the main frame, which serve to guide the push button 51 during movement of the same. The push button 51 is also provided with a plate 13 secured to the underside thereof which has a vertically disposed elongated slot 15 for engaging the knee pivot lpin 63 of 'the toggle linkage. A resilient spring strip 58 secured to the cover i I serves to bias the push button 51 outwardly to its normal position shown in Fig. 1.

rlhe latching lever 55, which serves to support the free end of the carrier lever 53, is pivotally supported on the main frame by means of a pivot pin 11 which extends through the side walls 2| of the main frame. The latching lever 55 is biasedto its latched position shown in Figs. l and 3 by means of an intermediate lever 19 which is pivoted to the main frame by means of a pivot pin 8| and biased in a clockwise direction by means of a compression spring 83, the spring 83 'acting through the intermediate lever 19 to bias the latchlng lever to its latched position.

The release button 59 is connected to the intermediate lever 19 above its pivot 8| by means of a, rod 86, so that when the release button 59 is pushed inwardly, the intermediate lever 19 is rotated in a counter-clockwise direction about its pivot pin 8| to move the latching lever 55 also in a counter-clockwise direction about its pivot pin 11 to released position.

The manual operation of the circuit breaker is as follows: With the breaker in the open circuit position as shown in Fig. 1, let it be assumed The closing push button 51 is manually depressed by the operator. The inward movement of the closing The lower end' push button is transmitted to the knee pivot pin G3 of the toggle by means of the plate 13 and edges of the slot 15 to effect movement of the knee pivot pin toward the left, as viewed in Fig. 1. This movement of the knee pivot pin toward the left by the push button 51 moves the toggle links to the made or in-toggle" position, as shown in Fig. 3. In this position, the knee pivot pin 83 is located slightly to the left of a center line joining the pin 6| and the pin 65. Since the pivot pin which connects the lower toggle link 5| to the carrier 53 is held stationary by reason of the latching lever ,55 engaging the carrier 53, the movement o the toggle links 49 and 5| to their made" position effects rotation of the switch member 23 to the closed circuit position, as shown in Fig. 3. It will be noted that in this closed circuit position of the switch member', the compression spring 39 between t-he block 21 and the switch lever 33 is held compressed so as to exert a high contact pressure between the movable and stationary contacts. The reaction of this force is transmitted through the switching lever 33 to the toggle links 49 and 5| and tends to maintain them in their made or toggle position shown in Fig. 3. The reactive pressure is sufficient to hold the toggle links in their made position against the bias of the return spring strip 58, which biases the closing push button 51 in an outward direction.

To open the breaker, the release button 59 is depressed. The depression of the button 59 rotates the intermediate lever 19 in a counterclockwise direction about its pivot pin 9| against the bias of the spring 83. The counter-clockwise movement of the intermediate lever 19 effects counter-clockwise movement of the latching lever 55 about its pivot pin 11 to release the free end of the carrier lever 53. When the carrier lever 53 is released, the reactive force exerted by the spring 39in transmitted through the toggle links and causes a slight counter-clockwise movement of the carrier lever 53. The slight counterclockwise movement of the carrier lever 53 effects movement of the toggle links to their aligned or dead-center position, that is to say. effects a slight movement of the knee pivot pin 63 to the right toward dead-center position. At this point, the force exerted by the return spring strip 58 moves the closing push button 51 in an outward direction to effect collapse of the toggle links'49 and 5|. The collapse ofthe toggle links effects rotation of the switch member 23 to its open circuit position shown in Fig. 1.

Following release of the button 59, the spring 83 acts through the intermediate lever 19 to return the latching lever 55 to its latching position in engagement with the free end of the carrier lever 53, the carrier lever 53 having been previously returned to its normal position by the outward movement of the push button 51 under the influence of the return spring strip 58, so that the breaker is automatically reset for the next circuit closing operation.

A thermal trip means is provided for effecting automatic opening of the breaker in response to moderate overloads of predetermined duration. The thermal trip means comprises a bimetallic strip 85 secured at its lower end to the base 9. The bimetallic strip 85 is connected in series circuit with the contacts 29 and I1, and the free end thereof is provided with a projection 81 which engages a portion of thelltching lever 55. When an overload of predetermined value and duration occurs in the circuit controlled by the breaker, the bimetalllc strip 85. isheated a sumcient amount to cause it to flex upwardly toward the actuating mechanism. This flexing movement of the bimetallic strip effects rotation of the latching lever in a counter-clockwise direction to its released position to eiect opening of the breaker in the same manner as when the release button 59 is depressed. The provision of the elongated slot 15 in the plate 13 carried by the closing push button 51 provides the desirable trip-free action so that the switch member 23 may be moved to open circuit position in re' sponse to a tripping operation even though the closing push button 51 is held depressed. After the breaker has been opened, no current flows through the bimetallic strip 85 so that the strip coolsvand returns to its original position shown in Fig. 1, allowing the spring 83 and intermediate lever 19 to return the latching lever 55 to its latched position to reset the breaker.

An electromagnetic means is provided for the purpose of rapidly moving and extinguishing the arc formed between the stationary and movable contacts l1 and 29 during circuit interruption, and also for the purpose of tripping the breaker to open circuit position in response to heavy overloads and short circuit conditions. The electromagnetic means comprises a pair of coils 89 disposed on opposite sides o f the interrupting chamber |5 and path of movement of the movable contact. The coils 89 are wound upon and supported by aligned/,core members 9| of magnetlc material, theaxis of the coil members 89 and the cores 91 being disposed parallel to the base 9 ofthe breaker and relatively close to the actuating mechanism 25. The inner ends of the core members 9| are provided with pole pieces 93 which lie on opposite sides of the path of movement of the movable contact 29, outside the side walls of the arc chute |3. The twocoils 89 produce a strong magnetic blowout field between the pole pieces 93 which traverses the interrupting chamber |15 for rapidly moving and extinguishing the arc formed between the stationary and movable contacts during circuit interruption. The particular arrangement of the two coils 89 on vopposite sides of. the interrupting chamber with their aligned axes passing through the chamber produces an extremely strong blowout field which is capable of extinguishing large arcsin a very short period of time, thus increasing the switching power of the circuit breaker so that the same is capable of interrupting larger amounts of current.

The electromagnetic means also includes an armature 95 of magnetic material comprising a pair of legs 91 extending on opposite sides of the coils 89 and the actuating mechanism 25. The legs 91 of the armature are plvotally mounted on the transverse pivot pin 43 which forms the pivot axis of the switch member 23. 'Ihe two legs 91 of the armature are connected by a cross piece 99 which extends beneath the actuating mechanism and serves as a path for the flux produced by the coils 89. The pivot pin 43 which is of magnetic material also carries a part of the flux so that the cross piece 99 and the pivot pin 43 both form part of the magnetic circuit of the electromagnetic means. The upper ends of the two legs 91 of the armature extend outside Aof the outer ends of the two coils 89 to a position adjacent the outer ends of the cores 9|, there being only a relatively small air gap between the upper ends of the legs 91 of the armature and the core members 9|.

One of the legs 91 of the armature 95 is provided with an extension |0| which serves to engage and move the latching lever 55 to its released position when the armature is rotated in a counter-clockwise direction about the pivot pin v 43.to its attracted position in response to a heavy magnitude overload or short circuit condition.

The magnetic circuit of the electromagnetic means described above extends from the pole piece 93 of the left-hand coil 89 across the interrupting chamber |5 to the opposite pole piece 93, through the core member 9| of the right-hand coil to the right-hand leg 91 of the armature 95, through the cross piece 99 of the armature and the pivot pin 43 tothe opposite leg 91, and through the left-hand core member 9| back to the pole piece 93 of 4the left-hand coil 89.

The stationary contact l1 is secured to the offset end |03 of a T-shaped conducting member |05. The ends of the cross bar of the T-shaped 'member |05 serve to connect the stationary contact |1 with the ends |01 of the windings of the coils 89. The windings of the coils 89 consist of flat copper strips |09 which are wound on the core members 9| so as to produce elliptical-- so that the same does not extend so far from the switchboard or other fastening surfaces as in the prior art constructions. In addition, the space requirements in the two other main directions are also decreased.

'I'he circuit for the breaker extends from one terminal through a conductor (not shown) to the free end of the bimetal trip element through the bimetallic trip element 85 through the shunt conductor 41 to movable contact 29 and stationary contact |1, and from` the stationary contact |1 in parallel through the windings of the coils 89 to the opposite terminal ||3.

It is believed that the operation of the circuit breaker will be readidly understood from the above detailed description. The circuit breaker may be closed manually by depressing the closing switch button 51. The depression of the button 51 causes the toggle links to be moved to their made position to effect movement of the switch member 23 to closed circuit position in the manner previously described in detail. To open the breaker manually, the release button 59 is depressed. The depression of the release button 59 effects movement oi' the latching lever 55 to its released position to release the carrier 53. When the carrier is released, the spring 39 moves the toggle links from their made position toward their dead-center position so as to allow the return spring strip 58 to effect collapse of the toggle links and return the closing push button 51 to its normal or open circuit position. The collapse of the toggle links effects movement of the switch member 23 to its open circuit position.

With the breaker in closed circuit position, as shown in Fig. l, if an overload of moderate magnitude and predetermined duration occurs, the bimetallic strip 85 is heated so as to ilex in a direction toward the actuating mechanism 25.

This ilexing of the bimetallii.` strip moves the v ner as ,has been previously described in connection the invention.

with the manual operation.

When a high magnitude overload or short circuit condition occurs in the circuit controlled by the breaker, the armature 95 is moved to its attracted position with the upper ends of its legs against the pole pieces 9i. When the armature is movedgto attracted position, the extension HH thereof engages and moves the latching lever 55 to its released position to effect opening of the breaker in the manner previously described.

The spring 83 acting through the intermediate lever 'I9 returns the latching `lever 55 to itsl scribed in accordance with the provisions of the i patent statutes, it is to be understood that various changes may be made in the structural details thereof without departing from the spirit of It is desired, therefore, that the language of the accompanying claims be given the broadest reasonable interpretation permitted by the prior art.

I claim as my invention:

1. In a circuit breaker, a base of insulating material, a .iirst contact mounted thereon, said base also supporting electromagnetic blowout means for `moving and extinguishing the arc drawn at said contact including a pair of pole pieces on opposite sides of said contact, coil means for the pole pieces disposed at the side of said contact with its extended axis transversely crossing the arc path, said base likewise supporting a frame carrying a pivot pin which pivotally supports an armature movable by said electromagnetic means in response t'o predetermined overload conditions on said circuit breaker, said pivot pin likewise pivotally supporting an arm carrying the movable contact for said circuit bre'aker, actuating meansl for said arm pivotally mounted on said frame, said armature when moved in response to said predetermined conditions decreasing the reluctance of the magnetic circuit of said' electromagnetic means to increase the blowout action thereof.

2. In a circuit breaker, a base provided with an interrupting chamber, a stationary contact in said chamber and mounted on said base, a frame supported on said baseA and a movable contact pivotally mounted on said frame, said contacts being relatively movable in a plane perpendicular to said base, actuating means forl the contacts likewise pivotally mounted on said frame, combined electromagnetic blowout'and trip means including a pair of aligned coils disposed on opposite sides of the chamber and plane of movement of the contacts with their axes extending transversely across the chamber and plane oi' movement of said contacts parallel to said base, said chamber and coils being located close to said actuating means, and an armature pivoted on the same pivot as said movable contact operable by said electromagnetic means inresponse to predetermined overload conditions to cause said actuating meansvto open said contacts.

3. In a circuit breaker, a stationary contact, a

movement of the switch member to move and.

extinguish the arc drawn between the switch member and contact, and an armature pivoted about the same axis as said switch member movable by said electromagnetic means in response to predetermined o'verload conditions to cause said actuating means to move the switch member to open circuit position.

4. In a circuit breaker, a stationary contact, a movable contact therefor carried by a pivoted switch member, actuating means for said switch member for moving the same to open and to closed circuit position, combined electromagnetic blowout and trip means including a pair of aligned coils disposed on opposite sides of the path of movement of said movable contact for moving and extinguishing the arc drawn between said contacts, the axis of said coils extending transversely across the path of movement of said switch member, and an armature pivoted about the same axis as said switch member for movement by said coils in response to predetermined overload conditions to cause said actuating means to move the switch member to open circuit position.

5. In a circuit breaker, a stationary contact, a cooperating movable contact carried by a pivoted switch member, actuating means for said switch member for moving the same to open and to closed circuit position, electromagnetic combined blowout and trip means including a pair of aligned coils disposed on opposite sides of the path of movement of said movable contact for m'oving and extinguishing the arc drawn between said contacts, the axis of said coils extending transversely across said path, an armature pivoted about the same axis of said switch member for movement by said coils in response to predetermined overload conditions to cause said actuating means to move the switch member to open circuit position, said armature having a pair of legs extending adjacent the cuter ends of said coils for attraction thereby.

6. In a circuit breaker, astationary contact, a movable contact therefor carried by a pivoted switch member, actuating means for said switch member for moving the same to open and to closed circuit position, combined electromagnetic blowout and trip means including a pair of aligned coils disposed on opposite sides of the path of movement of said movable contact for moving and extinguishing the arc drawn between said contacts, the axis of said coils extending transversely across the path of movement of said switch member, and an armature pivoted about the same axis as said switch member for movement by saidv coils in response to predetermined overload conditions to cause said actuating means to move the switch member to open circuit position, said stationary contact being secured to the leg of a T-shaped conductor, the free ends of the cross bar of said conductor being connected to the ends of said coils.

HANS H. WILLMANN.

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