US2660638A

US2660638A - Circuit breaker

Info

Publication number: US2660638A
Application number: US251552A
Authority: US
Inventors: Francis L Geizheiser; Eugene J Walker
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1951-10-16
Filing date: 1951-10-16
Publication date: 1953-11-24
Anticipated expiration: 1970-11-24

Description

Nov. 24, 1953 F. L. GELZHEIS ER ETAL CIRCUIT BREAKER Filed Oct. 16, 1951 WITNESSES:

INVENTORS Francis L. Gelzhe iser ond Eugene J.Wo|ker.

. B1} 1 ATTORNEY Patented Nov. 24, 1953 UNITED STATES PATENT OFFICE CIRCUIT BREAKER Francis L. Gelzheiser, Pittsburgh, and Eugene J. Walker, Beaver, Pa, assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application October 16, 1951, Serial No. 251,552

6 Claims. (01. 200-88) This invention relates to circuit breakers and more particularly to circuit breakers for controlling lighting and moderate power circuits.

An object of the invention is to provide a circuit breaker embodying an improved thermally and magnetically responsive trip having one of the magnetic members mounted on the thermally responsive means, and the other magnetic member mounted for limited movement toward said one magnetic member.

Another object of the invention is to provide a circuit breaker having a housing lor enclosing the breaker and embodying an improved thermally and magnetically respo 've trip device wherein one of the magnetic .ters is mounted on the thermally responsive means, and the other magnetic member is mounted on the housing for limited movement toward the magnetic member on the thermally responsive means.

A further object of the invention to provide a circuit breaker having an enclosing housing and embodying an improved thermally and magnetically responsive trip device in which one of the magnetic members is mounted on the thermally responsive means, and the other magnetic memher is pivotally mounted on the housing.

Another object of the invention is to provide a circuit breaker embodying an improved trip device that is simple, reliable in operation, and inexpensive to manufacture.

The novel features that are considered characteristic 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 be best understood from the following detailed description of one embodiment thereof, when read in conjunction with the accompanying drawing.

In said drawing:

Figure 1 is a side elevatlonal view, the cover removed and partly in section, of a circuit breaker embodying the principles of the invention;

Fig. 2 is an enlarged elevational view of the trip device; I

Fig. 3 is a sectional view through the trip device taken on line III-III of Fig. 2 and looking in the direction indicated by the arrows.

The circuit breaker is of the type disclosed in Patent 2,551,822, issued May 8, 1951 to Melvin Bingenheimer, Eugene J. Walker and Julius Toth and assigned to the assignee of the present inven tion.

Referring to Fig. 1 of the drawing, the circuit 2 breaker comprises a housing l l and a cover plate !3 (Fig. 3) constructed of molded insulating material, stationary contact means it, movable contact means ii, an. operating mechanism l9 and a trip device 2|.

The stationary contact [5 is rigidly secured to the inner end of a conducting strip 23 seated in an angular slot molded in the housing I I. The outer end of the conducting strip is provided with a terminal connecting means, such as a screw 2?, for connecting the breaker in an electric circuit. At the opposite end of the housing ii is a conducting strip nected to the tr p device (to be later described) which is provided with a terminal connecting means, such as a screw 3! at its outer end for connecting the breaker in an electric circuit.

The movable contact ii is rigidly secured on the free end of a U-shaped switch arm 37 having its legs 5'! sup-ported in recesses 56 in the legs 55 of a ill-shaped operating lever 35 oi molded insulating material. The operating lever 35 is pivotally supported by trunnions 35 molded integral therewith and mounted in suitable companion openings (not shown) in the housing H and in the cover plate it. An operating spring 39 is connected under tension between the bight of the switch member 3? and a releasable carrier 33 pivoted on a pin ll supported in openings (not shown) in the housing I! t and in the cover plate I3.

The operating lever 35 is provided with an operating handle it molded integral therewith and extending outwardly through an opening Ed in the housing ll. lhe operating lever 35 is also provided with an arcuate member 53 molded integral therewith and cooperating with the housing ll to substantially close the opening 5! in any position of the handle 49. The switch arm 3'! is electrically connected by means of a flexible conductor 59 to one end of a thermal element 45 forming part of the trip device 2i which is suitably secured, preferably by welding, to the inner end of the conducting strip 29.

The switch arm 3? is operated to manually open and close the contacts liill by manipulation of the handle 49. Movement of the handle 49 in a clockwise direction carries the upper pivoted ends of legs 51 of the switch arm 37 across to the left or" the line of action of the operating spring as which then biases the switch arm to the open position and causes movement of the switch arm to open position with a snap action.

The contacts are manually closed by reverse it which at its inner end is conmovement of the handle. Counterclockwise movement of the handle 49 from the open position to the closed position moves the upper pivoted ends of legs 51 of the switch arm across to the right of the line of action of the spring 39 which thereupon acts to close the com tacts with a snap action.

An arc extinguisher is provided to quickly extinguish the are drawn when the circuit is interrupted. The are extinguisher may be of 1 any suitable type preferably of the type shown in aforementioned Patent #2551322, issued May 8, 1951 to Melvin Bingenheimer, Eugene J. Walker and Julius Toth and assigned to the assignee of the instant application.

The circuit breaker is adapted to be tripped open instantaneously in response to overload currents above a predetermined value, or in response to a short circuit current, and after a time delay on lesser overload currents, by means of the trip device 2!. Operation of the trip device 2l releases the carrier 33 whereupon the operating spring 39 moves the carrier 33 clockwise moving the line of action of the spring 39 across to the right of the center line of the switch arm 31. Thereafter the spring 39 acts to move the switch arm to open position with a snap action. The movement of the carrier is arrested by engagement with a projection 6| of the housing II.

The trip device 2| comprises the thermal element 45 connected by means of the flexible conductor 59 to the switch arm El and an electromagnet including a magnetic member consisting of an armature 53 mounted on the thermal element or bimetal element 45 and a magnetic member or magnet yoke 65 pivotally mounted on the end wall of the housing for movement relative to the magnetic member 53. ihe conducting strip 29 is secured to the end wall of the casing II by means of a screw H and the bimetal element 45 is rigidly secured by suitable means such as welding to the upper inner end of the conducting strip 29. Just below the point of attachment of the thermal element 45 to the conducting strip 29 the thermal element is formed inwardly at right angles and then downwardly substantially parallel to the conducting strip 29.

The magnetic member 53 is rigidly secured to and surrounds three sides of the thermal member 45. The magnetic member 53 is secured to the thermal or bimetal element 45 by means of a rivet it! which also serves to secure a latch The latch element 6? to the bimetal element. 61 normally engages and releasably restrains the carrier 33 in operative position.

The magnetic member (i is pivotally mounted on a pivot pin 69 supported in a pair of spaced brackets molded into or otherwise suitably secured to the end wall of the housing. A very light spring 11 normally biases the magnetic member 55 to unattracted position against a fixed stop 19 on the end wall of the housing.

With normal rated current flowing through the bimetal element 45 the magnetic member is in the position shown in Figs. 1 and 2. Upon the occurrence of an overload current above the rated current and below a predetermined value of, for instance, 1000% of normal rated current, the bimetal element 45 is heated by the current flow therein and deflects toward the right causing the latch 61 to release the carrier 33 whereupon the operating mechanism functions in the previously described manner to automatically open the breaker contacts.

The arrangement of the elements of the trip device is such that a cooperative tripping action obtained in response to overload currents in the higher range of overload currents below the predetermined value of, for instance, 1000% of normal rated current, This is accomplished by pivotally mounting the magnetic member or yoke 65 for movement relative to the magnetic mem ber 53. In the low range of overload currents up to, for example, 400% of normal rated current, the energization of the magnetic means moves the free end of the magnetic member 65 toward the member 63 but is insufficient to bend the bimetal element 45. Because the magnetic member 65 is pivotally supported on a fixed pivot at one end, this preliminary movement to reduce the air gap takes place without requiring the magnetic force to be large enough to bend the bimetal element 45 against its normal bias. However, upon the occurrence of an overload current of, for instance, between approximately 400% and 1000% of normal rated current, the reduced air gap increases the pull on the magnetic member 63 and on the bimetal element 45 so that the breaker will trip quicker by thermal bending of the bimetal element, than it would if both ends of the magnetic member 65 were rigidly supported.

Upon the occurrence of a heavy overload cur-- rent or short circuit current, such for example as 1600% or more of normal rated current, the current flowing through the bimetal element 45 energizes the electromagnetic means a sufficient amount to cause the magnetic member 65 to instantaneously attract and operate the magnetic member 63 thus bending the bimetal element and causing release of the carrier 33 and effecting instantaneous opening of the breaker contacts.

Before the contacts can be closed following an automatic opening operation, it is necessary to reset and relatch the mechanism. This is accom plished by moving the handle 49 clockwise to the full open position during which movement the legs 55 of the operating lever 35 engage a pin in the carrier 33 and moves the carrier counterclockwise about its pivot 4!. Near the end of its counterclockwise movement, the free end of the carrier 33 wipes by the latch 61, slightly bending the bimetal element which thereafter resumes its normal latching position. The switch arm isthen moved to close the contacts in the previously described manner by movement of the handle 49 counterclockwise to the closed position.

Adjusting means is provided whereby the trip device may be adjusted to vary the tripping point of the thermal trip means. The adjusting means comprises an adjusting screw threadedly engaging the upper end of the conducting strip 29 and having its rounded head bearing against a concave seat in the housing H. An opening 83 in the housing provides access permitting the insertion of a screw driver to turn the screw M to thereby adjust the trip device. The opening- 33 may be sealed after adjustment to preventtampering by unauthorized persons.

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 and arrangements of parts thereof may be made without do parting from some of the essential features of the invention. Thus, while the improved trip device is herein illustrated in connection with one specific form of operating mechanism with which it has certain particular cooperation, it will be apparent that the trip device may be used with other forms of mechanism.

We claim as our invention:

1. A circuit breaker comprising relatively movable contact means and means releasable to effect opening of said contact means, a trip device for effecting release of said releasable means comprising a thermally responsive element heated by the current of the circuit and operable When heated a predetermined amount in response to certain abnormal circuit conditions to effect release of said releasable means, electromagnetic means comprising a magnetic member mounted on said thermally responsive element, and a second magnetic member mounted on a fixed support for limited movement toward said first magnetic member in response to certain other abnormal circuit conditions to reduce the magnetic air gap and thereby apply a force to said thermally responsive element to assist said thermally responsive element to trip said breaker.

2. A circuit breaker comprising relatively movable contact means and means releasable to eifect opening of said contact means, a trip device for effecting release or" said releasable means comprising a bimetal element disposed to be heated by the current of the circuit, said bimetal element normally restraining said releasable means and operable when heated a predetermined amount in response to certain abnormal circuit conditions to effect release of said releasable an armature mounted on said bimetal element, and a magnet yoke mounted on a fixed support and movable toward said armature in response to certain other abnormal circuit conditions to reduce the magnetic air gap to thereby assist said bimetal element to release said releasable means.

3. A circuit breaker comprising relatively movable contact means and means releasable to ef- :fect opening of said contact means, a trip device for effecting release of said releasable means comprising a bimetal element heated by the current of the circuit and operable when heated a predetermined amount in response to certain abnormal circuit conditions to effect release of said releasable means, electroresponsive means comprisin an armature mounted on said bimetal element, and a tiltable magnetic member mounted on a fixed support, biasing means biasing said tiltable magnetic member to a normal position, sail tiltable magnetic member moving toward said armature in response to certain other abnormal circuit conditions to reduce the magnetic air gap to thereby assist said bimetal element to release said releasable means, and said electroresponsive means operating at times to bend said bimetal element and eiiect instantaneous release of said releasable means.

a. A circuit breaker comprising an enclosing housing, relatively movable contacts, means releasable to effect opening of said contacts, a trip device for effecting release of said releasable means comprising a, bimetal element normally releasably restraining said releasable means and operable in response to certain overload currents below a predetermined value to release said releasable means, eelctromagnetic means comprisins an armature mounted on said bimetal element, and movable magnetic member mounted on said housing and movable toward said armature in response to certain other overload currents below said predetermined value to reduce the magnetic air gap and assist said bimetal element in releasing said releasable means.

5. A circuit breaker comprising an enclosing housing, relatively movable contacts, means releasable to efiect opening of said contacts, a trip device for effecting release of said releasable means comprising a bimetal element normally restraining said releasable means and operable in response to certain overload currents below a pre-- determined value to release said releasable means, electromagnetic means comprising armature mounted on said bimetal element, and a magnet yoke mounted on said housing and having one end movable toward said armature in response to certain other overload currents below said predetermined value to reduce the magnetic air gap and assist said bimetal element in releasing said releasable means, and said electromagnetic means being operable in response to overload currents above said predetermined value to bend bimetal element and efiect instantaneous release of said releasable means.

6. A circuit breaker comprising relatively movable contact means and means releasable to ef fect opening of said contact means, a trip device for effecting release of said releasable means comprising a bimetal element, latch means on said bimetal element normally releasably restraining said releasable means, thermal bending of said bimetal element in response to certain overload currents below a predetermined value causing said latch means to release said releasable means, electroresponsive means comprising an armature mounted on said bimetal element, and a magnet yoke having one end pivoted and the other end free, pivot means mounted on a fixed support for pivotally mounting said magnet yoke, said magnet yoke moving about said pivot means in response to certain other overload currents below said predetermined value to move the free end of said magnet yoke toward said armature to thereby reduce the magnetic air gap and increase the magnetic pull on said armature, and said electroresponsive means bending said bimetal element in response to overload currents above said predetermined value to effect instantaneous release of said releasable means.

FRANCIS L. GELZHEISER. EUGENE J. WALKER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,242,066 Grady May 13, 1941 2,308,401 Taylor Jan. 12, 1943 2,320,437 Jennings June 1, 1943