US2416266A - Circuit breaker - Google Patents

Description

Feb. 18, 1947. w, LANDMQER 2,416,266

CIRCUIT BREAKER Filed Nv. 29, 1944 2 Sheets-Sheet 1 IN VEN TOR.

Feb. 18, 1947. E. w. LANDMEIER 2,416,266

CIRCUIT BREAKER Filed Nov. 29, 1944 2 Sheets-Sheet 2 IN VEN TOR.

Patented Feb. 18, 1947 CIRCUIT BREAKER Edwin W. Landmeier, Lakeside Park, Ky., assignor to The Wadsworth Electric Manufacturing 00., Inc., Covington, Ky., a corporation of Kentucky Application November 29, 1944, Serial No. 565,649

15 Claims. (Cl. 200-116) This invention relates to electric circuit breakers and is directed particularly to a simplifled switch structure having an operating handle for opening and closing the switch manually and a protective device responsive to electrical current conditions for opening the switch independently of the handle when abnormal current conditions occur.

The principal objective of this invention has been to provide a circuit breaker which is more reliable and free from operating imperfections than structures of this type which heretofore have been available.

A further objective has been to provide a circuit breaker having an indicator operating independently of the handle and plainly visible at the exterior of the unit for denoting a tripped or open circuit condition.

A still further objective has been to provide a circuit breaker of the so-called trip free type, that is, one in which the switch contacts cannot be maintained in closed position during prevailing overload or abnormal circuit conditions and to employ the operating handle for actuating the indicator as the means of resetting the device after it has been tripped. Otherwise expressed, a structure is contemplated in which the indicator forms a part of the resetting mechanism but is incapable of permitting the apparatus to be reset except when it is actuated by the switch handle and during a time that the handle itself holds the switch in an open position. Following resetting the handle is moved to a switch closed position whereby the contacts are reengaged only after the protective device has been reset. This arrangement relieves the protective device from any contact-making duty and thereby prevents it from becoming deteriorated or damaged by sparks or flashes, even though the protective device is in series connection with the contacts in the load circuit.

A still further objective has been to provide an apparatus in which the switch contacts are confined within an enclosure separate and isolated from the working members whereby the latter also are protected from any sparking which may attend switch operation.

Briefly, the present circuit breakers comprise a housing or base having two separate cavities; the mechanical operating parts are confined within one of the cavities and the electrical contacts movable relatively into and out of engagement with one another are housed within the other. The movable contact is sustained upon or is part of a movable member which is controlled by the switch handle to open and close the switch manually and is also controlled by a current responsive device to open the switch independently of the handle. The current responsive device may be either in the form of a thermally operated bimetallic element which acts as a latch to trip the switch if the abnormal current conditions are somewhat prolonged, or the protector may be in the form of a magnetic release which is actuated upon momentary overloads. The invention also contemplates circuit breakers in which both magnetic and thermal overload releases ar employed coniointly.

For resetting the trip whereby the movable contact is disengaged from the stationary contact the devices of the present invention have a. movable indicator which is exposed at the outside of the casing and which extends into the mechanism cavity where it connects with a linkage which is stiff in one position and broken or yieldable in another position. This linkage when stifl imparts the movement of the indicator to efiect resetting of the protective trip. The switch actuating handle breaks the linkage when the handle is in switch closed position whereby the indicator may be moved at will without effecting any deposition of the contacts. Conversely, when the handle is in switch-ofi position and has disengaged the contacts the linkage is stiff. In the preferred structure the indicator is positioned adjacent to the handle for engagement thereby when the handle is in off position, whereby the handle actuates the indicator to reset the trip through movement of the stiff linkage.

From the foregoing general description of the invention and from the following detailed description of the drawings in which a preferred embodiment of the apparatus is disclosed, those skilled in the art will comprehend the various modifications to which the invention is susceptible.

In the drawings:

Figure 1 is a. side elevation of the switch and circuit breaker thereof.

- Figure 2 is a top plan view.

Figures 3, 4, 5 and 6 are views illustrating the operating mechanism of the apparatus in the various phases of movement of the parts. According to these views Figure 3 shows the apparatus just following resetting of the trip, with the handle being moved toward switch-on position. Figure 4 shows the apparatus in the normal circuit protective condition with the switch closed. Figure 5 shows the arrangement of the parts after the circuit breaker has tripped and the operating handle is being moved toward resetting position. Figure 6 shows the operating handle engaging the indicator or resetting member, just before the parts have reached the condition shown in Figure 3.

Figure 7 is a fragmentary view showing the detail of the interconnection of the contact arm with a link operated by the handle.

Figure 8 is a sectional view taken on the line 8-8 of Figure 5.

aeiaaee Figure 9 is a sectional view taken on the line 9--9 of Figure showing a further detail of con- 'struction.

The circuit breaker shown in the drawings comprises a housing indicated generally at l, terminals 2 and 3 supported on the housing, a handle 4 accessible at the exterior of the housing, and an indicator or resetting element 5 which also is visible. The housing is made of insulating material or molded plastic composition and, as shown in the drawings, comprises two half sections 6 and 1 respectively, which join one another along the meeting faces '3. These half sections -are.faste1 ed together by means of the. rivets e which pass through aligned bores ill in the mating sections. In place of the two-part housing construction just described the housing may be of other types as understood by those skilled in the art, but the structure disclosed is desirable in that it facilitates fabrication and assembly at low cost.

At the interior of the housing there are two cavities, one indicated generally at H and the other indicated generally at l2. A ledge E3 on the outside forms a seat for a connector member l4 which threadedly receives one terminal screw 2. The connector member l4 extends through a recess IS in the housing wall into the cavity ll where it sustains a stationary contact 66. Ledge.

l3 has a recess I! which receives the depending portion of the terminal screw 2 and also has press-fitted into it a lug or boss portion 118 which v projects from the underneath face of the connector. This structure, in conjunction with a snug fit at the recess l5, provides a firm support for engagement by the handle at the opposite end of its stroke. It may also be noted that the handle is splayed out at its upper end thereby providing arcuate surfaces 3| and 32, one of which engages the stop while the other engages the rounded extremity of the indicator 5. While this construction is not necessary its ruggedness and simplicity are desirable.

The upper forward portion of the cavity l2 has a recess 33 for housing a compression spring 34 which urges a ball 35 toward the hub 21 of the handle for engagement of the ball with notches or cavities 36 at the hub periphery. These notches are spaced apart from one another to detain the handle in its switch-off and switchon' positions, and thereby prevent inadvertent movement of the handle.

Within the cavity I2 9. notched-out portion 31 of the handle hub is straddled by a link member 38 which is pivotally connected thereto through a pin 39. A cam 40 also is adjacent this portion of the handle hub and operates as described at a later point in the specification. The cam portion 40 swings through a clearance opening in the cavity and passes in-between the arms of the link 38.

Link 38 has its lower end in loose connection with a movable contact member which is indicated generally at 4 I. The link straddles the contact member, as in the case of the connection of the link with the handle, and the connection is formed through a pin 42 extending across the straddling portions of the link through a slot or for the connector. Within the cavity l l the connector I4 is bent upwardly, on' an angle, and then vertically into a slot or recess IQ for further support.

At the opposite end of the housing, terminal screw 3 is threaded into a connector plate 20 which passes through a slot in the housing on an angle and then vertically into the cavity l2 where it is bent over to provide a support 2| for a current responsive member 22. The support 2! and the extremity of the current responsive member are welded together in suitable manner.

In the structure shown in the drawings the current responsive device 22 is a bimetallic element connected in series circuit with the switch as described at a later point in the specification and, therefore, is responsive to the current flowing through the switch. Member 22, in the preferred form, extends backwardly along the overturned portion of the connector plate 20 and then drops down into the cavity l2 toward the bottom wall thereof, its lower end 23 constituting a latch or trip which is actuated as. the bimetallic element warps under the heating effect of an abnormal current. At the bend in the thermally responsive member 22 it is engaged by an adjustment screw 24 which passesthrough the connector 2 I, the head of the adjustment screw being located in a recess 25 in the back wall of the housing. Through adjustment of this screw the sensitivity of the trip may be controlled.

The handle 4 of the switch is mounted on an axle 26 having its ends journalled in the housing clearance opening in the movable contact member as shown in Figure 7. This arrangement permits limited movement ofthe contact member independently of the link. As an alternative the link 38 may be slotted equivalently to receive fixed trunnions extending outwardly from the sides of the movable member.

Contact member M is in the form of a bar, one end thereof projecting beyond the pin 42 to carry a movable contact 43 which is operable into and out of engagement with the stationary contact Hi and which, as seen in the drawings, is inclined to the angle of the stationary contact I6 for face to face meeting of the two. The forward portion of the bar passes through a slot in a barrier 44, fitted within aligned grooves in the housing, whereby the barrier delineates the switch contact cavity II from the mechanism cavity l2. The barrier prevents flashes or sparks which attend switch operation from gaining access to the mechanical elements of the barrier and thereby protects them from becoming damaged or burned.

Contact member 4i extends beyond the pin 42, in an opposite direction, and terminates in a latch or ledge 45 which is engaged by the terminal portion 23 of the current responsive trip member 22. The bar 4! forms part of the electrical circuit of the switch through a flexible connection 46 having one end fastened to the circuit protector 22 while the other end is connected to the contact bar.

A compression spring 41 which is seated in a cavity 48 formed at the bottom wall of the housing cavity l2 biases the bar 4| toward closed position of the contacts, and for the purpose cavity walls whereby longitudinal displacement oi the switch member 4| is prevented. This pin, like pin 42, passes through a slot or clearing in the bar 4|, and this slot 5| in conjunction with the slot through which the pin 42 passes permits the bar 4| to move about the fulcrum provided through engagement of the latch 23 with the latch ledge 45; such movement, of course, is under the influence of the spring 41.

The indicator or resetting member 5 extends downwardly into the cavity l2 and terminates therein at a head portion which is straddled by the upper extremity of a second linkage system indicated generally at 52. For purposes of clarity and to avoid confustion in identification of the parts the reference numerals which are applicable to the linkage 52 appear mainly on Figures 4 and 6, while the reference numerals which are applicable to the handle operated linkage appear mainly on Figures 3 and 5 and are omitted in Figures 4 and 6.

Linkage 52 comprises toggle connected members 53 and 54, pinned or riveted together through pin 55, the members being spaced apart respectively to straddle the head of the indicator 5 at the one end and to straddle the contact bar 4| at the other. The lower extremities of the members 54 are pivotally connected to the contact bar by means of pin 55.

As shown in Figure 9, the upper pair of links, 1. e., 53 respectively have stop elements 51 extending laterally therefrom toward one another and the lower links 54 respectively are spanned by the upper pair 53, wthereby the stop elements 51 bear against the edges of the links 54 to limit the movement thereof toward one off-center position as shown in Figure 6. In this position the center pin of the breakable linkage system is to one side of the line of pressure which is exerted upon the system through the indicator 5 and, by virtue of the action of the stops the linkage system is stifi and acts as a rigid link. To urge the parts in this direction toward this position center pin 55 is surrounded by a torsion spring 58, one end thereof abutting links 53 and the other end abutting links 54. Thus, through the action of this spring the links, when released, voluntarily will assume the rigid position.

For the purpose of breaking the toggle so that it becomes incapable of imparting to the bar 4| any movement of the indicator 5, whereby a tripfree action is obtained, one of the set ,of links, either 53 or 54, or both as the case may be, has a portion 59 extending therefrom for actuation with the cam 40 of the handle. When the handle is swung backwardly this cam pushes upon the portion 59 of the linkage, thereby moving the pivot 55 of the toggle system to the opposite side of the pressure line. In accordance with this movement the stop elements 51 are swung out of the path of the edges of links 54 and the linkage is broken; it is now capable of absorbing any movement of the indicator 5 without transmitting such movement to the contact bar. Thus the effectiveness and ineffectiveness of the linkage system for actuating the contact bar 4| is controlled in accordance with the disposition of the switch operating handle and the indicator, in turn, is capable of actuating the contact bar 4|, for the resetting of the trip at the latch 23 only after the contact bar simultaneously has been moved by the handle to a switch-open position. This arrangement prevents any sparking incidental to the completion of a circuit from occurring at the latch.

When the apparatus is in operation as a circuit controller with the switch contacts closed, the parts occupy the relationship shown in Figure 4. The handle is in its forward or "on" position: the toggle system 52 is broken and is held in broken position by virtue of the engagement of the handle cam 45 with the extended portion 58 of the breakable linkage. Indicator 5 is in its receded position, the upper edge, for purposes of comparsion, being shown adJacent to or substantially flush with the upper surface of the unit. Any movement imparted to the indicator at this time is capable only of moving the center point 55 of the breakable linkage a little farther back without altering position of the contact bar 4|.

The counterpart of this condition, that is, the condition in which the switch manually is opened while the circuit breaker is untripped is shown in Figure 3. Handle 4 has been rotated in a backward direction and the rotary movement of the handle has moved the links 38 downwardly, lowering the forward end of the contact bar against the spring 41 to separate the contacts. Pin 55 is at the upper extremity of the slot 5| in the contact bar and the pin 42, conversely, is at the lower extremity of the slot within which it rides.

When an abnormal condition occurs the current responsive controller 22, warped through heating by the abnormal current, releases the ledge 45 from engagement with it, whereupon the contact bar 4|, under the influence of the spring 41, moves upwardly. This movement effects separation of the contacts l5 and 43. The position of the parts just after tripping is that shown in Figure 5. The bar has moved upwardly through a limited distance and the pin 55 now rests at the lower extremity of the slot 5| within which it resides; the same relative position is occupied by pin 42 in its slot.

The breaker can be tripped through overload current conditions only when the handle extends forwardly to occupy the on" position. When the handle is thrown rearwardly the switch contacts are opened and the current responsive device does not function because it is out of circuit. When the handle is in the on" position and the switch member 4| is tripped the upward movement of the rear portion of the switch member is absorbed momentarily but in the linkage 52 which is held in a broken condition by the action of the handle cam. However, the linkage knee straightens itself under the influence of the spring 58 whereby the resetting pin 5 is moved outwardly from the casing to indicate that the breaker has been tripped.

To reset the mechanism, the handle 4 is swung in a rearward direction, as shown by the arrow in Figure 5, and in the first phase of its movement, the rotation of the handle lowers the link 88 to drop the contact bar 4| below its normal switch-open position. This movement is accommodated by the slots in the contact bar which are traversed by the pins 42 and 55.

As the handle is moved rearwardly, as shown in Figure 5, the cam 40 is swung away from the broken linkage and it straightens itself to assume its stiff condition. As the cam portion of the handle leaves the linkage, the indicator rises further, beyond the surface of the housing, and by the time the handle has approached the switchoff position the indicator is most extended. 'I'hereupon further movement of the handle in the same direction causes the indicator to be depressed. and inasmuch as the linkage now is 7 stiil', its motion is imparted to the bar M whereby the back end of the bar is lowered until the ledge 23 is accessible to the latch. By this time the current responsive controller has returned its element 22 to its normal position and the ledge is engaged thereby. After the breaker control is reset the handle is swung forwardly whereby the contacts are reengaged, the parts again resume the relationship shown in Figure 4, and the breaker is restored to service. I

The advantages of the breakable linkage system operating in conjunction with the indicator are that no movement of the indicator can alter the position or condition of the circuit breaker trip nor can the switch be held in a closed position contrary to the control of the circuit breaker. Thus, a closed circuit through the switch cannot be maintained while abnormal conditions are prevailing. However, for emergency service the ad- Justment screw 24 can be screwed inwardly sumciently so as to prevent the current responsive element from operating to release the switch member 4|, in which event the circuit breaking mechanism of the switch becomes inoperative. This provision adapts the unit for service in airplanes and other mechanisms where trip-free circuit breaking operation normally is desired but where provision is necessary for holding the switch contacts closed, regardless of the consequences of prolonged overload.

It is also to be noted that the point of pivotal connection of the link 38 with respect to the handle always is over-center in relation to the spring 41 whereby the pressure of the spring is exerted upon the handle to maintain the handle in "on or off position, In this manner inadvertent or unintentional movement of the handle is prevented. The detents for the handle cooperate with this structure and, additionally, provide "snap action of the handle for quick make and break of the contacts.

Having described my invention, I claim:

1. A circuit breaker comprising a stationary contact, a movable contact for engagement with the stationary contact, a handle, a current responsive releasing device, means for biasing said movable contact in a direction for engagement with, and when released, beyond said current responsive device, a first lever, operated by said handle, to actuate said movable contact into and out of engagement with-said stationary contact, and a second lever, in the form of a breakable member for moving said movable contact independently of said first lever, means for biasing the said breakable member toward a stifi unbroken position, and means controlled by said handle for breaking said breakable member when said handle moves said first lever to engage said contacts with one another.

2. A circuit breaker comprising a stationary contact, a movable contact actuable into and out of engagement with said stationary contact, a handle, first means for moving said movable contact by said handle, a current responsive device for controlling engagement of said stationary and movable contacts independently of said handle and said first means, an indicator member and a breakable connection between said indicator and said movable member for effecting resetting of said movable member after it has been controlled by said current responsive device, said handle constructed to break said breakable memher and prevent actuation thereof by said indica tor when said handle is moved'to a position in which said contacts are in engagement with one another.

3. A circuit breaker comprising a stationary contact, a, movable contact member cooperating .5 with said stationary contact, a handle for actuating said movable contact member, a current responsive device for controlling the disengagement of said cooperating contacts independently of said handle and operating as a trip, and means for resetting said trip, comprising a breakable linkage and means operated in conjunction with i said handle for breaking said linkage when said handle is moved to actuate said contacts into engagement with one another whereby the broken linkage is incapable of effecting resetting said trip until said handle is moved to disengage said contacts. 1 f-s 4. A circuit breaker comprising a stationary contact, a movable contact positioned for engagement and disengagement with the stationary contact, means for biasing the movable contact toward engagement with the stationary contact, a. first lever for controlling engagement of said contacts, a current responsive device controlling disengagement of said contact independently of said first lever, a second lever for moving said movable contact independently of said first lever to restore to said current responsive device the control of said movable contact following the exercise of such control, said second lever comprising a jointed connection effective for transmitting movement in one position and inefiective v for transmitting movement in another position, means controlled by said first lever for holding said jointed connection in ineffective position when said contacts are closed by said first lever. and means for restoring said jointed connection to eflective position upon movement of said first lever to open said contacts.

5. A circuit breaker comprising a stationa y contact, a movable contact biased toward said stationary contact, a first lever for moving said movable contact into and out of engagement with said stationary contact a current controlled trip for eifecting disengagement of said contacts independently of aid first lever, means including a second lever for restoring to said current responsive device the control of said movable contact following exercise of such control, a handle 5 foroperating said first lever, and means controlled by said handle for rendering said second lever inefiective to restore control of said movable contact to said current responsive device except when said handle ha been moved to efiect disengagement of said contacts through said first lever.

6. A circuit breaker comprising a casing having isolated chambers, a stationary contact, and

a movable member having a contact cooperating with said stationary contact within one of said chambers and means confined'within the other of said chambers, including a handle for moving said movable member, a current controlled trip for controlling movement of said movable memher independently of said handle to disengage said contacts, a resetting device to restore to said trip the control of said movable member following the exercise of control thereby, and means actuated by said handle for rendering said resetting device inefiective except when said handle has been actuated to disengage said contacts.

7. A circuit-breaker comprising a casing having isolated chambers, a stationary contact, and

a movable member having a contact cooperating with said stationary contact within one of said 9 chambers and means confined within the other of said switch member independently of said of said chambers, including a handle for movhandle upon occurrence of an abnormal current,

ing said movable member, a current controlled means for moving said switch member against trip for controlling movement of said movable said spring to restore to said current responsive member independently of said handle to dis- 5 device its control of said switch member, and engage said contacts, a resetting device to remeans for rendering said last named means instore to said trip the control of said movable effective upon movement of said handle to a cirmember following the exercise of control therecult closed position.

by, and means controlled by said handle for ren- 12. A circuit breaker comprising a movable dering said resetting device ineffective except 1 switch member, a stationary contact cooperating when said handle has been actuated to disengage therewith, a handle in off-center connection with said contacts, said resetting device being posi said switch member for moving it to switch open tioned adjacent said handle for actuation thereand switch closed positions, said switch member by when rendered effective. being movable independently of said handle for 8. A circuit breaker comprising a casing having movement to a switch open position, a current therein a stationary contact, a movable bar havresponsive device for controlling the independent ing a contact for engagement with said stationmovement of the switch member, means for reary contact, means for biasing the contacts tosetting said switch member following independward engagement with one another, a handle ent movement thereof, andmeans controlled by pivotally mounted in said casing, means for movsaid handle for rendering said resetting means ing said bar by said handle for manual control ineffective when said handle is moved to aposiof engagement and disengagement of the contion corresponding with the switch on position of tacts, a current responsive trip for controlling said switch member.

movement of the bar and disengagement of the 13. A circuit breaker comprising a movable contacts under the influence of said biasing switch member, a stationary contact cooperating means independently of the handle, an indicator therewith, a handle in off -center connection with extending through said casing and a toggle insaid switch member for moving it to switch open terconnecting the end of the indicator within the and switch closed positions, said switch member casing with said bar, said toggle being movable being movable independently ofsaid handle for to a stiff position wherein it is effective for transmovement to a switch ope position, 9: current mitting movement of said indicator to said bar sponsive device o co t o fi s t e d p nd nt to reset said trip following actuation thereof and movement 01 t Switch member, a link r s tsaid toggle also being movable to a second positing said sw tch m r f l w independent tion wherein it is broken and incapable of trans m v m nt th r f and a am p a in unis n mitting movement, and means controlled by said with said handle for breaking said link to render handle for holding said toggl in b ok d it ineffective when the handle is moved to a tion when the handle has actuated the contacts switch on position. into engagement. 14.'A circuit breaker comprising a casing, a

9. A circuit breaker comprising a contact bar, handle mounted on said casing, an indicator a stationary contact for engaging one d of th 40 mounted on said casing, a stationary contact and contact bar, a current responsive devi for na cooperating switch member mounted within gaging an op osite end of th nt t b said casing, said handle and said indicator being spring biasing aid contact her for o t 7 respectively interconnected with said switch past said current responsive device when released member for effecting m nt hereof indethereby and for biasing said contact bar toward Dendently O One another. a Current p s v said stationary contact, a handle, means for-opdevice for controlling movement of said switch crating said bar against said spring from said member independently of S handle a d Said handle comprising a link subject to the pressure indicator, d m ns o r l d by s id handle or the spring and having ctr-center connection for rendering d indicator ap b f pa twith said handle in both its on and of! positions, ing movement to said switch member. and means controlled by said handle for resetting 15. A circuit b a r comprising a casin havsaid bar when it has been released by said euring a switch member mounted therein for rockrent responsiv device, ing movement, means supported by said casing 10, A circuit br ak comprising t h for withholding said switch member against lonmember, a handle, means interconnecting said gitudinal displacement, e a l rocking Said handle with said switch member for effecting Switch member, e current responsive d c or movem nt thereof t opened and dosed circuit controlling movement of said switch member inositions, a c r t responsive device providing dependently of said handle and a resetting device latch for ai it h member about which Said having an indicator portion extending from said wit h member is movame t opened and closed casing positioned for engagement by said handle circuit positions, means for biasing said switch to effect resetting of Said switch m e and member to closed circuit position and for effectmeans controlled b d a e n o e position ing movement of said switch member to open thereof for rendering said resetting mechanism circuit position when released by said latch, a incapable o o n sa d switch member.

toggle for moving said switch member, and

means controlled by said handle for breaking EDWIN LANDMEIER- said toggle to render it ineffective when said handle has operated said switch member to REFERENCES CITED closed circuit position The following references are of record in the 11. A cirlcuit breaker comprising a switch memm of thi patent:

ber movab e to open and closed circuit positions,

a handle for moving said switch member to open UNITED STATES PATENTS and closed circuit positions, current responsive Number ame Date means including a spring for effecting movement 2,132,626 Jackson Oct. 11, 1938

Images