US2290367A

US2290367A - Circuit breaker with an automatic and manual release

Info

Publication number: US2290367A
Application number: US363706A
Authority: US
Inventors: Bottinger Gunther; Prange Kurt
Original assignee: Westinghouse Electric and Manufacturing Co
Current assignee: CBS Corp
Priority date: 1936-08-04
Filing date: 1940-10-31
Publication date: 1942-07-21
Anticipated expiration: 1959-07-21
Also published as: DE729567C; CH216606A; GB481407A; FR825136A; BE422958A; DE741351C; NL45995C; US2217462A; NL52541C; BE422957A; DE719663C; FR825137A; GB483204A

Description

y 1942- G. BGTTINGER ET AL ,290,367

CIRCUIT BREAKER WITH AN AUTOMATIC AND MANUAL RELEASE Filed Oct. 31, 1940 2 Sheet s-Shet 1 ATTORNE July 21, 1942- G. BOTTINGER ETAL CIRCUIT BREAKER WITH AN AUTOMATIC AND MANUAL RELEASE Filed Oct. 31, 1940 2 Sheets-Sheet 2 INVENTORS Gntfia-B'itizgerazd [Kant fizz/ye.

ATTORNEY gggNEssFs: I

Patented July 21, 1942 ICE CIRCUIT BREAKER WITH AN AUTOMATIC AND MANUAL RELEASE Giinther Biittinger, Berl Kurt Prange, Berlinin-Siemensstadt, and Spandau,

Germany, as-

signors to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application October 31 In Germany 7 Claims.

The invention relates to a circuit breaker with an automatic and manual release and provided with a toggle mechanism. The present invention covers a circuit breaker which is an improvement and further development of the circuit breaker mechanism disclosed in the copending application of Hans H. Willmann, Serial No. 157,028, filed August 2, 1937, now Patent No. 2,217,462, issued October 8, 1940, and assigned to the Westinghouse Electric & Manufacturing Company. In the circuit breaker mechanism disclosed in the aforementioned copending application, the knee pivot of the toggle is guided in an elongated slot of a part integral with the manually operable handle for closing the breaker, one end of the toggle being pivotally connected to a latching lever controlled by the release members and the other end thereof cooperating with the switch lever. The latching lever is releasably held in the closed circuit position of the circuit breaker by a holding lever having unequal arms, the longer arm cooperating with the latching lever and the shorter arm being actuated by the release members. The pressure betweenthe latching lever and the holding lever acts on the pivot of the holding lever. This switch mechanism presents the advantage over the switch mechanism of the known circuit breakers in that the time lag of the release is small, and the breaker can readily be manufactured at a relatively low cost on a large scale.

An object of the present invention is to provide a circuit breaker of a very compact design while ensuring the greatest possible interrupting capacity without impairing the reliability of operation. This may be accomplished according to the invention by designating the switch mechanism in the following manner: The switch lever is rotatably mounted in the neighborhood of the shortest possible line connecting the pivot of the latching lever and the base and is coupled through an intermediate link with the end of the toggle which is connected to a pivoted guide link. The switch lever extends substantially parallel to the base in the direction tawards the shortest line that can be drawn from the end of the toggle cooperating with the switch lever to the base. With the switch mechanism according to the invention the switch lever need only carry out very small control motions brought about by the toggle. In order to attain a relatively large distance of contact separation, the switch lever is made long. Since the switch lever is arranged substantially in parallel relation to the base, the circuit breaker has a relatively small height notwithstanding the long switch lever. Besides the small height, the circuit breaker has a small base surface, since the switch lever need not be any longer than the toggle with its locking parts.

, 1940, Serial No. 363,706

August 3, 1939 (Cl. 2001l6) The small dimensions of the circuit breaker are also due to the fact that the stationary contact cooperating with the switch lever is secured to a bar conductor which extends parallel to the base in the direction towards the shortest line that can be drawn from the pivot of the latching lever to the base, and the conductor has a gap therein bridged by a bimetallic strip which is disposed substantially parallel to the base. The design of such a circuit breaker makes it possible not only to arrange the bimetallic strip in a very small space but also to provide very simple current paths within the circuit breaker.

Of particular advantage is the provision of a gap or space between the free end of the bimetallic strip and the holding lever controlled thereby, which holding lever latches the latching lever of the toggle. The bimetallic strip must when heated traverse the gap or spac before it comes into engagement with the holding lever.

By designing the circuit breaker as described above oscillations of the bimetallic strip caused by the vibrations of the circuit breaker cannot falsely release the switch mechanism so that the circuit breaker according to the invention is protected to a high degree against vibrations.

The novel features that are considered characteristic of the invention are set forth in particular in the appended claims. The invention itself 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 drawings in which:

Figure l is a partly schematic view of a circuit breaker embodying the features of the present invention, the breaker being shown in open circuit position,

. Fig. 2 is a view similar circuit breaker in closed Fig. 3 is a vertical plete circuit breaker with the invention,

Fig. 4'is an end elevational view of the circuit breaker shown in Fig. 3, and

Fig. 5 is a side elevational view of the circuit greaker as view from the right-hand side of The invention will first be explained by reference to Figs. 1 and 2. Fig. 1 shows the circuit breaker in the open circuit position and Fig. 2 in the closed circuit position. The reference numeral I designates the base of the circuit breaker on which is mounted the switch mechanism. A stationary contact 2 cooperates with a movable contact 3 secured to a pivoted switch lever 4. The circuit breaker is adapted to be manually closed by means of a closing push button 5. In-

to Fig. 1 but showing the position,

sectional view of a comconstructed in accordance tegral with the closing push button 5 is a part I provided with an elongated slot 6 and having integral therewith a rod-like extension 8. The push button .5 and the rod-shaped extension 8 are guided along the stationary transverse walls 9. lfl.

In the elongated slot 6 moves the knee of a toggle consisting of the toggle links H, l2.

One end of the toggle is pivotally connected to 4 through a coupling member IS. The member l9 and switch lever 4 are rotatably mounted on the stationary pivot 20. Between the member l9 and the switch lever 4 acts a spring 2| wound around the pivot 20. One end of the spring presses against the member l9 and the other end against the switch lever 4 so that the spring tends to move the switch lever against the stationary contact 2.

An essential feature of the switch mechanism according to the invention is the fact that the pivot of the switch lever 4 is arranged in the neighborhood of the shortest line connecting the pivot M of the latching lever l3 and the base I. From here the switch lever extends substantially parallel to the base i in the direction towards the shortest line that can be drawn from the end of the toggle cooperating with the switch lever to the base. In this manner it is possible to accommodate-in the circuit breaker a relatively long switch lever. Since the switch lever is very long the break distance between. the contacts 2 and 3 is great. Owing to the great break distance the circuit breaker has a great interrupting capacity. In order to attain this great break distance the switch lever need not be any longer than the length of the upper part of the switch mechanism. Owing to the parallel arrangement of the switch lever and the linkage to the base I, the height of the circuit breaker can be made very small. Since the upper part of the switch mechanism does not require a great width, the design of the switch mechanism according to the invention is such as to obtain a very compact circuit breaker.

The spring 2| wound around the pivot 20 acts r not only as a contact pressure spring so as to ensure a reliable contact pressure but also serves to bring about a snap movement when the contacts are closed. The quick make action of the contacts is accomplished with the aid of a hook-shaped member 22 which is pivotally connected to the switch lever 4 and is under the action of a biasing spring and cooperates with the stationary transverse wall ID. The hook shaped member 22 is adapted to be moved out of engagement with the wall I by the part 'I of the push button 5 as the push button 5 approaches closed position, thus releasing the switch lever 4 for closing movement by the spring 2|.

Besides the spring 2| there are two further springs in the switch mechanism. These two springs are wound around the stationary pivot l3. One spring 23 is the circuit opening spring, one end of which presses against the stationary frame and the other end against the toggle conpivot sisting of the member l2 and the intermediate link H. The other spring 24 is a lifting spring for returning the closing push button 5 outwardly to open position when the breaker is tripped. One end of this spring presses against the stationary frame and the other end is connected to the part I of the push button 5.

A pin 5| on the member l9 extends laterally therefrom and is disposed to engage a portion of the switch member to the left of the pivot 20 when the member I9 is moved in a counterclockwise direction by the opening spring 23, upon opening operation of the breaker. The pin 5| picks up the switch member 4 after the member l9 has rotated a small amount in a counterclockwise direction and causes the switch member 4 to be rotated to open position shown in Fig. 1 with the member 19, by the action of the circuit opening spring 23.

Between the switch lever 4 and the base I is arranged a conductor bar 25 secured to insulating supports on the base I. The conductor bar is arranged above the base I and carries the stationary contact 2. From this contact the conductor bar 25 extends in the direction towards the shortest line connecting the pivot l4 of the latching lever l3 and the base I. The conductor 25 is interrupted as indicated at 26. This gap is bridged by a U shaped bimetallic strip 21 which is arranged according to the invention in parallel relation to the base I and has a free portion of substantial length extending laterally from the conductor 25. The free end of the bimetal strip 21 is bent back on itself as shown in Figs. 4 and 5, and the strip is arranged to deflect outwardly, i. e., away from the base I, to trip the breaker by moving the holding lever l5. In this manner thebimetallic strip is arranged in the circuit breaker in a very small space. Under certain circumstances a shunt resistance may be arranged in parallel relation in the bimetallic strip 21. This shunt resistance is not shown in I the drawings. The end of the conductor 25 opposite to the contact 2 leads to a terminal. From a second terminal extends a flexible conductor 28 which is connected to the switch lever 4. The two terminals are not shown in Figs. 1 and 2.

The operation of the switch mechanism according to the invention is as follows:

In Fig. 1 the switch mechanism is in the open circuit position in which the contacts 2 and 3 are spaced from one another. The hook-shaped member 22 comes into engagement with the rear side of the stationary transverse wall Hi. If the closing push button 5 is depressed the knee pivot of the toggle ll, 12 is moved in the downward direction and the toggle is extended. As shown in Fig. 2 which indicates the closed circuit position of the switching mechanism, the toggle is slightly overset. Since the latching lever I3 is in engagement with the holding lever l5 it cannot rotate and thus forms a support for one end of the toggle H, [2. Consequently, the link it rotates in the counter-clockwise direction. During this rotation the member I9 is rotated in the clockwise direction by the intermediate link H. The switch lever 4 is prevented from being moved at first, since the hook-shaped member 22 engages the rear side of the stationary plate ll. As soon as the closing push button 5 approaches the lowest position the part 1 of the pushbutton pushes the hook-shaped member 22 aside and releases the switch lever 4. The switch lever can then snap into the closed circuit position in g which the contacts 2 and 3 are in engagement.

v bar 39 of the open circuit member 38.

When the circuit breaker is being closed the circuit opening spring 23 and the lifting spring 24 becomes stressed. If the bimetallic strip 21 is actuated in response to an overload of the circuit to be controlled or if the circuit breaker is brought into the manually operated circuit position by the open circuit opening member hereinafter described, the holding lever l moves away from the latching lever i3 and re- I leases the latter. Upon the release of the latch: ing lever the guide link I6 is rotated under the action of the circuit opening spring 23. By this rotation the member I! and the spring 2| of the switch lever 4 are snapped, through the intermediate link ll, into' the open circuit position. At the same time the push button a is raised by the spring 24 from its lowest position.

Figs. 3 to 5 show an embodiment of the circuit breaker schematically shown in Figs. 1 and z. The base I consists of a sheet having a cavity at the rear and a narrow bottom of rectangular 7 form.

Terminals

29, 30 are mounted on an insulating body 3| at one end of the base I. From the base extend two

side walls

32 and 33 which are spaced from each other by the transverse walls 9 and ID. The side walls are-lined at the sides facing each other with

plates

34, 35 of insulating material. The side walls and the plates of insulating material form the bearings for the stationary pivots of the switch mechanism. in order to insulate the switch mechanism with respect to the switch lever 4, the coupling member I9 is made of insulating material. l

The switch mechanism according to, themvention presents, furthermore, the iollowing advantages.

The holding lever l5 which blocks the latching lever I3 is preferably in the form of a threearmedlever mounted on the stationary pivot 36. It has a long arm and two short arms. The long arm cooperates with the latching lever I3,

the second arm carries an adjusting screw3l opposite to the bimetallic strip 27. The third arm cooperates with a manually operable circuit opening member 38. The circuit opening member 38 is a push button and is provided with a bar 39 guided along the wall 33. The nose 40 of the bar 39 acts on the short arm of the holding leve'r I5. The stop lever I5 is under the action of the spring 4| wound around the pivot, 36. One end of the spring contacts with the arm of the stop lever carrying the adjusting screw 31 and the other end is connected to the The spring tends to move the holding lever l5 into the active zone of the latching lever l3. The movement of the holding lever in the active zone of the latching lever is, however, preferably latching lever is kept as small as possible. The

holding lever has a portion cut away so that when the holding lever is moved to released position it does not impede movement of the latching lever IS.

The holding lever l5 and the bimetallic strip 21 are preferably arrangedwith respect to each other in such a manner that the bimetallic strip in a cold state is spaced from the adjusting screw 31 of the holding lever. This gap must be traversed by the bimetallic strip when heated before it comes into-engagement with the holding lever. Owing to this spacing or gap, oscillations of the bimetallic stripwhich occur when the circuit I circuit breaker are avoided upon the occurrence of vibrations.

If various automatic circuit breakers according to the invention are arranged close to one another it is preferable under certain circumstances to provide the circuit breaker with a special current supply bar 44 connected to the conductor bar.25.

This additional current supply bar 44 is preferably connected to the portion of the conductor 25 arranged between the bimetallic strip 21 and the terminal3fl. The conductor 44 is preferably arranged in the cavity of the based and brought out at the end of the base opposite to the terminal 30. This additional current supply bar is employed if various automatic circuit breakers are to be connected to a common bus bar.

What is claimed is: g I

1. A circuit breaker comprising a base, a pivoted switch arm on said base, operating means therefor on said base comprising a pivoted latch ing lever means for releasably restraining said lever in one position, a toggle pivotally connected at one end to said latching lever, means for guiding I the other end of said toggle for movement in a fixed path, means including alink connecting the guided end of said toggle 'to said switch .arm, an operating member for moving the knee pivot of said-toggle to cause said toggle to move said switch arm to closed circuit position, trip means operable to effect release of said latching lever to cause movement of said switch arm to open circuit position, the pivot of said switch arm being disposed in close proximity to a line from the pivot of the latchirm lever normal to the base, said switch arm being disposed substantially parallel to the base and extending toward a line drawn from.

the guided endof the toggle normal to the base.

2. A circuit breaker comprising a base, a pivoted switch arm on said base, operating means therefor on said base ,comprising a pivoted latching lever, means for releasably restraining said lever ,in one position, a toggle pivotally connected at one end to said latching lever and at the other end to a pivoted guide link, meansineluding a link connecting the guided and of said toggle to said switch arm, an operating member having an elongated slot for engaging.

the knee pivot of the toggle, said operating member being operable to cause said toggle to move the switch arm to closed circuit position, trip means operable to effect release of said latching lever to cause movement of the switch arm to open circuit position, the pivot of said switch arm being located in close proximity to a line drawn from the pivot of the latching lever normal to said base, said switch arm being disposed substantially parallel to the base and extending in a direction toward a line drawn from the pivot of the guide link normal to said base 3. A circuit breakereomprising a base, a pivoted switch arm on said base, operating means therefor comprising a pivoted lever, means for releasably restraining said lever in one position, a. toggle pivotally connected at one end to said lever, means for guiding the other end of the toggle for movement in a eluding a link connecting the guided end of the toggle to said switch arm, an operating member operable to move the knee pivot of said toggle to cause said toggle to move the switch arm to closed circuit position, arm being located in close proximity to a line drawn from the pivot of said lever normal to the base, said switch arm extending substantially parallel to said base in a direction toward a line drawn from the guided end of the toggle normal to the base, a stationary contact engageable by the switch arm and secured to a conductor bar which lies parallel to the base and extends toward the normal line from the fixed path, means inpivot of said lever to the base, said conductor bar having a gap therein, and a strip of bimetallic material bridging said gap and disposed subthe pivot of said switch stantially parallel to said base for effecting release of said lever in response to predetermined ,overload'conditions to cause movement of the switch arm to open circuit position.

4. A circuit breaker comprising a pivoted switch arm, operating means therefor comprising a pivoted latching lever, a holding lever for releasably restraining said latching lever in one position, a toggle connected at one end to said latching lever and at its other end to the switch arm, an operating member for moving the knee pivot of the toggle to cause movement of the switch arm to closed circuit position, a manually operable tripping member for moving said holding lever to release thelatching, lever and thereby cause opening of the breaker, and a birnetal element heated in response to the current of the circuit for moving said holding lever to effect release of said latch.- ing lever in response to predetermined overload conditions, said holding lever having three arms, one of said arms being engageable with the latching lever to restrain said latching lever, another of said arms cooperating with said bitoward .a line drawn from the pivot of the latchmetal element, and the third arm cooperating with said manually operable tripping member, a spring biasing said holding lever into a position in which it engages said latching lever, and means, including a stop on said holding lever for limiting the distance 01' travel of the holding lever within its range of engagement with the latching lever.

B. A circuit breaker comprising relatively movable contacts, operating means therefor comprising'a manual operating member operable to close for moving the knee pivot of said toggle to close the breaker, a manually operable tripping member for moving said holding lever to effect release of said latching. lever to cause opening or the breaker, a bimetal strip operable in response to predetermined overload conditions to move said holding lever to effect release of said latching lever and thereby cause opening of the breaker, a stationary contact engageable by said switch arm, said contact being secured to a'conductor bar which lies parallel to the base and extends ing lever normal to the base, said conductor bar having a gap therein bridged by said bimetal strip which is also disposed substantially parallel to said base, the pivot of said switch arm being located in close proximity to a line drawn from the pivot of the latching lever normal to the base, and said switch arm extending substantially parallel to the base and toward a line drawn from the guided end of the toggle normal to the base, said holding lever having three arms, one of said arms being engageable with said-latching lever for restraining said latching lever, another of said arms cooperating with said bimetal strip, and the third arm cooperating with said manually operable tripping member.

7-. A circuit breaker comprising a hollow base plate, a pivoted switch arm on said base, operating means therefor on said base comprising a pivoted latching lever, a holding lever'ft': releasably restraining said latching lever in one position, a toggle pivotally connected at one end to said latching lever, means for guiding the other end of said toggle for movement in a fixed path, means including a link connecting the guidedend of said toggle to said switch arm, ,an operating member'for moving the knee pivot of said toggle to close the breaker, the pivot of said said contacts, a member releasable to cause opening oi said contacts, a holding lever for restraining said releasable member, a manually operable tripping member for moving said holding lever to release said releasable member, and a bimetal element heated in response to the current of the circuit and operable in response to predetermined overload conditions to move said holding lever to effect release of said releasable member, said holding lever having three arms, one of said arms being engageable with the releasable member to restrain said member, anoth er of said arms cooperating with said bimetal element, and the third arm cooperating with the manually operable tripping member, said bimetal element normally being separated from said holding lever by a predetermined distance through which the bimetal element must move before engaging the holding ,lever.

6. A circuit breaker comprising a base, a pivswitch arm being located in close proximity to a line drawn from the pivot of the latching lever normal to said base, and said switch arm ex tending substantially parallel to the base in a direction toward a line drawn from the guided end of the toggle normal to said base, a stationary contact engageable" by said switch arm,

said contact being secured to a conductor bar which lies parallel to said base'and extends toward a line drawn from the pivot of the latching lever normal to said base, said conductor bar having a gap therein bridged by a bimetal strip disposed parallel to said base, said bimetal strip being operable in response to predetermined overload conditions to move said holding lever to effect release of said latching lever and thereby cause opening of the breaker, and an additional conductor bar mounted inside the hollow base and connected at one end to the first mentioned conductor bar, the other end or said additional bar conductor extending out through the end of said base adjacent which the stationary contact is located.

GUNTHER no'rrmasa.

KURT PRANGE.