US2414796A - Electric circuit breaker - Google Patents

Description

2 Sheets-Sheet 1 C. BRESSON Filed June 26, 1940 Ja'n. 28, 1947.

ELECTRIC CIRCUIT BREAKER Jan. 28, 1947. c. BREssoN ELECTRIC CIRCUIT BREAKER Filed June 26, 1940 2 Sheets-Sheet 2 I m/entor' Patented Jan. 28,1947

ELECTRIC CIRCUIT BREAKER Charles Bresson, Lyon, France; vested in the Alien Property Custodian Application June 26, 1940, Serial No. 342,569 In Luxemburg June 27, 1939 2 Claims. 1

This invention relates to electric circuit breakers, and more particularly to a mechanism which causes the currentI interrupting means, following their separation responsive to the occurrence of a fault in the electric system protected, to be reclosed extremely rapidly.

One of the objects of the invention is to reduce the amount of energy required for such reclosing of the current interrupting means.

Another object of the invention is to provide an apparatus for reclosing the current interrupting means in an electric breaker, which comprises a mechanism for storing up potential energy during the separation of the current interrupting means, and redelivering said energy as additional energy for the reclosing of said current interrupting means. The stored energy is obtained from the kinetic energy of the movable parts of the circuit breaker.

The invention, the aforesaid object thereof, and such other aims and objects as may hereinafter appear, will be readily understood from the following description, taken in connection with the accompanying drawings of one embodiment of the invention herein given for illustrative purposes. the true scope of the invention being more particularly pointed out in the appended claims.

Referring to the drawings:

Fig. 1 is a vertical sectional view partly in elevation and partly diagrammatic of a circuit breaker, and an operating column therefor, and operating connections between the column and the movable contact of the breaker.

Fig. 2 is a top plan view of means for turning the operating column of Fig. 1 together with a diagrammatic circuit arrangement for controlling such means.

Figs. 3 and 4 are diagrammatic views showing certain of the operating parts in diierent operating positions.

Fig. 5 is a detailed view, partly in elevation and partly broken away, showing a gearing co-nnection between the column and the contact operating mechanism, and

Fig. 6 is a detailed view of a time lag device for controlling the reclosing of the circuit breaker contacts.

The invention is herein shown in its application to a polyphase circuit breaker, but it is understood that it is not to be considered as limited to said particular application. Said polyphase circuit breaker comprises a normal or main circuit breaker A (see Fig. 2) having connected in series therewith an ultra-rapid circuit breaker B which, upon the occurrence of a fault, acts 2 t immediately to break the circuit of the electric system to be protected, viz: in that phase only which is affected by said fault, and thereaiter recloses said circuit, before the normal or main circuit breaker A having a slow or delayed operation has time to operate. Said normal circuit breaker A is actuated to definitely break said circuit only in the event that the fault' persists.

The circuit interrupting means of breaker B comprises a stationary contact Cz (see Fig. 1) and a movable contact lever, the latter consisting of a rod C` which passes through an arc drawing chamber D and is actuated by suitable means, such as a lever L1, fulcrumed upon a fixed shaft L2 mounted in the frame Ct of the apparatus. Said lever L1 is pivotally connected to the upper end of said movable contact C by a short link I, and intermediate its ends, i. e. at P, is pivoted thereto one end of a link Be, whose other end is pivotally connected at P1 to the one end of a double lever P3 freely fulcrumed upon a horizontal shaft T and having its other end formed as a nose L5. An intermediate member or actuator E is splined upon said horizontal shaft T adjacent said lever P3 and carries a stop-stud Le. Said nose L5 abuts the stop-stud La due to the action of an energy storing spring R1 on said double-lever Pa, said spring R1 being connected between said pivot P1 and a stud P2 of said actuator E. Said spring R1 stores up energy, when the contact C is withdrawn from contact C2 and redelivers said energy subsequently to accelerate the movement of the movable contact C, when the circuit to be protected is reclosed. This will be fully explained hereinafter.

Said actuator E is operatively connected to a rotary column I by means of a beveled gear g2 mounted on the upper reduced end I2 of said column I (see Fig. 5) and engaging a beveled gear g3 secured on said horizontal shaft T which is rigidly fastened to actuator E. Upon the lower reduced end I1 of said column I which is adapted to rotate in suitable bearings located at both ends. is rigidly secured a crank arm Mg (see Fig. 2). The bearings of column I may be of any suitable conventional structure and are omitted in Fig. 1 of the drawings in order not to encumber the latter unnecessarily. A cam Ca engaging said crank Mg is mounted to rotate around a vertical shaft V (see Fig. 2). When the movable contact C is in engagement with the stationary contact C2, shown in Fig. 1. said crank Mg and said cam Ca are in the positions shown in Fig. 2 and further rotationI of said cam Ca counter-clockwise, i. e. in the direction of arrow f1 is stopped links la, Z4, one of which is pivoted to said arm Ld, and the other to the frame of the apparatus. A gear u, only a segment of which is shown in Fig. 2 in order not to complicate the drawings, is connected at S3 to one end of a spiral spring S, whose other end is attached to said cam Ca. l0 at S2, so that upon rotation of said gear'u counter-clockwise, said spring'S will be tensioned and cause said cam Ca to swing also counter-clockwise to rotate said crank arm Mg in the direction of arrow f1 when said toggle ls, Z4 is broken. In other l5 words after release of said cam Ca due to the breaking of toggle la, 14, cam Ca and therewith\`\ crank Mg are rotated under action of said spring S. As a result of this, contact C is separated from contact C2, as will be fully explained hereinafter. Said gear u is driven by an electric motor Mo through a worm W and tensions saidspring S, when said contacts C and C2 are closed and said cam Ca is locked against further counl ter-clockwise rotation by engagement of nose b with said stop roller at R2.

During its counter-clockwise movement, said cam Ca engages said crank Mg, whereby it swings the latter in the direction of arrow fz in Fig. 2

which causes contact C to move away from contact Ca within the arc-drawing vchamber D,

whereupon said crank My engages a stop Lr, and is temporarily locked by the latter against further movement (see position of crank Mg'indicated with a dotted line in Fig. 2). is pivoted at P5 to the frame of the apparatus and connected to said frame by a two-link tpggle Lc which is similarly constructed as toggle ls, Z4 above described. A piston Pr is operated after a certain time interval to break said toggle Lc and 40 thereby release said crank Mg so thatlt can cause said movable contact C to move towards the stationary contact C2 'and thereby close the circuit to be protected.A Said piston Pr is actuated and controlled for this purpose by a retarding or time lag device DM.

Said devices DM and Pr control the reclosing of the circuit ybreaker contacts each time after said contacts have been separated and after a certain period of time has elapsed. Such intervals are necessary for'the deionization of the air at the place where the fault occurred in the circuit to be protected by the circuit breaker.

The retarding or time lag mechanism DM and piston Pr actuated by said time lagr device are lower arm ofadouble-lever I2 of the retarding 65 mechanism DM. Said double-lever I2 swings around the same pivm` I 6 as a gear sector'l1 which is pulled by a main spring I8 in the direction `of arrow I9. A train of gears 20 including a first gear 2I having a ratchet wheel 22 is in en- 70 gagement with the gear sector I1. Said train of gears 20 is under control of an escapement 23 which permits the gears t0 turn but in eXac-tly timed continuously interrupted intervals in a manner well known. The double-lever I2 and 75 Said stop arm Lr 35 The retarding the gear sector I1 are operatively linked to each other by a short spring 24l in such a manner that the lever I 2 will follow the movementsy of the gear sector I1, when the latter is moved inthe direction of the arrow I9. As the gear sector I1 is in engagement with the train of gears 20 controlled by the escapement 23, the turning of said sector and of double-lever I2 occurs also in exactly measured timed- /intervals In the last position of the double-lever I2, its upper arm strikes a catch I3, which then releases a shorter arm 28 of a crank-lever Il, the latter being operatively connected to the piston Pr through a link I5. Thus, as a result of the release of the crank-lever I4, the piston Pr is released and is pushed downwards by a spring 2 placed over the piston rod and acting on the piston Pr. which breaks the toggle Lc whose function has been described above. During the contact closing of the circuit breaker, the upper arm N of said crank vMg swings in the opposite direction, as indicated by arrow f2 and thereby turns the double-lever I2 in the direction of the arrow f3. 'As a result of this, double-lever I2 pulls the gear sector I1 with the aid of the shortspring 24 in the opposite direction of arrow I9, whereby the main spring I8 is tensioned. The ratchet wheel 22 allows the movementl of the gear sector I1 in the opposite direction of arrow I9 without interference of the train of gears 20 and action of the escapement 23. During said movement, the upper arm of double-lever I2 returns the crank I4 in the initial position lin which the shorter arm 28 of crank lever I4 is held by the catch I3.

The gear sector I1 has a stop 25 which limits the rotation of said gear sector I1, when the latter is turned in the opposite direction of arrow I9, i. e. when the main spring I8 is tensioned. During this movement, said stop 25 engages the lower part of a timing lever 1 fulcrumed at the same pivot 26 as crank-lever I4. A dial 21, for example graduated in seconds indicating the time lag, is provided opposite Ithe upper end of said timing lever 1 By simply changing at will, the position of the timing lever 1 with respect to the dial graduation 21 the abutment for the stop 25 of gear sector I1 at the lower part of the timing lever 1, can be shifted, whereby the actuating time of the retarding mechanism DM is varied. Instead of the described 'retarding device any other mechanism of this type may be effectively used.

In the electric diagram of the new circuit breaker, illustrated in Figure 2, a transformer Ti is provided, whose primary is supplied with electric energy of the circuit to be protected by the circuit breakers A and B from a suitable alternating current source through mains MI and M2.

In the normal operation of the system, the parts of the circuit breakers are in the positions shown in Figures 1 and 2 and the contacts C and C2 of circuit breaker B are closed. If now a fault occurs in -the circuit to be protected, said transformer Ti through its secondary actuates a relay R and thereby closes a circuit through a coil of an ultra-rapid two-point switch CUR. As a result of this the latter switch CUR is actuated and a circuit through a coil BB is thereby closed causing an armature BBI controlled by coil BB -to move upwardly and break the toggle la, I4. Thereby, lever Ld is moved to the left and releases cam Ca. The latter now rotates under Crank Mg rotates column I (see Fig. 1) clockwise, and said column through the 4 described. When the position of the actuator E,

shown in Fig. 3 is about to -be reached, movements of lever LI, short link l, and movable contact C will be slowed down, as the system comprising link Be and lever P3 is approaching i-ts dead-center and lever LI is moved proportion- Be. Simultaneously, the rotary movement of column I is accelerated, as the crank Mg in contact with cam Ca has its operative edge so shaped that such movement is produced. When the lever P3 contacts a stop Bt, the system comprising lever P3, link Be, lever LI and movable contact C is stopped, but column I although not acted upon by cam Ca at this phase of operation continues to rotate on account of the impulse that it has previously received. This continued rotation of said column is transmitted to the actuator E, whereby on account of the mentioned stoppage of lever P3 and of the members linked thereto the spring Rl will be tensioned, as shown in Fig. 4. The `energy stored up by column I during the iirsi; phase of its accelerated movement is thus transferred to said spring -Rl whereby the movement of column I is slowed down. Thus, spring RI is strongly tensioned and accumulates the potential energy resulting from'the kinetic energy of column I. When column I reaches its end position, crank Mg takes the position indicated in dotted lines in Fig. 2. In said position crank Mg is locked by the stop arm Lr.

During the rotation of cam Ca, the latter strikes at the proper time a two-point break Ta, which then interrupts the circuit through coil BB so that armature BBI cannot break the toggle la, I4. Said two-pointbreak Ta'. is operatively connected to a mechanical time delayed actuator RM of any suitable conventional construction,

which is adapted to automatically reclose said circuit after a certain time interval has elapsed,

i, e. after the extinction of the arc drawn, whichA is in practice approximately 15 seconds, in order to prevent the circuit from being broken twice in rapid succession in the same arc drawing chamber D.

The reclosure of the contacts of switch B after release of crank Mg. takes place as follows: .In the beginning of the circuit breaking movement of the movable contact C, the upper arm N of crank Mg contacts the above described time-lag relay DM and sets it in operation. Upon the elapse of time, for which said. time-lag relay is adjusted, piston Pr is released by the time-lag relay DM, and the toggle Lc is broken by piston Pr. As a result of this, lever Lr withdrawn to release crank Mg and spring R1 can now re-deliver its energy which it has stored up during the contact separating movement of the movable contact C. Spring R1 causes the actuator E to'swing in the direction of arrowvh of Fig. 4, whereby stop-stud L8 oi' said actuator contacts nose L5 of double-lever P: and swings the latter in the directionof arrow f5. As link Be is operatively connected to lever Ps, said linkis moved downwards and together with it the free end of lever LI linked to the movable contact C. The movement of said contact C is accelerated as above described. and when said contact is about to close vresultant tensioning of said sprfng,

. '6 the circuit, its closing movement is damped by a conventional hydraulic damper Ah.

If upon closing of the circuit breaker B, the fault which caused the circuit breaker to interrupt the circuit to be protected has disappeared, the circuit of coil BD will remain broken by the contacts of relay RR, whose action is sufiiciently retarded. The operating circuit of said relay RR is broken by the ultra-rapid two-point switch CUR, and the main circuit breaker A will then not be actuated to break the circuit. If however,

' l, the fault should persist, relay R and consequentately with `respect to the movement of said link 1y the two-point switch CUR will automatically operate to cause relay RR to close the circuit of coil'BD with the .result that the main circuit breaker A is actuated to denitely interrupt the circuit.

The present invention enablesV all the energy use'd for separating the contacts of circuit breaker B to be stored on the conclusion of the circuit interrupting operation and to be re-utilized for the rapid reclosure of the main circuit by said circuit breaker B. Consequently, a much smaller motor Mo than heretofore required can be used, whereby the same speed for the closure is secured. By reducing the energy to be stored in spring S, the power of the motor Mo can be reduced by the same amount, while a speed of operation is obtained which is comparable to that heretofore obtained with circuit breakers using much more powerful motors without having means for storing the energy. during the opening movement.

I am aware that the present invention may be embodied in other specific forms without depart` tact to break the circuit by moving said movableA contact away from said fixed contact, said means comprising a rotary column, a spring operatively connected. between said column and said movable contact, a stop to arrest the movement of said .movable contact when the latter reaches the end of its circuit breaking stroke, whereby'continued rotation of said column is retarded by the means adapted to release said spring to cause it to redeliver its stored energy to allow said-movable contact to move towards said fixed contact to close the circuit, and a time lag device controlling the release of said spring.

2. In an electric circuit breaker, comprising a xed and a movable contact in the circuitto be protected by said breaker, operating means being constructed and arranged to actuate said movable contact to break the circuit, means for storing up energy during the circuit breaking operation, said operating means comprising a cam, a crank driven by said cam, and a toggle mechanism, said toggle mechanism being adapted to lock said movable contact in its open position after completion of the separating movement of said contact, means to break said toggle mechanism, and a timing device adapted to actuate'v said breaking means after a predetermined time lag to free said crank and 4'thereby allow said means for storing energy to cause the closing movement of the movable contact.

CHARLES BRESSON.

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