US2551303A - Automatic circuit breaker - Google Patents

Description

' y 1951 F. J. M. THEUNISSEN 2,551,303

AUTOMATIC CIRCUIT BREAKER Filed Dec. 3, 1945 20 46 49 a9 48 fix I 26' 4.9 i i 4 50 4a 40 a Z 21 43 35 29 25L 5? o 53 32a U 32 [Mentor fkA/vgozs 12 40 Mm: 795M535 4 fgf,

Patented May 1, 1951 AUTOMATIC CIRCUIT BREAKER Francois Jean Marie Theunissen, Brussels, Belgium Application December 3, 1945, Serial No. 632,442 In Belgium October 17, 1944 Section 1, Public Law 690, August 8, 1946 Patent expires October 17, 1964 6 Claims.

My invention relates to circuit-breakers.

My copcnding patent application No. 632,441 filed December 3, 1945, concerns an automatic circuit breaker provided with an electro-magnet through which the current passes, and the movable armature of which actuates means for liberating (by pawl, toggle, etc.) the movable contact, when an overload current sufficient to attract the said armature passes through the apparatus, said circuit breaker being essentially characterised by the fact that the said movable armature acts directly on the movable contact, independently of the liberating means actuated by said armature. By the direct action on the movable contact, must be understood both action on the contact and on its support, so long as the impulse of the armature is transmitted to the movable contact, without involving the liberating means.

The present improvements relate to modifications and improvements in the said circuit breaker, in particular for the purpose of further accelerating the opening of the circuit in case of a very heavy overload or of a short-circuit.

One of said improvements consists in that the electro-magnet is provided with an auxiliary armature which acts positively on the movable contact, independently of the main armature and as soon as the movable contact has been released by the liberating means by the action of th electro-magnet.

The auxiliary armature is advantageously formed by a part of the member serving to transmit the impulse of the main armature to the movable contact, which member can act on the support of the movable contact or can itself form the support of the movable contact. The main armature can, in particular, be slidably mounted about the said member which is provided with a stop on which the main armature is adapted to act after having released the liberating means.

The provision or" this auxiliary armature has enabled the speed of opening of the circuit to be further increased, since said auxiliary armature is directly afiected by the magnetic flux which should cause the release, and since it is therefore ready to act immediately on the movable contact, as soon as the latter is released, so that the auxiliary armature imparts without any delay a considerable acceleration to the movable contact. If said movable contact had any tendency to adhere to the fixed contact, it would be sharply pulled away from same by the subsequent direct action of the main armature on the movable contact or its support.

Other particularities and advantages of the invention will become apparent from the description of a few examples of constructions, which is given hereinafter with reference to the accompanying diagrammatical drawing, in which:

Figures 1, 2 and 4 show three variants of construction of a circuit breaker according to the invention, in the position in which the current flows, and

Figures 3 and 5 show partial views of the circuit breakers according to Figures 2 and 4, immediately after tripping.

In the case of Figure 1, the movable contact 2 is carried by a beam 3 pivoting about a fixed point 3a and subjected, at 31) to the action of a spring 4 which is attached to a second beam 5 pivoting about the fixed point 5a. The arrangement is such that, in the engaged position illustrated in the drawing, the line of action of the spring 4 passes between the points 3a and 5a and presses the contact 2 against the fixed contact 6. The beam 5 is held in this position by a pawl I, which can be actuated through the intermediary of an arm [0, against the action of a spring la. The current flows through the beam 3, the contacts 2, 6, the tripping coil 9 and a time relay formed by a bimetallic strip 8. When a moderate overload occurs, said strip acts on the arm III which releases the pawl I and enables the beam -5 to move in the direction of the arrow X by the action of the spring 6 until it contacts a suitable stop 52) and the line of action of said spring passes over to the other side of the point 3a. From this moment, the spring 4 acts to move the beam 3 and the contact 2 quickly, so as to open the circuit.

The coil 9 has a main movable armature formed by a core ll adapted to slide about a push rod which bears on the beam 3 and the part l2 of which is in contact with said beam and is made of non-magnetic material, whereas it part |2b is constructed of magnetic material, for example of mild steel, and forms an auxiliary armature of the magnetic relay. When a heavy overload occurs, for example a short-circuit, the armature H moves against the action of its weak retracting spring I3 until a rod [4, which is secured to said armature ll, abuts against the arm I0 and releases the pawl l, releasing the contact 2 through the liberating mean hereinbefore described. The auxiliary armature 12b being directly affected by the magnetic flux which should cause the tripping, transmits its impulse through the rod [2 to the beam 3 and imparts a considerable acceleration to the movable contact 2, as

soon as the latter is released by the liberating means, thereby producing an extremely quick opening of the circuit. The main armature ll continues its travel and acts on the rod l2 through the intermediary of the shoulder lZa, so as to add its impulse to that of the auxiliary armature l2b, thereby ensuring in particular the opening of the circuit if the movable contact 2 had a tendency to adhere to the movable contact 6.

In Figure 1, upward movement of the armature reacts through spring [3 on rod [2 and tends to displace it. At first, however, stem 12 is held by lever 3 urged by spring 4, which i sufficient to enable the armature to travel the short distance required for actuating lever l and releasing contact 2.

In the case of Figures 2 and '3, the current arrives by the terminal 29, passes through the fixed contacts 20, 2! which are short-circuited by the movable contact bridge 22, passes through the coil 23 and the bimetallic strip 24, and passes out through the terminal 25. The bridge 22 is supported by a movable rod, the part 26 of which is made of insulating material and is of larger diameter than the part 2'? which forms the auxiliary armature of the magnetic relay. The free end of the part 27 is pivoted on a two-armed pawl 28 which pivots at 29. Said pawl engages the nose of one of its arms in a pawl 30 pivoted on the fixed pivot 38, whereas the nose of the other end is held by a flap 32 which i held by a light spring 320. against the stop 33. A spring 34 tends to push back the rod 21 and the contact 22 in the open circuit direction. The pawl 28 is pivoted at 29 to a connecting link 35 which is pivoted at its other end on a bell-crank lever 36 which can swing about the fixed point 31 and the other end of which is provided with an elongated slot 38 in which is engaged a setting knob 39.

This knob is depressed in order to bring the circuit breaker back to the positions shown in Figures 2 and 4 after disappearance of the current defects which had brought it to the positions shown in Figures 3 and 5.

In order to produce the release of the movable contact, it is necessary to lift the pawl 30 so as to disengage the upper nose of the pawl 28, either by the action of the bimetallic strip 24, or by the efiect of the movement of the main armature 40 which is attracted towards the core 6| of the coil 23 compressing the retracting spring 42, and lifting the pawl 36 by means of a boss which is provided on said armature to act on the end of the pawl resting against the armature it. The movable contact is thus released, since the rod 2126 can be moved towards the right, assisted by the spring .54, disengaging the pawl 28 from the flap 32. The auxiliary armature 2'! being also attracted towards the core M, it transmits its impulse to the movable contact as soon as same has been released by the main armature 40. Toward the end of its travel, said armature 4i] encounters the shoulder of the rod 26 and then acts effectively in the case in which the movable contact might have a tendency to adhere to the fixed contacts. The connecting link 35 and the lever 36 have been displaced by the spring 43, so that the mechanism is in the position shown in Figure 3.

Figures 4 and show a modification of this construction. The spring M is replaced by a spring M which bears on an abutment 45, and

.also on the pin 56 forming the articulation between the pawl 28 and the rod 2?. The rod 21 slides in an opening of the pin 46. Suitable means is provided for insuring a pressure between the contacts. In one arrangement this is done by a spring 4'! bearing on the pin 46, and also on a washer 48 which i held by a nut 49 on the rod 21.

According to the invention, the movable contact is advantageously constructed in the form 'of a bridge 22 which is pivoted with limited play on the head 26a of the rod 26, and with a stiff fit on its pivot 50. Owing to thi articulation, the pressure is balanced on the two fixed contacts, when the circuit is closed, and owing to the stiff fit on the pivot 50, the movable contact retains, when the circuit i opened, the position in which the separation of the contacts takes place simultaneously at the contacts 20 and 2|, which has the effect of producing even wear of the contacts and of contributing to the speed of the break, in view of the fact that, from the start of the movement, the length of the arc is double the displacement of the contact 22.

It is obvious that various modification can be made in the construction of the apparatus without departing from the spirit of the invention. Thus, for example, the spring 32 (Figures 2 to 5), instead of bearing on the core ll, could bear on a shoulder of the rod 26, so that all the energy of the main armature 40 would be accumulated, from the beginning of its movement, for the purpose of its subsequent action on the movable contact.

What I claim is:

1. An automatic circuit breaker comprising a fixed contact, a movable contact, means normally resiliently urging the movable contact against the fixed contact, releasable spring-actuated means tending to open the movable contact, look-- ing means for restraining the spring actuated means, an electromagnet through which the circuit current flows, an unlocking member operatively connected to said locking means, actuating means responsive to said electro-magnet for actuating said unlocking member and freeing the spring actuated means in response to a heavy overload current flowing through said electromagnet, a principal movable armature for cooperating with said electro-magnet under the action of said overload current, a member directly operatively connected to the movable contact and provided with means arranged in the path of movement described by the principal armature whereby the member is operated by said armature after the unlocking of the movable contact, and an auxiliary movable armature cooperating with the electro-magnet and operatively connected to the said member for separately and directly acting upon the movable contact as soon as the spring actuated means has been released.

2. An automatic circuit breaker comprising a fixed contact, a movable contact, means for normally holding closed the movable contact on the fixed contact, releasable means for displacing the movable contact in response to an overload in the circuit, an electromagnet through which a circuit current flows, said displacing means including an operating member connected to the movable contact, a main movable armature actua'table by the electromagnet in response to a heavy overload and provided with means for acting upon said member during the movement of the member, and an auxiliary armature, actuatable by the electromagnet in response to a heavy overload, separately and directly acting upon said member as soon as the displacing means has been released.

3. An automatic circuit breaker according to claim 2, including connections whereby the releasable means for displacing the movable contact is operated by said main movable armature.

4. An automatic circuit breaker as claimed in claim 2 wherein said auxiliary movable armature is constituted by a part of said operating member.

5. An automatic circuit breaker as claimed in claim 2 including a second fixed contact, said movable contact being arranged to bridge said fixed contacts, one of said fixed contacts being electrically connected to said electromagnet and the other to the circuit line, said movable contact including a bridging member lightly, frictionally held against rotation on said operating member.

6. An automatic circuit breaker comprising a fixed contact, a movable contact, means for normally holding closed the movable contact on the fixed contact, releasable means for displacing the movable contact in response to an overload in the circuit, an electromagnet through which the current flows, said displacing means including an operating member itself comprising a rod connected to and adapted to actuate said movable contact, an abutment on said rod, a main movable armature actuatable by the electromagnet in response to a heavy overload being slidably mounted on said rod and arranged to act on said abutment when attracted by said electromagnet after the release operation of said displacing means, and an auxiliary armature constituting a part of said rod and actuatable by the electromagnet in response to a heavy overload, separately and directly acting upon said member as soon as the displacing means has been released.

FRANCOIS JEAN MARIE THEUNISSEN.

REFERENCES CITED The following references are of record in the file of this patent:

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