US2551302A

US2551302A - Automatic circuit breaker

Info

Publication number: US2551302A
Application number: US632441A
Authority: US
Inventors: Theunissen Francois Jean Marie
Original assignee: Individual
Current assignee: Individual
Priority date: 1940-04-23
Filing date: 1945-12-03
Publication date: 1951-05-01
Anticipated expiration: 1968-05-01
Also published as: GB600421A; CH256667A; NL76843C; FR866592A; US2551303A; BE457696A; NL73337C; FR54180E; BE441207A; NL119357B; GB599407A

Description

y 1951 F. J. M. THEUNISSEN 2,551,302

AUTOMATIC CIRCUIT BREAKER Filed Dec. 3, 1945 8 ax-ngrwuc I fm/emar Fkmvcozs J94 M215 EEC/1mm x Mal 412 #4,.

Patented May 1, 1951 AUTOMATIC CIRCUIT BREAKER Francois Jean Marie Theunissen, Brussels, Belgium Application December 3, 1945, Serial No. 632,441

In France April 23, 1940 Section 1, Public Law 690, August 8, 1946 Patent expires April 23, 1960 '7 Claims. 1

This invention relates to circuit-breakers having a magnetic relay or an instantaneously act-- ing release coil through which the current flowing through the circuit-breaker passes.

In known circuit-breakers, the attraction of the movable armature of this coil efiects the liberation of a mechanical release system (by pawl, knuckle joint, etc.) rapidly driving the movable contact in the direction causing opening of the circuit. In this type of apparatus the time of disconnection of a circuit-breaker comprises the time of mechanical opening, that is to say, the time necessary to manipulate pawls and for the successive placing in motion of the different parts of the mechanism, up to the moment when the fixed and movable contacts commence to separate, and the time or" the electric breaking of the circuit, that is to say, the time necessary for the extinction of the are which strikes between the contacts on the commencement of their separation.

The present invention has for its object to reduce the time of the mechanical opening of the circuit and this object is achieved by reducing or even eliminating all the successive movements, by causing the movable armature to act directly on the movable contact. It is well known that such arrangement considerably reduces the time taken by the mechanical breaking of the circuit, but they present the drawback of causing, at certain densities of the current, rapid vibrations of the movable contact which are of such a nature as to weld together the fixed and movable contacts. This is the case when the circuit-breaker is traversed by an alternating current the intensity of which approaches that necessary to cause the complete attraction of the movable armature.

These drawbacks are avoided in the case of the present invention by the fact that, apart from the direct action of the movable armature on the contact system, the armature acts also to operate a releasable system for producing a displacement of said movable contact. Thus the movable armature acts following the principles of the invention, not only to free the releasable system of release comprising generally a spring tending to cause the opening of the contacts as soon as the release system is unlocked or "freed, but also it transmits its impulse directly to the movable contact (or its equivalent holder), independently of the system of release, in such manner that the efiort of attraction of the armature is added to the action of the release spring. It should be noted that whenever referonce is made herein to action on the movable contact, it must be understood that this includes an action on an associated part or" this contact or on its holder.

According to the one embodiment of the invention, the movable armature system comprises two distinct armatures one of which is termed the principal and is intended to act on the movable contact by a direct kinematic connection, whilst the other, termed auxiliary controls the freeing of the release system. This auxiliary armature moves against a feeble resetting spring, so that it is attracted by an intensity of current below that corresponding to the attraction of the principal armature.

According to this embodiment, the principal armature acts from the commencement of its displacement, to shift the movable contact, this movable contact being carried by the principal armature itself or by a part actuated directly by this armature.

According to another embodiment, the movable armature causes, during its initial movement of attraction, the intervention of the release system, the direct action of the armature on the movable contact taking place only after the termination of the movement necessary to cause the said intervention. After having freed the release system, the movable armature therefore exerts, independently of this system, a striking action directly on the movable contact of which it thus accelerates the displacement.

The system of release may with advantage be that serving for the delayed release when the circuit-breaker is provided with such a release.

In order to retain the movable contact in its open position after the movable armature has ceased its action, the contact pressure between the fixed and movable contacts may be obtained, following the principles of the invention, by a rocking lever intended to be operated by the movable armature and subjected to the action of a resetting spring the line of action of which passes, on its manipulation, to the other side of its pivotal axis. Furthermore, the end of the spring associated with the said rocking lever is attached to another rocking lever the pivotal point of which is fixed in such manner that, in the position of engagement of the circuit breaker, the line of action of this spring passes between the pivotal points of the two said rocking levers. This second rocking lever is retained against the action of the spring by a pawl constituting with this rocking lever, the release mechanism specified above.

The annexed drawings show by way of nonrestrictive example several difierent methods of carrying out the invention.

In the drawings:

Figures 1 to 3 are diagrammatic views showiizng three different embodiments of the inven- In these difierent figures, the movable contact 2 is carried by a rocking lever 3 pivoting about a fixed point 3a. This rocking lever is subjected to the action of a spring l, one extremity of which is pivotally attached to the rocking lever 3 at 3b, whilst the other is pivotally attached to a second rocking lever 5 that is itself pivotally secured as at 511. The arrangement of the rocking levers 3 and 5, as also of the spring Q is such that in the position of engagement, that is to say, that shown in the figures, the line or action of the spring passes between the pivot points 3a and 5a of the two rocking levers. Under these conditions, the spring efiectively applies the movable contact 2 against a fixed contact 6. The rocking lever 5 is retained in the position shown by a pawl 7 adapted to be actuated by the extremity of a bimetallic blade inserted in the circuit of the fixed and movable contacts through the winding of a release coil 9. The extremity of the bimetallic blade acts as shown, on a supplementary arm l rigidly connected to the pawl 1; in the case of an over-load, the bimetallic blade 8 causes the displacement of the pawl I. The second rocking lever moves in the direction of the arrow X under the action of the spring 4 until the line of action of this spring has passed on the other side of the pivotal point 3a. In practice a stop 5b will be provided for the lever 5. From this moment, the spring 4% acts to displace rapidly the contact-carrying rocking lever 3 and to effect the opening of the circuit. For proper operation, a suitable stop for lever 5 is provided, such as is shown at 5b.

In the case of Figure l, the movable armature of the release coil 9 is constituted by a core ll sliding about a thrust rod 12 of non-magnetic material and bearing directly on the rocking lever 3. If a considerable overload should occur the core I l moves against the action of its feeble resetting spring 13 until a rod is integral with the core abuts against the lever arm H3, and displaces the pawl I thus causing the release. On the occurrence of a short-circuit, the core ll acts not only in the manner described above, but it also carries along with it the thrust rod I2, by contacting with a collar Ma. The thrust rod I2 acts to cause the immediate displacement of the contact-carrying rocking lever 3 and thus causes the opening of the circuit in a very short space of time, independently of the movement accomplished by the release system 5'i.

In Figure 1, upward movement of the armature reacts through spring 13 on rod !2 and tends to displace it. At first, however, stem I2 is held by lever 3 urged by spring 5, which is sufiicient to enable the armature to travel the short distance required for actuating lever l8 and releasing contact 2.

In the case of Figure 2, the core ii is keyed directly on the thrust rod I2. An auxiliary armature i5 is slidably disposed on this thrust rod, in. association with a feeble spring 16. In the case of a considerable over-load, the core I I does not have an actuating force suflicient to cause the direct displacement of the rocking lever 3. However, the auxiliary armature i5 moves and compresses the spring It and operates the pawl 1 through the intermediary of a lever i1 and an arm [8. On the occurence of a short-circuit, the core II causes oscillation of the rocking lever 3 independently of the movement which might have been communicated to this rocking lever by the liberation of the release system 5, i by the auxiliary armature 15.

In the case of Figure 3, the operation is similar to that of Figure 2 except that the action of the auxiliary armature ii: on the pawl l takes place through a rod system 1% bearing against a conical part of this auxiliary armature to.

Naturally, a similar arrangement may be applied to the case of Figure l.

The invention is also not restricted to the method of release shown since without departing from the scope of the present invention any other release system may be utilised. Thus in Figures 2 and 3, a system of magnetic release may be substituted which would be constituted only by the principal and auxiliary armatures H and i5 and which acts as follows; on a considerable over-load, the auxiliary armature i5 is attracted against the action of the feeble resetting spring it? and approaches the principal armature ii. The dimensioning of the system is such that at the end of the attraction movement of the armature 55, the reduction of the gap is such that, for the same current, the principal armature H is strongly attracted and suddenly shifts the rocking lever 3 carrying the movable contact.

The invention presents not only the advantage of causing an extremely rapid separation of the contacts, but also of proportioning the opening effort to the intensity of the current causing it, since the armature is attracted all the more forcefully the stronger the current. Further more, the release spring which, alone, can cause the opening of the circuit as soon as the movable contact is dis-engaged, may be made comparatively weak. This has as a result the reduction of the stresses on the pawls, thus increasing the precision of their operation and reducing their wear. This circuit-breaker is particularly useful as a small circuit-breaker with great circuitbreaking capacity, mounted on a base or in the form of a plug with pins or for screwing.

What I claim is:

1. An automatic circuit breaker comprising a fixed contact, a movable contact, means normally resiliently urging said movable contact against said fixed contact, spring actuated means movable from one position to another position tending to open the movable contact, locking means for restraining the last mentioned means to one position, a release coil through which a circuit current .ilows, a liberating member operatively connected to said locking means and connected to be responsive to an overload current through the coil for unlocking said spring actuated member, a member directly mechanically connected to the movable contact, and a movable armature for cooperating with said release coil under the action of said overload current to act first on said liberating member and subsequently directly on the member directly connected to the movable contact.

2. An automatic circuit-breaker according to claim 1, wherein the liberating member comprises a delayed action element through which the circuit current flows and means by which it unlocks said releasable device independently of said movable armature, under the action of an overload current which is not sufficient to cause the attraction of the said armature by said coil.

3. An automatic circuit-breaker according to claim 1, wherein the liberating member comprises a bimetallic blade traversed by the circuit current and means enabling it to unlock said releasable device independently of said movable armature, under the action of an overload current which is not sufficient to cause attraction of said armature by said coil.

4. An automatic circuit breaker according to claim 1, in which the means for urging the movable contact against the fixed contact comprise a rocking lever connected to the movable contact and acted upon by said armature, a pivotal axis for said lever, and a resetting spring for said lever disposed on one side of said axis and arranged in such a manner that, at the moment of opening of the contacts, the line of action of said resetting spring passes to the other side of said axis.

5. An automatic circuit breaker according to claim 1, in which the means for urging the movable contact against the fixed contact comprise a first rocking lever connected to the movable contact and acted upon by said armature, a pivotal axis for said lever, a second rocking lever, a pivotal axis for said second rocking lever, a resetting spring for said first lever disposed to have its line of action on one side of said first axis and having its ends attached to said first and second rocking levers, and the restraining means includes an element retaining said second lever against the action of said resetting spring, the pivotal axis of said second lever being arranged and located in such a manner that, on release of said second lever from said element, the line of action of said spring passes to the other side of said first axis.

4 6. An automatic circuit breaker comprising a fixed contact, a movable contact, means normally resiliently urging said movable contact against said fixed contact, means for displacing said movable contact from closed position, a release coil through which a circuit current flows, means for actuating said displacing means in response to an overload current through the circuit breaker, a rod positioned to act on the movable contact, a main armature mounted on said rod, an auxiliary armature carried loosely on said rod and connected for actuating the displacing means in response to an overload.

'7. An automatic circuit breaker according to claim 6, wherein said auxiliary armature is slidably mounted on said rod, and including a weak spring located between the auxiliary armature and an abutment on said rod.

FRANCOIS JEAN NIARIE THEUNISSEN.

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

UNITED STATES PATENTS Number Name Date 585,030 Harrington June 22, 189'? 1,330,094 Simon Feb. 10, 1920 1,433,952 Kendall Oct. 31, 1922 1,726,233 Krantz Aug. 27, 1929 1,989,497 Reed Jan. 29, 1935 2,027,238 Lindstrom Jan. '7, 1936 2,072,163 Frank et a1 Mar. 2, 1937 2,329,362 Swingle Sept. 14, 1943 2,345,105 Dorfman et al. Mar. 28, 1944 2,360,684 Jennings Oct. 17, 1944 2,370,024 Dyer Feb. 20, 1945 FOREIGN PATENTS Number Country Date 297,184 Germany Aug. 2, 1930 342,143 Germany Aug. 8, 1919 866,592 France May 26, 1941