US2281385A - Electric circuit breaker - Google Patents

Description

April 1942- J. M. SAINT-GERMAIN ETAL 2,281,385

ELECTRIC CIRCUIT BREAKER Filed May 17, 1940 Inventors: Jacques Marie SainUGermain, Georges salachowsky,

8 ThZi r Attorrweg.

Patented Apr. 28, 1942 2,281,385 ELECTRIC CIRCUIT BREAKER Jacques Marie Saint-Ger Paris, France, Electric Company, a co Application May 17, 1940, Serial No.

chowsky,

main

and Georges Balaassig-nors to General rporation of New York In France June 22, 1939 Claims.

Our invention relates to an electric circuit breaker and more particularly to a breaker oi'the fluid jet or impulse type.

An object of our invention is to provide an improved circuit breaker which will be efllcient and positive in its interrupting eii'ect throughout the entire range of current rating.

Another object of our invention is to provide a circuit breaker which will operate with an arc duration which is substantially independent of the voltage and current interrupted.

A further object 01' our invention is to provide a circuit breaker which has a large interrupting capacity and high interrupting speed and which has an operation tree of any dangerous overvoltages regardless of the electrical characteristics of the system which is to be interrupted.

We accomplish these and other objects by providing an electric circuit breaker which will interrupt the current in successive phases in an improved and novel manner. The first phase of current interruption takes place between relatively movable contacts by the passage 01' an arc-interrupting fluid across the are formed between the relatively movable contacts after an are 01' sufllcient length has been formed, so that its interruption will take place without danger of restriking. The second phase'of current interruption takes place between one or the relatively movable contacts and an auxiliary electrode which is electrically connected to the other of the relatively movablecontacts through a resistor. This electrode is also movable. into the region between the relatively movable contacts-so that when the are between the contacts is interrupted an arc of much smaller intensity will restrike between one or the contacts and the electrode. An arc-extinguishing fluid is then injected across this second arc to interrupt it.

Further objects and advantages of our invention will become apparent from the following description referring to the accompanying drawing, and the features of novelty which characterize our invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

In the drawing, Fig. 1 is a side elevation partly in section or a high voltage electric circuit breaker embodying our invention; Figs. 2 and 3 illustrate a portion 01 the electric circuit breaker illustrated in Fig. 1 in its two successive phases of operation.

Referring to the drawing, in Fig. 1 we have illustrated a high voltage vertical electric circuit breaker oi the impulse type which includes relastationary cylinder I5 The member N therefore acts as an interrupting chamber and also as a plunger piston, since it is mounted for reciprocatory movement. 'The plunger piston I may be moved in any suitable manner and we have found a practically eiilclent structure obtaintsavzh'eln the piston is attached to themovable con c ment and may be moved by any suitable structure, such as by an operating member I1 and links II which are in a pedestal I. The pedestal II also forms a base member on which a hollow cylinder 2| is moun A hollow cylinder 2| is in turn mounted on the cylinder II, the former .acting as a housing for my improved circuit The circuit breaker may be suitably connected in a line through terminal; 22 and 23.

tacts 24.

Any suitable source 0! arc-extinguishing tluid completely immersed in is employed, such as air, a source under pressur is piped to the interrupting chamberwith a valve arrangement disposed to be opened when it is desired to extinguish the arc.

The operation of our improved electric circuit breaker is as follows:

when it is desired to interrupt the circuit 22, 23 the actuating member I1 is moved so as to allow the shaft i8 and the movable contact II to move away from the contact ll. Upon this movement an arc is formed between the relatively movable contacts as will be seen in Fig. 2. Since the plunger I4 is mounted for movement with the movable contact H the plunger will also descend and cause the arc-extinguishing fluid which is in the cylinder I to be expelled. In order to provide an arrangement so that the are between the contacts l and II will be interrupted only when a suflicient length of arc has been formed, we provide perforations or openings 25 in the side walls of the cylinder IS in such a plane that the arc-extinguishing fluid may be displaced through these perforations until they are closed by the side walls of the plunger H. when the perforations oropening 25 have been closed a sufllcient length of arc will have formed between the relatively'movable contacts so that it may be interrupted, without the danger of restriking. when the openings 25 are closed by the side walls of the plunger piston ll the displaced arc-extinguishing fluid will no longer pass through the perforations but will pass into the interrupting chamber, across the are between the relatively movable contacts and out through transverse vents 2. A barrier 21 is provided below the vents so as to force the arc-extinguishing'fluid to pass transversely of the interrupting chamber and between the relatively movable contacts before it passes out through the vents 26, The barrier 21 may also act as the support for the member I on the movable contact H.

As soon as the current approaches zero the arc is interrupted momentarily at the interrupting contacts by the oil blast. When the recovery voltage appears the arc restrikes to the auxiliary electrode l2 so that the current passes through the resistor it connected to the auxiliary electrode l2 and thence to the contact Hi. This is because the auxiliary electrode and movable contact will have reached a positidh, illustrated in Fig. 3. At this time the second phase of the current interruption will take place, since the auxiliary electrode is now moved into the region between the relatively movable contacts. As above described, a second, arc will have struck between the auxiliary electrode and the contact Ill. However, the intensity of this are will be much less than was the intensity of the are which existed between the relatively movable contacts, since the current now passes through the current limiting resistor I3; Thus, regardless of the intensity of the arc-extinguishing fluid Jet, no overvoltage need be feared at the moment the arc between the relatively movable contacts is. interrupted. Furthermore, the interruption of this arc is facilitated by the fact that when a resistance is inserted in a circuit the speed at which the voltage recovery lessened.

When our improved electric circuit breaker is in the position illustrated in Fig. 3, vents 28 which are in the side walls of the plunger piston H are no longer obstructed by Some of the arc-extinguishing fluid will therefore be displaced across the arc between the contact ll and the auxiliary electrode and out through the transverse vents 28. Since, as above stated,

the contactrod l0."

the auxiliary electrode to the vents 20.

this latter are is very weak owing to the effect of the resistor I3 it will be easily extinguished by the arc-extinguishing fluid which finds its way through the region between the contact I. and Thus. owing to the slight density of the current which has to be interrupted with the extinguishment of the latter are and to the damping effect of the resistor 11, this second interruption proceeds with a very small amount of oscillations and without noticeable over-voltages,

It is interesting to note that during the closing of the circuit breaker the resistor [3 acts as an impact resistance and reduces considerably the current in-rush, for instance, in case the circuit breaker is closed on a transformer at no load.

In view of the foregoing it will be seen that we have provided a new and improved high speed circuit breaker for high tension circuits that employs a method which interrupts the current in two successive phases in an improved and effective manner. In the first phase the arc is not interrupted until a sufficiently long are has been formed so that it may be broken without danger of striking, and in the second phase a reduced current are is formed between one of the contacts and the auxiliary electrode. This latter are being relatively weak may be easily broken by the passage of arc-extinguishing fluid across it.

Although we have shownan'd described particular embodiments of our invention, we do not desire to be limited to the particular embodiments described, and we intend inthe appended claimsto cover all modifications which do not depart from the spirit and scope of our invention.

What we claim as new and desire to secure by Letters Patent of the United States, is:

1. An electric circuit breaker for .high voltage power circuits including relatively movable interrupting contacts, an auxiliary electrode movable adjacent to the arc gap formed between said contacts, aresistor, said resistor being electrically connected between said auxiliary electrode and one of said contacts, actuating means for said relatively movable contacts and said auxiliary electrode; ,said relative movement of said contacts and said auxiliary electrode causing I first, formation of a predetermined length of are takes place is considerably 4 the circuit is completely opened.

gap and arcing between said interrupting contacts and finally, reduced arcing between said electrode and one of said contacts, and means including an arc-extinguishing fluid for extinguishing in sequence said arcs sothat the circuit is completely opened.

2. An electric circuit breaker for high voltage power circuits'including relatively movable interrupting contacts, an auxiliary electrode movable adjacent to the arc gap formed between said contacts, a current limiting resistance interconnecting said electrode and the circuit, actuating means for said contacts and said auxiliary electrode, said relative movement of said contacts and said auxiliary electrode causing flrst, arcing between said interrupting contacts and finally, after predetermined separation of said contacts arcing at reduced current between said electrode and one of said contacts, and means including an arc-extinguishing. fluid for causing said are between said interrupting contacts to be extinguished after a predetermined length of arc has been drawn so that its interruption will take place without danger of 'restriking and for finally extinguishing said reduced current are so that 3.- An electric circuit breaker for high voltage power circuits includingrelativei-y movable interrupting contacts, an auxiliary electrode movable into the region between said contacts, a resistance interconnecting said electrode and the circuit for limiting current flow through said electrode, actuating means for said contacts and said auxiliary electrode, said relative movement of said contacts and said auxiliary electrode causing first, arcing between said interrupting contacts and second, reduced current arcing between said electrode and one oi said contacts ai'ter interruption 01 said first-named arcing, an arc-extinguishing fluid, an insulating piston structure operatively connected to one of said relatively movable contacts and said electrode, and means including said piston structure for causing said fluid to pass over said arc between said interrupting contacts to extinguish it after predetermined separation of said contacts and for causing said fluid to pass over said second mentioned are and extinguish it.

4. An electric circuit breaker including relatively movable contacts, an auxiliary electrode movable into the region between said movable contacts, actuating means for said contacts and said auxiliary electrode, said relative movement of said contacts and said auxiliary electrode causing arcing between said contacts and between said electrode and one of said contacts, an arc-extinguishing fluid, a movable hollow piston structure having an open end and a plurality of groups of transverse vents, a relatively stationary cylinderoi slightly larger diameter than said piston and so constructed and arranged as to receive the open end of said piston, and perforations in said cylinder, said piston structure being movable with said actuating means for causing said fluid to be displacedj' from said cylinder through said perforations until the arc between said contacts is of a, predetermined length at which time said piston walls will substantially close said perforations and allow said fluid to ma over the are between said contacts to extinguish it and through one of said groups of vents and for causing said fluid to pass over said arc between said electrode and said one of said contacts to extinguish it and through said other of said groups oi vents.

5. An electric circuit breaker for high voltage power circuits comprising relatively movable interrupting contacts, means for separating said contacts to form an arc gap of predetermined length, means for directing a fluid blast through said gap for extinguishing the power arc, an auxiliary electrode movable in accordance with said contact separating movement to a position adjacent to said arc gap for defining a second arc gap shorter than said first-named arc gap whereby the recovery voltage atterarc interruption at said contacts will establish a second are at said second arc gap, a current limiting resistance interconnecting said electrode and the circuit for decreasing the intensity of said second arc, and means for also directing a fluid blast across said second arc gap for flnally interrupt ing the circuit.

JACQUES MARIE SAINT-GERMAN. GEORGES BALACHOWSKY.

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