US2277422A - Electric circuit breaker - Google Patents

Description

March 24, 1942. l.. s. WALLE MATER/AL lnventor-z C s S- le, swf* b9 f H GAJEVOLv/NG /MsuLnT/A/G is Att car-neg.

l l l l l l Patented Mar. 24, 1942 2,217,422 ELECTRIC cmcU'rr nimma Ludwig' S. Walle, Lansdowne, Pa., assignmto General Electric Company, a corporation of New York Application March 8, 1940, Serial No. 322,9084

' 1'o claims." (61.200-151) My invention relates to electric circuit breakers and more` particularly to arc-extinguishing devices for circuit breakers of high interrupting capacity.

Within comparatively recent times and concomitant with various developments and improvements of apparatus of this general character, there has been an increasing tendency to employ air circuit breakers or the like instead of oil circuit breakers in the construction of electrical generating stations, substations and associated equipment for the generation and distribution of electric power. This is based largely on the desire to eliminate oil from electrical equipment insofar as possible so as to reduce the fire hazard y andl danger of explosions to a minimum.

Many vcircuit breakers have been proposed which eliminate the iire hazard due to oil by employing a iiuid blast, such as air or-other gas, for example, for arc-extinguishing purposes. As a general rule, these circuit breakers require a source of fluid pressure and associated control apparatus which greatly increases the expense and complication of the apparatus. It would be desirable to have an electric circuit breaker which eliminates the firey hazard associated with oil circuit breakers and yet wherein no complicated means need be provided for producing a source of uid under pressure which may be utilized for arc-extinguishing purposes.

Accordingly, it is an object of my invention to provide a new and improved electric circuit breaker of high interrupting capacity which is simple and compact, utilizes a minimum number of moving parts, and which is relatively inexpenthereby to` insure shorter arcing time, less danger of restriking and therefore higher interrupting capacity.

Further objects and advantagesof my invention -will become apparent as the following description proceeds and the features of novelty which characterize my inventionwill be pointed out with particularity in the claims annexedv to and forming a part of ythis specification.

For a better understanding of my invention, reference may be had to the accompanying drawticularly to Fig. 1, I have illustrated a circuit breaker embodying my invention contained in `a suitable insulating casing I0. This casing or housing may be constructed 'of any desirable insulating material and may even comprise laminated wood or the like.r Casing I0 is provided with an insulating liner II which is made of a material from which gas is evolved under the in.-.

fluence of theheat of the arc drawn in the circuit breaker, which, at least in part, aids in extinguishing the arc. Thisl liner may comprise inorganic materials, such as boric acid, ammonium alum, or organic materials, such as horn fibre and the like, or material formed of methyl methacrylate, as described and claimed in United States Letters Patent No. 2,157,815, granted May 9, 1939, upon an application of Ralph V. Boyer, and assigned to the same assignee as the present invention.

The relatively movable contacts of the circuit breaker illustrated in Fig. 1 comprise a pair of stationary electrodes or contacts I2 and I3 suitably fastened to a pair of terminal members I4 and I5, respectively, which are iixedly mounted to insulating housing I0 by any suitable means I6, and a movable horizontally positioned rod contact memberor electrode I1 adapted to cooperate with fixed contacts I2 and I3, thereby providing two series breaks in the electric circuit when the circuit breaker is opened. Stationary contacts I2 and I3 are provided with contact tips I 2' and I3', respectively, formed of an arc-resisting metal while movable rod contact member I1 is provided with contact tips IIa and IIb also formed of a suitable arc-resisting metal. The contact tips I2' and I3 of the respective xed contacts I2 and I3 are provided with slightly inclined surfaces which cooperate with somewhat similar surfaces on contact tips I'Ia and IIb of contact member I1 to insure good electrical contact when the circuit breaker is closed. If desired `any suitable .well known wip ing means may be provided.

In order to produce relative movement between movable horizontally positioned contact rod l1 including contact tips Ila and Ilb and iixed contacts I2 and I3; I provide a barrier 2U of insulating material vertically reciprocal in casing II) in a pair of slides formed by suitable guide bars 2l fastened to the interior of housing I0. Barrier 20 is adapted to pass through openings 22 and 23 in housing I0 and may be con- `nected by means 24 to any suitable operating mechanism, `not shown, which may, for example, .comprise a suitable solenoid or spring-operating mechanism, or any other arrangement well known in the ar't.

Rod contact member I1 is suitably mounted in xed relationship with vertically reciprocating barrier 20 by being supported in an insulating tube 25 which passes through an opening formed in barrier 20 and is suitably attached to the latter. Upward movement of barrier 20 will cause a separation of rod contact I1 and associated xed contacts I2 and I3 to interrupt the electric circuit associated with terminals Il and I5 oi the circuit breaker while closing of the circuit breaker is accompanied by downward movement of 'barrier 20. y

In order to obtain high interrupting capacity of the circuit breaker as well as a compact design, I provide cylindrical envelopes or bushings 26a and 2Gb slidably mounted over the respective ends of rod contact member I1 protruding from barrier 20. These sleeves or bushings 26a and 2Gb are formed of a suitable gas-evolving material similar to that from which liner II is formed. Sleeves or bushings 26a and 2Gb are shorter than the associated portion of contact member I1 protruding from' barrier 2U and are provided with spring members 21a and 2lb, respectively, suitably mounted in a countersunk portion in bushings 26a and 26h for biasing said bushings away from barrier 2D so as to tend to enclose rod contact member I'I more completely. The lower edges of sleeves 26a and 2Gb remote from barrier 20 are arranged in the downward movement thereof to engage with inclined surfaces IB' and I9 of protrusions I8 and I9 respectively which may be integral with insulating liner Il so as to allow the contacting surfaces IIa and I 1b of horizontally positioned rod contact member I'I to extend beyond the ends of sleeve bushings 26a and 2Gb and protrusions I8 and I9 hold bushings 26a and 2Gb in this retracted position when |the circuit breaker is in the closed position illustrated in Fig. 1 so that electrical contact between arcing tips I'Ia, I'Ib and I2', I3' respectively. may be made. When barrier 20 is moved upwardly by suitable means, not shown, to interrupt the electric circuit associated with terminals Il and I5 of the circuit breaker, spring means 21a and 21h force sleeves or bushings 26a and 2Gb, respectively, away from barrier 20 and against the liner Il of gas-evolving insulating material. When this occurs, contact II is completely enclosed in chambers formed by bushings 25a and 26h and liner II so as to be isolated from fixed contacts I2 and I3. The arcs drawn upon interruption of the circuit are snuffed out when the ends of bushings 26a and 26h rub along insulating liner II and high-speed interruption is obtained. The open condition of the circuit breaker is illustrated by the position'of contact member I1 and associated bushings 26, shown dotted in Fig. 1. l

In order that the arc gases and arc products formed during the interruption of the circuit may escape from casing or housing III, suitable exhaust ports 2B and 29, respectively. lare provided in housing I0 adjacent fixed contacts I2 and I3.

The operation of the circuit breaker will be obvious to those skilled in the art in view of the detailed description included above. However, when the circuit breaker is in the position illustrated inl Fig. l. protrusions It and I9 of liner II hold bushings 26a and 2Gb against the tensions of their respective associated springs 21a and 2lb, whereby contacting surfaces I1a and I 'Ib of rod contact Il may engage with the arcing tips IZ' and I3', respectively, of fixed contacts I2 and I3. Interruption of the circuit is obtained by moving barrier 2U upwardly, carrying movable rod contact I l along therewith, whereupon the electric circuit is broken and an arc is drawn between arcing tips I2' and I la and I3' and IIb, respectively. Further upward movement of barrier 2li will allow bushings 26a and 2Gb to move away from barrier 2D toward insulating liner II. The heat of the arc will cause gases to be evolved both from liner il and from bushings 26a and 2Gb which will aid in the extinguishment of the arcs. Slidable movement of bushings or sleeves 26a and 26h will continue until the bushings are free from fixed contacts I2 and I3, whereupon these bushings will rub against liners II snuiiing out the arc and completely enclosing iixed contact member I'I in a cylindrical chamber formed of an insulating material emitting an arc-extinguishing gas. The

open position of the circuit breaker is indicated in dotted lines in Fig. 1 and, in view of the fact that contact member II is completely surrounded by insulating material in this position, the separation of the contacts for isolating purposes need not be so great to prevent restriking of the arc as in prior art arrangements wherein one of the contacts is not completely isolated from the other. This makes for a more compact arrangement. The arc gases formed during the circuit interruption process are allowed to escape through exhaust ports 28 and 29.

While I have shown a particular embodiment of my invention as applied to electric circuit breakers, it will be apparent to those skilled in the art that my invention is not limited to the construction shown but that changes and modiiications may be made without departing from the spirit and scope of my invention and I aim in the appended claims to cover all such changes and modifications.

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

1. In an electric circuit breaker, the combination comprising a casing, a plurality of relatively movable contacts supported within said casing, means for producing relative movement between said contacts tn make or break the electric circuit associated with said circuit breaker, a sleevelike bushing of gas-evolving insulating material movably positioned on one of said contacts and arranged so as to allow said one contact to protrude therefrom to engage another of said ccntacts during the closed circuit position of said circuit breaker, and means for causing effective withdrawal of said one contact into said sleevelike bushing upon separation of said relatively movable contacts and for causing said bushing to engage said casing so that high-speed interruption of said circuit may be obtained.

2. In an electric circuit breaker including a casing, the combination of a pair of relatively movable contacts associated with said casing, means for producing relative movement between said contacts to interrupt the current in an associated electric circuit, a sleeve of gas-evolving insulating material movably positioned on one Aof said contacts and biased so as to tend to extend beyond the end of said one contact, means for moving said insulating sleeve so that said one contact protrudes therefrom to engage with said other contact during the closed circuit position of said circuit breaker, and means for allowing said biasing means to become effective upon separation of said relatively movablev contacts to cause said sleeve to engage said casing so as to isolate completely said one contact whereby high-speed interruption of said circuit may be obtained.

3. In an electric circuit breaker, the combination comprising a pair of relatively movable contacts, means for producing relative movement between said contacts to interrupt the current in an associated electric circuit, an insulating sleeve movably positioned on one of said contacts, a surface for limiting the vmovement of said sleeve by engaging with the end thereof adjacent the contacting portion` of said one contact, said insulating sleeve being arranged so that said one contact may protrude therefrom to engage said other contact during the closed circuit position of said circuit breaker, and means for causing said insulating sleeve to engage said surface for snuiiing out the arc drawn upon separation of i said relatively movable contacts.

4. In an electric circuit breaker, the combination comprising a pair of relatively movable contacts, a casing for` said contacts, means for producing relative movement between said contacts to interrupt the current in an associated electric circuit, an insulating sleeve movably positioned on one of said contacts, a liner for said casing arranged to engage the end of said sleeve adjacentv the contacting portion of said .one contact when said first-mentioned means are operative, said insulating sleeve being arranged to allow said one contact to protrude therefrom to engage said other contact during the closed circuit position of said circuit breaker, and .means for causing said insulating sleeve to engage said liner for snuillng out the arc drawn upon separation of said relatively ,movable contacts.

5. In an electric circuit breaker, the combination of a casing, a pair of relatively movable contacts mounted within said casing, means for producing relative movement between said contacts to interrupt the current in an associated electric circuit, an insulating bushing movably positioned on one of said contacts, the end ofwhich is adapted to be moved against one of the walls of said casing to define a chamber within said bushing, said bushing being positioned so that guished by the combined snunlng action of said sheath and liner and the arc-extinguishing gas evolved therefrom.

'7. In an electric circuit breaker, the combination comprising a casing, a pair of relatively movable contacts supported within said casing, means for producing relative movement between said contacts to make or break the electric circuit associated4 with said circuit breaker, an envelope of gas-evolving insulating -material movably positioned on one of said contacts, a liner of gas-evolving insulating material for said casing for limiting the movement of said envelope by engaging with the end thereof adjacent the contacting portion of said one contact, said envelope being arranged so that said one contact may protrude therefrom to engage said other contact during the closed 'circuit position of said circuit breaker, and spring means for biasing said envelope so as to engage said liner .upon separation of said relatively movable contacts, wherebythe arc drawn by such separation cauSes'gas to be evolved which together with the snuing action of said envelope and liner rapidly extinsaid contact protrudes therefrom in the closed circuit position oi said circuit breaker, J and means for causing said contact to be enclosed f completely in said chamber upon separation of said relatively movable contacts whereby interruption of said circuit is insured.

6. In anelectric circuit breaker, the combination comprising a casing, a pair of relatively movable contacts supported within said casing, means for producing relative movement between said contacts to make or break the electric lcircuit associated with said circuit breaker, a sheath of gas-evolving insulating material movably positioned on one of said contacts, a liner of gasevolving insulating material for said casing for limiting the movement of said sheath by engaging with the end thereof adjacent the contacting portion of said one contact, said sheath being arranged so that said one contact may protrude therefrom to' engage said other contact during the closed circuitposition of said circuit breaker, and means for causing said sheath to engage said. liner upon separation of said relatively movable contacts whereby said arc is rapidly extinguishes said arc.

. 8. In an electric circuit breaker, the combination comprising a pair of relatively movable contacts, a 'casing for said contacts, means for producing relative movement between said contacts to interruptthe current in an associated electric circuit, an insulating sleeve movably positioned on one of said contacts, and insulating means associated with said casing for causing movement of said `insulating sleeve upon engagement Withsaid last-mentioned means so as to allow said contact to protrude therefrom to engage said other contact during the closed circuit position of said circuit breaker.

9. In an electric circuit breaker, the combination comprising a pair of relatively movable contacts, a casing for said contacts, means for producing relative movement between said contacts to interrupt the current in an associated electric circuit, an insulating sleeve movably positioned on one of said contacts and arranged to engage said casing to limit movement in one direction thereof, said insulating sleeve being arranged so that said one contact may protrude therefrom to engage said other contact during the closed circuit position of said circuit breaker, means for causing said insulating sleeve to engage said casv ing for snufng out the arc drawn upon separationof said relatively movable contacts, and exhaust ports in said casing whereby the arc products during such circuit interruption may escape.

10. In an electric circuit-interrupting device including a casing, the combination comprisinga pair cf arcing electrodes associated with said casing, a member of gas-evolving insulating material surrounding one of said electrodes and adapted to engage said casing, said member being movable relatively to said one electrode under certain operating conditions of said circuitinterrupting device, and means tending to cause said member to engage said casing to enclose said one electrode completely so that high-speed interruption of an arc between said electrodes may .be obtained.

LUDWIG S. WALLE.

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