US2180147A - Electric circuit interrupter - Google Patents

Description

Nov. 14,1939. w. no 2,180,147

ELECRIC CIRCUIT INTERRUPTER Filed' June 3, 1337 lnye'ntdrz. V wilhejmH p'p, by W 6.0?

is Attorney.

I Patented Nov. 14, 1939 UNITED STATES PATENT OFFICE) 2 ,180,147 amcrmo cmcmr m'rmmur'rea Wilhelm.- Hiipp,

Berlin-Heiligensee, Germany, as-

signor to General Electric Company, a corporation of New York Application June 3,

In Germany 1937, Serial No. 146,183

July 21, 1936 v 1% Claims. (Cl. 200 -14-1 proved circuit interrupter of the aforesaid type determined position.

, and forming a part of which is effective to interrupt the are without involving high induced voltages, fiashover or reignition of the arc and excessive deterioration of the interrupter structure.

Magnetic blowout circuit interrupters, such as air circuit breakers for example, have been proposed wherein a strong blowout field is utilized to extend and lengthen the are rapidly into an arc cooling structure, such as are splitters for example. In certain instances the magnetic blowout field may be so powerful that the arc, referring specifically to an inductive alternating current circuit, is extended to such length and ruptured so suddenly that high flashover voltages are induced causing damage to the installations and under certain circumstances fiashover or reignition of the arc.

In the case of alternating current it is particularly important that the blowout field be controlled, since a comparatively powerful blowout and leakage field may extend the arc to such. length before rupture that the large quantities of ionized gases formed by the arc tend to cause reignition after interruption at the current zero.

In accordance with the present invention a comparatively powerful blowout field acts locally on the are so as to cause high acceleration of the extending movement thereof, and the field is weakened or opposed after predetermined extension of the arc so as to maintain the are or at least a portion thereof at a substantiafly pre- Interruption of the arc takes place at the preferred extended length thereof so that dangerous flashoveryoltages and reignition of the are are substantially precluded.

My invention will be more fully 'set forth in the following description referring to the accompanying'drawing, and the featurespf novelty which characterize my invention will be pointed out with particularity in the claims annexed to this specification.

Referring to the drawing,

Fig. 1 is an elevational view, partly in section, of a magnetic blow-out circuit breaker embodying the present invention; Fig. 2 is a plan view, partly in section, of the electrode or contact structure of Fig. 1, and Fig. 3 is a diagrammatic illustration of the action of the blow-out field on the arc.

The circuit interrupter illustrated comprises relatively movable contacts or electrodes l and there is provided electromagnetic 2 between which an arc is formed upon opening of the circuit. Each contact is electrically connected to an arcing horn 3. For the purpose of concentrating a magentic blow-out field at a. localized region between the contacts, magnetic core material, such as iron, is inserted at 4 in eaclr contact so as to restrict the contact crosssection at 5. The cores 4 are provided with iron pole pieces 6 which are also set in recesses" in the opposite sides of the contacts as illustrated by When the contacts are separated to open the circuit, an arc is formed in the space between the contacts. The blow-out in a well-known manner by the electromagnetic means above described, extends from the pole pieces into the arc gap, as indicated. by the flux lines I (Fig. 2), and rapidly moves the arc to the top of the contacts at 8 as illustrated by Fig. 1. This part of the movement of the arc is very rapid as a comparatively strong magnetic field is concentrated onthe arc during its initial extension. As the arc continues to extend under influence of the field, it travels over the contact surfaces to the arcing horns 3 as indicated.

For the purpose of limiting extension of the are beyond a predetermined length orposition, means at 9 for creating an opposing field. In the present instance, this means comprises a core"! of magnetic material, such as iron, and a. conducting ring H composed of copper for example forming a short-circuited conductor about the core. The core, 10 is of appreciable mass as illustrated so that it occupies an appreciable part of the arc chamber and is located in the usual arc chute I2 transversely-of the direction of extension of theme and intermediate the ends thereof. The spacing of the core from the initial arc position at 8 depends on the interrupting requirements of the breaker and, in certain cases, may be comparatively close thereto.

As above pointed out, separation of the contacts l and 2 to open the circuit causes formation of an arc therebetween which is driven rapidly by the concentrated field to the upper position at 8 and from there by the leakage field toward the core structure l0 as indicated by the direction arrows. The movement of the arc roots along the upper surfaces of the contacts is slower by reason of the reduction in strengtl'P of the blow-out field, and the arc is extended to the position indicated at l3 wherein the core limits further appreciable extension of the central part of the arc.

field, which is created duces in the core. Immediately it has passed the neutral zone N-N to position is, however, the

reversed blow-out field tends to drive it down= word as indicated by the direction arrows. The central part of the are, therefore, tends to adjust itself to an intermediate position with respect to the core, so that it is not further ezr= tended by the blow-out field. The end portions and extremities of the are are, however, still subject to the weakened blow-out field and are extended a limited distance toward the arc split= ters id as indicated where the arc is interrupted at a current zero. The are in this position, i. e. I18, can oscillate due to the pulsations or the A. C. blow-out field and at each oscillation will be driven into the arc splitters, if not interrupted at the first current zero.

For the purpose oi maintaining the arc in the central plane of the contacts and centrally oi the arc chute, the arc surfaces i and 2' oi the contacts are symmetrical with respect to the magnetic blow-out held. That is, the siufaces can be mutually convex so as to conform generally to the flux paths at each contact. Accordingly, the are, if originating atone side 01? the contacts, is acted on by a iorce component tending to drive it toward the central axes indicated at dhe are, therefore, is we in a concentrated blotv=' out held when initially formed.

it should be understood that my invention m not limited to specific details of construction and arrangement thereof herein illustrated, and that changes and modifications may occur to one skilled in the art trlthout departing from the spirit of my invention. .7

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

1. An electric circuit internniter oi thenoag= assure? netic blowout type comprising electrodes between which an arc is formed upon opening of the circuit, an arc-extinguishing chamber, magnetic blowout means for extending said arc into said chamber, and electromagnetic means positioned in said chamber substantially transversely of the are path for creating an opposing field in accordance with the currentoi said are and thereby preventing extension of said are beyond the limits defined by said opposing field, said electromagnetic means comprising an ii'on core of appreciable size as compared with the size of said chamber and a short-circuited conductor sur rounding said core.

2. An electric circuit breaker comprising relatively movable contacts between which an arc may form upon opening or the circuih'means for creating" a magnetic field for rapidly extendins said arc beyond said contacts, an are extinguishing chamber into which said are is extended, and means located in said chamber transversely of the path of extension oi said are for creating an opposing nelcl tending to limit extension of said are beyond a predetermined position, said means comprising a metallic core oi magnetic material occupying an appreciable part of said chamber and extending between side walls thereof, and a short circuiting conductor surrounding said core.

3. An electric circuit breaker comprising rela= tively movable contacts between which an arc may form upon opening or the circuit, means for creating a magnetic field for rapidly extending said are beyond said contacts, an arc extinguishthe chamber into which said are is extended, and means located in said chamber transversely of the path of extension or said are for creating an opposing iield tending to limit extension oi said are beyond a predetermined position, said means comprising an iron cylinder exmnding between side Walls of said chamber, and a short circuiting copper sleeve surrounding said cylinder.

none.

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