US2145706A - Electric circuit interrupter - Google Patents

Description

Jan. 31, 1939. F, BRANN 2,145,706

ELECTRIC CIRCUIT INTERRUPTER Filed Dec. 17, 1937 Inventor: Fritz Jemn,` by 561ML? A His Attorney.

Patented Jan. 3l', 1939 u PATENT OFFICE y 145cm ancorato omcm'r mamen lFritz Braun, Dresden, Germany, assigner to General Electric Company, a. corporation of New York Application December 17, 1937, Serial No. 180,381 In VGfci'mimy January 5, 1937 3 Claims.

VMy invention relates to electric circuit interrupters, ymore particularly to circuit breakers of the impulse 'type for high voltage power circuits and has for its principal object the provision of an 5 improved circuit breaker ofthe above type that Y is simple and rugged in construction, compact in design and capable oi operating with a comparatively small amount of arc-extinguishing liquid and positive and'eflicient in operation throughout the entire interrupting range of the breaker.

\ Circuit breakers of the impulse type have been proposed wherein the piston or equivalent blast producing device is provided with a spring that is charged by the movable Contact structure during the circuit-clos1ng operation. therefore effective to produce an oil blast intend-- ed to interrupt the circuit when the-breaker is opened. A primary disadvantage ot these break ers is `that the oil blast is often ineffective by reason of its tardy application. The blast should be applied to the arcat the very instant o its formation in order to prevent excess pressure in the breaker. That is, the are pressure generated upon separation oi the contacts may, if arc interruption is delayed, actually block operation ci the piston with the result that the oil blast is not applied at the proper time. Also, in the case ci closing on a short circuit, thecarc pressure, interruption is not rapid, may be so great that the breaker is damaged or destroyed.

Tin accordance with my invention an energy@ storing device operatively related to the blastproducing piston is charged prior to actual ciosing of the circuit and is arranged in the case of normal opening of the circuit so as to cause or initiate an oil blast in advance of contact separation.` Accordingly, an arc-extinguishing blast is under way in anticipation of formation of the power arc.

In the case of closing a breaker embodying my invention on a short circuit, immediate opening as in trip-free operation is accompanied by an oil blast since the power storing device is eiective even prior 'to contact engagement to initiate the oil blast. Y

My' invention will be more fully set forth in the following description referring to the accompanying drawing, and the features of novelty which characterize my invention will be pointed oout with particularity in the claims annexed to and forming a pfart of this specification.

Referring to' the drawing the single gure thereof is an elevational view, partly in section, `of a circuit breaker embodying my invention in the circuit closed position thereof.

The piston isY (Cl. 20G-150) v The impulse type circuit breaker illustrated comprises an insulating casing A adapted to contain an arc-extinguishing liquid such as oil. At the lower part of the casing immersed in the oil is the xed contact structure l formed in the 5 present instance as a socket contact that is mounted on a conducting spider structure 2 elec tricallyconnected to the breaker terminal indicated at 3. The movable contact coacting with the `fixed contact comprises a rod contact t l0 guided for reciprocal rectilinear movement and electrically connected to the other terminal conductor indicated at 5. lin the position shown the contacts E and are in engagement to close the circuit between the terminals and tu'.

For the purpose of interrupting the arc formed upon separation of contacts l and there is pro-k vided a piston mounted for reciprocal movement within a cylinder t forming part of the structure at the lower part of the breaker casing be to neeth the lined contact. i suitable energy-stop ing device, such as a spring is mounted between the piston and the lower wall oi the casing so es to bia-s the piston upward toward the xed contact. The piston forms in eiiect a partition in 25 the casing so that oil above the partition is urged upward toward the contact structure when the piston is projected upward by the spring l.

An insulating bailie having a central aperture 9 Athrougrr which the rod contact :i can move to 30 engage the Contact l defines an interrupting chamber i' in which the xed Contact and piston are disposed.l Additional bafiie structure It may likewise be provided if desired for deecting oil in a manner well known in the art.

For the purpose of balancing the arc pressure formed upon 'separation of contacts I and! at the piston 6 a by-pass H is formed in the casing between vthe space above the bale 8 and the lower side of the piston. With this arrangement the 40 piston 6 can operate substantially independent oi the arc pressure so as to project a uniform stream of oil through the arc.

Referring more particularly to the means for controlling the piston and charging the spring 1, the movable contact 4 is provided with a fixed collar I2 in abutting engagement with an insulating U-shaped member I3 guided in and extending through the insulating partition 8. The member I3 extends beyond the contact tip of the rod l 50 so as to engage the piston E and depress the same to a position below the rod contact. It will therefore be noted that the piston 6 is depressed and the spring 1 charged prior to actual engagement of the contactsl and I. Therefore, at the u 2 instant the contacts engage, the piston is in readivness if the occasion demandstoproiect an arcextinguishing blast through the arc. In operation the breaker is closed by lowering the rod I`by any suitable actuating means so that Athe member Il as it is guided through the partition l'engags the piston 8 to depress the same and charge the spring 1. Through this operation the oil beneath the piston 'is admittedvto the arc chamber l through suitable non-return valves Il mounted in the piston. The oil is also forced into the upper compartment through the by-pass il. In the position illustrated the spring, 1 is completely charged and in readiness to bias the piston 6 upward to project oil from the chamber l to the upper chamber. t

When the breaker is opened by elevation of the rod 4 the upward movement oi the piston controlling member I3 permits following movement of the piston l although the contacts.i and I are still in engagement. The oil starts to iiow from the chamber l" at' the clearance between the baille 8 and contact lso that when the arc is actually formed lbetween the contacts a high velocity oil jet starts to flow through the baiiie opening 9 to interrupt the arc. The'bame 8 is` preferably located as closely as. possible to the fixed contact i so that the arc length will be very short. The piston controlling member Il, which -is slidably mounted on the rod 4, is limited in-its upward movement by the baille structure I although the rod contact l can bewithdrawn to an isolating position.

. It will be noted that incase of closing of the breaker on short circuits the prior charging of spring 1 is particularly advantageous in causing an interrupting blast at the instant the contacts engage. That is, in normal trip-free operation the breaker.

- the breaker is reopened at the instant of contact engagement where a short circuit or fault still exists on the line. This immediate application of i the oil blast is effective to reduce the duration oi the arc and thereby limit the pressure within The piston i also is obviously very effective in the case of small currents which often generate insumcient gas pressure to interrupt the are by an oil blast.

l 1t wm ne apparent that a tubular contact having vents disposed above the bale 8 can 'be used in place of the solid rod contact 4 if desired as such a construction is well known in practice. In such an arrangement shown for example by Prince Patent 1,922,862, granted Aug. 15, 1933 for Electrical switching apparatus" `the piston Q would force the oil into the tubular contact so as to squeeze the arc in radial directions towards a position within the tube. There will also be a transverse blast oi' oil-through thev arc when the removable contact has cleared the baule I.

It should be understood that my invention is not limited to specii'lc details 'of construction and arrangement thereof herein illustrated, and that changes.v and modications may occur toone skilledin the -art without departing from the spirit `of my invention.

'anced at said piston, and means extending beyond and operable with the movable contact for depressing said piston and charging said spring during the circuit-closing operation prior to actual engagement of said contacts.

2. An electric circuit breaker of the impulse type comprising a casing containing an arc-e.

tinguishing liquid, fixed and m9va'ble4contacts adapted f to separate in said liquid, insulating baille structure disposed in said casing arranged to denegachamber in which said xed contact is disposed, a piston likewise disposed inusaid chamber, a spring for biasing said piston 1n a direction to cause a blast of said liquid through the are formed at said fixed contact upon opening of the circuit, said casing forming a by-pass around said bane., and piston, and insulating means operable with said movable contact through said baiile for depressing said piston and charging said spring in accordance with the circuit-closing operation prior tov actual engagement of said contacts. l

3. An electriccircuit `breaker comprising a cas-f ing containing an arc extinguishing iluicl, rela-` tively movable contacts adapted toseparate in said iiuid, a piston immersed in said uid, a'

spring for biasing said piston ina direction to cause a blast of said uid through the arc formed 4upon separation of said contacts, an insulating baille for directing said iiuid blast through the arc path, said casing forming a pressure equalizing by-pass around said baille and piston, and means forming an extension of and operable with one of said contacts for engaging said piston sub.

stantially in advance of engagement of `said contacts. continued -closing -movement of said contacts causing charging of said spring whereby vspring energy for creating'a fluid blast is available at the instant said contacts engage.

` FRITZ BRANN.

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