US1934454A - Oil blast circuit breaker - Google Patents

Description

NOV. 1933- 5. J. SPURGEON OIL BLAST CIRCUIT BREAKER Filed April 15. 1932 uummm W b a 00% His Attor-h g.

Patented Nov 7, 1333 011. BLAST cmourr BREAKER Samuel J. Spurgeon, Birmingham, Ala., assignor to General Electric Company, a corporation of New York Application April 13, 1932. Serial No. 604,955

' 6 Claims. (01. 200-150) Myinvention relates to electric circuit interrupters, and more particularly to circuit interrupters of the oil-blast type wherein a blast of insulating liquid is directed across an are causing interruption of the circuit.

- The principal object of my invention is the provision of an improved circuit interrupter of the aforesaid type which shall be positive and efficient in operation, and simple and compact in construction for a given interrupting capacity rating.

My inventionwill 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 out with-particularity in the claims annexed to and forming a part of this specification.

Referring to the drawing, Fig. 1 an elevational View, partly in section, .-of circuit interrupting apparatus embodying my invention and Fig. 2 is a similar view, partly in section, illustrating another form of my invention.

The circuit interrupting apparatus shown in Fig. 1 comprises relatively movable contact structure including a pair of fixed contacts 1 and 2 and a coacting movable bridging member 8 forming two breaks in series arranged so that separation of the contacts occurs within an;insulating The fixed contacts 1 and 2 are supported at the lower ends of the insulating bushings 6 and 7, respectively, through which the lead-in con- .ductors 8 and 9 extend connecting with the fixed contacts. In order to provide for a limited amount of overtravel of the bridging member 3 at the end of the circuit closing operation, the contacts 1 and 2 are each resiliently mounted with respect to conductingstuds 10 and 11. The resilient con nections comprise springs 12 and 13 mounted on guide stems 14 and 15, respectively, which are slidably mounted for limited movement within the studs 10 and 11. The bridging member 3, which may be actuated as by the lift rod 16, is of suitable conducting. material and may be formed by a hollow tube in the manner illustrated, the bridging member completing the cir cuit between the contacts 1 and 2 in the closed circuit-position shown. 3

For the purpose of effecting a blast of on across one of the arcs formed during opening of the switch to cause interruption of the circuit, the insulating casing 4 substantially encloses both pairs of contacts so that the pressure genmechanically strong and, by way of examp1e, may

erated by arcing at one pair is effective to cause a blast of oil across the arc formed at the other pair. Since the insulating casing 4 is subjected to bursting pressures, the structure should be G be a laminated structure impregnated with a phenolic condensation product cured under heat and pressure. In the present construction the casing 4 is formed by two sections which are suitably secured and clamped together as at 17, the upper section being clamped in position by the studs 10 and 11 to the lower enlarged ends of the lead-in conductors 8 and 9. The lower section of the casing is provided with openings 18 and 19 in which the contact portions of the bridging member 3 are guided.

In the operation of circuit breakers of the oilblast type it may be undesirable to subject the entire arcing chamber to high pressures and to move an unnecessarily large amount of oil in creating the circuit interrupting blast. Excessive pressures within the arcing chamber may cause damage to or destruction of the casing and often oil throw during circuit interruption which is very "objectionable. For thepurpose of localizing the high pressures within the insulating casing 4, and for moving a minimum amount of oil in creating the oil blast, the arcing chamber comprises a comparatively small .bulbular pressure generating chamber 20 having a restricted exhaust operiing 21 which is continuous with a diverging nozzle-like passage 22 near the outer or exhaust end of which the contact 2 and bridging member 3 coact. Accordingly, the pressure generated by arcing in the chamber 20 when the switch is 0 opened is effective to cause a high velocity blast of oil through the nozzle-like passage 22 'and the are formed near the exhaust portion thereof and into the main oil body exteriorly ofthe arcing chamber. In order completely and effectively to subject'the arc to the action of the oil blast,

.the exhaust opening of the passage 22 is provided with a plurality of insulating bafiles or arc splitters 23 which are preferably stream-lined and arranged transversely of the length of the are so that the oil blast tends to divide the are into a plurality of sections. With this arrangement the sure equalizing apertures 24 communicating with the hollow interior of the bridging member 3 permit a certain relief of pressure through the opposite end of the bridging member which is open. By arranging the pressure relief apertures 24 along the sides of the bridging member in the chamber 20 there will be no flow of -oil across the pressure generating are into the .bridging member so as to cause an undesirabledecrease in the intensity of the pressure generating are before the circuit is finally interrupted.

In case the circuit breaker is used for carrying heavy load currents, the arcing-contact structure above described is generally inadequate and primary or main current-carrying contacts are also necessary. For this purpose the actuating rod 16 at its lower end has mounted thereon a laminated bridging member 25 arranged to engage in the closed circuit position the stationary contacts 26 and 27 which are formed as conducting rings mounted exteriorly of and surrounding'the insulating casing 4 and connected to the lead-in conductors as at 28 and 29, respectively. Ac-

cordingly, upon downward or circuit opening movement of the actuating rod 16, which may be bifurcated as shown to extend on opposite sides of the casing 4, the main current-carrying contacts separate prior to the arcing contacts shown by reason of the overtravel of the latter contacts, continued lowering of the bridging member 3 causing initial separation of the contacts 1, 3 to form the pressure generating arc and subsequent separation of the contacts 2, 3 to form the are which is driven by the oil blast between the arc splitters and extinguished. The opening stroke may carry the contacts of the bridging member 3 outside of the arcing chamber in which case the .arc is extinguished prior to uncovering of the openings 18 and 19. Immediately after circuit interruption, the arcing chamber is refilled with oil through the various openings and the breaker is in readiness for reclosure and a subsequent opening operation.

In the construction shown in Fig. 2 the insulating casing 4, which is supported as by the bracing members 6' and 'l at the lower ends of the'insulating lead-in bushings 6 and 7 is arranged so that the oil blast is directed downwardly into the body of oil and the relatively movable contacts operate through opposite sides of the casing. The insulating casing forming the arcing chamber is in general constructed similarly to that described in Fig. 1- with the exception that both sectionsot the casing are provided with oppositely disposed apertures for receiving the contacts 30 and 31 for causing the pressure generating arc and contacts 32 and 33 arranged adjacent the exhaust of the nozzle-like passage 22 through which the oil blast is directed. In this arrangement the actuating means for the contacts comprises a pair of lever arms 34 and 35 pivotally connected, as at 36 and 37, with respect to the bushings 6 and 7, so that simultaneous rotation of said arms in opposite directions, as in jawfashion, causes engagement and disengagement of the aforesaid contacts. ,The upper extremities of the arms 34 and 35 are connected by the insulating links 38 and 39 to the lift rod 40 so that reciprocal vertical movement of said lift rod causes jaw-like operation of the arms 34 and 35. The contact 30 is suitably insulated from the conducting arm 34, as at 30', and connected to the lead-in conductor 9 by a flexible insulated 'lead 9', arm 35 is suitably insulated at its pivot from conductor 9 and a flexible conductor 34' connects conductor 8 to the arm 34 so that 0on v tacts 30, 31 and 32, 33 form two breaks in series.

arcing-contacts being normally biased into engagement as by a spring 41 mounted within a recess 42 in the corresponding switch arm in which the arcing contact is guided. It will be apparent, of course, that contacts 30 and 32, for example. may be fixed and the arm 35 mounted for pivotal movement to open and close the contacts.

If desired, the contacts may be formed as hollow tubes, as shown in contacts 32 and 33, for the purpose of relieving excessive'pressures on the contact mechanism. The degree of pressure relie! is, of course, a matter of design depending upon the interrupting capacity of the switch and other factors.

As in the case ofFig. 1, the opening operation includes separation of the primary contacts, if such are used, after which an initial pressure generating arc is formed by separation of contacts 30 and 31 in the chamber- 20. The resulting oil blast through the passage 22 drives the are formed between the contacts 32 and 33 between the arc splitters 23, thereby interrupting the circuit. In this design there is no unbalance of forces and, as in the previous case, the pressure is localized in the chamber 20 and the quantity of oil in the passage 22 is comparatively small, so that a high velocity blast is directed through the are formed adjacent the arc splitters 23.

In certain cases it may be desirable to create the oil blast by a spring actuated piston or the like, the piston being released in any suitable manner upon opening of the switch. For the purpose of simplicity the usual accelerating springs for causing high speed opening of the switch have been omitted.

It should be understood that my invention is not limited to specific details or construction and arrangement thereof herein illustrated, and that changes and modifications may occur to one skilled in the art without departing from the spirit of my invention.

' What I claim as new and desire to secure by Letters Patent of the United States, is-- 1. An electric circuit interrupter of the oilblast type comprising relatively movable contacts forming two breaks in series, an insulating casing having a diverging nozzle-like passage within and near the exhaust of which an are at one break is formed upon opening of said contacts, an insulating liquid within said casing, and a plurality of insulating bailles forming are splitters disposed at said exhaust opening transversely of the length of said arc, the are at the other break causing a blast of insulating liquid through said passage upon separation of said contacts, said are splitters arranged so that the arc is driven into the same by said blast and extinguished.

2. An electric circuit interrupter of the oil-blast type comprising relatively movable contacts forming two breaks in series, an insulating casing immersed in and containing an insulating liquid. said casing having a bulbular pressure chamber and a nozzle-like exhaust passage in which the arcs at said breaks are formed respectively. and a plurality of insulating baflles disposed at the exhaust opening of said passage, the pressure generated by arcing within said chamber causing a blast ci insulating liquid through said passage 3nd driving the other are between said insulating allies.

i 3. An electric circuit interrupter comprising like exhaust passage, the contact ends of said bridging member extending through the walls of and within said chamber and passage respectively for engaging said fixed contacts, and a plurality of insulating baflles disposed at the exhaust opening of said casing, the arcingpressure generated in saidchamber during opening movement of said bridging member causing ablast of insulating liquid through said passage for driving the are formed. therein between said insulating baffies. Y

4. An electric circuit interrupter oi the oil-blast type comprising relatively movable contacts ineluding a pair of fixed contacts and a movable tubular bridging member for connecting the same, an insulating casing forming a pressure generating chamber and a communicating exhaust passagein each or which a fixed contact is disposed.

the contact ends or said bridging member extending through a wall of said casing to engage said fixed contacts, said member provided with apertures at the opposite ends thereof tending to equalize arcing pressure on said bridging member upon opening of the circuit. I

5. An electric circuit interrupter or the oil-blast type comprising a casing immersed in an insulating liquid forming a pressure generating chain.-

ber and an exhaust passage, and relatively movable contact structure including a pair 0! arms pivoted for jaw-like movement and a pair 0! contacts carried by each arm arranged to extend through apertures in said casing and cooperate to form, a pressure generating arc in said chamber and an arc in said exhaust passage, said lastnamed are being traversed by a blast of insulating liquid created by-the pressure in said chamber.

6. An electric circuit interrupter of the oilblast type comprising a pair or fixed contacts, a coacting movable bridging member forming with said contacts two breaks in series, and a casing containing an insulating liquid within which said breaks are located, said casing comprising a substantially nozzle-shaped structure forming a. bulbular pressure generating chamber within which one of said breaks is located, and a diverging exhaust passage in whichthe other break is located leading from said chamber.

samurai J. sPURqEoN.

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