US1991884A - Circuit breaker - Google Patents

Description

Feb. 19, 11935. w, DYER 1,991,884

0 IRCUIT BREAKER Filed Nov. 26, 1930 INVENTOR L/oyd W Dyer A ORNEY Patented Feb. 1 9, 1935 PATENT. OFFICE CIRCUIT BREAKER Lloyd W. Dyer, 'Swlss'vale, 2a., assignor to Westinghouse Electrlc and Manufacturing Company, a corporation of Pennsylvania Application November 26, 1930, Serial No. 498,386

9 Claims.

The invention relates to circuit interrupters and particularly to circuit interrupters wherein the contacts are separated and the are is extinguished in an exceedingly short interval of time.

Application Serial No. 678,248 of H. L. Rawlins gled June 29, 1933 is a division of this applica- One object of the invention is to provide a circ'uit interrupter, that operates at high speed, with an arc-extinguishing device that prevents arc reinitiation after the arc is extinguished, as the current passes through the zero point of its cycle wave.

Another object of the invention is to provide an arc-extinguishing device, for a circuit interrupter of the above-mentioned type, that will trap the arc-extinguishing fluid about the arc in such manner that the fluid will be decomposed by the are for effecting the liberation of un-ionized gas which passes through the arc stream.

A further object of the invention is to provide an arc-extinguishing-device, for a circuit interrupter of the above-mentioned type, that shall maintain the arc in its originally established path and cause the gas resulting from decomposition of the surrounding liquid to pass through the arc stream.

The trend of the art, relative to electric-transmission systems, is toward circuits of higher voltages. One of the greatest limitations to the continued increase of the voltage ratings of such systems is, no doubt, the inadequacy of the circuit-interrupting equipment, the present circuit interrupters b ing incapable of reliably handling the more desirable high voltages,

The tremendous power that is developed in the modern high-voltage systems, in the presence of a short circuit condition, must be dissipatedand the arc extinguished in an exceedingly short interval of time and prevented from re-striking if no harmful results are to ensue. Violent surges usually occur when several cycles of alternating current occur before the arc is completely interrupted. If the present type of circuit interrupter.

is made large, in proportion to the increased voltage of the system, the clearances between the live conductors and the grounded enclosing casings .will be increased to such an extent that the entire structure will assume undesirable proportions.

In practicing the invention, I avoid the necessity of increasing the size of the higher-voltage circuit-interrupting structures by decreasing the time requiredto interruptthe circuit. I accomplish this by increasing the speed of contact travel to procure a. more rapid separation of the contact members and employ are de-ionizing devices for extinguishing the arc upon the occurrence of the first zero .point in the current a1ter--' nating cycle wave and which prevent the are from being reinitiated after extinguishment. In such construction, the circuit is interrupted almost immediately upon the occurrence of a predete mined circuit condition, before excessive press es-are permitted to accumulate, and no deleterious effects from surges result in the system or in the circuit-interrupting structure.

The invention will be best understood by referring to the following specification, taken in conjunction with the accompanying drawing, wherein:

Figure 1 is an elevational view, partially in section, of a circuit interrupter embodying features of the invention.

Fig. 2 is a sectional view, in elevation, of the arc-extinguishing structure.

Fig. 3 is a sectional view of the structure illustrated in Fig. 6, taken along the line III-III thereof.

The invention comprises, in general, a tank 1 having a cover 2 that supports insulated conductor bushings 3. Arc-extinguishing devices 4 are provided on the ends of the bushings 3, having contacts 5 thereof bridged by conducting contact rods 6 and a bridging member 7 to complete the circuit. The bridging member 7 is supported on a lift rod 8 that is releasably retained against the bias of anaccelerating mechanism 9 by a latching mechanism 11, all of which elements are contained within the tank 1. The tank is also provided with an arc-extinguishing liquid 12 in which the arc-extinguishing devices 4 are immersed.

In Patent No. 1,872,382 issued August 16, 1932 on an application of Ch'ristain Aalborg et al. and 40 assigned to the assignees of the present invention, a high-speed circuit interrupter is set forth, a portion of the mechanism of which is disclosed in Fig. 1. In this structure, the movable members are made as light as possible, in view of the strength and conductivity requirements.

'hardened copper is employed for the contact rod 6 and bridging member 7, while wood micarta is employed in the lift rod 8. The reduction of weight in the moving parts decreases their inertia and permits their rapid acceleration by the accelerating mechanism 9.

A metal rod 13 is attached to the upper end of the collar 14 which supports the lift rod 8. The accelerating mechanism 9 surrounds the rod 13 and comprises an outer spring and an inner spring 16 between which a sleeve 17 is utilized to prevent the turns of one spring from interfering with those of the other. The springs 15 and 16 are disposed between a flat washer or bumper plate 18 in the housing 19 and a washer 23, which abuts the collar 14 on the lift rod 8 and serves to force the movable contacts downwardly, at high velocity, when the rod 13 is released. The housing 19 is secured to the side of the tank 1 by bolts 22. and a suitable retaining and guiding structure 24 is provided about the springs 15 and 16.

The upper end of the rod 13 is provided with a metal head 25 which may pass through an opening 26 in the housing 19, and the rod 13 is releasably retained in closed position by a latch 27, a portion of which is cut away to form a recess 28, in which a steel ball 29 is forced by the action of a cam 31 that is biased upwardly by the spring 32 as is more fully described in the above-noted copending application, this construction makes the movable contacts and bridging bar trip free of the closing mechanism at the top of the lift rod so that the mechanism connecting the lift rod to the closing mechanism-does not have to be accelerated when the breaker is tripped.

The operation of the device will now be described. When the tripping arm 39 is actuated, the cam 31 is forced downwardly against the spring 32, thereby releasing thesteel ball 29 and the latching member 27 to completely release the accelerating mechanism 9 and the lift rod 8. The tension in the springs 15 and 16, acting between the washers 18 and 23, causes the bridging bar 7 and conducting rods 6 to be rapidly accelerated downwardly to establish arcs between the ends of the rods 6 and the stationary contact member 5. When the plate 23 has reached its lowermost position, the head 25 strikes against the bumper plate 18, and the continued movement of the accelerated members causes the springs 15 and 16 to be compressed and the movement of the members retarded and brought to rest without damage to the members.

The arc-quenching medium 12, that may be oil, water or any other gas-evolving substance, is retained in intimate contact with the are by the plates 56 which divide the chamber 4 into a series of sub-chambers 63 which communicate with each other only through the openings 62 when the contact rod 6 is withdrawn. In this construction, the arc is being drawn into fresh sections of the liquid, and the gas evolved from the liquid, owing to its intimate contact with the arc, passes through the arc stream and escapes through the openings 64.

The un-ionized gas, passing longitudinally throughv the arc stream, de-ionizes the stream and causes the are core to contract.

This de-ionizing process and the contraction of the core continues until a zero point of the cycle wave occurs, at which time, the arc is extinguished. As the cross-section of the are core is exceedingly small at this moment, complete deionization of the arc path immediately occurs, and reinitiation of the arc isprevented when the current and voltage again increase in value. In this construction, an arc is established and completely extinguished within one cycle of alternating current. I

When the contact members are moved within the arc-deionizing-and-extinguishing device at an exceedingly high rate of speed, similar to that effected by the disclosed accelerating mechanism,

.will be completely consumed at the portion of the are stream where the arc is initially established,

and, for this reason, a greater length of arc will be required. When employing the high-speed contact movement in combination with the grid structure, the structure and the contact travel may be shortened, because of the fact that the critical arc length only will be required to effect complete arc extinguishment.

The constructional details of the arc-extinguishing device, that utilizes the accumulated gases for accelerating the deionization process, are illustrated in Figs. 2 and 3, wherein a receptacle 55 encloses a plurality of spaced plates or units of plates. In Fig. 2, separate plates 56 are joined to the walls of the receptacle 55 and are spaced apart by insulating bushings 5'? that cover through bolts 58.

An upper chamber 59, between the receptacle cover 61 and the topmost plate 56 is unvented except for an opening 62 through which the arc is drawn. A plurality of chambers 63, provided below the chamber 59, are vented by small orifices 64 contained in the periphery of the receptacles 55, as shown in Figs. 2 and 3. When the arc is drawn through the alined holes 62 in the center of the plates 56, as the rod 6 is moved downwardly from engagement with a stationary contact member 65, gases are generated by the decomposition of the liquid trapped in the chambers 59 and 63.

As the arc is drawn in the successive chambers, the gas, evolved upon the decomposition of the trapped liquid, builds up a pressure and escapes to the adjacent lower chamber, wherein high pressure has at that time not yet been developed. For this reason, the gas must pass through the arc stream at each of the central openings 62 in the plates 56 as the contact rod 6 clears each opening 62. In this construction, the gases under pressure pass longitudinally through the arc stream at'the same time that gas is being fed radially thereinto as the liquid in the particular chamber is being decomposed. The vents 64 from the individual sub-chambers come into use successively as the contact rod 6 clears each opening 62 and vent the gases laterally and radially from each of the sub-chambers as pressure is built up after the arc has been drawn thereinto.

The i'ntermingling of these gases produces a turbulent motion within the arc path that more rapidly effects the recombination of the ions in the arc path, than is effected when the radially supplied gas alone is passing therethrough. After the gases become heated and ionized, they are forced out of the arc stream by the fresh gases that are continually being evolved and are vented from within the receptacle 55 through vents 64 that are provided along the side walls thereof.

It will thus be seen that I have provided a circuit interrupter that is capable of interrupting circuits of exceedingly high-voltage ratings. I accomplish this interruption by means of an accelerating mechanism that effects rapid sep aration of the contact members and substantially or gas thereirom at a plurality of points around instantaneous arc establishment, and by the deionizing means which extinguishes the arc in the first hall cycle of alternating current occurring after contact separation. I eifect this extinguishment by supplying un-ionized gas to the arc stream, longitudinally and radially thereof, that turbulently passes through the arc stream and causes the hot ionized gases thereof to become cool and de-ionized;

While I have described one particular embodiment of the invention, it is to be understood that many changes, additions, omissions and substitutions may be made therein without departing from the spirit and scope of my invention, as set forth in the accompanying claims.

I claim as my invention: r 1. The combination with separable contact members 'of a circuit interruptengof a plurality of spaced insulating members having openings.

through which the contact members extend, an insulating chamber having venting means on all sides thereof for enclosing the said members, and a gas evolving substance within said chamber.

2. The combination with separable contact members of a circuit interrupter that extend through slots in a plurality of spaced insulating members, of an insulating chamber having vents in its sides for-supporting and closely engaging the said insulating members said'vents being positioned around the periphery and along the length of said chamber.

3. An insulating chamber associated with the arc-quenching liquid of a circuit interrupter, a plurality of sub-chambers formed within the chamber by a plurality of insulating Plates having central openings, therein and the main portion of the outer periphery of each of said subchambers being closed, a movable contact member extending through said openings, and vents in the sides of the chamber communicating with the said sub-chamber for permitting radial flow the periphery of the chamber after the arcis 4. An insulating chamber submerged in the arc-quenching liquid of a circuit interrupter and a major portion of the outer periphery of saidchamber being closed, a plurality of sections withv the, liquid, longitudinally through the are,

stream, and means for venting the gas radially through the side walls of said chamber through-. out its length and at a plurality of points around its perip ry.

- 5; In a circuit interrupter, an arc-extinguish- 'ingchamberhavlngthemaior portionofitsside walls normallyclosed and a plurality of sub-' chambers formed therein by a plurality of insulating plates having openings therethrough, means ior drawing an are through said openings, said are drawing means having about the same cross-sectional area as said openings, and means for individually-venting each of said sub-chambers through the side wall of said chamber site 7 the are is drawn. v

8. In a circuit interrupter, an arc extinguishing chamber having the major portion of its side walls normally closed and a plurality of subchambers formed therein by a plurality of insulating plates having openings therethrough, means for drawing an are through said openings into each of said sub-chambers successively, the area of said openings being not greatly in excess of the cross-sectional area of said means for drawingthe arc,'and means for venting each of said sub-chambers laterally through the side wall of the chamber.

7. In a circuit interrupter, an arc extinguishing chamber having a side wall of insulating material and a plurality of partitions of insulating 'material dividing said chamber into a plurality .of sub-chambers, said partitions having aligned openings therethrough, a contact member fixedly mounted adjacent one endof said chamber and acontactmembermovablethroughsaidaligned openingstodrawanarcfromsaidfixedlymoimtedcontactintosaidsub-chambersin" meanspermittingflowoffiuidradialiythrough said side walls of said at a number of 3 points therearotmd and which function successively as the arc is drawn into said sub-chambers.

8. In a circuit interrupter, an arc extinguishing chamber having the major portion of its side walls normally closed and a plurality of subchambers formed therein by a plurality of insulating plates having openings therethrough, means for drawing an are through said openings,

and means for individually venting each of a' plurality of said sub-chambers through the side wall of said chamber after the arc is drawn, some of said venting means being through one sideoi 'the chamber and other of said venting means being through theopposite side of said chamber.

9. In a circuit interrupter, an arc extinguishing chamber having the major portion of its side walls normally closed and a plurality otsubchambers formed therein by a plurality of insulating plates having openings therethrough, means for drawing an are through said openings into each of said sub-chambers successively, and means for venting each-of a plurality of said. sub-chambers laterally through the' side wall of the chamber, and adjacent sub-chambers having at least a part ofv said venting means through op-- posite side walls of the chamber.

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