US3160726A

US3160726A - cromer

Info

Publication number: US3160726A
Authority: US
Priority date: 1962-01-15
Publication date: 1964-12-08
Anticipated expiration: 1981-12-08
Also published as: FR1310386A

Description

Dec. 8, 1964 c. F. CROMER 3,160,726

DOUBLE-BREAK CIRCUIT INTERRUPTERS OF THE GAS-BLAST TYPE WITH VENTED INTERMEDIATE CONTACTS Filed Jan. 16, 1961 3 Sheets-Sheet 1 1 3 cu i aijfl I i I 5N1? 1 l u ii 3x. U-

B X J 0i .9' INVENTOR Charles F. Cromer ATTORNEY Dec. 8, 1964 c. F. CROMER 3,150,726

DOUBLE-BREAK CIRCUIT INTEIRRUPTERS OF THE GAS-BLAST TYPE WITH VENTED INTERMEDIATE CONTACTS Filed Jan. 16, 1961 5 Sheets-Sheet 2 Dec. 8, 1964 c. F. CROMER 3,

DOUBLE-BREAK CIRCUIT INTERRUPTERS OF THE GAS-BLAST TYPE WITH VENTED INTERMEDIATE CONTACTS Filed Jan. 16, 1961 5 Sheets-Sheet 5 QC" fi24 Fig. 4.

United States Patent poplars-unease UlRCUlT TERMEDHATE CQENTAQTS Charles l3. Cromer, Leveigreen, Fa, to Westinghouse Electric Corporation, East Pittsburgh; Pa, a corporation of Pennsylvania Filed in, wet, Ser, No. 325247 8 Claims. (Cl. Nth-148) This invention relates to circuit interrupters in general, and more particularly, to circuit interrupters of the fluidblast type.

A general object of the present invention is to provide an improved circuit interrupter, particularly adaptable for high-power application and in which relatively high-rates of rise of recovery-voltage transient are encountered.

A more specific object of the present invention is to provide an improved interrupting structure for a highpower circuit interrupter in which the current, to be interrupted, is interrupted in two steps, the first step consisting of inserting an impedance, such as a resistance, serially into the circuit, and the second step consisting of breaking the residual current by a series isolating break.

Another object or the invention is to provide an improved circuit-interrupting unit for a circuit breaker in which a fixed main contact gap is obtained to prevent the accumulation of considerable ionized gas, which would result if the gap were lengthened by continued movement of the movable contact structure.

Still a further object of the present invention is to provide an improved arc-extinguishing structure in which by a novel arrangement and configuration of the cooperable parts, considerably improved arc-extinguishing action and consequent circuit interruption are obtained.

A further object of the present invention is the provision of an improved circuit-interrupting structure which is readily adaptable for use either with a shunting impedance, such as a shunting resistance, or is adaptable for use omitting such a shunting impedance.

Another object of the invention is the provision of a circuit interrupter of the type set forth in the immediately preceding paragraph in which the rte-arrangement of the interrupter may be accomplished with a minimum of effort.

Yet another object of the present invention is the provision of an improved gas-blast circuit interrupting unit, in which a relatively tubular intermediate contact structure is cooperable with the relatively stationary contact structure, and the blasting of gas may take place through the tubular intermediate contact structure to assist in the final interruption of the circuit at a series disconnecting break.

Further objects and advantages will readily become apparent upon reading the following specification, taken in conjunction with the drawings, in which:

FIGURE 1 is an end elevational view of a multi-pole high-power circuit interrupter embodying features of the present invention;

FIG, 2 is a longitudinal, sectional view taken through one of the tank structures of the circuit interrupter of FIG. 1, illustrating the internally-disposed arc-extinguishing assemblage, such assemblage being illustrated in the closed-circuit position;

FIG. 3 is a considerably enlarged substantially vertical sectional view taken through the right-hand circuit-interrupting unit of the arc-extinguishing assemblage illustrated in FIG. 2, the contact structure being illustrated in the fully open-circuit position; and,

FIG. 4 is a view similar to that of FIG. 3 but illustrating a modified type of circuit-interrupting unit.

3,15%,726 Fatented Dec. 8, 1964 Referring to the drawings, and more particularly to FIG. 1 thereof, the reference numeral 1 generally designates a three-pole multi-phase, double-pressure cornpressed-gas circuit interrupter. FIG. 1 illustrates an end view of the structure, and consequently only the end tank 2 is shown. A mechanism housing 3 is disposed at the end of the three breaker tanks 2 and encloses a suitable operating mechanism, not shown, which is efiective to simultaneously actuate the arc-extinguishing assemblages 4 (PEG, 2) disposed interiorly of the tank structures 2.

Extending downwardly interiorly within the tank structures 2 are pairs of terminal bushings 5, 6, which serve to carry the controlled circuit into the tanks 2. The tanks 2 and the mechanism housing 3 are supported upon steel beam 7 supported upon a concrete foundation 8. Preferably the ends of the tanks 2 contain hinged covers 10, ill, which permit inspection within the tank structures 2.

With reference to FIG. 2 of the drawings, it will be observed that supported at the lower ends 12, 13, of the terminal bushings 5, 6, respectively, are support castings Me, 15, which fixedly support into position the arc-extinguishing assemblage 4.

The arc-extinguishing assemblage 4 generally comprises a plurality of serially-related arc-interrupting units 16 of the gas-blast type, the configuration of which is more readily apparent from an inspection of FIG. 3 of the drawings. Disposed adjacent the right-hand end of the arc-extinguishing assemblage is a high-pressure storage tank 17" A blast-valve mechanism 18 is operable to control the blasting of gas out of the hi h-pressure storage tank 17 and toward the three gas-blast interrupting units 16 to effect are extinction thereat.

The movable contact assemblage 20 generally comprises a pair of outer longitudinally-extending insulating operating rods 21, which are bridged by cross-bars 22 (FIG. 3), to the middle portions of which are fixedly secured the movable isolating contacts 23, as shown more clearly in PEG. 3. The rod-shaped isolating contact 23 makes engagement with a movable tubular intermediate contact structure 24, and forces the same against spring pressure 25 t ward the right, as viewed in FIG. 3, and into engagement with a relatively stationary contact structure, generally designated by the reference numeral 26. It will be observed, with reference to FIG. 3, that the relatively stationary contact structure 26 comprises a cluster of finger contacts 27, and a centrally-disposed arcing horn In the closed-circuit position, indicated by the dotted lines 29, it will be observed that the arcing born 23 protrudes interiorly within the tubular intermediate contact structure 24, so that good contacting engagement is provided by the fingers 27.

With further reference to FIG. 2, it will be noted that an opening accelerating spring 31 biases the movable contact assemblage 2% toward the left in an opening direction. This movement is resisted by the tension exerted by an operating rod 3;. formed of insulating material, and interconnecting the movable contact assemblage 2t? with an external operating mechanism disposed within mechanism compartment 3. Reference may be had to United States patent application, filed January 23, 1959, Serial No. 788,668 by Russell N. Yeckley, loseph Sucha and Benjamin P. Baker, now Patent No. 3,057,983, and assigned to the assignee of the instant application for a minute and detailed description of the several parts associated with the circuit interrupter 1. For the purpose of understanding the present invention,

however, it is only necessary to know that operation of the blast-valve mechanism 13 is operable to force the blast valve 33 (FIG. 3) toward the right, away from its seat 34 and permit the blasting of gas in the direction indicated by the arrows 35. The gas blast not only blasts into the first interrupting unit 116, but also passes down a plurality of insulating

blast tubes

36, 37 and into the adjacent gas-blast interrupting units 16 to effect are extinction therein. The arrangement is such that sufiicient gas-blast pressure exists simultaneously in all three interrupting units 16 at the time of actual contact parting. As a result, simultaneous extinguishing action is exerted Within each of the interrupting units 16.

Reference may be had to U.S. patent application filed October 17, 1960, Serial No. 63,201 by Russell N. Yeckley, Joseph Sucha and Roswell C. Van Sickle, and assigned to the assignee of the instant application for a description of the blast-valve mechanism 118. The operation of this blast-valve mechanism 18 forms no part of the present invention and consequently a description thereof is deemed unnecessary.

With reference to FIG. 2 of the drawings, it Will be observed that a pair of insulating tie-bars 39 mechanically interconnect the end clamp castings 14, 15, and serve to fixedly secure into proper position the stationary contact structure 26, associated with each of the gas-blast interrupting units 16. In addition, it will be observed that the stationary contact structures 26, associated with the middle and left-hand interrupting units 16, contain rightwardly-extending relatively stationary contact fingers 40, which serve to guide the adjacently-disposed movable contacts 23, and to carry current therefrom to the adjacent stationary contact structure 26 of the adjacent unit 16.

During the opening operation, the mechanism, not shown, disposed interiorly within the mechanism housing 3 is unlatched to thereby permit the crank-shaft 43 to rotate in a clockwise direction. Because of the biasing action exerted by the opening accelerating spring 3 1, the entire movable contact assemblage 20, comprising a plurality of the movable contacts 23, interconnected by the insulating tie-bars 21, will move as a unit, toward the left in a circuit-opening direction. With reference to PEG. 3, it will be observed that the presence of the compression spring 25 will force the intermediate contact structure 24 toward the left maintaining contact with the movable isolating contact 23. Upon separation between the arc-resisting tip portion 30 of the tubular intermediate contact 24 from the stationary contact fingers 27, a maincurrent are 44 will be established, and will quickly transfer, because of the gas blast, to the arcing horn 28 and the inner surface 45 of the tubular intermediate contact 24.

To facilitate the interruption of heavy current, and also to assist in the interruption of circuits having high rates of rise of recovery voltage, a shunting impedance, generally designated by the reference numeral 46, and comprising a resistance tube 47, is inserted serially into the circuit. An alternate construction could be a helical resistance wire winding, or even stacked resistance rings could be used. The material of the resistance rings could be filled with carbon granules and a suitable binder for the requisite resistance value. This will assist in the interruption of the main-current are 44 and will improve the power factor of the circuit after insertion into the circuit. The insertion of the resistance modifies the voltage recovery transient of the main gap.

The movable tubular intermediate contact structure 24- will move to the left until the flange portion 48 thereof strikes a fixed stop 50 establishing a fixed gap between the stationary contact 26 and the tubular contact 24. The disconnecting contact 23 does not necessarily break immediately. It could, and perhaps should stay in engagement until the main arc 44 has been completely interrupted in the main gap to avoid unnecessary burning and arc products. The maximum arcing time in the main gap would then determine the overlap between disconnecting contact 23 and intermediate fingers 53. A residual current arc, designated by the reference numeral 52, will finally be established between the disconnecting contact 23 and intermediate contact 24. Because of the improvement in the power factor of the circuit, and also because the magnitude of the current has been considerably diminished by the insertion of the impedance 47 into series circuit, the interruption effort required to interrupt the residual current are 52 is relatively slight. In this connection, it will be observed that the gas blast passes centrally down through the tubular intermediate contact 24 and assists in the interruption of the residual current are 52.

As viewed in FIG. 3, it will be noted that a plurality of segmental intermediate current fingers 53 are provided, being biased radially inwardly by compression springs 54 to provide good contacting pressure between the

contacts

23 and 53 in the closed-circuit position of the interrupter. In addition, the segmental contact fingers 53 preferably have an arc-resisting tip portion 55 to resist the eroding action exerted by the are 52.

As stated hereinbefore, the residual current are 52 is quickly interrupted by the gas blast passing interiorly through the movable intermediate contact 24, and circuit interruption is thereby quickly brought about. The movable disconnecting contact 23 continues to move to a fully-open isolating position, as indicated by the fully open-circuit position of the interrupter in FIG. 3. Merely for the purpose of illustrating the invention have the main-current and residual-current arcs 44, 52 been drawn into the illustration of FIG. 3, although it must be remembered that the contact parts are illustrated in the fully open-circuit position of the interrupter 11.

As the power requirements of the utilities continue to grow, the magnitude of fault currents considerably increases. This is accompanied by higher current values and also high rates of rise of recovery voltage transients. Furthermore, emphasis is being placed more on line faults, in which the rate of rise of recovery voltage can become very severe, and it is desirable to modify interrupting structures to enable them to interrupt such high rates of rise of recovery voltage with less difficulty.

It has been demonstrated experimentally that interrupting times can be decreased by forcing the are into the hollow moving contact of the circuit breaker at short arc lengths or at short gaps between the moving contact and the relatively stationary arcing horn, and thus performing its interrupting function. However, for successful interruptions of capacitive currents, speed is of prime importance, which means that the contacts must have a maximum separation and maximum creepage onehalf cycle after parting.

It is evident that as the arc lengthens and the current is increased, more and more are products are formed and greater thermal expansion of the gases occur. As a result, the discharge nozzle becomes clogged and an interrupting limit is reached. This means that the orifice must be increased in diameter or the driving pressure increased, or bothneither of which is desirable for compact arrangements.

The present invention proposes an improved interrupting construction in which:

(1) The arc length or contact separation is not random, but fixed at a predetermined maximum, assuring thereby a minimum amount of are products and thermal expansion, which, in turn, provides for a reduction in nozzle diameter and more compact assembly.

(2) An impedance, such as a resistor, shunt to modify the rate of rise of recovery voltage.

(3) An auxiliary contact to interrupt the resistor current.

The interrupting unit 16 consists essentially of a firstbreak stationary finger contact and arcing horn assembly 26, intermediate movable contact assembly 24, a resistor shunt assembly 46, and a movable disconnecting contact assembly 23.

FIG. 3 shows the contact structure in the fully opencircuit position. To close the contacts, the moving con tact rod 23 moves toward the right, and the circuit is made up through the resistor 47 when the disconnecting contact 23 engages the finger assembly 53. This move ment continues until the overlap position of the intermediate contact 24 reaches the dot-dash line 29 of FIG. 3. In the fully closed position, the main interrupting contact assembly is biased toward the open circuit position by the compression spring 25, which is confined between the main interrupting contact 24 and the blast shield assembly 55. The blast shield assembly 56 comprises the guide 57 and the stop 5%. This assembly is, in turn, mounted to the tie-bar rods 39 and maintained in a fixed position. The insulating guide nozzle 5'3 performs a dual function of not only acting as a close-fitting, lowfriction insulating guide, but also acts as a closure member to direct the gas flow through the tubular intermediate contact assembly 24.

During the opening operation, both contact assemblies 23, 24 withdraw together as a unit, until the intermediate contact assembly 24 strikes the stop St). The compression spring 25 not only provides sufiicient force to accelerate the intermediate contact assembly 24 but also acts as an initial high-force, kick-off spring, for the breaker. The movable contact assembly 23 continues to move, and just prior to parting with the finger contacts 53 will have traveled in the order of four or five inches, for example, which should allow ample time to interrupt the main current arc 44, and make the circuit transfer through the resistor assembly 47.

The transfer of the main current into the resistor as sembly 4'7 takes place in the following manner: The main current are 44, drawn between the relatively stationary contact 26 and the tubular intermediate contact assembly 24, is blasted into the expanding tubular contact 24. At current Zero, this blast establishes sufficient dielectric to transfer the electrical circuit through the resistor 47 and maintain adequate strength to prevent re-ignition. The are products are swept out of the arc region down the tubular intermediate contact 24 and out of the lateral ports 60. The blast-shield assembly 56 prevents any hot gases from impinging on insulating surfaces.

As the contact assembly 23 continues to move toward the open position it draws a residual-current are 52 between the

contacts

23, 53. This resistor current is very low in value, say 200 to Silt) amperes, for example, and is easily interrupted by even a very slight gas flow down the tubular contact 24.

FIG. 4 illustrates a modified type of interrupting unit 61 in which the impedance shunt 46 is omitted. it has been noted on tests that when interrupting very high currents, the interrupting times varied from 2.5 cycles to 2.9 cycles. It appears that the breaker will not interrupt at 2.4 cycles, which has a relatively short gap (less than one inch), but will interrupt each time at the 2.5 cycle position (in the order of 1 to 1 /2 inch gap). At 2.9 cycles the gap has become quite long (approximately 2.8 inches) and the interrupter, due to arc products, may start clogging and possibly fail if interruption of higher current values are attempted. It is, therefore, of no advantage, and becomes somewhat disadvantageous to draw a long main current are.

If the moving contact is stopped at some optimum gap, say 1.5 inches, then the 2.4 cycle position can be passed without lengthening the gap to some excessive value. Since interruption in some circuits can be made without aid of a shunting resistor, under certain circuit conditions, the modified interrupter construction 61 of FIG. 4 is advantageous in that the resistor 47 is omitted, and yet the main contact gap distance is set at the optimum value. Without the employment of the shunting resistor 47, the moving contact 23 becomes merely an isolating break With no interrupting function to perform. The opening and closing operations would remain the same as described above in connection with the interrupter unit 16 of FIG. 3.

From the foregoing description of the invention, it

will be apparent that there is provided an improved interrupter construction 16 embodying a relatively stationary contact structure 26, an intermediate contact structure 24 and a movable disconnecting contact structure 23. Particularly advantageous results are achieved by the use of a tubular intermediate contact structure 24, through which the gas blast may be exhausted and facilitate interruption of the residual current are 52.

For certain applications it is advantageous to eliminate the shunting resistance 47 and to maintain the main gap distance at an optimum value as illustrated in FIG. 4.

Certain features of the orifice construction for the interrupting unit 16 are set forth and claimed in US. Patent Application, filed October 7, 1960, Serial No. 61,284 by Robert G. Colclaser and Russell N. Yeckley, and assigned to the assignee of the instant application.

Although there have been illustrated and described specific structures, it is to be clearly understood that the same were merely for the purpose of illustration, and that changes and modifications may readily be made therein by those skilled in the art, without departing from the spirit and scope of the invention.

I claim as my invention:

1. A gas-blast interrupting unit for a circuit interrupter including a relatively stationary contact, a movable tubular intermediate contact separable from said relatively stationary contact to establish a main-current arc, an impedance shunted across the stationary and intermediate contacts, means including a relatively tight-fitting insulating orifice member about the intermediate contact for defining a pressure chamber about the relatively stationary contact, a source of gas pressure, means for admitting at times compressed gas from said source into said pressure chamber whereby a blast of gas is substantially wholly forced through the tubular movable intermediate contact to extinguish said main-current are, a movable isolating contact cooperable with the intermediate contact to establish a residual-current arc, and the blast of gas forced through the tubular movable intermediate contact being used not only to extinguish the maincurrent are, but, additionally, the same gas being used, at least in part, to extinguish said residual-current arc.

2. A gas-blast interrupting unit for a circuit interrupter including a relatively stationary contact, a movable tubular intermediate contact separable from said relatively stationary contact to establish a main-current are, an impedance shunted across the stationary and intermediate contacts, means defining a stop for opening movement of the tubular intermediate contact, means including a relatively tight-fitting insulating orifice member about the intermediate contact for defining a pressure chamber about the relatively stationary contact, a source of gas pressure, means for admitting at times compressed gas from said source into said pressure chamber whereby a blast of gas is substantially wholly forced through the tubular movable intermediate contact to assist in extinguishing the main-current arc, a movable isolating contact cooperable with the intermediate contact to establish a residual-current arc, and the blast of gas forced through the tubular movable intermediate contact not only being used to effect extinction of the main-current arc, but, additionally, being used at least in part to extinguish said residual-current are.

3. The gas-blast interrupting unit according to claim 2, wherein biasing means are provided for biasing the intermediate contact to the open-circuit position.

4. A gas-blast interrupting unit for a circuit interrupter including a relatively stationary contact, a movable tubular intermediate contact separable from said relatively stationary contact to establish a main-current arc, an impedance shunted across the stationary and intermediate contacts, said tubular intermediate contact having an annular flange portion and segmental fingers at one end thereof, means including a relatively tight-fitting insulating orifice member about the intermediate contact for defining a pressure chamber about the relatively stationary contact, a source of gas pressure, means for admitting at times compressed gas from said source into said pressure chamber whereby gas may be forced through the tubular intermediate contact to effect extinction of said main-current arc, and a movable isolating contact cooperable with the intermediate contact to establish a residual-current arc.

5. The combination in a gas-blast interrupting unit of a relatively stationary contact structure, a movable tubular intermediate contact separable from said relatively stationary contact structure to establish a main-current arc, said movable tubular intermediate contact having a flange portion and side vent openings, an enclosing blast shield, a compression spring seated on said flange and against one end of said blast shield, a shunting impedance electrically connected between the stationary and intermediate contacts, means including a relatively tight-fitting insulating orifice member about the intermediate contact for defining a pressure chamber about the relatively stationary contact, a source of gas pressure, means for admitting at times compressed gas from said source into said pressure chamber whereby a blast of gas is substantially Wholly forced through the tubular movable intermediate contact, and a movable disconnecting contact cooperable with said intermediate contact to establish a residual-current are.

6. The gas-blast interrupting unit according to claim 1,

3 wherein the movable tubular intermediate contact has side vent openings therein.

7. A gas-blast interrupting unit according to claim 1, wherein stop means are provided so that the arcing tip portion of the movable tubular intermediate contact al- Ways remains Within the pressure chamber about the relatively stationary contact.

8. A gas-blast interrupting unit according to claim 1, wherein the end of the tubular movable intermediate contact is provided with intermediate fingers making overlapping contacting engagement with the movable isolating contact, whereby assurance is obtained that the maincurrent are Will be extinguished prior to the establishment of a residual-current arc.

References Cited in the file of this patent UNITED STATES PATENTS 2,075,749 Paul Mar. 30, 1937 2,117,261 Thommen May 10, 1938 2,146,685 Prince Feb. 7, 1939 2,293,320 Thommen Aug. 18, 1942 2,757,261 Lingal et al. July 31, 1956 FOREIGN PATENTS 610,946 Germany Mar. 19, 1935

Claims

1. A GAS-BLAST INTERRUPTING UNIT FOR A CIRCUIT INTERRUPTER INCLUDING A RELATIVELY STATIONARY CONTACT, A MOVABLE TUBULAR INTERMEDIATE CONTACT SEPARABLE FROM SAID RELATIVELY STATIONARY CONTACT TO ESTABLISH A MAIN-CURRENT ARC, AN IMPEDANCE SHUNTED ACROSS THE STATIONARY AND INTERMEDIATE CONTACTS, MEANS INCLUDING A RELATIVELY TIGHT-FITTING INSULATING ORIFICE MEMBER ABOUT THE INTERMEDIATE CONTACT FOR DEFINING A PRESSURE CHAMBER ABOUT THE RELATIVELY STATIONARY CONTACT, A SOURCE OF GAS PRESSURE, MEANS FOR ADMITTING AT TIMES COMPRESSED GAS FROM SAID SOURCE INTO SAID PRESSURE CHAMBER WHEREBY A BLAST OF GAS IS SUBSTANTIALLY WHOLLY FORCED THROUGH THE TUBULAR MOVABLE INTERMEDIATE CONTACT TO EXTINGUISH SAID MAIN-CURRENT ARC, A MOVABLE ISOLATING CONTACT COOPERABLE WITH THE INTERMEDIATE CONTACT TO ESTABLISH A RESIDUAL-CURRENT ARC, AND THE BLAST OF GAS FORCED THROUGH THE TUBULAR MOVABLE INTERMEDIATE CONTACT BEING USED NOT ONLY TO EXTINGUISH THE MAINCURRENT ARC, BUT, ADDITIONALLY, THE SAME GAS BEING USED, AT LEAST IN PART, TO EXTINGUISH SAID RESIDUAL-CURRENT ARC.