US3590190A

US3590190A - Gas blast circuit interrupter with movable flow director engagable with a stationary resistance inserting means during opening and closing

Info

Publication number: US3590190A
Application number: US773510A
Authority: US
Inventors: Robert G Colclaser Jr; Charles F Cromer
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1968-11-05
Filing date: 1968-11-05
Publication date: 1971-06-29
Anticipated expiration: 1988-06-29
Also published as: CH499869A; AT295638B; BE741219A; DE1955148A1

Abstract

In order to reduce the rate of rise of the recovery voltage of a kilometric or short-line fault, resistors are connected in the circuit to be interrupted during an opening operation. A resistor is provided on each one of two terminal bushings extending through the ends of the housing for each interrupting unit of a circuit breaker. The resistors also function to divide the voltage equally across the two series breaks in the interrupter and they function as damping resistors to prevent restrikes during opening and excessive over voltages during closing. During opening, the resistors are inserted in the circuit and then are disconnected. During closing, the resistors are inserted in the circuit and then shorted out of the circuit. The resistor contacts are mounted on a stationary flow director and are engaged by the outer surface of a conductive movable flow director which is concentric with the movable hollow contact.

Description

United States Patent [72] Inventors Robert G. Colclaser, Jr.

Delmont;

Charles F. Cromer, Trafford, both of, Pa. [21] Appl. No. 773,510

[22] Filed Nov. 5,1968

[45] Patented June 29, 1971 [73] Assignee Westinghouse Electric Corporation Pittsburgh, Pa.

[54] GAS BLAST CIRCUIT INTERRUPTER WITH MOVABLE FLOW DIRECTOR ENGAGABLE WITH A STATIONARY RESISTANCE INSERTING MEANS DURING OPENING AND CLOSING 9 Claims, 4 Drawing Figs.

3,160,727 12/1964 Colclaser, Jr. et a1. ..2(l0/144 X (APRI) 3,291,947 12/1966 VanSickle 200/148 (.8) 3,371,176 2/1968 Leeds 200/148 (.8) FOREIGN PATENTS 1,238,546 4/1967 Germany 200/148 Primary Examiner-Robert K. Schaefer Assistant ExaminerRobert A. Vanderhye AtlorneysA. T. Stratton, C. L. Mcl-Iale and W. R. Crout ABSTRACT: In order to reduce the rate of rise of the recovery voltage of a kilometric or short-line fault, resistors are connected in the circuit to be interrupted during an opening operation. A resistor is provided on each one of two terminal bushings extending through the ends of the housing for each interrupting unit of a circuit breaker. The resistors also function to divide the voltage equally across the two series breaks in the interrupter and they function as damping resistors to prevent restrikes during opening and excessive over voltages during closing. During opening, the resistors are inserted in the circuit and then are disconnected. During closing, the resistors are inserted in the circuit and then shorted out of the circuit. The resistor contacts are mounted on a stationary flow director and are engaged by the outer surface of a conductive movable flow director which is concentric with the movable hollow contact.

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BACKGROUND OF THE INVENTION This invention relates, generally, to circuit interrupters and, more particularly, to interrupters of the compressed-gas type suitable for extra high voltage (El-IV) service.

US. Pat. No. 3,291,947 issued Dec. 13, 1966 to R. C. Van Sickle and assigned to the Westinghouse Electric Corporation discloses a circuit breaker suitable for EHV (extra high voltage) service. The breaker has a plurality of series-connected interrupter units or modules per phase, each unit comprising a metal housing enclosing a rotatable bridging crossarm carrying contacts at each end of the arm which engage relatively stationary contacts supported by bushings extending through the ends of the housing. The radially extending portions of the arm are hollow to permit compressed sulfur hexafluoride, SF gas to flow outwardly therethrough to extinguish the arcs established at the two series breaks when the movable contacts are separated from the stationary contacts by rotating the arm. In addition to the movable contact assembly, each end of the arm also carries an insulating orifice for directing the flow of gas through the stationary contact structure and the movable contact assembly both of which are of a hollow construction, thereby providing double flow of the interrupting gas.

The circuit rate of rise of recovery voltage of a short-line, or kilometric, fault which is one located a relatively short distance away from a circuit breaker on a transmission line can be reduced by providing an interrupting arrangement in which a shunting resistor is first inserted in the circuit and then the residual current is cleared in a second interrupting gap. Accordingly, an object of this invention is to incorporate a shunting resistor in a circuit interrupter having a rotatable bridging crossarm. 6 Another object of the invention is to provide for first inserting the resistor in the circuit being interrupted and then disconnecting the resistor during an opening operation of the interrupter.

A further object of the invention is to first insert the resistor in the circuit and then shunt it from the circuit during a closing operation of the interrupter, thereby utilizing the resistor to damp surge voltages caused by prestrikes during closing or by restrikes during opening.

Still another object of the invention is to mount the resistor and an insulating orifice on the stationary contact structure of an interrupter, thereby keeping down the weight of the rotatable bridging crossarm of the interrupter.

A still further object of the invention is to provide a contact arrangement in which no solid insulation is stressed by the I recovery voltage of a circuit.

Other objects of the invention will be explained fully hereinafter or will be apparent to those skilled in the art.

SUMMARY OF THE INVENTION In accordance with one embodiment of the invention, a stationary contact assembly comprising a generally tubular member surrounded by spring-biased contact fingers is mounted in an opening extending through a foot on the inner end of each one of two bushings extending through the ends of the housing for each interrupter unit of a circuit breaker. An interrupting chamber is formed by an insulating member having one end mounted on the bushing foot. A shunting resistor is connected between the bushing foot and a metal ring mounted on the other end of the insulating member. The ring is engaged by the wall of a hollow angularly extending flow director on the end of the rotatable bridging crossarm of the interrupter. A generally tubular movable contact member carried by crossarm is disposed inside of and spaced from the flow director and is engaged by the contact fingers in the closed position. During opening, the movable contact is separated from the fingers first to insert the resistor in the circuit. The resistor is then disconnected when the flow director pulls out of the ring, and the residual current is interrupted. During closing, the fiow director first engages the ring to insert the resistor in the circuit. The resistor is then shorted out of the circuit when the movable contact member engages the contact fingers.

BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of the nature and objects of the invention, reference may be had to the following detailed description, taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a view, partly in section and partly in elevation, of a circuit-interrupting unit embodying principal features of the invention;

FIG. 2 is an enlarged view, in section, of one of the arc extinguishing units for the interrupter, the contacts being shown in the partly open position;

FIG. 3 is a view, similar to FIG. 2, showing the contacts in the open position; and

FIG. 4 is a detailed view of a modified contact arrangement for the interrupter.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, and particularly to FIG. 1, the circuit interrupter shown therein may be generally of the type described in the aforesaid US. Pat. No. 3,291,947, issued Dec. 12, 1966 to R. C. Van Sickle and assigned to the Westinghouse Electric Corporation. As shown in the drawing, the circuit interrupter comprises a low-pressure metal tank or housing 11, a high-pressure reservoir chamber 12, which may be mounted inside the housing 11, a hollow rocker crossarm l3 rotatably mounted on a generally cylindrical bearing support 14 having a flange portion 15 attached to the reservoir 12 by bolts 16, a generally cylindrical blast valve 17 slidably disposed inside the bearing support 14, a lever 18 for operating the blast valve 17, a cam 19 for actuating the lever 18, an actuating mechanism 21, fully described in the aforesaid copending application, for driving the cam 19 and also the rotatable crossarm l3, terminal bushings 22 one of which extends through each end of the housing 11, and a hollow vertically disposed insulating column 23 for supporting the interrupting unit.

Each terminal bushing 22 may be ofa type suitable for extra high voltage service. The bushing is attached to the housing 11 by means of a mounting ring 24. Each bushing has a conductor 25 extending therethrough with a bushing foot connected to the inner end of the conductor 25. The supporting column 23 has a metal cap portion 27 at its upper end which may be attached to a ring 28 by bolts 29. The ring 28 may be secured in an opening in the bottom of the housing 11 by welding or other suitable means.

As shown, a relatively stationary contact assembly 31 is supported by the foot 26 of each terminal bushing 22. The assembly 31 comprises a generally tubular members 32 disposed in an opening 33 extending through the foot 26 and having a flange 34 attached to the foot 26. Spring biased contact fingers 35 surround the tubular member 32. As shown more clearly in FIG. 2, the contact fingers 35 have one end pivotally mounted on the tubular member 32 and are biased toward the member 32 by compression spring members 36 disposed between a tubular retainer 40 and the fingers 35. A hollow insulating member 37 has one end mounted on the bushing foot 26 around the outside of the contact fingers 35. The member 37 is spaced from the fingers 35 and forms an interrupting chamber for directing the flow of the interrupting gas as will be described more fully hereinafter. The member 37 is preferably composed of polytetrafluoroethylene sold under the trade name Teflon."

In order to reduce the rate of rise of the recovery voltage of a kilometric or short-line fault, a resistor 38 is connected in the circuit to be interrupted during an opening operation. One terminal of the resistor 38 is connected to the bushing foot 26 and the other terminal is connected to a conducting ring 39 mounted on the upper end of the insulating member 37. A resistor 38 is provided on each terminal bushing 22. In addition to reducing the rate of rise of recovery voltage, the resistors also function to divide the voltage equally across the two series breaks in the interrupter and they function as damping resistors to prevent restrikes during opening and excessive over voltages during closing.

As also shown more clearly in FIG. 2, each end of the crossarm 13 has an angularly extending hollow conducting flow directing portion 41 constituting a resistance contact which engages the metal ring 39 when in the closed position, A generally tubular contact member 42 constituting a main contact is carried by the arm '13 and is disposed inside of and spaced from the flow director 41. The upper end of the member 42 has a flange 43 thereon which is attached to the arm 13. As shown in FIG. 1, the lower end of the contact main member 42 engages the contact fingers 35 when in the closed position. As indicated in FIG. 1, the stationary and the movable contact assembly at each end of the crossarm are of a similar construction.

The housing 11 contains an interrupting gas, preferably sulfur hexafluoride (SP at a relatively low pressure. The high pressure chamber 12 contains the interrupting gas at a relatively high pressure. The high pressure gas is supplied to the chamber 12 through an insulating tube 44 which is disposed inside the column 23 and extends from a main high crossarm reservoir (not How pressure gas may be drawn from the housing 11 through the column 23, compressed by a compressor (not shown) and returned to the main high pressure reservoir which, as previously stated, is connected to the chamber 12 through the tube 44.

During an opening operation, the cross arm 13 is rotated in a direction first to disengage the movable main contact member 42' from the contact fingers 35 to draw an are 45 between the member 42 and the stationary member 32. At this time the blastvalve 17 is opened to admit gas from the high pressure chamber 12 into the hollow crossarm 13. As shown by the arrows in FIG. 2, the flow director 41 and the insulating member 37 cooperate to cause the gas to flow downwardly between the flow director 41 and the contact member 42, then across the are 45, and thence upwardly through the inside of the member 42 and downwardly through the inside of the member 32, thereby providing double flow of the interrupting gas. When the are 45 is interrupted, the resistor 38 is inserted in the circuit since the flow director 41 constituting a resistance contact is still engaging the contact ring 39. As the arm 13 continues to move, the flow director or resistance contact 41 is disengaged from the metal ring 39, thereby drawing a residual current are 46 between the end of the resistance contact 41 and the ring 39 as shown in FIG. 3. Since the flow director has now pulled out of the chamber formed by the insulating member 37, the interrupting gas is now free to flow across the are 46, thereby interrupting the residual current and completely disconnecting the resistor 38 from the circuit.

During a closing operation, the cross arm 13 is rotated in the opposite direction first to engage the flow director 41 with the contact ring 39, thereby connecting the resistor 38 in the circuit. When the movable contact member 42 engages the contact fingers 35in the closed position of the arm 13 the resistor 38 is shorted out of the circuit. Thus, overheating of the resistor is prevented since it is in the circuit only a short time during both the opening and the closing operations.

It will be noted that the resistor 38 is permanently connected across the insulating member 37. Thus, no solid insulation is under stress when the contact members of the interrupter are in the open position. Only the gas gap between the end of the flow director 41 and the contact ring 39 is under stress at this time.

In the modified structure shown in FIG. 4, a spring biased contact 51 is movably mounted in the ring 39 to engage the flow director 41. A retaining ring 52 may be secured to the ring 39' by brazing or other suitable means. The contact 51 may be connected to the ring 52 by a flexible shunt 53. The contact assembly is mounted on the end of the insulating member 37'. The resistor 38 may be connected to the contact assembly in the same manner as to the contact ring 39.

From the foregoing description it is apparent that the invention provides for incorporating a shunting resistor in a circuit interrupter having a rotatable bridging crossarm in a manner to enable the resistor to be inserted in the circuit for a short time during an opening operation and also for a short time during a closing operation. The moving contact structure is simplified and its weight is reduced as compared with prior interrupters having rotatable bridging crossarms. The gas flow during an interrupting operation is directed in a manner to obtain the most efficient interruption of the are drawn between the contact members of the interrupter. The shunting resistor is permanently connected across the insulating member which forms the interrupting chamber, thereby preventing a stress on this member by the recovery voltage. Certain features of the present invention are set forth and claimed in US. Pat. application filed July 28, 1965 by Winthrop M. Leeds, Ser.-No. 475,437 and assigned to the assignee of the instant application.

Since numerous changes may be made in the abovedescribed construction and different embodiments of the invention may be made without departing from the spirit and scope thereof, it is intended that all subject matter contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

We claim as our invention:

1. In a compressed-gas circuit interrupter, in combination, a metal housing containing interrupting gas at a relatively low pressure, a reservoir chamber containing interrupting gas at a relatively high pressure, terminal bushings extending through opposite ends of the housing, a generally tubular conducting arcing member mounted on the inner end of each bushing, contact fingers surrounding said tubular conducting arcing member, an insulating flow-directing member having one end mounted on the bushing around the contact fingers, a conducting ring mounted on the other end of the insulating member, resistance means connected between the ring and the inner end of the bushing, a bridging crossarm rotatably mounted in the housing, contact means carried by the crossarm including two hollow concentric conducting members one engaging the contact fingers and the other bearing against said conducting ring in the closed position, said arm being rotatable in one direction first to disengage the said one member from the contact fingers to insert the resistance means in the circuit and then to disengage the said other member from the ring to disconnect the resistance means, and

said arm being rotatable in the opposite direction first to engage the contact means with the ring to insert the resistance means in the circuit and then to engage the'contact means with the contact fingers to short out the resistance means.

2. The combination defined in claim 1, wherein the resistance means is supported by the bushing.

3. The combination defined in claim 1, including a bearing support attached to the reservoir chamber, and wherein the bridging crossarm is hollow and is rotatably mounted on the bearing support, and including valve means disposed in the bearing support for controlling the flow of interrupting gas through the hollow crossarm.

4. The combination defined in claim 3, wherein the interrupting gas flows through the hollow crossarm and the hollow contact means.

5. The combination defined in claim 1, wherein the insulating flow directing member causes the gas to flow through the contact member on the arm and the tubular member on the bushing.

6. A compressed-gas circuit interrupter comprising a housing containing interrupting gas at a relatively low pressure, a reservoir chamber containing interrupting gas at a relatively high pressure, terminal bushings extending through opposite ends of the housing, each bushing having a conductor extending therethrough with a bushing foot connected to the inner end of the conductor, the bushing foot having an opening therethrough, a generally tubular stationary conducting arcing member disposed in the opening and attached to the foot, spring-biased contact fingers pivotally mounted on said member, a hollow insulating member having one end mounted on the foot around the contact fingers, a contact ring mounted on the other end of the insulating member, resistance means connected between the ring and the bushing foot, a hollow crossarm rotatably mounted inside the housing, each end of the arm having an angularly extending flow director thereon constituting a resistance contact, a generally tubular contact member disposed inside of and spaced from the flow director and constituting a main movable contact, said arm being rotatable in one direction first to engage the resistance contact with the ring and then to engage the main movable contact member with the contact fingers, said arm being rotatable in the opposite direction first to disengage the main movable contact member from the contact fingers and then to disengage the resistance contact from the ring, and valve means for controlling the flow of gas from the reservoir chamber through the crossarm.

7. The circuit interrupter defined in claim 6, including a hollow bearing support attached to the reservoir chamber, and wherein the hollow crossarm is rotatably mounted on the bearing support.

8. The circuit interrupter defined in claim 7, wherein the flow director cooperates with the insulating member to direct the flow of gas through the tubular main moving contact member and through the tubular stationary member.

9. The circuit interrupter defined in claim 6, including a springbiased contact movably disposed in the ring, and wherein the arm is rotatable in one direction first to engage the resistance contact with the spring-biased contact in the ring and then to engage the contact main movable member with the contact fingers, said arm being rotatable in the opposite direction first to disengage the contact member from the contact fingers and then to disengage the flow director from the spring-biased contact in the ring.

Claims

1. In a compressed-gas circuit interrupter, in combination, a metal housing containing interrupting gas at a relatively low pressure, a reservoir chamber containing interrupting gas at a relatively high pressure, terminal bushings extending through opposite ends of the housing, a generally tubular conducting arcing member mounted on the inner end of each bushing, contact fingers surrounding said tubular conducting arcing member, an insulating flow-directing member having one enD mounted on the bushing around the contact fingers, a conducting ring mounted on the other end of the insulating member, resistance means connected between the ring and the inner end of the bushing, a bridging crossarm rotatably mounted in the housing, contact means carried by the crossarm including two hollow concentric conducting members one engaging the contact fingers and the other bearing against said conducting ring in the closed position, said arm being rotatable in one direction first to disengage the said one member from the contact fingers to insert the resistance means in the circuit and then to disengage the said other member from the ring to disconnect the resistance means, and said arm being rotatable in the opposite direction first to engage the contact means with the ring to insert the resistance means in the circuit and then to engage the contact means with the contact fingers to short out the resistance means.

9. The circuit interrupter defined in claim 6, including a spring-biased contact movably disposed in the ring, and wherein the arm is rotatable in one direction first to engage the resistance contact with the spring-biased contact in the ring and then to engage the contact main movable member with the contact fingers, said arm being rotatable in The opposite direction first to disengage the contact member from the contact fingers and then to disengage the flow director from the spring-biased contact in the ring.