US3268697A

US3268697A - Compressed-gas circuit interrupters having exhaust valve structures

Info

Publication number: US3268697A
Authority: US
Inventors: Morioka Shoji
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 1963-10-31
Filing date: 1964-10-07
Publication date: 1966-08-23
Anticipated expiration: 1983-08-23

Description

United States Patent Japan Filed Oct. 7, 1964, Ser. No. 492,168 Claims priority, application Japan, Oct. 31, 1963, 38/ 58,802 Claims. (Cl. 200-448) This invention relates to compressed-gas circuit breakers in general, and more particularly to improvements in an exhaust-valve assembly and accompanying actuating mechanism for a compressed-gas circuit breaker.

Although not necessarily limited thereto, the present invention is particularly adapted for use with so-called high-potential circuit breakers of the type in which an arc-extinguishing chamber is insulated from the ground through a supporting insulator, or insulators, and filled with a gas, such as sulfur-hexafiuoride (SP gas under high pressure. In such interrupters, it is common to provide an exhaust valve structure disposed downstream of an interruption point between contacts, this exhaust valve being opened at the instant the circuit is interrupted to thereby create a flow of compressed fluid, which acts to extinguish an are between the separated contacts. In such applications it is, of course, desirable to reclose the exhaust valve structure as soon as possible after the interruption and are extinguishment in order to minimize the escape of the arc-extinguishing gas, which may be expensive, and also to prevent a reduction in pressure of the same.

Many arrangements have been devised heretofore for actuating the movable contacts of the circuit breaker to effect a circuit interruption, while at the same time opening the exhaust valve for a short period of time. For example, cams mechanically interconnected with the movable contacts of the breaker have been employed to open the exhaust valve. Another arrangement for opening the exhaust valve in previous prior-art constructions utilizes a pneumatic piston and cylinder arrangement for opening the valve, the piston and cylinder being mechanically independent of the contacts but actuable upon separating movement of the contacts. Such systems, while workable, are not entirely satisfactory in that the blasting time, during which the exhaust valve is open, can be adjusted only with difiiculty, and the mechanisms in volved are quite complicated.

A general objectof the present invention is to provide new and improved apparatus for actuating the exhaust valve structure of a compressed-gas type of circuit breaker, which apparatus is considerably simplified over previous constructions of this type.

More specifically, an object of the invention is to provide an exhaust-valve construction for a compressed-gas circuit breaker in which the valve and the movable contacts of the circuit breaker are operatively interconnected with a reciprocable actuating rod, such that in one stroke of the actuating rod, the exhaust valve will be opened momentarily and then closed with the valve being reset for a subsequent opening operation independently of movement of the actuating rod.

Still another object of the invention is to provide an exhaust-valve construction for compressed-gas circuit breakers, wherein the compressed gas assists in opening the exhaust valve, but does not materially impede closing movement of the same.

Another object of the invention is to provide an improved exhaust-valve structure for a compressed-gas circuit interrupter of the pressurized tank type.

The above and other objects and features of the inven- "ice tion will become more apparent from the following detailed description, taken in conjunction with the accompanying drawings, which form a part of this specification, and in whichi FIGURE 1 is a cross-sectional view of a compressedgas circuit breaker incorporating the improved exhaustvalve construction of the present invention, and the actuating mechanism therefor, the circuit interrupter being shown in the closed-circuit position;

FIG. 2 is an enlarged broken-away cross-sectional view of the exhaust valve of the invention, showing the man ner in which it opens momentarily; and,

FIG. 3 is a broken-away cross-sectional view, similar to that of FIG. 2, but showing the manner in which the exhaust valve is closed and reset preparatory to a subsequent opening operation.

With reference now to the drawings, and particularly to FIG. 1, thereof the circuit breaker 1 shown is of the high-potential type, and includes a live metallic tank 2 filled with a gas, such as sulfur-hexafluoride (SP gas under high pressure, and supported at the upper end of an insulating column 3. Extending through the opposite ends of the live metallic tank 2 are two insulating terminal bushings 2', which support a pair of stationary contact structures, both of which are designated by the reference numeral 5. It will be noted that the upstanding insulating column 3 is hollow and provides a passageway 3a for replenishing to the tank 2 gas under high pressure from a reservoir, not shown. Engageable with the contact structures 5, which may be of the finger-type, are movable contacts, or blades 4, these movable blades 4 serving to complete the circuit between contacts 5 when the circuit breaker is in the closed-circuit position as shown in FIG. 1.

Provided on the contact structures 5 are stationary arcing contacts 6, which, in conjunction with exhaust nozzles 7 and the exhaust valve structure 8, hereinafter described, effect rapid extinguishment of the are (not shown) created by disengagement of the blades 4 with the stationary contact structures 5. The nozzles 7 form an integrtal part of a valve body 16 having integrally formed therein a lower cylindrical spring-support cavity 16a. The purpose of spring cavity 16a will hereinafter be described in detail.

The movable contacts, or blades 4 are pivotally connected to a downwardly-depending cylindrical portion 2a of the tank 2, as at 11. These blades 4 are moved from open to closed-circuit positions, and vice versa, by means of a vertically reciprocable valve rod 9, which passes through the cylindrical spring cavity 16a of the valve body 16. The valve rod 9 is connected, as shown, to a second vertically reciprocable operating rod 20 of insulating material which extends downwardly through the hollow interior 3a of the insulating support column 3. In accordance with usual practice, the lower end of the insulating operating rod 20 is prevented from moving upwardly by means of a latch mechanism, not shown, which is tripped during an opening operation, to permit thereby upward movement of

rods

9 and 20, when it is desired to open the breaker and interrupt the connected circuit.

The actuating valve rod 9 is operatively interconnected with the movable contacts, or blades 4 by means of a pair of floating linkages 10 pivotally connected to the rod and blades, as at

pivot locations

12 and 13, respectively. Integrally formed on the valve rod 9 is a third, or tertiary exhaust valve 9a, best shown in FIGS. 2 and 3, which carries a circular valve gasket 912. Between the third or tertiary valve 9a and the bottom of the cylindrical cavity 16a formed in exhaust valve body 16 is a coil spring 14 tending to urge the operating and

valve rods

8 and 9 upwardly, whereby the movable contacts, or blades 4 will move inwardly toward the rod 9 in a circuit-opening direction to disengage them from the stationary contact structures 5. Under closed-circuit conditions, however, the blades 4 and the

rods

9 and 20 are held in the positions shown in FIG. 1 with the blades in contact with the stationary contact structures by means of the aforesaid latching mechanism at the bottom of operating rod 20, which is tripped to permit upward movement of the operating and

valve rods

9, 20 only when it is desired to break the connected circuit.

Secured to the top of the valve rod 9, by means of nut 90, is an inverted, generally cup-shaped first or primary exhaust valve 17. The primary exhaust valve 17 is provided with a lower circular valve rib 17c (FIGS. 2 and 3) adapted to engage and seat upon a circular valve seat 16c formed on the valve body 16. Slidably received on the valve rod 9, above the tertiary exhaust valve 9a, is a second auxiliary valve 18, which includes a circular valve gasket 18a adapted to engage and seat upon a circular valve seat rib 16d formed on the valve body 16 (FIGS. 2 and 3). Formed in the auxiliary or secondary exhaust valve 18 are ports, or vents 18b, which cooperate with the valve gasket 9b of tertiary exhaust valve 9a in a manner hereinafter described. A compression spring 15 is interposed between the exhaust valve 17 and the secondary exhaust valve 18 to normally hold the second exhaust valve 18 in engagement with the tertiary exhaust valve 9:1, as shown in FIG. 1.

In FIG. 1, the circuit breaker 1 is shown in its closedcircuit position wherein current flows from one of the contact structures 5, through the movable blades 4 to the other stationary contact structure 5. The circuit breaker 1 is normally held in its closed-circuit position by the aforesaid latching mechanism, not shown, except for which the compression spring 14 and the pressure of the gas within tank 2 would tend to move the valve rod 9 upwardly and thereby break contact between separable contacts 4 and 5. When it is desired to interrupt the circuit as, for example, when a fault condition occurs in a connected power-supply system, the latching mechanism, connected to operating rod 20, is released, whereby the valve rod 9 is forced upwardly at high speed due to both the action of the compression spring 14 and the pressure of the gas within tank 2. Upward opening movement of the valve rod 9 then causes the movable contacts or blades 4 connected to the rod 9 by the links to disengage from the stationary contacts 5 to strike arcs therebetwcen, not shown. At the same time, the exhaust valve 17 is moved upwardly and opened, as shown in FIG. 2, to permit the high-pressure gas within tank 2 to be exhausted through the interrupting exhaust nozzles 7. The flow of gas thus formed transfers the arcs to positions between stationary arcing contacts 6 and stationary nozzles 7, whereby the established arcs are rapidly extended through the exhaust nozzles 7 and extinguished by the flow of exhausting gas passing axially of the established arcs.

The foregoing interrupting action occurs as the valve and operating rod 9 moves upward-ly, but before the tertiary exhaust valve 9a on the rod 9 moves the secondary exhaust valve :18 into seating engagement with the valve seat rib 16d. The spacing between the primary exhaust valve 17 and the tertiary exhaust valve 9a is such that immediately after the arc is extinguished, the valve gasket 18a on the secondary exhaust valve 18 will engage the circular valve seat rib 16d on valve body 16, as shown in FIG. 2, whereby the escape of high-pressure gas from tank 2 is terminated. At this point, the movable contacts or blades 4 are moved to their fully-opened circuit positions inwardly of the stationary contact structures 5, whereupon the interruption operation is completed. It will be noted that no high-pressure gas can escape from the tank 2 through the vent openings 18b formed in the secondary exhaust valve 18 at this time due to the fact that the tertiary exhaust valve 9a is in seating engagement with the underside surface of the secondary exhaust valve 18.

A closing operation will now be described. If a closing force exerted by an operating mechanism, not shown, is transmitted to the rod 9 through the insulating operating rod 20, the valve and actuating rod 9 begins to move downwardly against both the force of the compression spring 14 and the reaction due to the gas supplied to the underside of the tertiary exhaust valve 9a. In this process, the movable contacts or blades 4 also move outwardly from the rod 9 to effect a closing operation. The secondary valve 18, however, remains in seating engagement with the valve seat rib 16d due to the pressure of the high-pressure gas within tank 2. In this respect, it will be appreciated that the force of spring 15, upon downward movement of the rod 9 and exhaust valve 17, must be less than that produced on the underside of the secondary exhaust valve 18 by the pressure of the highpressure gas disposed within tank 2 to maintain valve 18 closed during the downward stroke of the rod 9. After the tertiary exhaust valve 9a becomes disengaged from the underside of the secondary exhaust valve 18, upon downward movement of the actuating rod 9, a small supply of the high-pressure gas within tank 2 will escape through the ports 18b, as will be appreciated. This escape of gas, however, is negligible.

After the rod 9 has been moved downwardly to its ultimate closing position, the primary exhaust valve 17 reaches the valve seat on the valve body 16 to form a small closed space A, as shown in FIG. 3. Consequently, the gas under high pressure contained within the tank 2 rapidly fills the space A through the port openings 18b to render the gas pressures on both sides of the secondary exhaust valve 18 equal to each other. At this point, the secondary exhaust valve 18 rapidly returns back to its open initial position, as illustrated in FIG. 1, by virtue of the force of compression spring 15, whereupon the closing operation of the circuit breaker 1 is completed.

With the arrangement as above described, the energy of the gas under high pressure supplied to the exhaust I valve 17 during the interrupting operation can be utilized to open the contacts 4, 5. This permits the compression spring 14 to be smaller and of lighter construction than normal, and also insures that the primary exhaust valve 17 connected directly to the movable contacts 4 permits a flow of gas for the requisite period of time required for the interrupting operation to be completed. Furthermore, the exhaust valve 17 effects reciprocating movement simultaneously with movement of the movable contacts or blades 4, and the closing operation is performed without any high opposing force exerted upon the exhaust valve 17. Finally, the consumption of high-pressure gas is materially reduced as compared with previous constructions of this general type.

Although the invention has been shown in connection with a certain specific embodiment, it will be readily apparent to those skilled in the art that various changes in form and arrangement of parts may be made to suit requirements, without departing from the spirit and scope of the invention.

I claim as my invention:

1. In a compressed-gas circuit interrupter of the type having a tank supplied with gas under pressure, at least one terminal bushing extending into the tank and having a stationary contact thereon, and a movable contact in the tank for selectively engaging said stationary contact; the improvement in means for forming an arc-extinguishing flow of fluid within the tank upon separation of the movable contact from the stationary contact, comprising valve-seat means forming an opening in a wall of said tank, an exhaust-valve member movable into and out of engagement with said valve-seat means, apparatus operatively connected to said movable contact for unseating said valve member from said valve seat when the movable contact separates from the stationary contact to thereby exhaust gas from the tank and form said arc-extinguishing flow of fluid, and auxiliary exhaust valve means arranged to close and substantially seal said opening after said exhaust-valve member has opened and the arc is extinguished but before the exhaust valve member is again seated on said seat, whereby the escape of gas from the tank during an interruption operation of the circuit interrupter is minimized.

2. The improvement of claim 1, and including means for unseating the auxiliary valve means after the exhaust valve member is again seated on said seat means following an interruption operation.

3. In a compressed-gas circuit interrupter of the type having a tank supplied with gas under pressure, at least one terminal bushing extending into the tank and having a stationary contact thereon, and a movable contact in the tank for selectively engaging said stationary contact; the improvement in means for forming an arc-extinguishing flow of fluid within the tank upon separation of the movable contact from the stationary contact, comprising a valve body forming an opening in a wall of said tank, an exhaust-valve member operatively connected to said movable contact and arranged to move from closed to open positions with respect to said opening when the movable contact separates from the stationary contact to thereby exhaust gas from the tank and form said areextinguishing flow of fluid, and auxiliary exhaust-valve means operatively connected to said exhaust valve member and arranged to close and substantially seal said opening after said exhaust valve member has opened and the arc is extinguished, but before the exhaust valve member has again closed upon movement of the movable contact from open to closed positions, whereby the escape of gas from the tank during an interruption operation of the circuit interrupter is minimized.

4. The improvement of claim 3, and including means for opening said auxiliary valve means to thereby subject the exhaust valve member to the pressure of the fluid within said tank after the exhaust valve member has closed to cove-r said opening.

5. In a compressed-gas circuit interrupter of the type having a tank supplied with gas under pressure, a pair of terminal bushings extending into the tank and having stationary contacts thereon, and movable contacts in the tank for selectively engaging said stationary contacts; the improvement in means for forming an arc-extinguishing flow of fluid within the tank upon separation of the movable contacts from the stationary contacts, comprising a valve body forming an opening in a wall of said tank, a reciprocable actuating rod connected to said movable contacts, said actuating 'rod being movable in one direction to separate the movable contacts from the stationary contacts and movable in the reverse direction to engage the movable contacts with the stationary contacts, an exhaust-valve member carried on one end of said actuating rod and movable upon movement of the actuating rod in said one direction from a closed position where it covers said opening in the valve body to an open position to exhaust gas through the opening, and auxiliary exhaust valve means carried on said actuating rod and arranged to close and substantially seal said opening after said exhaust-valve member has moved to an open position and the arc is extinguished, but before the exhaust-valve member has again closed upon movement of the actuating rod in said reverse direction.

6. In a compressed-gas circuit interrupter of the type having a tank supplied with gas under pressure, a pair of terminal bushings extending into the tank and having stationary contacts thereon, and movable contacts in the tank for selectively engaging said stationary contacts; the improvement in means for forming an arc-extinguishing flow of fluid within the tank upon separation of the movable contacts from the stationary contacts, comprising a valve body forming an opening in a wall of said tank, a reciprocably-actuating rod connected to said movable contacts, said actuating rod being movable in one direction to separate the movable contacts from the stationary contacts and movable in the reverse direction to engage the movable contacts with the stationary contacts, an exhaust-valve member carried on one end of said actuating rod and movable upon movement of the actuating rod in said one direction from a closed pcsition where it covers said opening in the valve body to an open position to exhaust gas through the opening, a member fixed to'said actuating rod and spaced from said one end thereof which carries said exhaust-valve member, and a secondary exhaust valve slidably received on said actuating rod between the exhaust valve member and said member which is fixed to the actuating rod, whereby movement of the actuating rod in said one direction will cause the exhaust-valve member to open while simultaneously causing said secondary exhaust valve to thereafter move to a position where it covers said opening and thereby prevents the further exhausting of gas from said tank after the exhaust-valve member has initially opened and the arc has been extinguished.

7. The improvement of claim 6, wherein the spacing between said member fixed to the actuating rod and said exhaust-valve member is such that the secondary exhaust valve will be moved to a position where it closes said opening immediately after separation of said contacts and extinguishment of the resulting arc.

8. In a compressed-gas circuit interrupter of the type having a tank supplied with gas under pressure, a pair of terminal bushings extending into the tank and having stationary contacts thereon, and movable contacts in the tank for selectively engaging said stationary contacts; the improvement in means for forming an arc-extinguishing flow of fluid within the tank upon separation of the movable contacts from the stationary contacts, comprising a valve body forming an opening in the wall of said tank, a reciprocably-actuating rod connected to said movable contacts, said actuating rod being movable in one direction to separate the movable contacts from the stationary contacts and movable in the reverse direction to engage the movable contacts with the stationary contacts, a primary exhaust-valve member carried on one end of said actuating rod and movable upon movement of the actuating rod in said one direction from a closed position where it covers said opening in the valve body to an open position to exhaust gas through the opening, a tertiary exhaust valve surrounding said actuating rod and secured thereto at a point removed from the primary exhaust valve member, a secondary exhaust valve slidably received on said actuating rod between the primary exhaust valve member and said tertiary exhaust valve, whereby the tertiary exhaust valve will cause the secondary exhaust valve to move to a position Where it closes said opening upon movement of the rod in said one direction and after said primary exhaust valve member has opened to permit the escape of gas from said tank, and openings in the secondary exhaust valve which are covered by said tertiary exhaust valve upon movement of said actuating rod in said one direction, but which are uncovered by the tertiary exhaust valve upon movement of the actuating rod in the reverse direction, the arrangement being such that when the primary exhaust valve member becomes reseated, fluid under pressure in said tank will pass through said passageways in the sec ondary exhaust valve to equalize the pressure on opposite sidesthereof and permit the secondary exhaust valve to slide on the actuating rod into engagement with said tertiary exhaust valve preparatory to a succeeding interruption operation of the circuit interrupter.

3,268,697 7 8 9. The improvement of claim 8, and including coil- References Cited by the Examiner spring means surrounding said actuating rod and inter- UNITED STATES PATENTS i tl seco nii zff; exhiu ifii 6 ans Va ve mem er an 3,078,875 2/1963 Farrell et a1 137630.15

10. The improvement of claim 8 and including coil- 5 3134876 5/1964 Chang et ZOO-148 spring means in abutment with said tertiary exhaust valve secured to the actuating rod for urging said actu- ROBERT SCHAEFER P'lmary Examme" ating rod in said one direction. P. E. CRAWFORD, Assistant Examiner.