US3590189A

US3590189A - Pneumatic operating mechanism for a circuit interrupter with piston device having an opening piston and a closing piston

Info

Publication number: US3590189A
Application number: US762479A
Authority: US
Inventors: William H Fischer; Wayne S Aspey
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1968-09-25
Filing date: 1968-09-25
Publication date: 1971-06-29
Anticipated expiration: 1988-06-29
Also published as: BE739214A; BR6912375D0; ES371161A1; SE365895B; DE1947758A1; AT290660B; YU224669A; GB1266373A; FR2018833A1; CH493923A

Abstract

A circuit interrupter has a movable contact structure which is piston actuated. The operating piston rod has an opening piston and a closing piston secured thereto, so that upon entrance of high-pressure gas on one side of the opening piston, the opening piston will move to the open position carrying with it the movable contact structure. The closing piston, secured to the piston rod, has high-pressure gas acting on one side thereof at all times. A shock absorber structure may be used, and if used is also fixedly secured to the movable operating piston rod for the movable contact structure. Upon exhausting the high-pressure gas from the one face of the opening piston, the closing pressure, constantly acting upon one side of the closing piston, will effect a closing operation of the contact structure.

Description

United States Patent [72] Inventors WilliamH.F'scher Pittsburgh;

Wayne S. Aspey, Monroeville. both of, Pa. [21] Appl. No. 762,479 [22] Filed Sept. 25, 1968 [45] Patented [73] Assignee June 29, 1971 Westinghouse Electric Corporation Pittsburgh, Pa.

[$4] PNEUMATIC OPERATING MECHANISM FOR A CIRCUIT INTERRUPTER WITH PISTON DEVICE HAVING AN OPENING PISTON AND A CLOSING CLOSED POSITION HIGH PRESSURE Primary Examiner- Robert S. Macon v AttorneysA. T. Stratton, Clement L. McI-Iale and Willard R.

Crout ABSTRACT: A circuit interrupter has a movable contact structure which is piston actuated. The operating piston rod has an opening piston and a closing piston secured thereto, so that upon entrance of high-pressure gas on one side of the opening piston, the opening piston will move to the open position carrying with it the movable contact structure. The closing piston, secured to the piston rod, has high-pressure gas acting on one side thereof at all times. A shock absorber structure may be used, and if used is also fixedly secured to the movable operating piston rod for the movable contact structure.

Upon exhausting the high-pressure gas from the one face of the opening piston, the closing pressure, constantly acting upon one side of the closing piston, will effect a closing operation of the contact structure.

MAINTENCE JACK LOW PRESSURE HIGH PRESSURE- PATENTEU JUN29|97| 3.590.189

sum 2 pr 4 V LOW PRESSURE PRESSURE SF LOW \\PRESSURE PATENTEU JUN29 :97:

SHEU 3 UF 4 LOW PRESSURE HIGH PRESSURE PATENTEU M29 I971 SHEET [1F 4 MAINTENCE JACK CLOSED POSITION LOW PRESSURE FIG .4

HIGH PRESSURE HIGH PRESSURE CROSS-REFERENCE TO RELATED APPLICATIONS Reference may be had to U.S. Pat. application filed Dec. I0, 1968, Ser. No. 782,63l by William H. Fischer and Wayne S. Aspey.

BACKGROUND OF THE INVENTION As well known by those skilled in the art, in modern circuitinterrupting structures it is necessary to effect quick-opening and quick-closing operations. The industry trend has been toward shorter opening cycles, such as, for example, two cycles of alternating current. This is necessary to quickly diminish the amount of energy generated during the arcing period, and also, for application to reclosing circuit breakers, to prevent a loss of synchronism of connected electrical equipment.

It is, therefore, necessary to provide an operating mechanism for the movable contact structure of a circuit interrupter, which is quick-acting, reliable, adaptable for multiple-reclosing operations in the event that the fault is only temporary in nature.

In addition, it is desirable to cushion the movable parts near the extremities of their opening and closing operations. For this purpose, shock absorbers of some kind have generally been employed.

It has been customary heretofore to provide a piston structure mechanically connected to the movable contact, so that the interrupter can be opened or closed upon the application of high-pressure gas. However, such structures have been lacking in speed of operation, and have not been readily adaptable for reclosing circuit-interrupter arrangements.

SUMMARY OF THE INVENTION In accordance with a preferred embodiment of the present invention, there is provided an operating piston rod connected to the movable contact structure of a circuit interrupter, which operating piston rod has both an opening piston and a closing piston secured thereto. The arrangement is such that high-pressure gas constantly acts on one face of the closing piston; and the opening piston, being of larger cross-sectional area, has, for opening periods, high-pressure gas acting on one side thereof, with an exhausting of such high-pressure gas during the closing operations.

Also fixedly secured to the operating piston rod, connected to the movable contact structure, is a shock absorber piston, which acts to compress gas near the ends of the opening and closing operations, with throttling being provided to bring the rapidly moving contact parts to a cushioned stop.

It is, accordingly, one object of the present invention to provide a quick-opening and quick-closingpneumaticoperating mechanism for the moving-contact structure of a circuit interrupter.

Another object of the present invention is to provide a quick-opening and quick-closing operating mechanism for a circuit interrupter, which has provision for cushioning the movable parts near the ends of both the'opening and closing strokes.

Still a further object of the present invention is the provision of an improved operating mechanism for the movable-contact structure of a circuit interrupter, which is readily accessible for maintenance operations, and, additionally, is readily accessible for regulating the various parts without dismantling the entire structure.

Still a further object of the present invention is the provision of an improved operating mechanism for the movable contact of a circuit interrupter, which provides relatively constant opening and closing movements regardless of variations in the operating high-pressure gas.

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

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an end elevational view of a three-phase circuit interrupter embodying the principles of the present invention;

FIG. 2 is an enlarged cross-sectional view taken through the interrupting assemblage of the circuit interrupter of FIG. 2 with the contacts in the closed position;

FIG. 3 is an enlarged longitudinal partly sectional view taken through the movable contact structure of the circuit interrupter with the contacts shown in the open position;

FIG. 4 is an enlarged vertical sectional view taken through the improved pneumatic operating mechanism of the present invention, the several parts being illustrated in the closed-circuit position; and

FIG. 5 is an enlarged sectional view taken through the pressure regulator.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, and more particularly to FIG. 1 thereof, the reference numeral 1 generally designates a threephase circuit interrupter. The three-phase circuit interrupter I of FIG. 1 comprises a plurality of spaced phase-units mechanically interconnected to a single ground potential operator.

With reference to FIGS. I and 2, it will be observed that, generally, the circuit-interrupting structure 1 is of generally U- shape. Extending upwardly from a stationary supporting frame structure 4! is an arc-extinguishing assemblage, generally designated by the reference numeral 6 (FIG. 2), and comprising one or more pairs of movable-contact structures 7, which are separated and engaged, or closed in a high-pressure atmosphere 8.

Extending upwardly from the other side of the circuitbreaker structure 1 is a terminal-bushing structure 10 (FIG. 1), which comprises a high-voltage conducting rod extending through a gaseous SF environment. Preferably, the gas is sulfur-hexaflouride (SF gas, which is used because of its high dielectric strength properties. It is also used in the arc extinguishing operation to interrupt the are under pressure.

The movable-contact structure 7 in each of the arc-extinguishing assemblages 6 is actuated by an operating piston rod 14, more clearly shown in FIGS. 3 and 4 of the drawings. This operating rod 14 has an opening piston 15 and a closing piston 16 fixedly secured thereto. In addition, the operating-rod piston structure 14 has a shock-absorbing piston 18 also secured thereto to cushion the movable contact parts of the circuit breaker near the ends of its high-speed opening and closing movements.

It will be noted that the opening piston 15 moves within an operating cylinder 20 of relatively large diameter, whereas the closing piston 16 moves within an operating cylinder 21 of relatively small diameter. Additionally, it will be observed that the upper face 16a of the closing piston 16 has high-pressure gas acting thereon at all times. High-pressure gas is admitted, at times, to the lower face 15a of the opening piston 15, as viewed in FIG. 4, during the opening operation, and is exhausted therefrom during the closing operation, such control being obtained by the use of a three-way control valve, generally designated by the reference numeral 23, and mechanically controlled by an operating valve rod 15 (FIG. 2) extending generally vertically.

U.S. Pat. application filed Nov. I8, 1968 Ser. No. 776,510 by William H. Fischer and Wayne S. Aspey more clearly illustrates the internal details of the ground-potential operator (not shown), but for the purpose of understanding the present I therethrough during a breaker-opening operation. FIG. 3 shows the movable-contact structure 29in the fully open-circuit position, high-pressure gas existing in the region 31, and downstream valves 33 being closed to prevent a continuing exhausting flow-of gas through the separable movable contact structure 7. This feature of the equipment is set forth in more detail, and claimed in US. Pat. application filed Sept. 16,

1968 Ser. No. 759,992, and assigned to the assignee of the present invention.

The operating mechanism 27 of the present invention has been found to provide very good operational life, and hasmet the two-cycle duty requirements imposed thereon. As mentioned hereinbefore, generally, the main elements are the large opening piston 15, the relatively small closing piston 16, and the shock-absorbing piston 18. Additionally, the main valve 23 controls the opening and closing operations. As an additional feature, there is provided a flow regulator 35 and a hand jack 37, which will effect slow opening and closing contact operations for maintenance purposes.

An opening operation begins when the valve-control rod 25 is moved downwardly, for example, threequarters of an inch. This moves the three-way valve 23 from its closed to its open position, thereby permitting high-pressure SF, gas to flow into the large piston area a driving the opening piston 15 upwardly very' rapidly.

A closing operation begins when the valve-control rod is driven upwardly, for example, three-quarters of an inch. This causes the valve 25 to move to the breakenclosed position, and the high-pressure gas in the large piston area 15a below the opening piston 15, is dumped, or exhausted to the low pressure. The top of the closing piston 16 has high-pressure gas acting on it at all times. The circuit interrupter l closes with a force equal to the pressure times the closing-piston area 16a.

To cushion the ends of the opening and closing high-speed operations, there is provided an SF, shock absorber 39, which is operated by trapping SF, gas, compressing it and building up a back pressure force, and forcing such gas through holes in the cylinder portion 41 of the shock absorber 39. Bolts 43 are used to adjust the flow through the cylinder holes 41a. Check

valves

45, 46 are used at either end to allow free flow of the gas in one direction, and blocking the flow of such gas in the other direction.

Preferably, a linearly movable pressure-sensitive flow regulator, or baffle (FIG. 5) gives constant opening and closing travel regardless of the operating pressure. During operating conditions, the pressure in the high-pressure source can vary over a considerable pressure range, for. example, from 180 psi. to 300 p.s.i. This high pressure acts in the operating cylinder chamber 22 (FIG. 5) to move the baffle piston 35 to the right under high-pressure conditions, as viewed in FIG. 5 to a position as shown partially blocking off the flow of high pressure to the opening piston 15, thereby compensating for such a high-pressure condition. The reverse happens when the pressure of the high-pressure source drops. It has been found by experimentation that adequate speed control can be obtained without it, but if finer speed control is required, it is desireable to use it.

There is to be noted that with the construction of the improved operating mechanism 27, the shock absorber 39 can be adjusted without removing the gas within the breaker, and also the lowpressure gas volume is kept to a minimum.

The movable contact-operating rod 14 is connected to a generally ladder-shaped operating rod-structure 48 (FIG. 3), which effects opening and closing movements of the one or more movable contacts 29 within the arc-extinguishing assemblages 6, and, additionally, operates the downstream valves 33 pneumatically connected to the interior of contact structures 7. Generally the manner of arc interruption is such as to exhaust'high-pressure gas through the interior of the separable contacts 7 themselves during the opening operation. When the operation is completed, the arc having been extinguished, the downstream valves 33 are closed by the mechanical connection to the aforesaid ladder-shaped structure 48.

-Sulfur-hexafluoride (SP6) gas atthe pressures being used (220 psi. normal) will begin to condense at 50 F. and below. Drains 34 (FIG. 4) are provided to remove this liquid from the mechanism 27. In FIG. 4 the piston rod 14 has a hollow center 14a. The liquid collects on the piston 16 and drains by gravity into the hollow shaft 14 through radial holes 34. It drains out of shaft 14 at the bottom again through radial holes 34. It drains out of shaft 14 at the bottom again through radial holes 36 into intermediate sump 14b, which is connected to the high-pressure source through pipe 24, where heat is provided and the liquid is again vaporized.

In place of the SP gas described for use in the shock absorber 39, a hydraulic shock absorber could be substituted, if desired.

Although there has been illustrated and described specific structure, it is to be clearly understood that the same was 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.

We claim:

I. An operating mechanism for a circuit interrupter including, in combination:

a. separable contact structure including a movable contact for establishing an arc;

b. a piston device for actuating said movable contact including a closing piston and a separate opening piston both secured to a piston rod;

0. said piston rod being mechanically connected to the movable contact; and,

d. the cross-sectional area of the opening piston being larger than the cross-sectional area of the closing piston.

2. The combination according to claim 1, wherein highpressure gas constantly acts on the closing face of the closing piston, and high-pressure gas is alternately admitted and exhausted from the opening face of the opening piston.

3. The combination according to claim 1, wherein a shock absorber piston is also fixedly secured to the said piston rod to cushion the opening and closing operations of the contact structure.

4. The combination of claim 2, wherein a three-way opening control valve controls the admission and exhausting of highpressure gas to said opening face of the opening piston.

5. The combination of claim 3, wherein the shock absorber piston reciprocates within a perforated shock absorberoperating cylinder.

6. The combination according to claim 1, wherein the piston rod is extended externally of the circuit interrupter and is adaptable for operation by a hand jack for maintenance purposes.

7. The combination according to claim 5, wherein regulating screws are exposed and control the perforations of the shock absorber-operating cylinder thereby rendering them'accessible for adjustment.

8. The combination according to claim 3, wherein check valves are provided at the ends of the operating cylinder for the shock absorber.

9. The combination according to claim I, wherein a pressure-sensitive flow regulator is disposed between the opening piston and the valve controlling the flow thereto.

10. The combination of claim 3, wherein high-pressure gas constantly acts on both sides of the shock absorber piston.

II. The combination of claim 5, wherein high-pressure gas constantly acts on both sides of the shock absorber piston.

12. A compressed-gas operating mechanism for a circuit interrupter comprising, in combination:

a. means defining a low-pressure chamber having at least a portion of a stepped operating cylinder projecting therewithin;

b. means defining a high-pressure chamber and disposed contiguously of said low-pressure chamber and having a shock-absorbing cylinder disposed at least partially therein;

sorbing cylinder is perforated.

14. The combination of claim 12, wherein the shock-absorbing cylinder has check valves disposed at opposite ends thereof.

15. The combination of claim 12, wherein high-pressure gas constantly acts on one side of the closing piston and high-pressure gas is alternately admitted and exhausted from one face of the opening piston.

Claims

1. An operating mechanism for a circuit interrupter including, in combination: a. separable contact structure including a movable contact for establishing an arc; b. a piston device for actuating said movable contact including a closing piston and a separate opening piston both secured to a piston rod; c. said piston rod being mechanically connected to the movable contact; and, d. the cross-sectional area of the opening piston being larger than the cross-sectional area of the closing piston.

2. The combination according to claim 1, wherein high-pressure gas constantly acts on the closing face of the closing piston, and high-pressure gas is alternately admitted and exhausted from the opening face of the opening piston.

4. The combination of claim 2, wherein a three-way opening control valve controls the admission and exhausting of high-pressure gas to said opening face of the opening piston.

5. The combination of claim 3, wherein the shock absorber piston reciprocates within a perforated shock absorber-operating cylinder.

7. The combination according to claim 5, wherein regulating screws are exposed and control the perforations of the shock absorber-operating cylinder thereby rendering them accessible for adjustment.

9. The combination according to claim 1, wherein a pressure-sensitive flow regulator is disposed between the opening piston and the valve controlling the flow thereto.

11. The combination of claim 5, wherein high-pressure gas constantly acts on both sides of the shock absorber piston.

12. A compressed-gas operating mechanism for a circuit interrupter comprising, in combination: a. means defining a low-pressure chamber having at least a portion of a stepped operating cylinder projecting therewithin; b. means defining a high-pressure chamber and disposed contiguously of said low-pressure chamber and having a shock-absorbing cylinder disposed at least partially therein; c. a piston rod having a closing piston of relatively small diameter and a separate opening piston of relatively large diameter and a shock absorber piston all secured to and movable with the piston rod; d. separable contact means including a movable contact for establishing arcing; and, e. the piston rod being mechanically connected to the movable contact.

13. The combination of claim 12, wherein the shock-absorbing cylinder is perforated.