US3699289A

US3699289A - Operating device for electric switching apparatus for high voltage

Info

Publication number: US3699289A
Application number: US181872A
Authority: US
Inventors: Sten Berneryd; Hans Backskog
Original assignee: ASEA AB
Current assignee: ABB Norden Holding AB
Priority date: 1970-10-02
Filing date: 1971-09-20
Publication date: 1972-10-17
Anticipated expiration: 1989-10-17
Also published as: SE346050B; CA934417A

Abstract

In an operating system for high voltage gas blast circuit breakers, the opening impulse is transmitted from earth to high potential by means of an insulating tension rod. A high initial acceleration of the rod is obtained by means of an electrodynamic operating device positioned at the lower end of the rod. This operating device comprises a stationary coil and an operating plate connected inductively to the coil and directly joined to the tension rod.

Description

United States Patent Berneryd et a].

[ Oct, 17, 1972 OPERATING DEVICE FOR ELECTRIC SWITCHING APPARATUS FOR HIGH VOLTAGE Inventors: Sten Berneryd; Hans Backskog, both of Ludvika, Sweden Assignee: Allrnanna Svenska Elektriska Ak- V tiebolaget, Vasteras, Sweden Filed: Sept. 20,1971

Appl. No.: 181,872

Foreign Application Priority Data Oct. 2, 1970 Sweden ..l3378/70 U.S. Cl. ..200/148 R Int. Cl. .t ..H0lh 33/42 Field of Search ..200/148 B, 148 R [56] References Cited UNITED STATES PATENTS 3,256,414 6/1966 Giammona et a1. ....200/l48 B 3,420,972 1/1969 Pucher ..200/148 R 3,532,843 10/1970 Pucher .;..200/l48B Primary Examiner-Robert S. Macon Att0mey Jennings Bailey, Jr.

[57] ABSTRACT 9 Claims, 2 Drawing Figures PATENTEnnm 1 1v m2 srzw BER/vamp BY HANS @MLKSKQG OPERATING DEVICE FOR ELECTRIC SWITCHING APPARATUS FOR HIGH VOLTAGE RELATED APPLICATIONS This application is related to US. application, Ser. No. l4l,l74, filed May 7, 1971, which shows an operating system in which some features are common with the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a means for operating at least one contact in an electric switching device for high voltage and relates primarily to voltages of the order of 1,000 kilovolts. The means is of the type in which a movement impulse is rapidly transferred from earth to high potential through a tension rod.

2. The Prior Art In the operation of switching devices forextremely high voltages, very short and exact switching times are required. This can be achieved as proposed in application, Ser. No. 883,134 to Grune et al. filed Dec. 8, 1969, by using electro-dynamically operated pneumatic operating members placed in the immediate vicinity of the contacts at high potential and arranging release of the operating members fromearth potential by means of an electro-optical signal transmission system. In such an arrangement, the operating energy for the electro-dynami'c system must be accessible at high potential. However, it has been found both difficult and expensive to arrange the supply of this energy satisfactorily. Such an energy feeding system is not necessary if an insulating tension rod is used to transfer the required impulses from an operating member placed at earth potential to a pressurized gas valve placed at high potential to operate the contactsfln a previously known construction of this type (US. Pat. No. 3,420,972), the. movement of the rod is effected by supplying pressurized gas to a cylinder space in which an operating piston joined to the lower end of the rod is axially displaceable. The initial acceleration which can be imparted to the rod in this construction is insufficient for circuit breakers for very high voltages, and it is also difficult to regulate the speed of the rod as a function of the time. The possibility of this is particularly desirable when the rod is to be used to transmit impulses to both a power interrupter contact and a resistor interrupter contact with a certain time delay between the impulses.

SUMMARY OF THE INVENTION The object of the present invention is to effect an operating means which in the above respects is more suitable than corresponding previously known constructions.

As in the embodiment shown in patent Ser. No. 3,420,972, the operating means according to the present invention comprises a pressurized gas valve placed in the vicinity of the contacts of the switching device at high potential, the movable valve member being controlled from earth potential by means of an insulating tension rod arranged inside a support insulator filled with compressed gas, the tension rod being joined to two pistons which are axially displaceable along cylindrical surfaces at the upper and lower ends of the rod, the upper side of the upper piston being in communication with the open air. The invention is characterized in that the tension rod is arranged upon operation of the contacts to be moved in downward direction from an upper end position in which the upper side of the lower piston lies in sealing abutment with one valve seat and is thus influenced by the pressurized gas in the support insulator on a surface which is smaller than the surface of the upper piston, whereas, when said lower piston is lifted from its seat upon operation of the switching device, it is influenced by the pressurized gas over its entire surface, which is greater than the surface of the upper piston, an electrodynamic operating device being arranged at the lower end of the tension rod to operate the switching device, the electro-dynamic device consisting of a stationary coil and an operating plate connected inductively. to the coil and joined to the tension rod. Since the operating plate in the electro-dynamic operating system is attached directly to the tension rod an extremely quick initial acceleration of the rod is achieved. Since also the entire surface of the piston is immediately influenced by the pressurized gas when the piston is lifted from its seat, the quick movement will continue even after the electro-dynamic force has disappeared.

The operating device may suitably be designed so that the lower piston also acts as operating plate, in which case a separate plate is not necessary. This involves a considerable simplification.

Switching apparatus of the type in question are usually designed for automatic rapid re-closing and it is thus desirable for the tension rod to be quickly returned to its initial position after operation. This can easily be achieved by means of a valve plate joined by a spring to the lower piston and closing the outlet opening from a cylinder chamber arranged under the lower piston. At the final stage of the opening movement pressurized gas is supplied to this cylindr chamber from the upper side of the piston through a pressure equalizing channel.

In certain switching devices it is necessary to supply power impulses to at least two contacts with a certain time delay between the impulses, but with a common .release signal. For this purpose, the device according to the invention can be designed so that at least two pneumatic valves at high potential are arranged to 'be influenced by a number of cams supported by the tension rod. Suitable time delay between the release impulses to the various contacts can thus easily be adjusted by attaching the cams to the rod in such a way that the distance between them can be altered.

In order to achieve exact intervals between the various release impulses, it is desirable for the movement of the tension rod to be kept substantially constant after the first rapid acceleration. This can be achieved by reducing the driving force on the tension rod after a certain time, which can be realized relatively easily by means of a damping piston, as is clear from the following description BRIEF DESCRIPTION OF THE DRAWINGS The drawings show an embodiment of the invention,

FIG. 1 showing the principle for transmission of the release impulses from earth to high potential, while,

FIG. 2 shows the operating member arranged at earth potential in closer detail.

FIG. 1 shows schematically two pneumatic valves 1 and 2 placed at high potential and intended while emit power impulses to a power contact and a resistor contact, respectively, in an electric switching device, for example an air blast circuit breaker. The valves are shown in their normal positions in which the pneumatic operating mechanism of the contacts, not shown, is in communication with the open air through two conduits 3 and 4 and

outlet channels

5 and 6. Release of the contacts is effected by opening the valves 1 and 2 so that the two conduits 3 and 4 are placed under pressure from a hollow support insulator 7 filled with pressurized gas and is fed by a conduit 8 from a source of pressurized gas arranged at earth potential. The valves 1 and 2 are opened by two cams 9 and 10 which are attached to a vertical tension rod 11 of insulating material arranged inside the support insulator 7 which rod is provided at its upper end with a piston 12 and at its lower end with a piston 13 having a larger diameter than the piston 12. The pistons are axially displaceable along cylindrical surfaces 14 and 15 at the upper and lower ends of the rod. Between the pistons and the cylindrical surfaces are sealing rings. The lower side of the lower piston 13 limits a cylindrical space 16 which during normal operation is in communication with the open air through an axially arranged outlet opening 17.

In the position of rest of the switching device, the lower piston 13 is pressed against a valve seat 18 (FIG. 2) arranged on the upper side of the piston due to pressure on the piston 12 at the upper end of the rod. The switching device is operated by a previously charged capacity being discharged through an induction coil 19 arranged around the valve seat 18 so that a current is induced in the piston 13 which is made of material having good electrical conductivity, for example aluminium, or has a short-circuiting ring made of such material. As a result the piston 13 is pushed away from the valve seat 18 with considerable force. The gas pressure in the support insulator 7 then operates over the entire surface of the piston 13 so that the movement continues even after the force coming from the electrodynamic operating device has ceased.

The tension rod 11 is returned when pressure equalization is achieved in the cylindrical space 16 below the piston 13 through a by-pass flow channel 20 after a valve plate 22 connected by a spring 21 to the piston 13 has closed the outlet opening 17 to the atmosphere. When the piston 13 has returned to the valve seat 18 the plate 22 is returned by the spring 21 since atmospheric pressure is reestablished in the cylinder space 16 through an equalizing hole 23.

Instead of letting the piston 13 act as operating plate in the electro-dynamic operating device, the electrodynamic and pnuematic functions can be separated by placing an induction coil 27 with a separate operating plate 24 completely outside the cylinder space 16, as indicated by dotted lines in FIG. 2. The electro-dynamic system can then more easily be dimensioned so that greater operating power is obtained. Furthermore, a more favorable I'ield pattern is obtained around the coil and the efficiency of the system is thus improved.

In order to achieve an exact time interval between the release moments of the contact devices controlled by the two valves 1 and 2 it is desirable for the speed of the tension rod during the latter stage of the operating movement to be kept substantially constant. This can be achieved by throttling the opening 26 surrounded by the valve seat 18, with the help of a damping piston 25 on the tension rod 11. The supply of blast air to the space above the piston 13 is thus closed off and the downward driving force on the tension rod is reduced.

The invention is not limited to the embodiment shown. The tension rod 11, for example, need not affect the contacts of the switching device through camcontrolled pneumatic valves. Thus, the rod may be connected to the contacts or made to operate the contacts in any other suitable manner. The operating device may also be combined with conventional means for damping and braking.

We claim:

1. Means for operating at least one contact in an electric switching device for high voltage comprising a pneumatic valve (I) placed at high potential, a hollow supportinsulator (7) adapted to be filled with compressed gas carrying said pneumatic valve at its upper end, an insulating tension rod (11) movable upward and downward within said support insulator, means forming cylindrical surfaces (14,15) adjacent the top and bottom of said support insulator, a valve passage between the cylindrical surfaces having a valve seat, upper and lower piston means (12,13) connected to said tension rod and slidable within said cylindrical surfaces, the cross-sectional area of the lower piston means being greater than that of the upper piston means, the cross-sectional area of the valve seat being less than that of the upper piston means, the top surface of the upper piston means being exposed to atmospheric pressure, means "for moving said tension rod downwardly from an upper end position in which the top surface of the lower piston means lies in scaling abutment with said valve seat (18) and is thus influenced by the pressurized gas in the support insulator on a part of its surface which is smaller than the surface of said upper piston means, whereas, when said lower piston means is lifted from its seat upon operation of the switching device, it is influenced by the pressurized gas over its entire surface, said tension rod moving means comprising an electro-dynamic operating device at the lower end of said tension rod to operate the switching device, said electro-dynamic' operating device comprising a stationary coil and an operating plate means, said plate means being connected inductively to said coil and joined to said tension rod.

2. Means according to claim 1, in which the operating plate meansconstitutes the lower piston means.

3. Means according to claim 1, in which the cylindrical surface adjacent the bottom of the support insulator encloses a cylindrical space below the lower piston means which is in communication with the open air through an axially arranged outlet opening (17).

4. Means according to claim 3, a spring carried by the lower piston on the bottom side thereof, and a valve plate carried by the spring which, when the tension rod, upon operation of the switching device, has moved a certain distance from its upper end position, closes said outlet opening.

5. Means according to claim 1, in which in the lower cylindrical surface there is at least one channel which, when the rod has moved a certain distance, provides largement carried by the tension rod and movable into the hole during downward movement of the rod to throttle the flow of gas from the interior of the support insulator into the space above the lower piston.

8. Means according to claim 1, including at least two pneumatic valves, cams on said tension rod engageable with said pneumatic valves.

9. Means according to claim 8, in which said cams are adjustably mounted on said tension rod.

Claims

1. Means for operating at least one contact in an electric switching device for high voltage comprising a pneumatic valve (1) placed at high potential, a hollow support insulator (7) adapted to be filled with compressed gas carrying said pneumatic valve at its upper end, an insuLating tension rod (11) movable upward and downward within said support insulator, means forming cylindrical surfaces (14,15) adjacent the top and bottom of said support insulator, a valve passage between the cylindrical surfaces having a valve seat, upper and lower piston means (12,13) connected to said tension rod and slidable within said cylindrical surfaces, the cross-sectional area of the lower piston means being greater than that of the upper piston means, the cross-sectional area of the valve seat being less than that of the upper piston means, the top surface of the upper piston means being exposed to atmospheric pressure, means for moving said tension rod downwardly from an upper end position in which the top surface of the lower piston means lies in sealing abutment with said valve seat (18) and is thus influenced by the pressurized gas in the support insulator on a part of its surface which is smaller than the surface of said upper piston means, whereas, when said lower piston means is lifted from its seat upon operation of the switching device, it is influenced by the pressurized gas over its entire surface, said tension rod moving means comprising an electro-dynamic operating device at the lower end of said tension rod to operate the switching device, said electro-dynamic operating device comprising a stationary coil and an operating plate means, said plate means being connected inductively to said coil and joined to said tension rod.

2. Means according to claim 1, in which the operating plate means constitutes the lower piston means.

5. Means according to claim 1, in which in the lower cylindrical surface there is at least one channel which, when the rod has moved a certain distance, provides equalizing communication between the two sides of the lower piston.

6. Means according to claim 3, in which the cylindrical space is provided with a small opening (23) putting it in permanent communication with the open air.

7. Means according to claim 1 having a wall adjacent and above the lower piston, said valve passage comprising a hole through said wall of substantially greater cross-section than the cross-section of the tension rod, the tension rod passing through the hole, and an enlargement carried by the tension rod and movable into the hole during downward movement of the rod to throttle the flow of gas from the interior of the support insulator into the space above the lower piston.