US3185802A

US3185802A - Gas blast circuit breakers having at least one tubular contact

Info

Publication number: US3185802A
Application number: US124948A
Authority: US
Inventors: Amalric Jean
Original assignee: Merlin Gerin SA
Current assignee: Merlin Gerin SA
Priority date: 1960-07-18
Filing date: 1961-07-18
Publication date: 1965-05-25
Anticipated expiration: 1982-05-25
Also published as: CH373794A; FR1270584A

Description

J. AMALRIC Filed July 18. 1961 May 25, 1965 GAS BLAST cmcurr BREAKERS mvme AT LEAST ONE TUBULAR CONTACT United States Patent 3,185,802 GAS BLAST CIRCUIT BREAKERS HAVING AT LEAST ONE TUBULAR CONTACT Jean Amalric, Grenoble, Isere, France, assignor to Etablissements Merlin & Gerin Filed July 18, 1961, Ser. No. 124,948 Claims priority, application France, July 18, 1960, 4,274, Patent 1,270,584

4 Claims. (Cl. 200-148) This invention'relates to gas blast circuit breakers and more particularly to those having at least one tubular contact.

Amongst the problems encountered in the construction of gas blast circuit breakers, two are especially important, that is to say, the break-down voltage between the contacts in the open position, and the exhaust of the gas blast in such a manner as to assure the maximum efficiency of the extinguishing gas.

The break-down voltage between the contacts is determined by the testing voltage of the chamber. It 'determines, in its turn, the length of travel of the movable contact or contacts. Since it is necessary to make this length as small as possible, met-a1 screens are usually provided which surround the contacts in opened position and render the electric held between them as uniform as possible. In the closed position of the contacts, these electrodes define an annular space through which the gas blast exhausts at the moment of the separation of the contacts. The thickness of this annular space plays an important part in the exhaust of the gases, and it is necessary to give it a value which assures maximum efficiency in the extinction of the are. It is found that for high voltages the break-down distance determined by the testing voltage, and the optimum thickness of the annular space are fairly similar so that no especial problems are encountered in the choice of their dimensions. On the other hand for high-voltage circuit breakers comprisingseveral interrupting chambers, it is necessary, in order to keep the number of chambers as low as possible, to impose very high dielectric stress on the chambers. As a result it is necessary to provide break-down distance between the open contacts of as great .a length as is compat ble with the stroke of the movable contact or contacts. In this case the screens torm an annular space whose thickness is considerably greater than that necessaryfor a good escape of the gases and an optimum blast efiiciency. It has therefore been necessary to adopt comprise solutions.

It is an object of the present invention to avoid the necessity for a compromise solution and to make possible the choice of break-down distances and of annular space dimensions guaranteeing optimum working conditions.

Other objects and advantages of the invention will become readily apparent upon reading the following specification in conjunction with the accompanying drawing.

In this drawing there is schematically shown in axial section an arc extinction chamber of the type which is continually held under pressure and which is actuated according to the invention. In the drawing, 11 denotes a body of insulating material constituting the wall of the chamber .11 which is connected through the tube 12 with a compressed air reservoir 13. The upper part of the chamber is closed by a cover 14 while the lower part of the chamber is closed by a bell shaped member 15. The piston 17 can be moved in a cylinder 16, the latter being solid with the cover 14. On the cylinder 16 there is mounted a rfixed screen 18. The piston 17 is arranged to entrain the first movable contact 19 at a given moment. The movable contact 19 is hollow and opens into a cavity 33 closed by a valve 34 which can vent it to atmosphere. A sleeve 20 is fixed on the contact 19 and is actuated by,

on the one hand, a spring 30 which is supported by the piston 17 and, on the other hand, by the spring 31 which is supported by the cover \14. The first movable contact co-operates with a second movable contact 23, also h0llow, which at its lower end carries a valve 25. This valve is actuated by a piston 26 which slides in a cylinder 27 and on which the spring 28 acts. The contact 23 is provided with an exhaust opening 24 near the valve 25. A screen .29 is fixed on the second contact and is similar to the fixed screen v1-8. The valve 25 is controlled by the pneumatic delay device or

relay

37, 38, 39 and 40 through a piston 26. The

pneumatic valves

42, 43 can put the interior of the chamber 11' in communication with the interior of the cylinder 16 by means of the tubes 44' and 45, or vent the cylinder 16 to atmosphere. The valve 34 is controlled by a pneumatic delay device or

relay

46, 47 through a piston 36. All these valves and pneumatic relay devices are controlled through the tube 48 from a control point.

The circuit breaking device functions as follows:

When the breaker is in the closed position, the

contacts

19 and 23 are in theposition indicated in FIGURE 1. When the circuit breaker is in the open position, the first movable contact is withdrawn so as to be entirely within the screen 18 while the second contact is in the position shown in the drawing. 'The interior of the chamber 11' which is always in direct communication with the reservoir v13 is still under pressure. To open the circuit breaker, compressed air is passed into the tube 48. At first this air acts on the piston 36 opening thereby valve 34 and on the pistons 42' and 43 of

valves

42 and 43 lowering thus said valves. The compressed air also penetrates into the cylinder 27, and the piston 26, at the same time as it raises the Valve .25 from its seat, moves the second contact 23 upwards. The latter moves the first contact 19 in the same direction. The interior of the bell shaped member 15 and the space 33 are vented to atmosphere through the aperture 49. The

valves

42, 43 have now blocked the tubes 45 and vented to atmosphere the interior of the cylinder '16. The compressed air in the breaker chamber can now act on the piston 17. If we denote the distance between the

screens

18 and 29 in the closed position of the chamber by a and the stroke effected by the second contact 23 by b, the piston 17 will act upon the sleeve 20 after having effected a stroke of b plus an additional stroke to compress the spring '30. At this instant, having acquired a certain velocity, it entnains the contact 19 and causes a rapid separation of the two

contacts

19 and 23, for the contact 23 has stopped, being retained by the piston 26. The distance between the two screens, at the moment of the separation of the contacts and of the initiation of the arc is therefore a-b. The two screens, therefore, define at this moment an annular blast space of a thickness a-b through which the compressed air present in the chamber passes into the two hollow contacts, cooling the are under optimum conditions and removing the ionised gases at first respectively into the bell shaped member 15 and the space 33, and then to the atmosphere. After a certain time corresponding to that necessary for the extinction of the arc, the

delay devices

37, 38, 39, 40 and 46, 47 whose operation will not be described since it does not form part of the invention, cut off the supply of compressed air coming through the tube 48 and at the same time vent the

cylinders

27 and 35 to atmosphere. The piston 26 urged by the spring 28, and in consequence, the second contact 23 return to their initial position. -It is the same as regards the piston 36 and the valve 34 which again close the space 33. The interior of the cylinder 16 is still vented to atmosphereyand this allows the piston 17 to continue its stroke until the contact 19 is within the screen '18. The chamber 11' bei g completely closed by the valve 25 and by the

valves

42, 43, pressure is rapidly reestablished. The distance between the two screens is again equal to a. To close the contacts, it suffices to put the tubes 48 in communication with the atmosphere. The

valves

42, 43 return to their initial position, the compressed air passes through the tubes 45, 44 and 45', 44' into the cylinder to, pressure is re-established on the two faces of the piston 17 and the spring 31 now entrains the contact 19 into its closed position.

It will be realised that the solution according to the invention enables the travel b and the distance a to be given values which assure :a maximum efiiciency of blowing while the insulating distance can be given the value required by the testing voltage of the chamber.

What is claimed is:

1. A gas blast circuit breaker comprising in combination two aligned relatively movable elongated contact members, at least one of said contact members being tubular, a pair of screen members defining around said contact members a substantially annular space through which the gas blast exhausts into at least one of said contact members at the moment of their separation, means to bring said screen members nearer to each other just before the moment of separation of said contact members, and means to bring said screen members to their original relative position after extinction of the are drawn between said contact members.

2. A gas blast circuit breaker comprising in combination two aligned movable cylindrical contact members, at least one of said contact members having a tubular term, a pair of screen members defining around said contact members a substantially annular space through which the gas blast is exhausted at the moment of separation of said contact members, one of said screen members being fixed, the other of said screen members being disposed on one of said contact members, said last named contact member etfecting a reciprocating movement during the opening of the circuit breaker and urging the other con tact member in the same direction during its forward movement. 1

3. A gas blast circuit breaker comprising in combination two aligned movable cylindrical contact members, at least one of said contact members having a tubular form, a pair of screen members defining around said contact members a substantially annular space through which the gas blast is exhausted at the moment of separation of said contact members, one of said screen members being fixed, the other of said screen members being disposed on one of said contact members, said last named contact member effecting a reciprocating movement during the opening of the circuit breaker, and an exhaust valve rigidly connected to said last named contact member.

4. A gas blast circuit breaker comprising in combination two aligned relatively movable tubular contact members, a pair of screen members defining around said contact members a substantially annular space through which the gas blast exhausts into said contact members at the moment of their separation, means to bring said screen members nearer to each other during the beginning of the blast period, and means to bring said screen members to their original relative position at the end of said blast period.

References Cited by the Examiner UNITED STATES PATENTS 3,027,439 3/62 Upton et al. 200148 FOREIGN PATENTS 432,453 7/35 Great Britain. 575,887 3/ 46 Great Britain.

BERNARD A. GILHEANY, Primary Examiner,

Claims

1. A GAS BLAST CIRCUIT BREAKER COMPRISING IN COMBINATION TWO ALIGNED RELATIVELY MOVABLE ELONGATED CONTACT MEMBERS, AT LEAST ONE OF SAID CONTACT MEMBERS BEING TUBULAR, A PAIR OF SCREEN MEMBERS DEFINING AROUND SAID CONTACT MEMBERS A SUBSTANTIALLY ANNULAR SPACE THROUGH WHICH THE GAS BLAST EXHAUSTS INTO AT LEAST ONE OF SAID CONTACT MEMBERS AT THE MOMENT OF THEIR SEPARATION, MEANS TO BRING SAID SCREEN MEMBERS NEARER TO EACH OTHER JUST BEFORE THE MOMENT OF SEPARATION OF SAID CONTACT MEMBERS, AND MEANS TO BRING SAID SCREEN MEMBERS TO THEIR ORIGINAL RELATIVE POSITION AFTER EXTINCTION OF THE ARC DRAWN BETWEEN SAID CONTACT MEMBERS.