US3018352A

US3018352A - High tension air blast circuit breakers with a plurality of series connected breaking gaps per pole

Info

Publication number: US3018352A
Application number: US843130A
Authority: US
Inventors: Schulz Richard
Original assignee: ASEA AB
Current assignee: ABB Norden Holding AB
Priority date: 1958-10-10
Filing date: 1959-09-29
Publication date: 1962-01-23
Anticipated expiration: 1979-01-23
Also published as: FR1226377A; CH372728A; DE1063682B

Description

Jan. 23, 1962 R. SCHULZ 3,018,352

HIGH TENSION AIR BLAST CIRCUIT BREAKERS WITH A PLURALITY 0F SERIES CONNECTED BREAKING GAPS PER POLE Filed Sept. 29, 1959 3 Sheets-Sheet 1 EN 27 2s 2s I a 1 8 i I VENTOR.-

Fir/Gard 5 (22112 fiffomey.

Jan. 23, 1962 R. SCHULZ 3,018,352

HIGH TENSION AIR BLAST CIRCUIT BREAKERS WITH A PLURALITY OF SERIES CONNECTED BREAKING GAPS PER POLE Filed Sept. 29. 1959 5 Sheets-Sheet 2 L 5 so INVENTOR. .Kr/zard 50'' [Z Jan. 23, R. SCHULZ HIGH TENSION AIR BLAST CIRCUIT BREAKERS WITH A PLURALITY OF SERIES CONNECTED BREAKING GAPS PER POLE Filed Sept. 29, 1959 15 Sheets-Sheet 3 Fig.3

I VENTOR. Flt/10rd 5c uZZ United States Patent M 3,018,352 HIGH TENSION AIR BLAST CIRCUIT BREAKERS WITH A PLURALITY 0F SERIES CONNECTED BREAKING GAPS PER POLE Richard Schulz, Friedberg, Hessen, Germany, assignor to Allmiinn-a Svenska Elektriska Aktiebolaget, Vasteras, Sweden, a corporation of Sweden Filed Sept. 29, 1959, Ser. No. 843,130 Claims priority, application Germany Oct. 10, 1958 2 Claims. (Cl. 200148) In high tension air blast circuit breakers having a plurality of series connected breaking gaps per pole, arrangements must be made by which the recovery voltage upon a breaking is distributed as equally as possible over the separate breaking gaps of the breaker pole. For this purpose ohmic resistances are suited, which damp the over voltages which are generated upon interruption of a power line or a transformer operating at no load. The more low-ohmic these resistances and the higher the residual current flowing through the resistances after an opening of the main breaking gap, the more effectively are the over-voltages dampened.

In circuit breakers which operate without a series connected switch, it is necessary to interrupt the residual current through the resistances by auxiliary breaking gaps, the contacts of which open a short time after the main breaking gaps. In air blast circuit breakers this delay is generally caused by pneumatic arrangements. The auxiliary breaking gaps are often designed like spark gaps and the residual current is extinguished by the contacts being drawn apart in a container filled with compressed air. If, however, the residual currents through the resistances are high, it will be necessary to subject the auxiliary breaking gaps to blast air. Such arrangements are known. In an air blast circuit breaker, the main breaking gaps of which in operation are permanently arranged in compressed air, it has been suggested to use the decrease in pressure which occurs upon an opening of the main breaking gap, for subjecting the auxiliary breaking gaps to a blast of compressed air by an arrangement according to which compressed air in a limited space is allowed to flow into the space containing compressed air of lower pressure so that the auxiliary breaking gaps are subjected to blast air. This device has the disadvantage that the gases ionized in the auxiliary breaking gap flow to the main breaking gap at its nearest point and these may cause the main breaking gap to be re-ignited.

Another device according to which the extinguishing gases from the auxiliary breaking gap flow out through the main blast valve has the disadvantage that the blast valve with its comparatively large area of flow must be held open until the residual current through the auxiliary breaking gap has also been safely interrupted. This, however, means an undesirable, high consumption of compressed air and makes it necessary to use large compressed air containers.

The invention avoids these disadvantages and relates to a device for air blast circuit breakers with a plurality of series connected main breaking gaps per pole and each main breaking gap connected in parallel with a resistance and an auxiliary breaking gap, by which comparatively high residual currents may be interrupted with an unusually low consumption of compressed air.

The invention is characterized in that a passage is provided leading past the auxiliary gap to free air, with a blast valve in the passage which is closed shortly after the passage is open to free air by the pressure in the container, and that the valve which controls the opening of the passage also serves for connecting the passage to the interior of the container.

The contact of the auxiliary breaking gap, which contact is connected to a piston, can suitably be movably 3,618,352 Patented Jan. 23, 1962 ICC arranged in a piston housing. By venting the space enclosing the piston housing, upon a breaking action, first the contact with its piston is moved and then the piston housing, because of the influence of the compressed air in the extinguishing chamber. The piston housing closes the outlet opening for the compressed air in its end position while the contact with its piston is returned to its primary position in the piston housing. While the spring, which upon a breaking action has been set by the movement of the piston housing, is held set by the influence of the compressed air in the extinguishing chamber, the holding force is neutralized upon a closing action by the supply of compressed air on the back of the piston housing and the piston housing is returned by the spring force to its primary position, so that the auxiliary breaking gap is closed. If the auxiliary breaking gap is subjected to comparatively high voltages, the opening for the movable contact in the piston housing is suitably designed as an insulating nozzle.

The invention will be more easily understood with reference to the accompanying drawings. FIGURE 1 shows the main breaking gap and the auxiliary breaking gap built together. FIGURE 2 shows the auxiliary breaking gap and its operating mechanism when the auxiliary breaking gap is closed. FIGURE 3 shows the auxiliary breaking in an intermediate position and FIG- URE 4 the auxiliary breaking gap in an open end position. 1 designates an extinguishing chamber filled with compressed air, which chamber is supported by a pillar insulator, not shown, and in which chamber the stationary contact 2 and the movable contact 3 have been arranged. The resistance 4 with the

auxiliary breaking gap

5, 6 is connected in parallel with the main breaking gap 2, 3. The movable contact 3 of the main breaking gap, which contact is held in closed position by the spring 7, is controlled by the compressed air which, for an opening action, is supplied through the pipe 8. Upon this the piston 9 and the diiterential piston 10 are moved to the left, the valve 11 is closed and the blast valve 12 is opened. Through the latter the compressed air in the chamber may flow through the breaking gap 2, 3 at 13 to the open air. The valve 11 closes the channel 14 and at the same time causes the space 15 to be connected to the open air. The contact 3 of the main breaking gap is moved to the right and the are generated is subjected to a blast of pressure air and is extinguished. The channel 16 in the differential piston 10 after some time causes the pressure on both sides of this piston to be equalized so that the piston 10 under the influence of the spring 17 and the movement of the contact 3, is returned to its initial position and the blast valve 12 is closed again. The compressed air in the space 1 holds the movable contact 3 in open position counter-acted by the spring 7. The piston 18 connected to the movable contact 3 then rests against the smaller surface of the diiterential piston 10 and closes the blast valve 12.

FIGURE 2 shows the

auxiliary breaking gap

5, 6 connected in parallel to the main breaking gap 2, 3. A piston 19 is connected to the movable contact 5 of the auxiliary breaking gap, which piston under counteraction of a spring 21 can be moved in the piston housing 20. The piston housing 20 is biased by a spring 22 and is arranged in the space 23, which through the openings 24 communicates with the pipe 25. The pipe 25 is, as FIG- URE 1 shows, connected to the stop valve 26, through which the pipe 25 can be connected either to the container 1 or, through the opening 27, to the open air. The valve piston 28 is controlled by the pressure in the pipe 8. When the main breaking gap is closed, as FIG- URE 1 shows, the pipe 8 is not filled with compressed air. The pipe 25 now communicates with the extinguishing chamber 1 and is consequently filled with compressed air, so that the piston housing 20 and the contact 5 are held in closed position by the spring 22. 29 designates the nozzle rigidly connected to the piston housing 20, which nozzle may be designed as an insulating nozzle and has an opening therein for the movable contact.

FIGURE 1 shows the auxiliary gap in closed position. If the pipe 8 is supplied with compressed air, the main breaking gap is opened and, immediately after, the valve head 28 is moved to the left, whereby the pipe 25 is emptied through the opening 27. The consequence is that the compressed air in the chamber 1 acts through the openings 30 on the piston 19 and moves this upwards against the counter-action of the spring 21 until the piston meets the pin 31 in the piston housing 20 (FIGURE 3).

The generated arc is, during the course of this, extinguished in the nozzle 29. Due to the influence of the compressed air the piston 19 with the contact 5 and the piston housing 20 is moved further upwards so that the spring 22 is compressed. The extinguishing gases from the auxiliary breaking gap flow through the

channels

30, 32, 33 and the openings 24 (FIGURE 4) into the pipe 25 and out to the open air. In the upper position of the piston housing 20, the opening 35 and by that the openings 24, are closed by blast valve 34 seating over opening 35 so that in this position the compressed air is kept from flowing out to the open air. The pressure on both sides of the piston 19 has now been equalized through the channels 32 so that the spring is able to move the movable contact 5 of the auxiliary breaking gap closer to the stationary contact 6 while maintaining a sufficient insulating distance.

Upon a closing action, the piston housing 20 with the valve head 34 is influenced, through the pipe 25, by compressed air so that the spring 22 moves the piston housing downwards and the auxiliary breaking gap is closed. At this the movement is dampened due to the air in space 23 being compressed -I claim:

1. A high tension air blast circuit breaker comprising a container for compressed m'r, a main breaking gap, a resistance and an auxiliary breaking gap connected in series with each other and in parallel with the main breaking gap, means forming a passage extending from the container past the auxiliary gap to free air, blast valve means in said passage on the opposite side of the auxiliary gap from the container operable by the pressure in the container to close the passage after connection of the passage to free air, and stop valve means for selectively connecting the part of the passage on the opposite side of the blast valve from the container to free air and to the container, said auxiliary breaking gap having a movable contact, a movable piston housing rigid with the blast valve, a piston movably arranged in said housing and rigid with the movable contact, said contact and piston, when said part of the passage is connected with free air, being moved relative to said housing to open the auxiliary breaking gap and means for returning said contact and piston to their original position in the housing when said blast valve is closed.

2. A high tension air blast circuit breaker according to claim 1, in which the piston housing is provided with an opening for the movable contact, said opening being shaped like a nozzle, the portion of the housing forming the nozzle being of insulating material.

References Cited in the file of this patent UNITED STATES PATENTS 2,747,055 Forwald May 22, 1956 2,786,117 Forwald Mar. 19, 1957 2,786,119 Forwald Mar. 19, 1957 2,908,788 Forwald Oct. 13, 1959 FOREIGN PATENTS 167,384 Australia Apr. 6, 1 956