GB928916A - Air-blast circuit breaker with multiple interruption - Google Patents

Abstract

928,916. Gas-blast switches. A. G. BROWN, BOVERI & CIE. June 13, 1960 [June 13, 1959], No. 20703/60. Class 38 (5). Each phase of an air-blast circuit-breaker comprises a plurality of elements each of which has two power interrupting units and a voltage disconnecting unit subjected to air blast, one of the power interrupting units being in parallel with a low-ohmic resistor. In Fig. 1 an auxiliary compressed-air container 1 supplied through an insulator 15 carries power interrupting units 2, 3 connected in parallel with high and low ohmic resistors 4, 6 and controlled by valves operated by pistons 7, 8 housed in a casing 9 normally exhausted of air, the voltage disconnecting unit 5 being secured to the insulator containing the unit 3. The breaker is opened by admitting air from container 1 to the casing 9 to depress pistons 7, 8, unit 3 opening before unit 2 and both reclosing after air from an insulator 14 has opened unit 5. The units have exhaust valves 13, 13a and pistons 7, 8 have pressure-equalizing holes and restoring springs 16. The breaker elements may be arranged in a row or symmetrically with respect to a plane. In a modification, Fig. 2 (not shown), one end of the low-ohmic resistor is secured to the auxiliary air container and the other end carries the second power unit and high-ohmic resistor, the container also carrying the voltage disconnecting unit whose air supply is used to operate the two pistons and produce the same opening sequence as before. In Fig. 3, main valves 17 controlling the operation of units 2, 3 are arranged in intermediate casings 19 connected, when units 2, 3 are open, to the auxiliary container 1, the high-ohmic resistor being omitted. To open, air is admitted through insulator 14 to depress pistons 22, open valves 17 and exhaust casings 19, thus allowing air from container 1 to open units 2, 3 and flow to exhaust until valves 17 reclose and casings 19 refill with air. This construction may be modified, Fig. 4 (not shown), so that the contacts of the power units are contained in a single intermediate casing enclosing a further casing receiving the moving contacts and a common reclosing spring and being connected to a main valve and piston mounted on the intermediate casing. The latter is connected to the auxiliary air container through a hollow fixed contact forming part of the lower unit and supported by a bushing which is mounted on the auxiliary container and carries the intermediate container.