GB485926A - Improvements in and relating to high-speed electric circuit-closing mechanism - Google Patents

Abstract

485,926. Protective cut-out arrangements. BRITISH THOMSON-HOUSTON CO., Ltd. Nov. 23, 1936, No. 32030. Convention date, Nov. 25, 1935. [Class 38 (v)] In a method of effecting high-speed circuitclosing operations by means of controlled gas or vapour discharge paths, the closing operation is first effected by controlling the discharge paths to permit a flow of current, and the operation is completed by automatically closing associated mechanical switches connected in the circuit, whereupon the current supply in the discharge path is interrupted. The invention is particularly applicable for switching in a compensating choke 2 for the protection of a high-voltage lead 1, to prevent disturbances on sudden unloading of the lead. The choke is adapted to be connected to the lead through a mechanical switch 4 and a vapour discharge device 5 or grid-controlled valves in parallel. In the arrangement shown, the discharge device 5 with auxiliary ignition electrode 51 is connected in series with a resistance 3, which is in shunt with the exciting winding of a relay 6 which, when current flows through the valve, closes the circuit of the closing coil 41 of the switch 4. The auxiliary electrode 51 is controlled from a device 7 in dependence on an auxiliary discharge path 8, the control grid of which is controlled automatically by means of a relay 9 in dependence on an electrical condition, e.g. power factor, of the circuit 1. Between the device 7 and the electrode 51 a relay 11 is provided, which is opened, when the switch 4 closes, by means of auxiliary contacts 42 on the latter. A time relay may be provided between the relay 6 and the coil 41 so that for short-period disturbances the choke 2 may be switched in via the valves, without closing the switch 4. In case it is desired to effect the rapid connection of the choke 2 manually, the relay 9 may be replaced by a push-button control. The Specification as open to inspection under Sect. 91 was not limited to circuit-closing operations, and described an arrangement, Fig. 3 (Cancelled), for the protection of switches 72 ... 74 at a distance from a sub-station 60 against strong short-circuit currents. In the event of a short-circuit at the position X<1> or X<11> at the end of the lead 10, disconnection is effected through the main switch 71 at the sub-station. The valve 70, which functions in dependence on the short-circuit current, connects the beginning of the lead to earth, or connects individual phases together, and thereby relieves the switches 72 ... 74 from the short-circuit and causes the switch 71 to open. This subject-matter does not appear in the Specification as accepted.