GB288181A - Improvements in or relating to electrical regulating systems - Google Patents

Abstract

288,181. Metropolitan-Vickers Electrical Co., Ltd., (Assignees of Levy, C. C.). April 2, 1927, [Convention date]. Systems depending on the use of two or more machines.-The voltage of an electrical transmission system is maintained within predetermined limits and the power-factor corrected by an alternating-current synchronous machine automatically connected and disconnected from the system and associated with automatic voltageresponsive devices controlling the excitation of the machine. Devices automatically responsive to the excitation are provided for disconnecting the machine from the system while the excitation remains within the predetermined limits and line conditions are normal. As shown, the rotatable field winding 5 of the synchronous motor 4, 5 is fed with continuous current at 6 through a variable resister 9 which is increased or decreased by a reversible motor 31 energized from a battery 17 by a regular 15 responsive to under-voltage or over-voltage relays 13, 14 fed from a transformer 11, 12. The motor is automatically disconnected from the system by a relay 27 energized in accordance with the voltage or current of the excitation circuit and connected to the closing coil 23 of the circuit interrupter 3 and to relay 24. The operation of the relays 13 or 14 energizes a slow-closing quick-release relay 16 which operates a relay 19 provided with switches 21, 22. The switch 21 keeps relays 19 energized after relay 16, has been de-energized, while switch 22 connects the closing coil 23 with battery 17 and in parallel with relay 24 which is constructed similarly to relay 16. The circuit interrupter 3 remains closed while the switch of relay 24 is open. Relay 27 intermittently short-circuits the relay 24 through contacts x, y in response to over or under excitation of the motor and since the relay 24 is slow-acting to close, it is necessary for the line conditions to become normal before the switch 22 can be opened to de-energize the closing coil 23. The apparatus may be employed with the starting arangements according to Specifications 164,678 or 166,878, [both in Class 38 (iii), Electric motor control systems &c.], and suitable connections therefore are described.