GB545105A - Improvements relating to automatic regulation of the voltage of synchronous generators - Google Patents

Abstract

545,105. Automatic control systems. BRITISH THOMSON-HOUSTON CO., Ltd. Aug. 8, 1941, No. 10109. Convention date, Aug. 10, 1940. [Class 38 (iv)] Voltage.-To prevent the reduction of the field strength of an alternator below that necessary to prevent its falling out of synchronism, a field regulator controlling separate circuits 22, 23 for raising and lowering the excitation in response to voltage requirements has contacts 29, 30 included in one circuit whereby a minimum excita-. tion may not be passed and may have contacts 33, 34 in parallel with the other circuit whereby the excitation may be raised independently of the regulator. These contacts become effective at different values of excitation according to the load on the generator ; the contacts 30, 34 may be moved by a Selsyn transmission from the prime mover throttle valve while the contacts 29, 33 are moved in accordance with the position of the field rheostat 9. The regulator shown is described in Specification 388,805, and comprises, in addition to slow raise and lower contacts 17, 18 controlling a motor driving the rheostat, rapid raise and lower contacts 18, 19 which control relays 26, 27. Contacts 31, 32 are accordingly arranged to operate simultaneously with contacts 29, 30 to interrupt the circuit of the rapid lowering relay 27.