GB593627A - Improvements in and relating to the operation of self-excited d.c. generators - Google Patents

Abstract

593,627. Electricity supply; exciting dynamo electric machines. ENGLISH ELECTRIC CO., Ltd., and SHAW, N. H. June 13, 1945, No. 14993. [Classes 35 and 38 (iv)] An auxiliary source of D.C. power is tem-À porarily inserted in series or parallel with the field circuit of a self-excited D.C. generator to assist build-up of its output voltage after a momentary overload. As shown, the generator 1, 1a is an exciter for an alternator 2, 2a, the generator field 1a normally being controlled by the alternator volts through an automatic regulator 4. A battery 6 is automatically connected in series with the field 1a under conditions of low generator and alternator volts by a contactor 7 and remains so connected until the generator volts become excessive. The contactor is controlled by relays 8, 9, contacts 4a which close when the regulator 4 is in the all-out position (viz. when the alternator volts are low) and contacts 3a which are closed so long as the circuit breaker 3 of the alternator is closed. Relay 8 has contacts 8a which close in response to low generator volts and, if the alternator volts are also low, the contactor is energized over contacts 3a, 4a, 8a to insert the battery in the field circuit. Rectifier 5 prevents discharge of the battery through the regulator. Upon build-up of the generator volts to an excessive value, normally closed contacts 9a of over-voltage relay 9 open a byepass around the now open contacts 8a and allow contactor 7 to drop out and disconnect the battery. In a modified arrangement, relays 8, 9 may be omitted and the battery connections controlled by regulator 4. The battery may be connected by contactor 7 across a field discharge resistance in series with field 1a, the contactor having further contacts which shortcircuit the resistance when the battery is out of circuit. Specification 528,789 is referred to.