GB358035A - Improvements relating to the control of dynamo electric machines - Google Patents

Abstract

358,035. Running generators in parallel. BRITISH THOMSON-HOUSTON CO., Ltd., Crown House, Aldwych, London, and WHITAKER, F. P., 237, Clifton Road, Rugby. April 2, 1930, No. 10486. [Class 38 (iv).] Regulation, automatic.-Where a number of similar dynamo-electric machines G1, G2 share a bus-bar load and have field rheostats R mechanically connected to a common control device M, an auxiliary rheostat A in series or shunt with each main rheostat is individually and automatically controlled so that the excitation of a single machine may be adjusted for connection and disconnection with the bus-bars. A two-position relay 15 controls a pilot motor N actuating an auxiliary rheostat, so that when the voltage of an incoming machine is above that of the bus-bars it is automatically reduced to a value equal to or somewhat greater than the bus-bar volts, whereupon the relay moves to its other position and effects closure of the contactor C connecting the machine to the bus-bars. Auxiliary contacts on this contactor then cause the pilot motor to eliminatethe auxiliary resistance A. For disconnection a circuit is closed manually at Q through normally closed contacts of a further two-position relay 13 responsive to the output of the machine, which circuit causes the pilot motor N to insert the auxiliary resistance and cause the machine output to be reduced until the relay 13 drops and closes a circuit through its other contacts and a further relay 12 to de-energize the closing coil of the machine contactor C, whereupon the pilot motor is reversed to cut out the auxiliary rheostat and the relay 12 is de-energized.