GB804713A - Improvements relating to electrical supply systems - Google Patents

Abstract

804,713. Automatic voltage control systems. STONE & CO. (DEPTFORD), Ltd., J. Oct. 18, 1955 [July 20, 1954], No. 29682/55. Divided out of 804,711. Class 38 (4). In a system in which the field of a generator is excited from an A.C. supply via a rectifier and a saturable reactor, the reactor is automatically controlled so as to give constant voltage control up to a certain load current and constant current control thereafter. As shown, the generator is a self-excited alternator supplying an external load via a main rectifier, but it is stated that it could be a D.C. generator having either a tapped armature winding, an auxiliary pole-face winding, or even a separate A.C. generator to provide the necessary A.C. for the field supply. The alternator 1 charges the battery 2 over a main rectifier 3 and is selfexcited over a rectifier 5 and saturable reactor 8. The reactor 8 has a reference winding 6 in series with a barretter 7 and a main control winding 9 connected across both the battery and the rectified output of a load current transformer 12. The rectifier 11 which is connected to the current transformer 12 is blocked until the load current rises to a predetermined value when it conducts and energizes the winding 9 to reduce the output voltage to maintain the current constant. In a modification, Fig. 1 (not shown), the reference winding 6 is in shunt with a neon tube instead of in series with the barretter. It is stated that the reactor with permanent magnet reference and additional feed-back windings as disclosed in Specification 804,711 may be used instead of the simple reactor.