GB671645A - Improvements in or relating to regulating systems for dynamo-electric machines - Google Patents

Abstract

671,645. Exciting dynamo-electric machines. WESTINGHOUSE ELECTRIC INTERNATIONAL CO. May 27, 1948 [June 2, 1947], No. 14338/48. Classes 35 and 38 (iv). The exciter of a generator is controlled in dependence on the voltage of the load circuit, and also in dependence on the output of the generator and its field excitation to maintain the field above a certain value. The pilot exciter 30 of the A.C. generator 10 is selfexcited by a series winding 32, small adjustments being made on an adjustable shunt winding 34. The exciter is controlled by windings 36, 60. The control winding 36 is connected through a reference network 42 and potential transformer 44. The network comprises a non-linear impedance circuit 46 and a linear impedance circuit 48 connected through rectifiers 50, 52 to the winding. At a predetermined line voltage the rectifier outputs are equal and balance each other, but any departure of line voltage is reflected as a current in winding 36 in an appropriate direction. The control winding 60 is energized in dependence on both the voltage across the generator field winding 20 tapped off a potentiometer 26, and the output of the generator as measured by network 64. The network 64 is fed both from current transformers 78, 80 and potential transformer 44 so that its rectified output depends on the output of the machine. When the excitation voltage falls below a certain value, the voltage derived from network 64 passes current through the winding 60 to increase the excitation. A resistor 76 may be non-linear to provide temperature compensation. Specification 671,646 is referred to.