GB617075A - Improvements in or relating to dynamo-electric amplifying generators - Google Patents

Abstract

617,075. Exciting dynamo-electric machines. WESTINGHOUSE ELECTRIC INTERNATIONAL CO. Nov. 30, 1945, No. 32406. Convention date, Nov. 30, 1944. [Classes 35 and 38 (iv)] An amplifying generator has an unsaturated field structure comprising poles of regularly alternate polarity wound so that co-operating pairs form independent flux paths through the armature which has one pair of brushes excited by one flux path to feed the winding on another flux path, thus obtaining multi-stage amplification. As shown in Fig. 1, the poles P1, P2, P3 and P4 are mounted in a magnetic frame F, the first excitation being supplied to windings W1, W2 at terminals A1, A2. The corresponding brushes B1, B2 energize in turn windings W3, W4 which have their effect on the main output brushes B3, B4 which supply the output terminals C1, C2. In order to modify the response of this machine, e.g. in order to neutralize the linkage between the sets of poles, additional windings fed from the output terminals may be carried on the poles PI, P2. In a further modification, Fig. 3, which shows these windings as S1, S2, the field flux paths D, E are magnetically separated by a non- magnetic shim N. In yet another modification, the pole structures are carried in a non-magnetic frame, e.g. of aluminium and the pole shoes of each pair extend towards each other to reduce leakage further, axial separation of the structures being used as well if desired. A greater number of stages may be achieved by using a corresponding number of pole structures and brushes connected to field windings. Figure 7 shows an arrangement in which two control windings are used on the machine which is adapted to control the output voltage of a main generator MG driven at constant speed by a motor 4. The control generator CG according to the invention is used to supply current to the field winding 5 of the main generator. A reference voltage is supplied across an adjustable potentiometer from A.C. mains 14 by a rectifier 12 and any variation of the output voltage 2, 3 causes current to flow in a field winding 7 and is amplified to modify the output of the generator MG. The output can be governed by regulating the excitation of a further winding 8 by means of a rheostat 17 which may be coupled mechanically to 11. Oscillations are damped out by transformers 15, 16 connected across the pairs of brushes.