GB671164A - Improvements in frequency changers - Google Patents

Abstract

671,164. Dynamo-electric machines. BRITISH THOMSON-HOUSTON CO., Ltd., WALKER, J. H., and GIBBS, W. J. Feb. 21, 1950 [March 16, 1949], No. 7199/49. Class 35. A synchronous frequency changer of the single- or double-unit type has a field winding arranged in three sections, the current in each of which is displaced relatively to one another. The Figure shows a single-unit frequencychanger, the stator windings 2, 4 of which are wound so as to be connected to 25- and 60-cycle mains respectively. The rotor carries two exciting windings 6, 7 co-operating with the stator windings 2, 4, respectively. The current in section of the winding 6 is displaced by 120 degrees and is fed by the exciters 9, 10, 11 in conjunction with 3-point cross-connected potentiometer 13. Thus the exciting winding 6 has means to displace angularly the axes of its poles relatively to those of the other winding. Two of the sections of the other rotor winding 7 are fed from the same pole of an exciter 20 while the third section of the winding 7 is connected to the other pole of the exciter 20 and to one of the incoming leads of the winding 6. Instead of the exciters and potentiometer, rectifiers and transductors or a single D.C. generator having three brushes uniformly displaced over its commutator, may be used. A motor 22 drives a shaft on which all the exciters are mounted. For starting purposes, the winding 7 may be connected to a liquid resistance 21. The windings in the rotor(s) and stator(s) may be interchanged.