H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
H02P9/00—Arrangements for controlling electric generators for the purpose of obtaining a desired output
H02P9/14—Arrangements for controlling electric generators for the purpose of obtaining a desired output by variation of field
H02P9/24—Arrangements for controlling electric generators for the purpose of obtaining a desired output by variation of field due to variation of make-to-break ratio of intermittently-operating contacts, e.g. using Tirrill regulator