单选题The frequency of an AC generator is adjusted by means of the （）Amain alternator field rheostatBexciter field rheostatCprime mover governor controlDequalizing reactor
单选题
The frequency of an AC generator is adjusted by means of the （）
A
main alternator field rheostat
B
exciter field rheostat
C
prime mover governor control
D
equalizing reactor
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