单项选择题
The DC excitation to the field of brushless synchronous is generally produced by （）
A.an exciter driven by the same shaft with the generator B.an exciter driven by external prime mover C.generator itself D.either A and B
单项选择题 Which of the following equipment is not pollution prevention equipment?（）
单项选择题 The initial voltage of self-excitation generator set up by（）
单项选择题 “380V/220V Y/△” noted on the nameplate of a non-synchronous motor means that（）
