EXCITATION CONTROLLER FOR SYNCHRONOUS MACHINE

PROBLEM TO BE SOLVED: To stably operate a synchronous machine even when system abnormality occurs by outputting a pulse, provided that the used voltage regulator is switched to an automatic voltage regulator from a manual voltage regulator, when the function of the manual regulator is restored and, while the pulse is outputted, by outputting a command which shifts the phase angle of a rectifier by a specific angle against the automatic voltage regulator to a phase control circuit. SOLUTION: When the function of a manual voltage regulator is restored, a single shot circuit 33 outputs a pulse to a transfer circuit 26, provided that the used voltage regulator is switched to an automatic voltage regulator 15 from the manual regulator. The circuit 26 outputs a command which shifts the phase angle of a rectifier 3 by 90 deg. from that of the regulator 15 to a phase control circuit 16. Therefore, a synchronous machine can be operated stably even when system abnormality occurs, because the manual voltage regulator is quickly switched to the automatic voltage regulator 15.