| 摘要 |
PURPOSE:To prevent erroneous operation of an overspeed detector at low load state, by a method wherein when rotational speed of a motor-generator gents over a prescribed value, thyristor gate input of a separately excited inverter to drive the motor is stopped. CONSTITUTION:A regulator AFR controls thyristors S1-S6 to constitute a separately excited inverter corresponding to rotor position signal from a distributor DB, and supplies current to motor winding of a motor-generator BL-MG. Thereby, AC voltage is outputted from generator winding of the motor- generator. AVR controls field current of an exciter EX so that the generating voltage becomes a set value. A control block 10 blocks gate pulse of the thyristors S1-S6 when rotational speed signal 101 becomes more than N2. An overspeed detector 4 renders off a high-speed breaker HB if the rotational speed signal 101 attains N3 (> N2).
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