| 摘要 |
<p>PURPOSE:To make it possible to cut off the field current without using a breaker exclusively for the field cutting off by controlling an exciter in a state of by-pass operation in case the field cutting off is performed. CONSTITUTION:In a state of normal operation, a DC breaker 7 and AC breaker 8 are closed, the AC power supply is controlled and rectified by a thyristor rectifier 2 and is supplied directly to a field winding 1F of a synchronous machine 1. In case the field cutting off is performed, the thyristor rectifier 2 performs the by-pass operation, and the DC breaker 7 is opened as well as the AC breaker 8. Accordingly, the field current which has so far been supplied to the field winding 1F is circulated through a discharge resistor 4 and the thyristor rectifier 2, and the field current rapidly attenuates. According to the constitution, a field cut-off circuit is constituted of the normal DC breaker and normal AC breaker.</p> |
