| 摘要 |
<p>PURPOSE:To improve the reliability of a chopper electric railcar by connecting a DC voltage detector in parallel with an overvoltage suppressing thyristor. CONSTITUTION:When a regenerative brake command is applied, a breaker 3 is closed to charge a filter condenser 7. When the voltage which was detected by a DC transformer 14 has exceeded the prescribed low level, a low voltage protecting relay 40 operates to compose a regenerative brake circuit. When a trolley line voltage becomes the prescribed high level, an overvoltage suppressing thyristor 21 is fired by the output of a comparator 23. When the thyristor 21 is fired, a comparator 39 will operate to release a low voltage protecting relay 40, and breakers 10, 3 and a high speed breaker 4 will open. In this manner, a plurality of protecting functions can be performed by less number of devices, thereby improving the reliability and reducing the weight of an electric railcar.</p> |
