| 摘要 |
<p>PURPOSE:To prevent an inverter and an induction motor from thermally damaging by providing a discriminator for discriminating an improper power drive and an improper recovery. CONSTITUTION:When an input current In arrives at a current Ip corresponding to the level of a reference voltage 22A at recovery instructing time, the output of a comparator 22 changes from '0' to '1'. The output of an AND circuit 23 varies from '0' to '1' by the AND condition of the output signal of the comparator 22 and a regeneration command signal B. If the output of the circuit 23 is '1' even after 0 time, the output of an ON delay circuit 24 becomes 1, a flip-flop circuit 25 is operated to open a breaker 2. Even when an input voltage In arrives at one side IB level corresponding to a reference voltage 27A at power drive instructing time, the delay circuit 24 and a flip-flop 25 operate to open the breaker 2.</p> |
