| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a controller for an induction motor which can secure the life of the induction motor by performing the restart at power recovery after momentary power failure, in simple constitution as much as possible, in the induction motor which is started and driven especially without an inverter device. <P>SOLUTION: A momentary power failure detector 4 detects the voltage of a power bus 3, and immediately after detection of momentary power failure, it sends out a breaking (opening) command 7 to a breaker 2 so as to break a main circuit. A residual voltage detector 5 detects the voltage phase from the residual voltage of the induction motor 1 in the state of free run, and outputs a residual voltage phase signal 9. A residual voltage phase synchronization detector 6 receives a recovered power voltage phase signal 8 and the residual voltage phase signal 9, and when the difference between both phases becomes a specified value Δθ or under, it sends out a making (closing) command 10 to the breaker 2 so as to make the main circuit. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
