| 摘要 |
PROBLEM TO BE SOLVED: To dissolve the problem in a conventional starter such as that the switching to full voltage application occurs before reaching synchronization and it damages a start contactor or the like if the user decides the time limit of starting by a timer, to start a squirrel-cage induction motor in condolfer starting method or reactor starting method. SOLUTION: A timer TIMER detects a motor IM reaching the synchronization velocity by the time limit being set with measurement. A current sensor CC judges the motor reaching the synchronization velocity from the change of a motor current. An AND circuit AND detects the synchronization with the logical product of both outputs of the timer and the current sensor. In the collective start of a plurality of units of motors, the synchronization detection by time is set with a common sensor, and the current sensor detects the synchronization from the individual currents of each motor, and the AND circuit detects the synchronization with logical product of both outputs.
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