| 摘要 |
PROBLEM TO BE SOLVED: To provide a method and an apparatus for controlling voltage of a lifting magnet that achieves miniaturization, high efficiency, and simplification in the apparatus. SOLUTION: In the method for applying voltage in the forward/backward directions of a coil 6 in a lifting magnet 5, a voltage exceeding a rated voltage is applied in the forward direction when attraction starts, the rated voltage is applied in the forward direction after specific time, the application of voltage is stopped and at the same time an reverse current that flows in the coil 6 is monitored when release is started, and the application of voltage is turned on and off in the forward direction to cancel the reverse current. After that, a specific voltage is applied in the backward direction for demagnetization and a current in the backward direction due to the application is monitored, the application of voltage in the backward direction is turned on and off to prevent the current from exceeding a target current, and the application of voltage in the backward direction is stopped after the specific time.
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