| 摘要 |
PROBLEM TO BE SOLVED: To provide a controller of a lifting magnet capable of preventing damages of opening/closing elements due to counter electromotive force when current is blocked by simple structure.SOLUTION: A controller 1 is constituted by being equipped with: an electromagnet 10; an AC power source 20; a rectifier 30 connected with the AC power source; a first circuit for exciting the electromagnet by supplying current rectified by the rectifier to the electromagnet in a first direction; a second circuit for supplying the current in an opposite direction of the first direction; a pair of first opening/closing elements 41, 42 for opening/closing the first circuit; a pair of second opening/closing elements 43, 44 for opening/closing the second circuit; an AC opening/closing element 45 for opening/closing a current path between the AC power source and the rectifier; and a control circuit for making an interval between the electromagnet and the rectifier into a closed circuit by turning AC opening/closing elements OFF for first predetermined time, turning the first opening/closing elements OFF, and turning the AC opening/closing elements and the second opening/closing elements ON after elapse of the first time prior to switching of the current path from the first circuit to the second circuit. |
