| 摘要 |
PURPOSE:To obtain high reliability and large energy saving effect, by a method wherein the operation of an electromagnet for operating an electromagnetic brake is monitored and the timing of switching from forced excitation to holding excitation is determined based on the result of the monitoring. CONSTITUTION:An exciting current, conducted through the electromagnet of an electromagnet brake device 2, is detected by a CT 6 and is compared by a microcomputer 4 with the preceding sampling value sequentially whereby the changing condition of the exciting current is decided and the phase of a thyristor 3 is controlled. During the attracting movement of an armature for the electromagnet, forced excitation, in which a voltage five times or more the voltage under normal holding excitation is impressed, is effected. When attraction is decided that it is finished, the forced excitation is stopped and the excitation is shifted to a normal holding excitation, in which is impressing voltage is low. According to this method, the period of time of the forced excitation may be shortened and energy saving may be achieved in accordance with the shortened period of time.
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