| 摘要 |
PURPOSE:To obtain a motor controller which can normally monitor disconnection with reduced power consumption by feeding the exciting coil of an electromagnetic contactor with a check current low enough not to operate the electromagnetic contactor and then judging abnormality such as disconnection based on the magnitude of the check current. CONSTITUTION:Exciting coils 7a, 9a, 10a are normally fed with low check current intermittently from a monitoring power supply circuit 24 with a predetermined period. Magnitude of the check current is detected through a current detecting circuit 27 and a detection signal is fed to a comparing circuit 29 where it is compared with a normal set value. When the check current drops below the set value, a disconnection detection signal is provided to a display and an alarm is outputted. Since the check current is low enough not to actuate an electromagnetic contactor, power loss is reduced and since the auxiliary contact of the electromagnetic contactor is not required as a disconnection detecting means, the controller can be implemented in an electronic circuit resulting in a high operational reliability. |
