| 摘要 |
PURPOSE:To detect the disconnection of a solenoid valve and the abnormality of driving contactors by a simple circuit wherein two driving contactors are provided at the opposite ends of the solenoid valve of a direction control valve for driving a control rod and are connected to power lines for alternate operation. CONSTITUTION:Driving contactors 2A and 2B operating in response to two driving instructions S1A and S1B are provided on the opposite sides of a solenoid valve 1 of a direction control valve for driving a control rod, respectively. Voltage detecting circuits 3A and 3B are provided for the driving contactors 2A and 2B respectively, and outputs S2A and S2B thereof and the driving instructions S1A and S1B are inputted to a comparator circuit 5. On the occasion of diagnosis, the driving contactors 2A and 2B are opened and closed alternately. By this constitution, the disconnection of the solenoid valve 1 or the abnormality of the driving contactors 2A and 2B can be detected economically and with improved reliability by a simple circuit without using a pulse circuit.
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