| 摘要 |
PURPOSE:To dispense with maintenance with a longer life of a contact by emplying a switch adapted not to be opened or closed normally and a semiconductor switch. CONSTITUTION:When an operation command switch 5 is closed while a switch 3 is closed, a semiconductor switching element 2 conducts through a gate circuit 6 and a voltage of a power source 9 is applied to a motor 1 to start the operation thereof. When the motor 1 runs uncontrollably due to damage to the element 2 or the like, a logic circuit 8 detects an applied voltage of the motor 1 through a detection element 7 and provides a signal to a trip element 4 by confirming that the operation command is off. The switch 3 is opened to release the motor 1 from the power source 9. |
