| 摘要 |
PURPOSE:To check an overheating of motors, transistors, etc., by arranging on the motor circuit a galvano-resistor and a power relay contact in series as well as normally open relay contacts in parallel, closing the normally open relay at the time of motor trouble and disconnecting power at the time of trouble still continuing. CONSTITUTION:Closing switches 2 and 3, when trouble happens after a motor 5 starts, i.e., when the current of a galvano-resistor 6 rises unusually, as well as when terminal voltage of the motor 5 drops abnormally, a normally open relay contact 19 being connected to a power transistor 7 in parallel is closed and motor current is by-passed, the torque of the motor 5 increases, trying to be rid of motor freeze. However, when trouble continues even after the lapse of a set time, voltage, current trouble detector circuits 9 and 10 and a logic circuit 11 generate signals and afterward they are outputted to time circuits 13 and 12. When this wrong state continues after the lapse of a fixed time, a transistor 15 is turned to OFF by a hold circuit 14 and a power relay 4 becomes unenergized and held. |
