| 摘要 |
PROBLEM TO BE SOLVED: To prevent an overcurrent from flowing through a solenoid for a long time, so as to protect the solenoid against rise in the temperature and damages caused by burning, when a semiconductor switching element is in trouble as it is short-circuited. SOLUTION: When a semiconductor switching element 12 is short-circuited, a detection means 15 detects that the remaining voltage of the switching element 12 is below a set value,and an opening means 16 which is connected in series between a solenoid 11 and a power supply is opened, by which a current is prevented from flowing through the solenoid 11. An alarm 17, connected to the opening means 16 informs by voice or lamp of the fact that the semiconductor switching element 12 has become of order.
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