| 摘要 |
PROBLEM TO BE SOLVED: To dispense with a safety device for preventing the sudden operation of a device or the runaway of the device because of unstoppability when a power supply is ON without being aware of the short-circuit failure of a semiconductor element. SOLUTION: When the power source is ON in a non-power source state where a semiconductor element 8, the relay contact 21-1 of the dummy load relay 21 of a dummy load pat 11, and the relay contacts 22-1 and 23-1 of the breaking relays 22 and 23 of a safety breaker part 12 are in OFF state, an initial check state is formed to perform the failure inspection of the safety breaker part 12. When the safety breaker part 12 is not broken as the result of this failure inspection, the current route of the semiconductor element 8 is ensured in the dummy load part 11 to execute the failure detection of the semiconductor element 8. When the semiconductor element 8 is not broken, the failure detection by the dummy load part 11 is stopped, and the relay contacts 22-1 and 23-1 are ON to set an operating state.
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