| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem of tripping failures caused by deterioration of the internal light-emitting element in a photovoltaic element of those put into normally an 'on' state, when the semiconductor switching elements of a tripping circuit or interlocking circuit are turned on or off by such photovoltaic elements. SOLUTION: Resistors R4, R5 an switching circuits SW1, SW2 are provided for the photovoltaic elements PV1 to PV3 of a tripping output circuit and an interlocking circuit. Inspections are performed with a smaller current than in the ordinary state by turning off the switch circuits SW1, SW2 via timers T1, T2 with the output of inspection signals 11T. Such operations are also included in turning on of the switching circuits SW1, SW2, by increasing the input current of the photovoltaic elements when semiconductor switching elements are turned on at the time of the detection of failures and when the 'on' voltage of the semiconductor switching elements are high at trip operation. |
