| 摘要 |
PURPOSE:To prevent the burning of a unit at large by arranging a light emitting element and a light receiving element in the vicinity of a main circuit apparatus, which constitutes a unit, and its connection cable, and opening the electromagnetic contactor of the main circuit when the quantity of light that the light receiving element has received lowers a specified value. CONSTITUTION:Power is supplied from a power bus 1 to load 2 via a relay 4, an electromagnetic contactor 5, a main circuit 3, CT6, and a zero-phase current transformer 7. The value A/D converted 15 from the CT 6 and the zero-phase current transformer 7 and the on signals of the normal open contact 5a of an electromagnetic contact 5, a start switch 19, and a stop switch 20 are input into the logical operation circuit 13 of a control circuit 12 through an input circuit 16. A light emitting circuit 23 and a light receiving circuit 25 are arranged in the vicinities of these main circuit apparatus or the connection wiring between them, and when the quantity of light that the light receiving circuit 25 has received falls below the specified value, the logical operation circuit 13 de-energizes an exciting coil 5b, and opens the electromagnetic contactor 5. Hereby, the smoke by combustion is detected and the whole unit is prevented from falling into function incomplete condition, and proper tackling and treatment are executed. |
