| 摘要 |
PROBLEM TO BE SOLVED: To provide a semiconductor relay, capable of preventing a fault when excess current is permitted to flow in a semiconductor switch element connected between relay output ends. SOLUTION: A light-emitting element and a photovoltaic element 2 mutually face opposite. MOSFET 3, being the semiconductor switch element, is turned on when the electromotive force of the photovoltaic element 2 is impressed on between gate sources. Normally on-type MOSFET 13 being an excessive current interrupting semiconductor element is serially connected to the light- emitting element 1, where current detecting resistance 6 is connected between the source of MOSFET 3 and a relay output terminal 9b and the photoboltaic element 12 facing the light-emitting element 11 is connected to the control end of MOSFET 13. The light-emitting element 11 emits light, when the both end voltages of current detecting resistance 6 become more than a prescribed voltage value. When light electromotive force is generated in the photovoltaic element 12, the MOSFET 13 is turned off and light electromotive force is not generated in the photovoltaic element 12 so that MOSFET 3 is turned off. |
