Solid-State Relay

Abstract

Apparatus For Opening And Closing Electrical Circuits Including One Or More Normally-Open Switches And Normally-Closed Switches. A Normally-Open Switch Includes At Least One Mosfet Assembly Consisting Of A Plurality Of Mosfets Of Different Current-Carrying Capacities Connected In Parallel And Circuitry For Turning On The Mosfets In Time Sequence. The Normally-Closed Switch Includes A Pnp Bipolar Transistor, An Npn Bipolar Transistor, And A Circuit For Short-Circuiting The Emitter-Base Junctions Of The Two Transistors. The Base And The Collector Of The Npn Transistor Are Connected Respectively To The Collector And The Base Of The Pnp Transistor. The Normally-Open And Normally-Closed Switches Both Include A Means For Accommodating A Current Flow In Either Direction Through The Switch Terminals. The Apparatus Includes Two Relay Control Terminals For Receiving A Relay Control Voltage From An External Source And Includes A Means For Transforming The Relay Control Voltage Into The Switch Control Voltage Through One Or More Transformation Stages Where At Least One Transformation Stage Is Coupled To The Next Transformation Stage By A Transformer.