Solid State Relay Ssr Circuit Diagram. Solid state relays can be designed to switch both ac or dc currents by using an scr triac or switching transistor output instead of the usual mechanical normally open no contacts. In the diagram a vt is open at ordinary time and ssr is in on state.
In reality it is not a relay after all. Its main function is to switch the electrical signal or power. Solid state relay is a type of switch to activate load by using without any mechanical parts.
In this post we learn how to construct a simple solid state relay or an ssr circuit using a triac bjts a zero crossing opto coupler.
As shown in diagram b vt is closed and ssr is in off state at ordinary time. It operates a similar way as a relay. Three phase solid state relays their application in three phase motor circuits by paul bachman fellow engineer dr. Solid state relay ssr can be controlled directly by npn type or pnp type transistor as shown in circuit diagrams a and b below.
