Abstract: All Solid State Relays (SSR) manufactured till today are only capable of Single Pole Single Throw (SPST) switching. The main motive of Solid State Relay(s) was to replace the use of conventional Mechanical Relay(s) for various switching applications. As SSRs offer only SPST switching unlike Mechanical Relay(s) which offers all kinds of switching options like Single Pole Single Throw (SPST), Single Pole Double Throw (SPDT), Double Pole Single Throw (DPST) and Double Pole Double Throw (DPDT) packed inside a single enclosure, the usage of SSRs for switching applications are getting restricted. However in order to solve this problem, using various switching techniques and electronic circuits, we can make a combination of Solid State Relay(s) connected to an electronic module, so that we can make them switch under any configuration such as SPST, SPDT, DPST or DPDT by giving a desired D.C input signal(s). Moreover this module can also be used as anormal Relay Module to control individual Relay(s) separately by switching it to different D.C input signal(s).
Keywords: Relay, Solid State Relays, SPST, SPDT, DPST, DPDT, D.C.