This simple circuit designed around Solid State Relay S216S02 from SHARP. The S216S02 solid State Relay (SSR) is an integration of an infrared emitting diode (IRED), a Phototraic Detector and a main output Traic. These devices are ideally suited for controlling high voltage AC loads with solid state reliability while providing 4KV isolation from input to output.
A solid-state relay (SSR) is an electronic switching device that switches on or off when a small external voltage is applied across its control terminals. SSRs consist of a opto-isolator which responds to an appropriate input (control signal), a solid-state electronic switching device which switches power to the load circuitry, and a coupling mechanism to enable the control signal to activate this switch without mechanical parts. This relay designed to switch either AC load up-to 1KW. It serves the same function as an electromechanical relay, but has no moving parts. Solid-state relays have fast switching speeds compared with electromechanical relays, and have no physical contacts to wear out.
AC Solid State Relay – [Link]