Our solid state relay is designed around a pair of SCRs mounted on a heat-spreading metal base to eliminate thermal fatigue failures. To dissipate the heat developed naturally in an Solid State Relay (SSR) due to a nominal voltage drop across the device, the Solid State Relay (SSR) must be mounted on a Finned Heat Sink (FHS), or on a metal plate of adequate size. It is advisable to install an solid state relay where the ambient temperature is relatively low because its current-switching rating is decreased as its temperature increases.
Control resistance heaters up to 40 kW use solid state relay in conjunction with lower-rated temperature controllers. Three-phase loads can be controlled using 2 or 3 SSRs. Use 3 SSRs for Y-phase loads using a neutral line. Three Solid State Relay are also used when there is no neutral load to provide redundancy and extra assurance of control. Two SSRs will control "delta" loads.