The working principle of the micro-computer PLC control system is introduced which consists of SCM 8031,alternating current (AC-SSR) and direct current solid-state relay (DC-SSR).

As to the failures existing in dynamic reactive power compensation device with solid-state relay,the theoretical and experimental analysis is made for the residual voltage occurred during the switching of capacitor.

The principle,structure and characteristic of a solid-state relay the scope of AC-DC solid-state relay are discussed.

Based on solid state relay(SSR) s small volume,compact layout and strong EMI radiation,a layout simulation model of SSR PCB with control circuit and main loop was established by Ansofi.

The characteristic on input-output response and ambient temperature of solid state relay(SSR) is elaborated,the typical application of various SSR is introduced,which takes BESTALL SSR as the example,and the attentive matters of the SSR in use is pointed out.

By building a high frequency model of electronic elements and printed circuit board in solid state relay(SSR),extracting its parameters,an accurate simulation model of SSR was obtained.