The project is intended to design a system with three phase solid state relay. It consists of three single phase units and every phase id individually controlled by a power TRIAC along with RC snubber network for zero voltage switching.
Each phase requires opto-isolators for receiving switching signals coming from 8051 series microcontroller. With the help of a set of TRIAC s loads are connected in series, and driven by opto-isolators. The microcontroller generates pulses as output after zero voltage pulse and makes certain that the load is being switched on at zero cross of supply waveform. Low noise generation is assured by the zero crossing feature of TRIAC driver (an opto-isolator) that prevents abrupt inrush of current inductive and resistive loads. Two push buttons are used as a means of generating output pulses from microcontroller and does not coincide with zero voltage supply of waveform. The supplied voltage waveform to load can be viewed using a DSO or a CRO so as to verify the load switching at zero voltage point.