Voltage stability and precision are key specifications of an electron beam irradiator.A voltage control system was developed for smooth high voltage regulating on a power frequency electron accelerator.Pillar variac driven by servo motor was used as the regulating device

with a programmable logic controller as the control unit.An industrial PC was employed to realize human-machine interaction.Open-loop and closed-loop modes were employed to regulate the high voltage.Experimental results show that the speed

stability and precision for high voltage regulating were improved greatly

hence a much better performance of the electron accelerator.