The paper presents test results of special power supply unit D400-08-01TS of KP “Delta” together with stationary plasma thruster, as well as with cathode-neutralizer. In constant voltage mode, the power supply provides a “soft” thruster start without “long-term” surge current that is harmful to the power unit. Power characteristics, its functional block diagram and principle of operation are described. Electrical schemes of thruster and cathode neutralizer operation are described. Waveform of discharge voltage and current during start-up of the thruster and cathode-neutralizer are presented.