... of true RMS voltage, true RMS frequency, true RMS current, true power and power factor, IGBT module to reduce circuit complexity, PWM ... voltage selectable 3.40 to 499.9 output frequency range 4.Programmmable key lock setting output frequency 5.Easy ... resistive ,capactive ,inductive and non-linear load 13.Pure and stable sine wave output 14 .Self test at power on Variable Frequency Power Supply