A power source emulator is provided for testing programmable switchgear that switches to an alternative three-phase power source upon sensing a failure of a grid source. The emulator provides three simulated three-phase power sources for testing switchgear. Each source is identical in voltage and phase to the current normally distributed by the switchgear but has less than 1% of the amperage. Each power source includes a single three-phase contactor for simultaneously controlling all three phases of the power source, and three solid-state relays for controlling each of the three phases of the power source. A control circuit controls the three-phase contactor and each of the three solid state relays of each power source to simulate various types of power failures that the switchgear is programmed to respond to.