When measuring the output voltage when it is empty, it is a virtual voltage. It must be connected to a load of 20W or more to measure the correct output voltage.Input AC power, the output is also AC, not DC.The above mentioned 4000W refers to the ulti mate power when working under resistive load.The inductive load is 1/3 of the resistive load. The resistive load means that the inductive load such as a tungsten filament lamp or a heating wire is a series-excited motor, etc., and the circuit board electronic products are used with caution.This product is a metal case and must be grounded safely.Features:4000W High-power Motor Fan Variable Thyristor Electronic Voltage Regulator ControllerAdopts metal shell structure, high temperature resistance, flame retardant, not easy to rustCore chip adopts high power thyristorWith adjustable knob for stepless voltage regulationNo delay, anti-surge, anti-spike, RC absorption multiple protectionWith universal power socket and power supply lightWith heat dissipation port for fast heat dissipationInput Voltage: AC 220VOutput Voltage: 0~220V (Adjustable)Adjustable Voltage Range: 0~220VMax Power: 4000WRated Current: 9AMax. Current: 18APackage Contents:1*Voltage Regulator