When measuring the output voltage at no load, it is a virtual voltage. A load of more than 20W must be connected to measure the correct output voltage. Input AC power, and the output is also AC power, not DC power. The 4000W mentioned above refers to the final power when working under a resistive load. Inductive load is 1/3 of resistive load. Resistive loads refer to inductive loads such as tungsten lamps or electric heating wires, which are series motors. Circuit board electronic products should be used with caution. This product has a metal shell and must be safely grounded. Features: The 4000W high-power motor fan variable thyristor electronic voltage regulator controller adopts a metal shell structure, which is high temperature resistant, flame retardant and not easy to rust. The core chip uses a high-power thyristor with an adjustable knob and is stepless. Voltage regulation without delay, anti-surge, anti-peak, RC absorbs multiple protections with universal power socket and power light with heat dissipation port, fast heat dissipation Input voltage: AC 220V Output voltage: 0~220V (adjustable) Adjustable voltage range: 0~220V maximum power: 4000W rated current: 9A maximum. Current: 18A Package contents: 1*voltage regulator