Display voltage and current simultaneously in different color, red for voltage, green for current you have questions， us The monitors is powered by the circuit being measured, no need to connect power sources This meter is only applicable to three-phase, generators, voltage regulator and other sinewaves alternating current, not applicable to non-sinusoidal, high-frequency and voltage regulator and other occasion Voltmeter ammeter voltage ranges is 50-500V, current ranges is AC1-100A, Manufacturer: Kaeltsyn