Switch on signal from current, voltage transformer directly; Set PT/CT transformer ration according to your requirement. digital voltmeter panel ---Multifunction meter Technical ParametersValue InputNetwork3-phase 3-wire, 3-phase 4-wireVoltageRated valueAC100V, 200V, 400VOverload1.2 times continual, instantaneous: 2 times/30sPower consumptionless than 0.8VAImpedancemore than 200kΩCurrentRated ...