Application Method:1.Connect the measuring voltage to the 1 and 2 terminal.2.Connections of meter with internal current transformer as graph 1.(please refer the User Guide)Make the wire through the hole in the meter and the direction chose arbitrarily.3.Connections of meter with external current transformer as graph 2.(please refer the User Guide)Make the wire through the hole in the meter and connect the two wires of the secondary transformer to the 3 and 4 terminal.4.When poer on,the meter will display the measure result of the AC voltage(V),AC current(A)and active power(W)and the correlative red led will light up.Notice:The meter can only use to measure 50Hz AC city electricity, it will be destroyed when use to measure square wave, output of inverter and correction sine wave.Product Show: Model : D52-2047 measuring range: AC80-300VInstallation: Din Rail Product Features:1. At the same time shows the measured AC voltage, AC current, power factor, active power, electrical energy and the timing of the energy.2. The rail-type design is easy to install.Product parameters:Accuracy: 1%2 digitsAC voltage: AC 80.0-300.0VAC current: 0.0-100.0AActive power: 0.0-30000wElectric energy: 0.000-99999KwhElectric energy of cumulative time: 0.00-999.59hPower factor: 1.000-0.000Test speed: 2 times per second