Application : 1. Connect the measure voltage to the 1 and 2 terminal 2. Connections of meter with internal current transformer as graph 1. 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. 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 power on, the meter display the measure parameters. 5. When power on, you can press the button of last for 5 seconds, then the electric energy will to be zero and start to cumulate when release the button. And when power off, the meter can save the value of electric energy and go on cumulating data when the meter power-on next. Attention: The meter can only use for measure 45-65Hz AC city electricity. Size: 54x80x64mm colour: as shown Material: Plastic Package Contents: 2 x Watt-hour meter Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm. 1.Accuracy: 1% +/- 2 words 2.Range: AC voltage: AC 250-450V; The measuring range 250-450V, and it can be used in grid power, photovoltaic and inverter current; 250-450V only can use for 380V; AC Current:AC 0-100.0A, the current resolution is 0.01A .; Frequence: 45.0Hz - 65.0Hz; Power Factor: 0.00-1.00PF 3.Electric Power: 0-450000W,the electric power resolution is 0.1W when measure electric power between 0-9999.9W,otherwise the electric power resolution is 1W.Electric Energy: 0-99999kwh,the display of electric energy resolution is 0.01kwh when measure electric engery between 0-999.99kwh,the display of electric energy resolution is 0.1kwh when measure electric engery between 1000.0-9999.9kwh and the display of electric energy resolution is 1kwh when measure electric engery larger than 9999.9kwh 4.Speed: 2 times per second 5.Installation: Din-Rail