Automatic transfer switch can switch to Normal or reserve automatically. Please noted the switch can't turn on or turn off the generator. This switch Normal first. If normal on, the switch will switch to Normal . If normal off, and reserve on, the switch will switch to reserve . Press the button to Automatic, the switch will switch to Normal or reserve automatically. Press the button to Manual, Then you have to switch the Direction manually. Noted: will be interrupted when Switching. TOQ3D is terminal type automatic transfer device. It's suitable for 3 phases 4 wires (or 1 phase 1 wire) grid with AC 50/60Hz, rated voltage 400V/230V and rated current up to 63A. When one goes wrong (only test normal Phase A voltage and reserve Phase A voltage, only test loss voltage or loss phase),it will automatic connect one or several load circuits from one to the other automatically, to normal supply of load circuits. The automatic transfer switch conforms to IEC60947-6-1 and GB/T14048.11 Colour:white Material:ABS Size:150*138*111mm Package Contents: 1* automatic transfer switch Only the above package content, other products are not included. Note: Light 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.