Functions:
1.Over-voltage protection
2.Under-voltage protection
3.Over-current protection
4.Automatic recovery
5.Voltage display(voltage measurement)
6.Current display (current measurement)
7. Voltage calibration: Voltage +-9.5% adjustable.
8. Restore factory settings: press the down button for more than 12s
9. Fault inquiry: Press the UP button from more than 12S