1. occurs when the bus voltage down to the control panel means detects a threshold value setting circuit; pressure may be due to low input voltage and load requirements due to the large current output are coupled together, also may be caused by instantaneous overload.

2. AC power unit either blown fuse may also lead after the failure. Check the fuse unit to see if there is a fuse is blown;

3. damaged unit control board sometimes give the wrong instructions; replacement of defective or damaged parts.