As for the input which is one-phase-three-lines system, do check whether the grounding is good and ensure the voltage between zero line and grounding line is less than 5V. If the input grounding line of mains supply is null, the voltage could be 100V. If the users’ load has strict requirements on the voltage between the zero line and the grounding line of the power supply, make sure the grounding of the mains supply is good so as to avoid unnecessary loss.