This switch is mainly used to test whether the normal or standby power supply is normal. When the narmal power supply is abnormal, the backup power supply will work immediately to ensure the continuity, reliability and safety of the power supply. Auto mode : Common p ower supply must be City Grid Power.Backup power must be AC genarator. When there is only one power supply is working, the product will automatically switch to that power supply. When the common power supply and the backup power supply are supplied at the same time, the common power supply is used Preferentially. (Attention: in automatic mode, forcibly rotating the power switch handle will cause damage to the transfer switch).
Manual mode : Power supply should be transfered manually by rotating the handle. Industrial, residential and various occasions where continuous power failure is not allowed.Auto mode and Manual mode for choise. 250A 4P Dual Power Automatic Transfer Switch. Life Electrical:8000times; Mechanical: 3000times.