The dual power automatic switch refers to a device controlled by a microprocessor and used for starting and switching between grid power and grid power or grid power and generator power in a power grid system, which can supply power from a continuous source of power. Series dual power supply, when the common power suddenly fails or loses power, through the dual power supply switch, it is automatically put into the backup power supply (the backup power supply can also be powered by the generator under small load), so that the equipment can still operate normally. The most common are elevators, fire fighting, monitoring, lighting, etc.