The dual power automatic transfer switch is a device controlled by a microprocessor, which is used for switching between grid power and grid power or grid power and generator power in the power grid system, so that the power supply can be continuously supplied. The series dual power supply, when the common power suddenly fails or the power is cut off, it will be automatically put into the backup power supply through the dual power supply switch, (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 protection, surveillance, lighting, etc.