Double-power-supply automatic switching device and control method thereof

The invention discloses a double-power-supply automatic switching device and a control method of the double-power-supply automatic switching device. At any time when a first power supply exists, the device controls equipment to be supplied with power by the first power supply all the time, and only when the first power supply does not exists does the device control the equipment to be supplied with power by a second power supply. Because the device is only provided with two circuit beakers, electric operating mechanisms for the two circuit breakers, a phase sequence relay, two micro relays and two delay power-on time relays without intelligent controllers or voltage and current detection devices, the cost of the device is greatly lowered compared with a double-power-supply automatic switching device on the market. All components operate through circuits. The device is simple in structure, convenient to operate and high in economy and practicality.