Power supply detecting and switching device

The utility model relates to a power supply detecting and switching device which is connected with an external input power supply and a power supply switching executive circuit. The power supply detecting and switching device comprises a voltage detection circuit, a phase detection circuit, a logic judgment circuit and a power supply automatic switching circuit, wherein the voltage detection circuit reduces input voltage and outputs the reduced voltage to the logic judgment circuit; the phase detection circuit detects phase of the input voltage and outputs a fault node signal to the logic judgment circuit; the logic judgment circuit compares and analyzes received signals, judges the real-time status of input power supply and transmits a control signal and a node signal to the power supply automatic switching circuit; and the power supply automatic switching circuit drives the switching executive circuit corresponding to the power supply end according to the received signals. The power supply detecting and switching device has the advantages of simple structure, sensitive control, complete functions, short switching time and reliable control, and switching among power supplies is automatically realized by automatic detection of real-time conditions of input voltage, phase, overvoltage or undervoltage, open-phase, phase failure and the like. In addition, switching alarm is realized by a singlechip microcomputer circuit, and the power supply detection switching device is more suitable for being widely popularized and used.