Method of determining optimal time point during fire pump main power supply and standby power supply switching process

The invention provides a method of determining the optimal switching time point during the process when a main power supply is switched to a standby power supply of a fire pump. Particularly, instantly when the standby power supply is connected, as phase difference and frequency difference exist between back electromotive force generated by the motor and the standby power supply, the circuit and the equipment are damaged through direct connection, and the method aims to determine the optimal connection time point to reduce damage. Firstly, current signals of the standby power supply and the back electromotive force are acquired via a synchronous acquisition module; a signal analysis module is used for acquiring the phase difference and the instantaneous frequency between the standby power supply and the back electromotive force; the comprehensive influence degree value of the phase difference and the frequency difference is calculated through a linear weighting method, power supply switching is completed through controlling the switch when the comprehensive influence degree reaches requirements, problems of heating of the motor rotor in the pump caused by the frequency difference and the phase difference, vibration of a rotary shaft and the like are less serious, and the service lives of the pump and the entire circuit are prolonged.