Control method suitable for pressure relief device of water supply system with backpressure technology

The invention relates to a control method suitable for a pressure relief device of a water supply system with a backpressure technology, which comprises the following steps of: defining a set pressure value of a first pressure switch as P1, defining a set pressure value of a second pressure switch as P2, and when a switching value provided by the first pressure switch and an analog quantity provided by a pressure transmitter simultaneously reach action pressure P1 + (P2-P1) * 95%, starting the pressure relief device; the electric flow regulating valve is kept for 30 seconds, and if the pressure of the pressure transmitter is still higher than the operating value at the moment, the control cabinet controls the electric flow regulating valve to execute a valve opening program; when the valve is opened and the pressure of the pressure transmitter is reduced to P1 + (P2-P1) * 20%, the control cabinet controls the electric flow regulating valve to stop opening; and when the electric flow regulating valve is fully