The main and standby pumps can choose and combine multiple starting methods at will, various control forms, and automatically switch over in case of failure. The product has various protection functions such as overload, short circuit, phase loss protection, water leakage of the pump body, overtemperature and leakage of the motor, and complete status display. It also has single pump and multi-pump control modes, multiple main and standby pump switching modes and various Starting method. It is widely used in industrial and agricultural production and various types of buildings for automatic control of water supply, drainage, fire protection, sprinkler pipe network pressurization, HVAC cold and hot water circulation, etc..