Many people think that the lower the pumping head, the smaller the motor load. Under the misleading of this kind of misunderstanding, when purchasing a water pump, the head of the water pump is often selected very high. In fact, for centrifugal water pumps, when the pump model is determined, its power consumption is proportional to the actual flow rate of the pump. The flow rate of the water pump will decrease with the increase of the head, so the higher the head, the smaller the flow and the lower the power consumption. Conversely, the lower the head, the greater the flow, and the greater the power consumed.

Therefore, in order to prevent the motor from overloading, it is generally required that the actual pumping head of the pump should not be less than 60% of the calibrated head. Therefore, when the high head is used for pumping water with a low head, the motor is easy to be overloaded and generate heat, and it can burn the motor in severe cases. In case of emergency use, a gate valve for adjusting the amount of water must be installed on the outlet pipe (or block the small outlet with wood, etc.) to reduce the flow rate and prevent the motor from overloading. Pay attention to the temperature rise of the motor. If the motor is overheated, turn off the water outlet flow or shut down in time. This is also easy to misunderstand. Some operators think that blocking the water outlet and forcibly reducing the flow will increase the motor load. In fact, the opposite is true. The outlet pipes of the regular high-power centrifugal pump drainage and irrigation units are equipped with gate valves. In order to reduce the motor load when the unit starts, the gate valves should be closed first, and the gate valves should be opened gradually after the motor starts.