Abstract The energy relationship of motor was derived to measure the the efficiency of the pump motor. The results show that the motor efficiency is related to the input power and running current of the motor. The calculation formula of motor operating efficiency was obtained. The standard test data of six different types of three-phase asynchronous motor were used to conduct a theoretical verification. The input power and running current of the motor were adopted in the calculation of operating efficiency, and compared with the the actual efficiency of the motor. The results show that the overall error between the calculation efficiency and the actual operating efficiency of the motor is less than 1.8%. To further prove the reliability of the scheme, the centrifugal pump test bench was designed to verify the test. The motor end load was controlled by adjusting the pump valve opening degree to obtain the motor calculation efficiency under different working conditions. The test results show that the error between calculation efficiency and the test efficiency value is less than 1.06%. Compared with the general test method, the program can calculate the operating efficiency quickly and accurately by reading its input power and current while the motor is running, without measuring other data or stopping the measurement, which greatly improves measurement efficiency.
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