What causes the actual power of the motor to be low?
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Another new problem has arisen. I measured the motor current today; it’s a motor with a rated power of 7.5 kW, yet the current while it’s in operation is only 3.8 A. Calculating based on this, the actual power is only 380*3.8=1.44 kW – the difference in rated power is quite significant. This motor is so energy-efficient! Is it even more power-efficient than when it’s idling? Is this abnormal? I thought the water pump didn’t have an impeller, so I took it apart to check and it wasn’t damaged.
The three-phase power is given by P=√3*U*I*COSφ, where U represents the voltage, I represents the current, COSφ is the power factor, and √3 is a constant equal to 1.732. A typical value for COSφ is 0.85. The power of the motor is related to the flow rate of the pump; when the flow rate is zero, the power is very low