The water pump motor is hot, but the current is not high – what could be the cause?
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The pipeline centrifugal pump is equipped with a 30KW four-stage motor; its rated current is 58A, while the current during operation is around 38–40A. The three-phase currents are also roughly equal to each other. However, the motor temperature is very high; it can reach around 70 degrees after 2 hours of operation, and we didn’t dare to keep it running for fear that the high temperature would damage the motor. What could be the problem if the temperature of the water pump motor is high but the current is not high? Additionally, at the same power level, which generates more heat: a two-stage motor or a four-stage motor?
The current is not high but the temperature is high; it’s likely a problem with the motor itself. Investigate from both electrical and mechanical aspects: measure and check the windings, examine the condition of the lubricant and bearings, verify that the fan is functioning properly for cooling, and check for any abnormal vibrations or noises in the motor
Is it a quality issue with the motor? We analyzed that if there are problems with the machinery, or issues such as motor bearings, it can lead to high loads and thus high currents; however, in reality the current is very low, much lower than the rated current during operation.
It’s a new pump; it has probably been in use for only a few dozen hours. It wasn’t used much after it was found that the motor temperature was too high
High motor bearing temperature is most commonly caused by too much grease.
Some new pumps do not have bearing grease applied; only rust preventive oil is used
Which part of the motor has a high temperature? Please clarify, OP