Hi guys

Our factory have three units 37kW centrifugal pump in boiler room of heating pipeline, operation with 37KW frequency inverter (centrifugal pump is running separately), but the inverter shows overheating and overload alarm messages, does the power of the inverter appropriate for the pump? is there specific standard or formula to calculate the output power of the inverter?

1) the inverter overheating and overload alarm you said should be considered separately.
The overheating alarm means the heat sink temperature is too high, it's the ventilation problem.
Overload alarm means over current situation, it should be the actual power exceeds the rated power of the inverter to cause overload. It's better to measured the actual current with an ammeter. If it's a little more, then decrease the pipeline valves (if lose a few flow do not impact on heating a lot)

2) No special calculation formula, the main factor is to match the motor power, and slightly greater than the actual operating current. low speed high torque required vector control frequency inverter.

Normally choose the 37KW universal frequency inverter should be OK for it, but you should consider the boiler room temperature and pay attention to ventilation, in addition, centrifugal pump has high current, the inverter for fan & pump is not a right choice.

Generally choose the frequency inverter by the same power level motor, some engineers like to select a larger one, but this will increase the cost. Different load characteristics have different operating current, you need to select the inverter according to the actual operate situation. You can use the ammeter to measure the actual motor current and check the inverter parameters, if such problems were caused by start conditions, you can modify parameters sometimes. From a professional point of view that there is no specific standard formula.