Variable-frequency centrifugal pump current indication
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There is a variable-frequency centrifugal pump on site. When it is in operation, its rotational speed reaches the full speed of 1500 revolutions per minute, yet the flow rate at the outlet is low – the rated flow rate is 12 m3/h, but in reality it is only 5 m3/h. The current during operation is 47 A, although it often exceeds 52 A, which causes the rotational speed to drop. I would like to ask everyone: current = power ÷ voltage. For a variable-frequency centrifugal pump, the voltage is proportional to the rotational speed; since it is operating at full speed, the voltage is 380 V. Power is proportional to flow rate – (12 m3/h corresponds to 18 kW, while 5 m3/h corresponds to approximately 8 kW). With lower power and higher voltage during operation, the current should be low. So why is it high? My academic performance isn’t that good; I guess I haven’t fully understood some of the concepts. I hope everyone here can offer me guidance
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Check to see if it’s a mistake in purchase – for example, if the pump is designed for transporting oil, using it to move water will result in a significant change in density, which can easily lead to overcurrent
The issues related to variable-frequency operation are not simply a matter of physical formulas; they need to be analyzed in light of specific operating conditions. At the very least, you need to provide parameters such as the head corresponding to the pump flow rate, the type of medium, and the motor power
Frequency conversion is related only to frequency; how is it connected to voltage? Moreover, the claim that one is proportional to the other – where does such a claim come from?