The load current of the centrifugal pump is overloaded
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There are 3 identical centrifugal pumps, each with a power rating of 30 kW, a flow rate of 110 cubic meters, and a head of 45 meters. After 4 years of operation, the problem has arisen that when the outlet pressure is adjusted to 4.8 kilograms, the current load exceeds the limit and the motor heats up. Currently, it is only possible to reduce the valve opening to 20%, which results in an outlet pressure of 5.3 kilograms. We contacted the manufacturer to ask why this is happening; no issues were found after disassembling the impellers. The manufacturer’s explanation was that there was a problem with the selection of the pump parameters – the required head was set too high – and suggested that we reduce the size of the impellers. Is this explanation reasonable? I just don’t understand it
The water pump should be fine; the motor and inlet valve need to be checked, as there may be a problem with the motor.
The explanation is unreasonable. You say that your centrifugal pump has been in operation for 4 years and that overcurrent only started to occur now; therefore, I suggest that you check the assembly gaps to see if there is any internal leakage. In other words, the pump may be delivering a large volume of fluid, but due to internal leaks such as those in the valves of the piping system or excessive gaps in the gaskets, fluid escapes. Of course, this is assuming that the efficiency of the drive motor has not decreased.
What is the export pressure after 4 years of operation? What is the inlet pressure again? What is the actual traffic volume? What is the medium being transported? What’s the density? From the original poster’s description, it’s not possible to tell whether there is a problem with the pump itself or whether the selection of the pump was incorrect.
If the pump itself is found to be in good condition, it is possible that the operating conditions have changed; for example, changes in the density and viscosity of the medium, as well as the inlet pressure and temperature, can also cause this phenomenon
If there were problems from the very beginning of production, it would mean there was an issue with the product selection. It’s been 4 years now, so it’s unlikely that the problem lies in the selection; are all three units experiencing the same issue?
Yes, all three units are in the same situation – the wrong model was chosen, which results in wasted electricity. When they were in use before, the traffic volume was sufficient
A Kaiquan centrifugal pump is used, with a 4-stage motor operating at 1470 revolutions per minute
We’ve encountered the same problem as well, but we have multi-stage pumps, and it has been resolved now
That can also be considered a multi-stage pump. In the past, we chose a too high head for our multi-stage pump, which resulted in cavitation; after reducing the head, everything worked normally again. Check the wear condition of the balance disc and shaft sleeve~! It’s been 4 years; these things should have been replaced long ago
If all three pumps are in the same condition, check whether the power voltage to the motors is lower than before