I’m asking experts to take a look at this issue: why is the current consumption of this centrifugal pump always above the rated level?
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One vertical centrifugal pump in our facility, along with 3 other pumps of the same model, is experiencing a problem: the current rises to overload levels as soon as the pump is started (even before the outlet valve is opened), and the overload condition persists even after the valve is opened. The rated current is 20.7A; after the pump starts operating, it remains around 25A with little decrease. The motor model should be fine; I calculated it again myself.
Could the poster provide some information on the operating conditions and the pump’s status? Medium, flow rate, head, density, temperature, motor power, pump model, impeller type, clearance, etc. It’s best to include pictures, as the model names vary from one pump manufacturer to another
Wrong selection? Was the matching done incorrectly by the manufacturer?
Is there an error with the medium, installation, selection, or piping?
Usually, it is the contact between moving and stationary parts that causes friction, leading to overload. If no signs of wear are found upon inspection, then it means the motor selected is too small. Check whether the medium density used in your calculations matches the actual density under operating conditions; an increase in medium density can also cause overload. To resolve this issue, either replace the motor or cut into the impeller, but the cutting amount should not exceed 10%, otherwise efficiency will drop significantly.
Thank you all for your help. I’d like to provide some additional details: the relative density of the medium TEG is 1.14, the flow rate is 4+2 m3, the temperature is room temperature. The rated maximum head is 50 m, the motor power is 11 kW. The pump model is 6LB50 (from Shenyang Grid), while the motor model is YB-2WTH (from Nanyang)
Medium: TEG; Relative density: 1.14; Flow rate: 4+2 m3; Temperature: room temperature; Maximum rated head: 50 m; Motor power: 11 kW; Pump model: 6LB50 (Shenyang Grid); Motor model: YB-2WTH (Nanyang): handshake
This post was last edited by Meng Cheng from Longgang Pump Industry on 2017-3-3 at 09:34. I couldn’t find any pictures of this pump on their official website either; all four of your pumps have this issue. I think you need to pay close attention to the process-related problems.
If this is the case when the pump is started, then it means the motor selected is too small