Seeking help with pump efficiency issues
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The last edit to this post was made by zx9527007 on 2010-5-4 at 09:25. Why does the current in the motor not increase but instead decrease when the efficiency of the centrifugal pump reaches its maximum?
Simply put, it can be seen from the performance curve of a centrifugal pump: when efficiency reaches its maximum, the flow rate and head are at their optimal values; this is when efficiency is highest and the load is most suitable, as a result the current drawn by the motor decreases. In other words, it is best for the centrifugal pump to operate at this point, as it is beneficial for both the pump and the motor
Your statement doesn’t make much sense; efficiency has no direct relationship with current. Perhaps when the power reaches its maximum (the optimal operating point), the increase in power is not very significant. (Look at the pump’s performance curve)
Current is related to flow rate, but not to efficiency. Your description of the phenomenon must not be clear! !
This is a problem from the pump’s design! ! ! When designing an impeller, the shape of the performance curve can be controlled. Once it becomes a pump, this issue doesn’t arise!
Perhaps at the beginning, the pump operates in a high-flow range, which results in a higher motor current. As the flow rate decreases and the pump operates at its optimal point, the current also decreases accordingly. In fact, the current is related to the flow rate; it isn’t directly connected to efficiency
This post was last edited by bage on 2010-5-12 at 14:07. What the original poster mentioned is only an individual phenomenon for centrifugal pumps. For some large-flow, low-head centrifugal pumps, the power curve first rises and then falls; that is, as the flow rate increases from low to normal levels, the current also increases, but when the flow rate becomes even higher, the power decreases and the current drops. It seems as though the current is at its highest when the efficiency is also at its highest. This is a phenomenon specific to individual centrifugal pumps, and it cannot be generalized.