Economic efficiency of using pumping units with variable-speed drives at low water supply

Summary

In the process of operating pumps with variable-speed drive at low water flow rates the reduction of the pumping unit efficiency factor is observed. It is suggested to determine the amount of energy lost during the operation of such pumping units with actual efficiency factor differing from the rated one. In some instances operating with low water flow rate results in power consumption increase. In this context experimental studies on determining the pumping unit efficiency factor at different impeller speeds were carried out. The results of the studies provided for identifying the optimal operation zone where the pumping unit efficiency factor was reduced by less than 2% of the maximum value, and the less economic zone where the efficiency factor was reduced to 35% of the maximum value. To evaluate the economic efficiency and determine the optimal operation area of pumping units with variable-speed drives at low water flow rate the efficiency curves for different pump impeller speeds are required. It is appropriate to include this data in pump catalogues.

Key words

adjustable electric drive , water supply , flow rate , head , frequency of pump impeller rotation , pump , water disposal , lifting efficiency , electric motor power