Speed control using a variable frequency drive is without no doubt the most efficient way of adjusting booster pump performance exposed to variable flow requirements. The speed control method results in a new Q/H curve at reduced head and flow.
The characteristics of the curves remain the same. However, when speed is reduced the curves become flatter, as the head is reduced to a higher degree than the flow.
For example, if the flow is reduced by 20 %, the motor’s power consumption falls to 65 % compared to the original consumption.
Grundfos E-pumps are variable speed pumps with a frequency converter built-in, and the Grundfos CUE is an external VFD that works with standard pumps.