300 400
(mwg)
1350rpm
1650rpm
100 300 (m
3
/h)
(m
3
/h)
400
1350rpm
1650rpm
Illustration 6: Example of Energy Savings
4.3.1 Example of Energy Savings
As shown in Illustration 7, the ow is controlled by changing the speed of a centrifugal pump, measured in RPM. By reducing the
speed only 20% from the rated speed, the ow is also reduced by 20%. This is because the ow is directly proportional to the speed.
The consumption of electricity, however, is reduced by up to 50% due to the variable-torque prole of the pump.
If the system only supplies a ow that corresponds to 100% a few days in a year, while the average is below 80% of the rated ow for
the remainder of the year, more than 50% of energy is saved.
See the dependence of ow, pressure, and power consumption on pump speed in RPM for centrifugal pumps in Illustration 7.
AJ300847815559en-000101 / 130R033722 | Danfoss A/S © 2020.09
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