Frequency converter



Energy conservation with Danfoss VLT® Frequency converter

Did you know, …

…that reducing the rotation speed of pump drives to 80% saves up to 50% of energy which could reduce the payback period for a frequency converter to only few month?

Example 15 kW motor:
A reduction of the power demand to 7.5 kW means energy cost savings of up to €5,256 per year. (Assumed price of electricity: €0.08 per kWh)


... that Danfoss VLT frequency converter can maximise the energy conversion efficiency for pumps and fan drives using a special control method – the “automatic energy optimisation” – and saves additionally 3% - 5% of energy costs?

Example 15 kW motor:
15 kW x 4% = 15 kW x 0.04 = 600 W

This equates to €420 of energy costs per year. (Assumed price of electricity: €0.08 per kW)


... that the high energy conversion efficiency of Danfoss VLT frequency converters can save up to €70 of energy costs per year every 100 watts difference in power loss?

Example 15 kW motor:
Loss performance with Danfoss VLT HVAC Drive: 392 W
Loss performance of other products with an energy conversion efficiency of 97%: 464 W
Energy conservation: 464 W – 392 W = 72 W

This equates €50.40 of energy costs per year. (Assumed price of electricity: €0.08 per kWh)

... that only about one-fifth of all recently sold three-phase motors with frequency converters is speed-controlled and therefore a lot of energy is wasted? The production of this energy pollutes our environment and wastes precious resources.

You can find further information about Danfoss devices here (pdf).



Energy optimisation of a ventilation-air conditioning unit
for six operation theatres in a hospital



Plant design before modification:

Motors: 2 rotation speeds
Fan: backward curved vanes, rotor d = 800 mm
Power control: inlet guide vane attached to fan
Drive: 5 V-belts SPC

Energy consumption per year before modification 513,753 kWh



Plant design after modification:

Motors: energy optimised 1 rotation speed
Fan: backward curved vanes, flow-optimised rotor d = 560 mm
Power control: rotation speed control via frequency converter
Drive: flat belt
Control: frequency converter

Energy consumption after modification per year 207.105 kWh

Energy conservation per year 306,648 kWh

Energy costs per kWh 0.1375 Cent

Savings per year €42,194

Saving per year 59.69%

Investment costs €77,587

Payback period of modification in 1.8 years