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How load type affects variable-speed drive savings

There are several factors affecting the energy savings you’ll enjoy from a variable-speed drive, including the type of load being driven. Here we look at the three main types of load.

Variable torque load

This load is typically found in centrifugal fan and pump applications. They offer the greatest energy-saving potential of any other load type, because a relatively small speed change results in a significant reduction in power usage.

Constant torque load

Common constant torque load applications include conveyors, agitators, crushers and air compressors. Unlike in variable torque loads, speed changes correspond exactly with power consumption. So although potential energy savings are not as high as with variable torque loads, they are still significant enough to warrant consideration.

Constant power load

In this case the power consumed does not vary and the torque is inversely proportional to the speed. Therefore, constant power applications such as machine tool spindles seldom offer energy-saving potential via speed reduction.

If you’d like more information on how Gibbons could cut your costs and increase your energy efficiency with ABB drives, give us a call on 01621 868138 or email

Variable-Speed Drives

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