Examples of energy savings from frequency converters

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Examples of energy savings achieved with frequency converters: Control of fans and pumps. 1. Previously, fans and pumps were controlled such that the AC motors operated at the line frequency, rotating at their rated speed, with the volume of air flow being regulated by a valve; if a very low volume of air flow was required, the corresponding duct valve would be closed, yet the motor continued to operate at its rated power even in such conditions. 2. Variable frequency technology is used to adjust the frequency supplied by the inverter to the motor, thereby reducing the motor’s speed and controlling the air volume; even when accounting for the losses associated with the use of the inverter, energy savings are still achieved. Air volume, flow rate, and rotational speed are directly proportional to each other, while power is directly proportional to the cube of the rotational speed. The main areas where energy savings are achieved are in fans and pumps. Furthermore, by using a regenerative braking unit or parallel connection of DC buses between inverters, the electrical energy generated during motor braking can be fed back into the power grid for use by other devices.