Energy Saving with Variable Frequency Drives


Energy Saving with Variable Frequency Drives

One of the big advantages of using variable frequency drives is energy saving. Energy savings can also be made by careful motor selection; energy costs over the life of a motor are fifty or a hundred times the cost of the motor, so choosing a high efficiency motor (IE3 or better, IE4) makes sense. EU regulations now mean a new IE2 motor must be operated with a variable frequency drive in any case.

Constant torque applications (such as conveyers, mixers, machines) will save some energy, but savings really notice with variable torque loads such as pumps or fans. A reduction in speed of 10% here gives a saving of about 25% in energy; 20% will save about half. Fitting a sensor to monitor your process (temperature, pressure, flow rate etc.) and using the closed loop control built into the drive will improve the system performance and save money as well. Payback time is often in months, rather than years. Variable frequency drives such as Invertek’s Eco drive offer many special features to work with pumps and fans as well. All Invertek drives also have an energy saving function (P-06 on E3; P1-06 on Eco and P2 drives) which will save a little more.

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