The energy input indicates how much energy is supplied to a system in order to achieve a desired state, for example. The example of a frequency inverter illustrates how the drive system absorbs energy in order to achieve a desired output and provide speed and torque for a load. The energy class (G value) indicates how efficiently a frequency inverter converts energy and rates the degree of efficiency on a scale from A (highest efficiency) to G (lowest efficiency).

Energy classes A-G. Copyright: (iStock/Serhii Brovko)

There are also IE and IES classes for frequency inverters.

Energy classes Frequency inverter. Copyright: 2023 Vogel Communications Group

They range from IE0 to IE2 (low to high) and apply to motors with a rated voltage of 100 to 1000 volts and a rated power of 0.12 to 1200 kilowatts. The IES classes not only evaluate the efficiency of individual components such as motors, but also the efficiency of the entire system, including the control and regulation. By using IES classes, industrial plants achieve optimum energy efficiency and can thus reduce energy consumption and emissions. The higher the efficiency class, the less energy is lost, i.e. the higher the efficiency and the more environmentally friendly the frequency inverter is. Danfoss frequency inverters already meet the strictest requirements of the energy efficiency standard IES 61800-9 and are classified as IE2.