The final versions of the DIN and European standards are based on the IEC standard; the minimum values of the EN standard are specified in an EU regulation regarding the implementation of Directive 2009/125/EC for selected types of motors.

Class codes

Class codes IE1, IE2, IE3 and IE4 have been introduced. This system is similar to the IP, IM and IC codes uses for many years in the electrical machinery industry. IE stands for ‚International Energy Efficiency Class‘ and is widely accepted.

IE efficiency classes
  • IE1 = Standard Efficiency
  • IE2 = High Efficiency
  • IE3 = Premium Efficiency
  • IE4 = Super Premium Efficiency
  • IE5 = (no specific name defined)
IE Chart

Comparison of efficiency classes

The increase in energy efficiency class is primarily achieved with asynchronous technology by using more active materials. With each increase in efficiency, the motor frame length changes and, if necessary, the motor frame size also changes. To avoid motor size jumps, various optimization options are available, such as increasing the slot fillings by means of adapted windings, use of higher-quality electrical laminations and, if necessary, copper as cage rotor material. 
The diagram shows the power-dependent efficiency curves of IE2 to IE4 motors from the scope of Regulation (EU) 2019/1781.

Exceptions to the classification requirement IEC 60034-30-1

  • Operating mode S2, S3<80 %, S4 to S10
  • Inverter-driven motors that cannot be operated directly from the mains.
  • Motors that cannot be independently measured, such as pump motors with wet rotors.
Efficiency Curve IE

Super Premium class IE4/IE5 for new technology

This efficiency class is described in the IEC 60034-30-1 standard for direct online operated AC motors and in the IEC TS 60034-30-2 for variable speed AC motors. In IEC TS 60034-30-2, minimum efficiencies for efficiency class IE5 are also specified for the first time.

Efficiency Class IE4 applies to all types of line operated AC electric motors. The efficiency class of Bauer permanent magnet synchronous motors for inverter supply have been derived from the efficiency class IE4/IE5 described in IEC TS 60034-30-2. These motors are generally rated by torque rather than power. The overall efficiency is determined taking into account the power dissipation in the inverter and the often considerable process gains achieved with speed control. A direct comparison of line operated motors and variable speed motors is therefore not meaningful.

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