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New efficiency classes for low-voltage three-phase motors (IE-Code)

Along with the international discussion on energy efficiency a worldwide harmonized energy efficiency classification system has been established for low-voltage three-phase asynchronous motors.

The efficiency factor defines the efficiency of motors when transforming electrical into mechanical energy. For many years low-voltage three-phase motors in the European Union have been sold in three efficiency classes EFF3, EFF2 and EFF1. Energy efficiency classification systems have been introduced and well-proven in many countries all over the world. They unfortunately differ from each other in terms of scope, wording and values. That was the reason for the International Electrotechnical Commission IEC to develop and publish an energy efficiency standard which replaces all the different national issues. In parallel IEC developed and issued a new standard for the determining the motor efficiencies. The new standard IEC 60034-30 defines and harmonizes worldwide the efficiency classes IE1, IE2 and IE3 for low-voltage three-phase motors.

 

New international efficiency classes of motors (IE = International Efficiency)

The new EN 60034-30:2009 defines worldwide the following efficiency classes of low-voltage three-phase asynchronous motors in the power range from 0.75 kW to 375 kW.

  • IE1 = Standard Efficiency (comparable to EFF2)
  • IE2 = High Efficiency (comparable to EFF1)
  • IE3 = Premium Efficiency

The higher the efficiency class the higher is the complexity of motor production and the higher is the amount of material to be used (as for instance copper). The motor price will increase accordingly. In relation to the motor life time the purchase price is only a few percentage points and due the saved energy cost the pay-back period is short.

 

New method for determining the efficiency

The method for measuring the efficiency of low-voltage three-phase asynchronous motors was revised with the new EN 60034-2-1:2007 standard. The new standard significantly increases the accuracy under defined laboratory conditions. It will replace the previous standard EN 60034-2:1996. The new standard can be applied from now. The old standard will become void in November 2010.

The efficiency levels according to EN 60034-30 are measured with the new method stipulated in EN 60034-2-1. In a direct comparison of both measuring methods at the same motor, it is expected that the efficiency levels determined according to the new method are up to a few percentage points below the efficiency levels using the old method. To achieve compatibility with the old EFF1 and EFF2 classes, the limit values of IE2 and IE1 classes were lowered slightly. For example, a today’s 11 kW, 4-pole EFF1 motor with 91,0% efficiency is identical with a new IE2 motor with 89,8% efficiency. The motor has not physically changed but measured with two different methods.

The EN 60034-30 defines requirements of efficiency classes, creating internationally consistent provisions. It has no legislative power and does not define mandatory efficiency levels to be used for the motors under this scope. This is left to the respective legislation in the individual countries or regions.