Minimum energy performance standards for electric motors: how Danfoss can help

17 March 2011

High efficiency motors can save a lot of energy over their lifetime - often more so when controlled by frequency converters, depending upon the duty. The savings can be easily calculated as well - for example, using the freely available Danfoss Energy Box tool. But apart from its obvious benefits, motor efficiency is shortly to become the subject of EU regulation, with the implementation of EU Directive 2005/32/EC.

The EU Directive 2005/32/EC outlines “a framework for the setting of eco-design requirements for energy-using products”. Starting in the summer of 2011, three-phase asynchronous motors are subject to mandatory minimum efficiency performance standards (MEPS) in the EU. EU regulations provide for increasingly strict motor efficiency requirements in a staged process extending to 2017.

The basis for these minimum efficiency classes, which are also called minimum energy performance standards (MEPS), is formed by the International Efficiency (IE) classes defined in IEC 60034-30, which are internationally recognised. The limits of these classes are in part comparable to those of the Eff classes widely used in Europe.

IE and Eff classes: major differences in details
The IE codes replace the former voluntary Eff classification of electric motors. The Eff classes are based on a voluntary agreement between the EU and the CEMEP in 1998.

Although the limits of the two standards are comparable, they differ in the underlying methods for determining efficiency. The efficiency of the Eff classes is based on the determination of individual losses (IEC 60034-2:1996), a method that dates back 100 years. By contrast, the efficiency of the IE classes is determined using a more precise method.

The measured results obtained using the accepted method for the IE classes are usually 2 to 3% worse than with the old method at power levels up to 10 kW and around 1% worse at power levels of 100 kW and above. The standard takes these differences into account for the harmonisation of the IE and Eff classes.

In addition to the IE1 to IE3 classes defined by the IEC 60034-30 standard, the draft version of IEC 60034-31 defines a new class: IE4.

Classes IE1 to IE3 are primarily oriented towards mains-operated motors, while IE4 also takes aspects relevant to variable-speed motors into account.
In summary the comparison between the IEC 60034-30 standard and the Eff classes are as follows:

IE1 (Standard Efficiency) is comparable to Eff2
IE2 (High Efficiency) is comparable to Eff1
IE3 (Premium Efficiency) is approximately 15–20% better than IE2
IE4 (Super Premium Efficiency) is not comparable as new class

Three-phase motors
Compliance with the MEPS is mandatory for the following types of three-phase motors:
– Duty cycle S1 (continuous duty) or S3 (intermittent periodic duty) with a duty cycle greater than 80%
– Pole count 2 to 6 Rated power 0.75 to 375 kW
– Rated voltage up to 1000 V
– Capable of operating direct online 50 and 60 Hz

Timeline
The first part of the EU directive 2005/32/EC becomes mandatory on June the 16th of this year. From this date onwards new installations must be with IE2 motors or better. In 2015 motors above 7.5kW must be classified at least IE3 or IE2 controlled by a variable speed drive (VSD). From 2017 this is also valid for smaller motors. Full classification is as follows:
From 16.06.2011 power range 0.75 - 375 kW must be with IE2
From 01.01.2015 power range 7.5 - 375 kW must be with IE3 or IE2 + VSD
From 01.01.2017 power range 0.75 - 375 kW must be with IE3 or IE2 + VSD