Efficient motors for air power

Unified worldwide efficiency classifications for low voltage three-phase asynchronous motors are being introduced as part of an international effort to increase energy efficiency.

HPC Compressed Air Systems reports that its HPC KAESER screw compressors are now equipped with premium efficiency motors in accordance with these standards

The efficiency of an electric motor is defined as the ratio of usable mechanical power to electric input power. In Europe, low-voltage three-phase motors were previously divided into EFF3, EFF2 and EFF1 efficiency classifications. Differences among various national systems with regard to scope and classification prompted the International Electrotechnical Commission (IEC) to develop a unified standard. In parallel, the IEC's improved methods for determining efficiency were revised and standardised. The new IEC 60034-30 standard defines and harmonises IE1, IE2 and IE3 efficiency classifications for lowvoltage three-phase motors worldwide. Former classifications The voluntary agreement between the European Committee of Manufacturers of Electrical Machines and Power Systems (CEMEP) and the European Commission, in effect since 1998, defined three efficiency classifications: EFF3 = Standard efficiency motors EFF2 = Improved efficiency motors EFF1 = High efficiency motors The minimum values for the various classifications were based on efficiency measurements in accordance with EN60034-2:1996.

New procedure for determining efficiency The EN 60034-2-1:2007 standard introduces new procedures for measuring the efficiency of lowvoltage three phase asynchronous motors, which has led to considerably greater precision under defined laboratory conditions. It replaces the former EN 60034-2:1996 standard. The old standard ceased to be valid in November 2010. A direct comparison of the two standards on the same motor shows that efficiencies measured using the new procedures are a few percentage points lower than those measured using the old standard.

New international efficiency classifications for motors The new EN 60034-30:2009 standard defines the following worldwide efficiency classifications for low voltage three phase asynchronous motors rated from 0.75 to 375kW: IE1 = Standard efficiency (equivalent to EFF2) IE2 = High efficiency (equivalent to EFF1) IE3 = Premium efficiency Implementation of the Ecodesign Directive 2005/32/EC (EuP Directive) is intended to proceed according to the following schedule: From 16.06.2011 - Minimum IE2 efficiency for asynchronous motors rated 0.75 to 375kW From 01.01.2015 - Minimum IE3 efficiency for motors rated 7.5 to 375kW, or a combination of frequency convertor and IE2 motor From 01.01.2017 - Minimum IE3 efficiency for motors rated 0.75 to 375kW, or a combination of frequency convertor and IE2 motor.

Energy saving Close cooperation with its electric motors partner, Siemens, has enabled HPC KAESER to equip virtually all of its screw compressor ranges with equally sized IE3 motors. The new SK Series is the company's first range of compressors to be equipped with these energy-efficient units. The remaining screw compressor ranges will follow suit through 2011 - well before the new standard becomes mandatory and providing customers with greater energy efficiency and cost-effective compressed air generation.