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.