Press information
Press contact Geoff Spear
Address Fraser Rd, Priory Business Park
Bedford, MK44 3WH
Telephone 01234 753227
E-mail [email protected]
Website www.Lenze.com
Using energy-efficient electric Motors
Meeting the International Energy Directives
October 2013
This article gives an overview of the current energy saving legislation for AC motors and
looks at forthcoming changes. High efficiency motors have certain drawbacks. These
are discussed and solutions are proposed.
Introduction
Legislation on the minimum efficiency levels for AC electric motors has been in
force since 2011. These regulations, often known in Europe as the ErP (Energy
related Products) Directive, will become increasingly stringent over the next 10
years. The ultimate aim is to reduce the effects of industrial activities on the environment. As electric motors are responsible for 40% of energy use in industrial
nations, they are clearly an essential target in the process of reducing our carbon
footprint.
The regulations
The European standard IEC60034-30:2008 defines three efficiency classes:
IE1 standard efficiency
IE2 high efficiency
IE3 premium efficiency
More recently IEC60034-31:2010 defined the efficiency levels for a higher motor stand-
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ard IE4, “super premium”. As an example of the increasing efficiency levels, the minimum efficiency for a 4-pole 7.5kW motor running at rated load are:
IE1 85%
IE2 88%
IE3 90.4%
IE4 92.5%
Regulations are in force across most industrialised countries with similar definitions and
efficiency levels. In the USA the EISA (Energy Independence and Security Act) applies.
In China they have set the standard GB18613-2006. The European ErP Directive has
set the following timescale for the introduction of efficient motors:
16th June 2011
– motors must meet the IE2 efficiency level
1st January 2015 – motors from 7.5 to 375kW must meet the higher IE3 efficiency level,
or must be “equipped” with an inverter variable speed drive.
st
1 January 2017 – the 2015 regulations are extended down to motors of 0.75kW.
Currently there is no timescale for the introduction of IE4 motors.
Scope and exceptions
The ErP Directive applies to AC asynchronous motors and geared motors in a power
range 0.75 to 375kW. Motors can be 2, 4 or 6 pole, for operation at 50 or 60Hz and
rated for continuous operation (S1 or S3).
The Directive covers motors that are ‘placed on the market’, that is manufactured in or
imported into the European Union. Effectively this means that all new motors sold must
comply if they are within the scope and are to be installed in the EU. End-users are
permitted to repair or rewind existing motors.
Current exceptions of brake motors, 8 pole motors and motors designed for extreme
temperatures/altitudes are expected to be brought into the scope towards the end of
2013. There will remain a number of other exceptions such as motors not designed to
run at 50/50Hz, explosion proof/ATEX motors and those with a rated voltage above
1000V. However the vast majority of industrial installations where the power is above
0.55kW will need to comply, either at the IE2 or the IE3 levels.
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Drawbacks of higher efficiency motors and alternative options
Manufacturing a motor with higher efficiently requires designs with more copper content
and higher manufacturing precision. This in turn results in higher costs and in some
cases significant increases in size. Justification of the higher purchase cost is usually
straight-forward: energy costs can amount to 90% of the lifetime cost for electric motors
and a 2-3% saving can result in payback times of less than 2 years. So there is no good
argument against the extra cost of high efficiency electric motors. However where the
dimensions of the higher efficiency motor are bigger (they are often longer and in some
cases one frame size bigger) there may be serious problems in upgrading machinery.
Fortunately there are options to avoid larger dimensions that do not conflict with the
regulations, and are also themselves energy efficient.
The use of a frequency inverter with an IE2 motor instead of an IE3 motor has already
been mentioned. This avoids the potentially larger dimensions of the IE3 motor. Where
the speed of the machine can be varied in response to demand, this is an excellent option. The ErP regulations are not specific about the way that IE2 motors should be
“equipped” with an inverter. However it is clear that they do not need to be a single assembly (terminal box inverter) and can be purchased from different suppliers. Selfcertification is likely to apply. A well-known application is fluid flow in pumps and fans. If
the speed can be turned down to match low demand, massive savings even up to 80%
of energy costs are possible. Speed variation can easily be automated by PID controls
in the inverter. Alternatively where motors have to run at partial loads, Lenze offer software built into the 8400 series of inverters that can save up to 30% of energy used.
The Lenze MF series of motors available from 0.55 to 22kW are rated to run with inverters at a setpoint of 120Hz. As such they fall outside the regulations and can be used
without restriction. The higher power delivered at 120Hz leads to motor size reductions
of one or even two frame sizes and the performance comes with good efficiency, actually around the top end of IE2 levels. MF motors are available on their own or with a full
range of gearboxes. They represent a good way of keeping small dimensions whilst
complying with the ErP regulations.
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New for 2014 is the Lenze Smart Motor, another product that is outside the regulations
because it is not rated at 50Hz. This new drive available in 63 and 80 frame sizes is a
combination of a standard motor with some clever electronics. It is designed for running
at fixed speeds that can be adjusted and set using at smartphone app. The Lenze
Smart Motor can be set to run at any speed from 500 to 2600 r/min. With 400% starting
torque available, there is often saving of one frame size and actual running efficiency is
high at IE3 levels.
Future introduction of the higher IE4 standard
Looking into the future, it is inevitable that the higher demands of IE4 efficiency levels
will become law, although it is unlikely in this decade. To reach these high levels motor
manufacturers have to move away from induction motors to permanent magnet, brushless servo and synchronous reluctance technologies. Manufacturing costs will step up
sharply and again there will be dimension changes. For powers up to 15kW, efficient
synchronous servo motors and geared motors are available now with the Lenze MCS
range. Running efficiencies are in a range from 80 up to 94% depending on power.
Whilst the inevitable escalation of electric motor efficiency regulations can be a headache for machine manufacturers, the end user gains with significantly lower lifetime operating costs. In some cases motors with higher efficiency will have larger dimensions.
Where this is a problem there are existing solutions based on electronic variable speed
technology that can minimise motor size whilst also offering higher efficiency.
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Lenze Type MH high efficiency motor to IE2
IE2 efficiency geared motor with inverter complies with IE3
Lenze MF motor is up to 2 frame sizes smaller
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New Lenze Smart Motor can be used without restriction
1127 words
About Lenze Ltd
Established 40 years ago in Bedford, Lenze Ltd now has 60 employees and achieves sales of about
£20M in power transmission equipment from the Lenze factories and other quality suppliers. Services to
UK customers include application engineering, software writing, training, commissioning and service
For more information, contact Geoff Spear at Lenze Ltd, Fraser Road, Priory Business Park,
Bedford MK44 3WH. Tel: 01234 753227. Fax: 01234 753220. Email: [email protected]
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