New legislation: Are you ready?

New legislation comes into effect in June across the UK and the entire EU regarding a minimum efficiency for industrial electric motors.Robin Cowley of Baldor UK explains the implications for industrial users and OEMs

From the 16th June 2011 only motors with an efficiency rating of IE2 or higher, can legally be 'put on the market'. This will have considerable consequences to all industrial users and original equipment manufacturers alike. This legislation, 'Ecodesign Directive 2009/125/EC' covers 3-phase motors in the power range of 0.75 through to 375kW.

Efficiency and standards As motors have evolved, manufacturers have achieved greater efficiencies by the use of better materials, improved design and advanced production techniques. This now presents users with a range of motor designs that offer different levels of efficiency.

The International Electrotechnical Commission (IEC) has published an international standard that defines 3 distinct energy efficiency classes for single-speed, three-phase motors (IE1, IE2, and IE3). This standard has also been adopted as a European and UK Standard (BS EN 60034- 30:2009). IE4 efficiency class is in development. The IE classes replace the previous 'CEMEP EFF' classes as the table below shows.

Energy savings Higher efficiency motors cost more to purchase because of the more intensive production techniques and additional material costs. However, the saving in operating energy costs can often offset the higher capital cost. For example, with an 11kW 4 pole motor at 8000 operating hours per year, the additional cost of an IE2 motor is paid back in 7 months, with an IE3 motor paying back in 10 months. Even at only 2000 operating hours per year, the energy saving repays the capital in about 3 years.

Therefore, while IE2 will be the mandatory minimum level until 2015 when it rises to IE3, assessing the economic viability of further investment up to IE3 level would be well advised now.

Moving to motors of the highest efficiency - IE3 and higher - will yield the highest savings in terms of energy and attract carbon tax credits. This in turn yields much shorter payback periods that are more readily acceptable financially. This type of motor will however often require some further engineering and logistical considerations to optimise the installation.

Transition matters To ensure a smooth transition, an understanding of the mechanical and performance differences of these motors is essential in order to realise maximum financial benefits and a trouble free installation. Energy savings are not the only benefits to premium efficient motors.

Mechanical differences - Higher efficiency motors can be larger physically due to the extra material, particularly at the low end of the kW range. They will have a smaller fan due to the cooler operating temperatures and therefore reduced acoustic noise levels. Overall a premium efficient motor will operate cooler internally with better steel, quieter, less mechanical stresses through tighter fits and better balancing.

This will result in providing a more reliable, longer life-cycle motor installation. Improved productivity from less down time is an additional benefit.

Electrical power requirements and considerations - Using a premium efficient motor will reduce the full load current drawn from the power supply. Therefore the electrical protection of the motor must be reviewed. Conversely, the starting current (or inrush current) will usually increase from 4 to 5 times full load for a normal efficiency motor, to 6 to 8 times full load for premium efficient motors.

Therefore, the motor overload protection system will also need to be reviewed.

Installation and application considerations - Checking the motor for oversizing is always recommended as changing to high efficiency offers the chance to optimise motor size. Higher efficiency motors operate at higher RPM for the same load and this can cause problems with the driven load, particularly fans, pumps and other quadratic type loads. Starting torque on higher efficiency motors can be less, therefore a check is needed against the characteristics of the driven load.

Under loading the motor does NOT improve efficiency. This may have been true with older, less efficient designs, but higher efficient motors will typically have the best power factor and efficiency at near full load.

Worldwide move It is worth noting that most of the industrialised world either already has or is currently setting up mandatory minimum efficiency & performance standards (MEPS).

In fact North America has had a MEPS equivalent to level IE2 since the mid 1990s and has now moved to the equivalent of IE3 under the EISA legislation. In this respect Europe has been slow to embrace higher levels of motor efficiency and even slower to adopt respective legislation.