New standards for measuring the efficiency of engines more accurately

Compared with other machines, electric motors are very efficient. A high efficiency of 90 kW engine converts 95% of the energy used in useful work. A single car engine uses efficiently 40-45%. But the large number of installed engines means that small changes in efficiency, involve a big difference. The new standard aims to achieve greater consistency in the form of action around the world.

Previously, different rules of evidence have been developed to meet requirements of application, without having the measure of the efficiency of the engine as a priority objective. These standards of measure gave an indication of the efficiency of the engine, but when they were used to compare values of efficiency, were to see engines with different ability to use energy and equally efficient, making the user the choice based on good information. "We welcome you to the new IEC international standard for testing of low voltage electric motors and particularly to the fact that the values of efficiency measure will be more harmonized throughout the world." "Have waited for a long time to develop this scenario," says Mikko Helinko, director of R & D of ABB motors. ABB has already made all the tests in accordance with the new standard in its range of engines and published the new values of efficiency during 2008 and early 2009, as soon as the tests were completed.

Efficiency decided the cost of operation of the engine and the emissions of CO₂. A high efficiency (Eff1) engine normally costs between 10 and 15% more than a standard efficiency (Eff2) engine. However, this difference in price is quickly amortised in energy saving. The cost of purchase of a motor represents only 1% of the total cost of their life cycle, energy consumption to be the largest part of its cost.

With the support of the European Commission, manufacturers representing 80% of production in Europe of standard motors agreed in 1998 to establish three bands of efficiency (Eff1, Eff2 and Eff3) for induction of 2 and 4 poles motors, 1.1 to assemblies. This efficiency was measured according to a modified version of the standard of evidence EN 60034-2 (1996).

The European system was correct in removing the market lower efficiency, Eff3 motors. However, it was less successful in introducing the category of highest efficiency, Eff1. Since the year 2000 to 2005, Eff3 motors market fell from a 43 to 4%. Eff2 increased from 54 to 85%; but Eff1 got only a 9% market share in 2005, from 3% in 2000.

Although it was only intended to be effective from 1999 until the end of 2003, this European scheme was retained. It represented a breakthrough for its time, but today is not a good indicator of the efficiency of the engine and can not be used to distinguish the types of more efficient engines in the band Eff1. This rule applied in Europe needs now to be replaced and get inside the global trend.

Today, 10 countries with a demand of global electrical energy from 47% in its directives have marked minimum efficiency levels in the engines. It is expected to join this club in 2012, 14 new countries. Among them, the people of Europe who are following the above scheme. This will cover 80% of global electricity demand.

The efficiency of the engine can be measured directly or indirectly.

The direct measure implies compare the input of electric energy with the power output on the axis. At first glance, this seems to be the easiest method, but direct measurement requires extremely precise measurement techniques and depends on the temperature of the room - a lower temperature will seem to the most efficient engine. With measure indirect, the power output is determined by measuring the electrical power input and the losses associated engine. In this case, the mechanical power is the electric power less losses.

The new standard, IEC 60034-2-1: 2007-09, allows several measurement methods:

• Direct measurement as used in North America (measure of the pair) standard IEE112-B

• Measure the additional losses determined by tests to partial loads (indirect method)

• Measure the additional losses estimated between 2.5 and 0.5% of the power input at rated load, depending on the size of the engine (indirect method)

• Mathematical calculation for additional losses

Under the new rule, manufacturers can choose which of the methods of measurement used. In the documentation of the engine, it should be noted that measurement method has been used. "ABB uses the method for the determination of the additional losses for measure to partial loads, that we believe can give a better reflection of the real value of efficiency", explains Helinko.

Previous standard vs standard current

As the previous method estimated additional losses and accordingly the total too low, the new calculated values of efficiency will be slightly lower. The new value of efficiency does not mean the design or the operation of the engine has changed, only that efficiency is now measured more accurately.

Most of the small engines used in the houses as washing machines, etc., are not covered because it is believed that they are under other schemes that try the efficiency of the entire application. Also does not apply to the electric motors for vehicles, which are often made to measure.

The method of current marking (Eff1, Eff2 and Eff3) is replaced by a new IEC classification of engines according to its efficiency (IEC 60034-30). Manufacturers have to test their engines. Each type must be tested individually, by what this entails a major effort.

IEC 60034-30 introduces a new classification (IE1, IE2 and IE3), which covers many more types of engines than previously: