Enhancing motor harmony
Efficient automation systems translate into true energy savings. A major step in that direction has focused first on industrial electric motors because of their vast installed base and continuing growth. Researchers say 300 million industrial motors are running worldwide, with 20 to 30 million being added yearly.
Efficient automation systems translate into true energy savings. A major step in that direction has focused first on industrial electric motors because of their vast installed base and continuing growth. Researchers say 300 million industrial motors are running worldwide, with 20 to 30 million being added yearly. Potential energy savings amounts to 20-30%, via efficiency improvements, according to a presentation at IEEE's Oct. 2007 Industrial Energy Efficiency Workshop by Conrad U. Brunner. Brunner is director of A+B International, a Zurich, Switzerland-based consultancy.
Motor developments derive from different regional designs (50 and 60Hz supply, metric vs. inch dimensions, etc.), without significant coordination of standards or market transparency, explained Brunner. Also, various “efficiency testing methods commonly used deliver different values and absence of clear, unified labels makes it difficult for end users to choose the most appropriate motor.”
A significant initiative to promote energy-efficient motor systems worldwide and harmonize related standards—called Standards for Energy Efficiency of Electric Motor Systems (SEEEM)—was launched in June 2006 in London. More than 40 international representatives from industry/business organizations, governments, utilities, universities, and energy agencies support SEEEM. The National Electrical Manufacturers Association (NEMA) and the American Council for an Energy-Efficient Economy (ACEEE) are current U.S. participants. “Global cooperative action is needed now to overcome barriers to wider deployment of energy-efficient motor systems, one of which is a lack of harmonization,” said Brunner, who also serves as coordinator for SEEEM.
Harmonizing test methods to ensure minimum energy performance standards (MEPS) for motors is a prime task. North American countries use a rigorous input/output testing method per IEEE standard 112 Method B, while European and Asian countries follow the International Electrotechnical Commission (IEC) 60034-2 testing standard that originally overestimated efficiency values. This was due to assuming that additional stray-load losses are a fixed 0.5% of full load input power (constant over the whole range of motor sizes). Reduced testing cost and time was the motive.
A later IEC standard (61972) adopted an advanced test method compatible with IEEE 112B, but CENELEC (European Committee for Electrotechnical Standardization) refused to adopt this standard in Europe, claiming additional equipment and labor costs. A compromise testing standard, IEC 60034-2-1, which includes methods of IEC 61972, IEEE 112B, and other refinements was published in Sept. 2007 for compliance.
Another notable SEEEM task addresses efficiency classes and promotes greater adoption of MEPS worldwide. IEC 60034-30 (2nd draft status, Aug. 2007) proposes four classes for motors in the 0.75-370 kW (1-500 hp) power range: IE1-standard; IE2-high efficiency; IE3-premium efficiency; and a future class, IE4-super premium efficiency. It harmonizes MEPS motors, such as EPAct, NEMA Premium, and Eff 1/Eff 2 into appropriate classes (see details in table online). IEC 60034-30 covers 60 Hz and 50 Hz motors, and offers mathematical formulas with efficiency curves to simplify usage. Publication is expected by end of 2008.
Beyond motors, SEEEM intends to focus on “core” motor systems (pumps, fans, and adjustable-speed drives), then on “total” motor systems—including heating/process systems, piping, and pumps—for even greater energy savings. That's the ultimate goal of standards harmonization. However, life-cycle cost analysis must play a greater role to overcome the barrier of higher initial cost.
The following table summarizes new proposed IEC efficiency classes for industrial motors worldwide, along with a timeline for adopting minimum energy performance standards (MEPS) by various countries.place before 2008. Double asterisks (**) correspond to passage of a new Energy Bill by the U.S. Congress in mid-December 2007 that includes the provision to lift motor MEPS to Premium efficiency within 3 years.
Harmonized Global Standards
Motor efficiency classification 2008
Sources: “International harmonization of motor standards saves energy,” presented by Conrad U. Brunner, A+B International, at IEEE Industrial Energy-Efficiency Workshop (Baltimore, MD, Oct. 2007) and Control Engineering.
Frank J. Bartos, P.E., is a Control Engineering consulting editor. Reach him at firstname.lastname@example.org .