By A PPI Special report
BRUSSELS,
March 3, 2009
(Viewpoint) -
Electric motors are still the workhorses of the pulp and paper business. In fact, motors are estimated to consume nearly 65% of all electricity used in industrial applications. But with energy costs on the rise, energy efficiency is more important than ever.
The good news: new testing standards are eliminating the inaccuracies in performance ratings so customers know exactly what they can expect.
While the true efficiency of motors has traditionally been based on estimated performance versus a highly accurate test method, this is no longer the case. New International Electrotechnical Commission (IEC) standards tighten up testing procedures and require motor original equipment manufacturers (OEMs) to publish more exact efficiency values for their products. For papermakers, this means greater certainty about true performance and expected consumption, as well as a simpler process for selecting motors to meet energy savings goals.
The new IEC standards
Unlike the old standards, which were partly based on estimated values, the new guidelines are actual measured values of losses in the motor, producing precise efficiency values. Thus, measuring winding, rotor and additional load losses are all affected by the new standards. For example, winding and rotor losses will now be based on actual measured temperature rises, recognizing that heat loss is equivalent to inefficiency.
The new standard is defined under two categories:
• IEC/EN 60034-2-1 specifies new rules concerning efficiency testing methods
• IEC 60034-30 defines new efficiency classes for motors, which cover almost all motors.
Prior to the new regulations, estimated additional losses resulted in total losses being calculated too low. As a consequence, IEC/EN 60034-2-1 specifies rules concerning the methods used to determine losses and efficiency, with the objective to calculate efficiency values more accurately. Obviously, the resulting values differ from those obtained under the previous IEC testing standard, IEC 60034-2: 1996.
But while the new figures will be lower, the motor’s design and performance has not changed; the difference is simply from the newly defined testing procedures. Additionally, manufacturers must now publish how efficiency values are measured.
IEC 60034-30 defines three IE efficiency classes for single-speed, three-phase, cage induction motors.
• IE1 = Standard efficiency (efficiency levels roughly equivalent to the existing EFF2 in Europe)
• IE2 = High efficiency (efficiency levels roughly equivalent to the existing EFF1 in Europe and identical to EPAct in the US for 60 Hz)
• IE3 = Premium efficiency (new efficiency class in Europe and identical to “NEMA Premium” in the US for 60 Hz).
What a more accurate efficiency value means
Compared with other machines, electric motors are very efficient, typically 95% for a 90-kW high efficiency motor. Now imagine the large number of motors installed today. Even small changes in efficiency can make a big difference to the industry as a whole in terms of energy saved or consumed. Likewise, electric motors can cost 100 times more to operate over its lifespan than an outright purchase. Thus, knowing the true motor efficiency is a tremendous value for planning replacements or additions, and a more accurate expected cost of operation.
Consider the following scenario in regards to how the IEC standard can be used to help decision making:
Single motor: According to the European Committee of Manufacturers of Electrical Machines and Power Electronics (CEMEP), when a 15-kW motor operates for 6,000 hours per year driving a water pump, an IE2 motor can provide an energy saving of 4 MWh each year when compared with an sub-IE1 motor. (This assumes 4-pole motor operating at full load, efficiency levels of 91.8% for EFF1 and 88.2% for EFF3 motor.
Complete plant: Similarly, a typical medium-sized plant with 149 motors rated between 0.37 and 132 kW could save approximately 3.4% of the annual cost of electricity for its motors by upgrading to EFF1 motors. Even greater savings are possible when energy efficient motors are used in conjunction with variable speed drives.
The effect on OEMS
While the new standard provides a more accurate way for papermakers to assess motors, companies such as ABB are embracing the more thorough testing methods. “We welcome the fact that the efficiency measurement standards for electric motors are becoming more harmonized worldwide,” says Mikko Helinko, senior vice president, research and development coordination for LV motors, for ABB. “We have waited a long time for a level playing field to be introduced.
In conjunction with the standards, ABB also recently announced a new line up in low-voltage AC motors and rearranged its standard motor portfolio into a three ranges: Standard Performance, Industrial Performance and Process Performance. The new products are nearly exclusively rated EI3 and the Standard Performance models include EI2 rated varieties. These kinds of economical options and the accompanying IEC rating, continue to simplify identifying the right motor for every purpose and determining how to best manage energy consumption.
Additional advantages with high efficiency motors
Energy savings are the most prevalent advantage of high efficiency motors. However, papermakers stand to gain more. Electric motors typically operate at cooler temperatures, which mean a longer lifetime and higher reliability with less maintenance. Cooler operation also allows motors to be fitted with smaller fans, resulting in lower noise levels.
By reducing energy consumption and costs, businesses can significantly boost their competitiveness. At the same time, they are also contributing to efforts to protect the environment by helping reduce overall CO2 emissions. It has been calculated that if high efficiency motors were used throughout Europe, energy savings equivalent to the output of several large power stations could be realized, resulting in a dramatic reduction in CO2 emissions. Small changes make an enormous difference.
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