Drive engineering: More efficient motors
The energy savings potential found in electric motors is enormous. The industry is working feverishly to tap it.23 Feb 2016
The American Council for an Energy-Efficient Economy (ACEEE) recently crowned Germany the “world champion” in energy efficiency. The latest research reports monitoring the transition to renewables sees Germany as being well on the way to achieving its energy efficiency goals. However, a need for action remains.
Around 70 percent of German industry’s need for energy is taken up by electric motors or electromotive systems. According to the German Electrical and Electronic Manufacturers’ Association (ZVEI) around 35 million three-phase motors are operated in Germany; many of them are well over ten years old. Only 15 percent of e-motors are equipped with electronic speed control. And only one fourth of new motors are speed-controlled although the potential savings are enormous.
On January 1, 2015 the second stage of the German motor act entered into law. The first stage, which went into effect in the summer of 2011, called for class IE2 energy efficient drives to be installed in typical industrial motors such as pumps, ventilators, compressors and band-conveyors. Stage 2 stipulates the choice between higher energy efficiency classes IE3 and IE2 with speed control. “New motors placed on the market with a rated output voltage of 7.5 to 375 kW must either achieve an efficiency class rating of IE3 or correspond to an efficiency class rating of IE2, but may then only be operated with an electronic speed controller,” according to the legislative text.
A frequency converter, which adjusts engine output according to need, controls the speed. Corresponding systems are among the most prevalent exhibits at the Motion, Drive & Automation trade fair. Energy efficiency is a key term at MDA 2015. Not only the motor act and diverse energy-efficiency labels are encouraging drive engineers to create new economical e-motors; many manufacturing companies have also set their own targets for power consumption.
One way drive engineering has responded to the desires of users are anti-friction bearings, such as those presented in Hannover by SKF. Unlike SKF standard bearings, which are already considered to be energy-efficient, the new SKF Energy Efficient bearings reduce friction torque by another 30 percent.
"Roller bearings affect energy consumption and the efficiency of drives through friction. Therefore, the desire for users to employ anti-friction bearings is evident,” assets a current whitepaper from Schaeffler Technologies. Schaeffler sees professionally reconditioning anti-friction bearings as one way to increase energy efficiency. “Large, expensive or somewhat worn products in particular can be recycled or repaired after professional examination and cleaning. Instead of ending up with scrap dealers, they could be used for another life cycle,” explains Stefan Trunk of Schaeffler Technologies. Trunk is speaking at the MDA Forum (Hall 24) on April 13 (2:00 p.m.) on energy efficiency and carbon savings by reconditioning anti-friction bearings. Energy efficiency is a key topic at the 2015 MDA Forum. “Energy efficiency in automation – the application is key” is the title of Roland Volk’s talk (Festo) at the forum. Rainer Behrendt of Parker Hannifin addresses whether speed controlled pumps is a solution for energy efficient hydraulic systems.
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