Efficient Electric Machines | Fabrication.net


Energy efficient motors, which can be two to eight percent more efficient than standard motors, owe their superior performance capabilities to new technologies and improvements in design and manufacturing.

Motors are found in a variety of industrial applications, powering everyday tools such as fans, blowers and pumps. According to the US Department of Energy, more than half of all electrical energy consumed in the United States is used by electric motors. And the National Electrical Manufacturers Association says electric motor systems account for 70 percent of manufacturing electricity use, presenting one of the greatest opportunities for energy savings and efficiency. Therefore, in the face of economic uncertainty and increasing sustainability initiatives, motor efficiency and lifetime energy consumption should be a major factor in the decision-making process when making a new purchase versus when rewinding a motor.

Energy efficient motors, which can be two to eight percent more efficient than standard motors, owe their superior performance capabilities to new technologies and improvements in design and manufacturing. Better electrical steel and more copper in the winding help reduce energy loss from a motor, which requires a smaller fan to dissipate heat. Neodymium magnets, which are used in electric vehicle motors, can produce motors with higher power density, higher power in a smaller frame. Manufacturing motors with low electrical loss steel and thinner stator sheets can reduce electrical losses. Lengthening the core and using more aerodynamic cooling fans can further reduce energy waste. Energy efficient motors, although more expensive initially, have longer insulation and bearing life, less vibration, and increased lifetime reliability.

“The purchase price of the motors is only about 2% of their cost of life based on a 20 year lifespan,” says John Malinowski, senior product manager, AC Motors at Baldor Electric Company. “Compared to the purchase price of an engine, the electricity to run the engine continuously is about 11 times the purchase price. Beyond the first thought on costs, a manufacturer could save thousands of dollars per year in energy costs alone.

The technological threshold

The NEMA Motor and Generator Section has implemented an Energy Efficient Motor Program to provide standardized, energy efficient products based on a consensus definition of “high end efficiency”. The US Department of Energy also continually encourages engine manufacturers to improve their efficiency, but Malinowski says, “We’re just about at the technological threshold, it’s gone.”

He adds that engine builders are now exploring new technologies for future industrial engines, such as making them with neodymium magnets, which results in a more power dense and high efficiency engine. “Although these motors are very efficient, their return on investment has been prolonged due to China’s rising costs on magnetic materials,” he said.

A fuel-efficient engine can be up to 96 percent efficient, but the potential of an efficient engine will go unnoticed if other system components are only running at 50 percent efficiency. Manufacturers who want to maximize the efficiency of their processes consider all possible opportunities, not just the engine. “You have to look beyond just replacing components,” says Malinowski, and advises manufacturers to look at the entire motor system, which may include the power distribution transformer, smart starter, or variable speed drive. , the electric motor, the mechanical power transmission components, as well as the driven load.

The efficiency of the driven load defines the level of power required to drive the device, and an older pump or compressor may not be as efficient as newer technology available today. Switching to a new pump or compressor can reduce engine power rating. An older gearbox, used to connect the motor to the load, can have an efficiency rating of 50-60%, while a new gear can have an efficiency of 95-96%. Upgrading to a newer helical or bevel gear can cut engine size and horsepower requirements almost in half.

“Although the systems are more complicated to make, this is where the real fruits are at your fingertips today,” says Malinowski. To help customers assess the energy needs of their motor and associated systems, Baldor Electric’s energy assessment teams are available to review the processes currently in use and see if there are opportunities to save energy. and increase productivity.

The real enemy of an engine

While power consumption is a major concern with engines, Malinowski says that “the enemy of an engine is heat really. It’s heat and friction. He explains that for every 10 degrees C hotter the engine gets, the life of the insulation is cut in half. Bearings heat up more, reducing grease shelf life and increasing the risk of bearing failure. Malinowski says the main cause of engine failure is that the bearings are poorly greased, with too much, too little, or an incompatible type of grease.

“Preventive maintenance is therefore good,” he adds. A number of new monitoring systems are available today that can now monitor bearing temperatures, vibration levels, resistances and ground level voltage. Once limited to large, critical industrial engines, this level of monitoring is increasingly available for smaller, less integrated engines. Wireless connectivity options are also being introduced, further expanding once-prohibitive monitoring options by cutting the thousands of feet of wire that would be required to connect a motor to the control room.

Motors have a significant impact on the total energy consumption of an industrial manufacturer, and as more manufacturers seek to maximize the efficiency of their processes, more efficient motors and systems will become a priority. And a good preventive maintenance program will help improve system reliability.

Malinowski says, “As people learn how to do these things and get adopted, it will be a good thing. “

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