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Making motors more energy efficient

For most consumers, a single glance at their monthly utility bill provides striking evidence of the need for cheaper alternative energy sources. Yet putting viable new options into widespread use in the U.S. is a formidable challenge, even though many serving in government are keenly aware of the need to develop new power sources. The road to implementing these sources may be uncertain and long.

In the meantime, there is an alternative strategy. Electric motors, such as those in our homes, consume over 25% of the electricity in the U.S. and many operate inefficiently. By dedicating ourselves to maximizing energy efficiency, we can significantly cut the costs of operating the standard electric appliances we all use as well as reducing the amount of energy they consume.

Consider the operation of the single-phase motors that are found in residential and small commercial appliances such as refrigerators, clothes washers and dryers, air conditioning units, pumps, and fans. Such motors are designed to run most efficiently at high loads, usually at least 70% of their full-rated load. Yet in real-world applications, motors often operate at less than 40% of full load for extended periods of time. Future models of these appliances could be made to run more efficiently with the use of a single-phase motor efficiency controller. In addition, existing lines of appliances can be fitted to enhance their efficiency as well.

How does an efficiency controller work? Consider a washing machine: more energy is required when the appliance is filled with many clothes and less when there are just a few items to wash. Yet most washing machines consume more electricity than they need when they are lightly loaded, wasting energy. By contrast, an efficiency controller will provide precisely the right amount of power to the washing machine to meet the demands of its motor at any given time. High-speed response circuits continuously monitor the current and voltage and adjust these accordingly, so that the motor maintains its rated speed and torque under variable loads. More specifically, when the voltage and current sine waves diverge greatly (i.e., when the phase lag increases), the motor is lightly loaded and operating inefficiently. The efficiency controller detects this and reduces the current and voltage appropriately. Conversely, when the load on the motor increases, the device registers this fact and increases the power to the motor so it doesn't stall.

This technology, which Power Efficiency Corporation has patented under the name E-Save Technology, is incorporated into a proprietary motor efficiency controller that is smaller than a business card. The controller is built around modern solid-state electronics, including silicon-controlled rectifiers, a high-speed processor, and power sensors. Our engineers have also written control algorithms that make the voltage and current adjustments faster and more accurate. We tested the controller on multiple motor sizes and has shown energy savings ranging from 10% to 20% at 60% of load to over 50% at no load. Specifically, for washing machines and dryers, testing with this technology has resulted in energy savings of 10% to 30%. Think of it as "cruise control" for electric motors--the amount of energy used by the motor changes according to load, but the speed of the motor always stays the same. (Editor's note: see inside the product--from its analog beginnings based on a device invented by NASA engineer Frank Nola in the 1970s--by watching the short video entitled "Watch PEFF on NASA TV" on main page of company's web site.)

In addition to saving energy, an efficiency controller can extend the life of the motor. A motor's life expectancy is directly dependent on operating temperature; every 10°C rise in operating temperature reduces motor winding insulation life by one-half. Higher operating temperatures reduce bearing life as well, which can considerably shorten motor life expectancy. An efficiency controller keeps the motor's temperature lower and thus helps prolong its use. A controller can also work as a soft starter, protecting motors from inrush currents on start-up.

As we have seen, by implementing technology today that maximizes the efficiency of home appliances, consumers can consume less energy overall while bringing about significant cost savings. Until alternative energy sources become a practical reality in our daily lives, aiming for this goal may be one of the best solutions available for energy conservation in our homes.

Steven Strasser is the chairman and chief executive officer of Power Efficiency Corporation, a clean tech company headquartered in Las Vegas that focuses on energy efficiency technologies for electric motors.

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