Putting a Premium on Motor Efficiency
By James Piper, P.E. - February 2013 - Power & Communication
Motors and the loads they drive represent some of the largest energy users in institutional and commercial facilities today. With many of these loads operating 24 hours a day and 365 days a year, maintenance and engineering managers looking for ways to improve their facilities' operating efficiency are focusing their attention more often on their facilities' motors, where even a small increase in efficiency can result in significant savings.
Today's new-generation motors are quite different from most motors installed in facilities. Improvements in their design and manufacturing have resulted in improved operating efficiencies.
One factor driving this improvement has been mandatory standards for motor performance. The Energy Independence and Security Act of 2007 established the minimum performance standards for a range of motors commonly found in facilities.
As manufacturers have improved their processes by using higher-quality materials and manufacturing techniques, many of the motors available today go beyond these minimum standards. As a result, managers have access to a expanded range of premium-efficiency motors.
Although these motors cost 10-15 percent more than standard-efficiency motors, managers can recover the additional first costs through energy savings, particularly in applications where the motor runs for more than 4,000 hours annually. Managers can expect to achieve a simple two-year payback. In most applications, operating efficiencies will increase 2-8 percent.
The first step for managers trying to determine the best application of premium- efficiency motors is to develop a plan that phases in upgrades of existing motors.
The first step is to identify all motors in the facility. For each motor, record nameplate data, including the motor's horsepower (hp), operating voltage, and operating speed. If the motor is a constant-speed model, measure and record its amperage and power factor, and identify the load it drives and the hours it operates annually, noting if the load is constant or variable.