Minimum Efficiency Standards for Electric Motors to Increase – DOE

DOE’s analyses estimate lifetime savings for electric motors purchased over the 30-year period that begins in the year of compliance with new and amended standards (2016-45) to be 7.0 quadrillion British thermal units (Btu). The annualized energy savings—0.23 quadrillion Btu—is equivalent to 1% of total U.S. industrial primary electricity consumption in 2013.


>” Nearly half of the electricity consumed in the manufacturing sector is used for powering motors, such as for fans, pumps, conveyors, and compressors. About two thirds of this machine-drive consumption occurs in the bulk chemicals, food, petroleum and coal products, primary metals, and paper industries. For more than three decades the efficiency of new motors has been regulated by federal law. Beginning in mid-2016, an updated standard established this year by the U.S. Department of Energy (DOE) for electric motors will once again increase the minimum efficiency of new motors.

The updated electric motor standards apply the standards currently in place to a wider scope of electric motors, generating significant estimated energy savings. […]

Legislation has increased the federal minimum motor efficiencies requirements over the past two decades, covering motors both manufactured and imported for sale in the United States. The Energy Policy Act of 1992 (EPAct) set minimum efficiency levels for all motors up to 200 horsepower (hp) purchased after October 1997. The U.S. Energy Independence and Security Act (EISA) of 2007 updated the EPAct standards starting December 2010, including 201-500 hp motors. EISA assigns minimum, nominal, full-load efficiency ratings according to motor subtype and size. The Energy Policy and Conservation Act of 1975 also requires DOE to establish the most stringent standards that are both technologically feasible and economically justifiable, and to periodically update these standards as technology and economics evolve.

Motors typically fail every 5 to 15 years, depending on the size of the motor. When they fail they can either be replaced or repaired (rewound). When motors are rewound, their efficiencies typically diminish by a small amount. Large motors tend to be more efficient than small motors, and they tend to be used for more hours during the year. MotorMaster+ and MotorMaster+ International, distributed by the U.S. Department of Energy and developed by the Washington State University Cooperative Extension Energy Program in conjunction with the Bonneville Power Administration, are sources for cost and performance data on replacing and rewinding motors.

Improving the efficiency of motor systems, rather than just improving the efficiency of individual motors, may hold greater potential for savings in machine-drive electricity consumption. Analysis from the U.S. Department of Energy shows that more than 70% of the total potential motor system energy savings is estimated to be available through system improvements by reducing system load requirements, reducing or controlling motor speed, matching component sizes to the load, upgrading component efficiency, implementing better maintenance practices, and downsizing the motor when possible.”<


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Energy Efficiency in Buildings – How VFD’s Save Energy

Have you wondered why Pumps and Fans are such a great opportunity to save energy using variable speed drives? ABB can help you estimate your energy savings a…


>”  Efficiencies of Motors and Drives

The full load efficiency of AC electric motors range from around 80% for the smallest motors to over 95% for motors over 100 HP. The efficiency of an electric motor drops significantly as the load is reduced below 40%. Good practice dictates that motors should be sized so that full load operation corresponds to 75% of the rated power of the motor. […]

The efficiency of an electric motor and drive system is the ratio of mechanical output power to electrical input power and is most often expressed as a percentage.

Motor System Efficiency =Output MechanicalInput Electrical x 100%

A VFD is very efficient. Typical efficiencies of 97% or more are available at full load. At reduced loads the efficiency drops. Typically, VFDs over 10 HP have over 90% efficiency for loads greater than 25% of full load. This is the operating range of interest for practical applications. […]

The system efficiency is lower than the product of motor efficiency and VFD efficiency because the motor efficiency varies with load and because of the effects of harmonics on the motor.

Unfortunately, it is nearly impossible to know what the motor/ drive system efficiency will be, but because the power input to a variable torque system drops so remarkably with speed, an estimate of the system efficiencies is really all that is needed.

When calculating the energy consumption of a motor drive system, estimated system efficiency in the range of 80-90 % can be used with motors ranging from 10 HP and larger and loads of 25% and greater.

In general, lower efficiency ranges correspond to small motor sizes and loads and higher efficiency ranges corresponds to larger motors and loads.

b. Comparison with Conventional Control Methods

Estimating Energy Savings

Fans and pumps are designed to be capable of meeting the maximum demand of the system in which they are installed.

However, quite often the actual demand could vary and be much less than the designed capacity. These conditions are accommodated by adding outlet dampers to fans or throttling valves to pumps.

These are effective and simple controls, but severely affect the efficiency of the system.

Using a VFD to control the fan or pump is a more efficient means of flow control than simple valves or inlet or outlet dampers. The power input to fans and pumps varies with the cube of the speed, so even seemingly small changes in speed can greatly impact the power required by the load. […]

In addition to major energy savings potential, a drive also offers built-in power factor correction, better process control and motor protection. […]”<*

* Extracted from:

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Infographic – Energy Efficiency – Variable Speed Motors & Drives

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Infographic – Energy efficiency. A solution.

Duane Tilden‘s insight:

Industry has been reported to consume between 40 and 60% (UN Report) of the world’s electrical supply.  Motors are the largest consumer of the industrial electrical supply and the greatest opportunity for industry wide savings.

Many motors are over-sized and run inefficiently.  Variable speed drives can significantly reduce industrial operating costs, with attractive payback period and reductions in energy consumption by up to 50% or more.

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