New regulations will improve energy efficiency beyond existing motor efficiency standards
The U.S. Department of Energy (DOE) has been setting energy conservation standards for consumer, commercial, and industrial products and equipment since the Energy Policy and Conservation Act (EPCA) of 1975. These evolving energy efficiency standards affect 90% of home energy use, 60% of commercial energy use, and 30% of industrial energy use.
Not only do these standards cover appliances and equipment, such as heaters, air conditioners, refrigerators, stoves, washers and dryers, and lights—they also include industrial equipment, such as motors, pumps, and compressors. U.S. regulations for motor-driven systems are changing to improve efficiencies beyond individual motors and can be found in energy conservation standards specified in the Code of Federal Regulations at 10 CFR, Part 431—Energy Efficiency Program for Certain Commercial and Industrial Equipment.
Regulations regarding motion control and drive systems are now moving to the forefront following earlier improvements in motor efficiencies. Items listed in Table 1 are in various steps of the DOE’s energy conservation rulemaking process, which will be impacted by the new efficiency standards.
Input welcome for rulemaking process
The motor efficiency and motor-driven systems rulemaking process has just been completed, effective June 1, 2016. The DOE must consider several things when amending or creating a new standard including economic impact, savings in operating costs, estimated energy savings, performance impacts, competition, energy conservation, and other factors.
Based on the EPCA, anytime the DOE establishes or amends regulatory requirements, a four-phase, rule-making process is followed. Each phase starts with a notice with supporting documents and comments, and with each phase, except the last, there is a comment period.
The four phases of the rule-making process occur over about 3 years, during which time the DOE encourages interested parties to participate.
- It starts with the framework phase with a request for information and test procedures to evaluate energy consumption.
- The second phase is the preliminary analysis of the technology and economics of the standard.
- The third phase is the notice of proposed rulemaking and creation and proposal of the rule.
- The fourth phase issues the rule.
The system efficiency requirements are in various stages at this point.
Electric motor efficiency
New DOE regulations require motor manufacturers to comply with efficiency targets. The amended electric motor efficiency standard rule redefines electric motors and establishes new classes of motors as regulated in 10 CFR Part 431, Subpart B, made final in May 2014. Its effective date was June 1, 2016. These new rules cover energy conservation requirements for electric motors with a 1- to 200-hp rating (see Figure 1).
The amended standard requires most single-speed induction motors from 1 to 500 hp to meet the National Electrical Manufacturers Association (NEMA) premium efficiency level. Although the standards for premium efficiency really haven’t changed much, the new standard closes loopholes and extends coverage to a new list of motors not previously covered. However, some motors are not yet affected by this amended standard.
The amended standard only affects motors designed for across the line starting. Inverter quality motors are exempt and probably will be indefinitely for technical reasons. Some of the motors added in the new rules include partial electric motors (gear motors), totally enclosed, nonventilated (TENV) motors, immersible electric motors, and U-frame motors.
The amended standard also helped eliminate loopholes by requiring the premium efficiency level for electric motors with nonstandard base or mounting feet, electric motors with nonstandard endplates or flanges, electric motors with special shafts, and footless motors.
Integral hp rule impact
The integral hp rules will continue to expand in the future as many motors are still not covered but are likely candidates for future regulations. A sampling of motors not covered includes servo motors, synchronous ac motors, medium voltage motors, dc motors, and single-phase enclosed motors.
The integral hp rule’s biggest impact to original equipment manufacturers (OEMs) and end users are related to form, fit, and function. To comply with efficiency requirements, some motors will become larger (often longer) to maintain NEMA size ratings. Some may have to use a larger NEMA frame than previously used, and many will get heavier due to increased use of copper and steel.
Many higher efficiency motors also will have less slip, meaning higher base speed. This could require some machines using motors to be redesigned or have their designs adjusted. Some motors that previously had other design designations may now require NEMA "DESIGN A." These motors often have higher inrush current, which could force design changes.
Premium efficiency motors can cost up to 20% more to manufacture with higher costs to purchasers. Higher costs are often driven by the need for more copper and high-grade steel for laminations. With the U.S. government driving these efficiency rules, U.S.-based manufacturers are jumping on board quickly, while some manufacturers in other countries are having trouble getting their steel up to spec.
Small electric motor rule
Although efficiency standards for small electric motors, both single-phase and polyphase rated from ¼ to 3 hp, were finalized back in 2015, this class of motors is back in the energy conservation discussion. An amended small motor efficiency standard is expected by the end of 2016 or early 2017.
Small motors are being considered for expanded scope coverage as the current regulations are limited to only open drip-proof motors. Many small, special-purpose motors were exempt from the rule, but will now be covered under the integral horsepower rule.
The small electric motor rule will focus on single-phase and fractional-horsepower motors. This small motor rule is a bit more complicated due to the variety of designs available. The use of magnets or electronics to improve efficiency, or multiple horsepower ratings for the same motor frame size, can add confusion to this rule.
All small electric motors imported to or sold in the U.S. must meet the new minimum efficiency standards, which have a big impact on HVAC and pump applications as small electric motors are commonly used in both types of equipment. While some small motors meet the rules, others will need to be re-designed to meet the efficiency requirements. Some other definite- or special-purpose motors are exempt, at least for now.
The premium efficiency motor requirements are based on a line-started, full-voltage motor running at 60 Hz, which covers the majority of motors, but new regulations are in process to cover variable speed motor types and systems.
Inverter-rated motors are designed to produce rated torque at the widest possible revolution per minute (RPM) range. With this wide range as a design requirement, motor efficiency is often a secondary concern. Because VFD output is pulse width modulated (PWM), the motor’s stator and rotor designs are optimized to produce high magnetizing flux when used with a PWM waveform, which often doesn’t coincide with high efficiency.
Other design considerations include electrical insulation rating and higher temperature operation. There are common areas for improvement involving the reduction of electrical and mechanical losses.
These inverter duty motor design considerations are one of the reasons not all energy conservation standards for motors and drives are driven by DOE regulations. Of particular interest to the industrial equipment marketplace is the Air-Conditioning, Heating, and Refrigeration Institute (AHRI) Certification Program for variable frequency drives (see Figure 2) and the VFD test standard AHRI 1210.
Currently, only one manufacturer is certified by AHRI, but Advanced Energy—an organization and test lab that investigates, tests, and implements new technologies for distributed generation, load management, conservation, and energy efficiency—expects to see others soon. The AHRI Certification Program for VFDs requires comprehensive performance tests.
End users can improve the efficiency of machines and processes by requiring suppliers to comply with this specification.
Motor-driven system efficiency
In pump, fan, blower, and other applications, the variable speed use of inverter duty motors makes it very difficult to create charts of efficiencies. For example, at what point does the test provide enough information to benefit the end user? What about the internal mechanics of the pump and its effect on efficiency? When testing, what specific speeds and loads should be used and for how long?
The application determines the speed and current profiles for the system, and these vary, making motor-driven system efficiency rules difficult to create and apply. There are newer regulations in various stages of development for motor-driven systems for "certain industrial equipment." A pump energy conservation standard exists, but it is currently in the rulemaking process and will be amended.
Fan, blower, and air compressor energy conservation standards are also in process, but no final rule has been published as of this writing. The commercial and industrial fan and blower standards are in phase two, which is preliminary analysis. A commercial and industrial air compressor energy conservation standard is also in phase two. These are new standards, so the effective dates for final rules are 2 to 3 years out. The DOE encourages involvement from manufacturers, organizations, and end users throughout this process.
Billions of dollars saved
The laws created by the DOE’s minimum efficiency standards reduce U.S. energy demands and cut greenhouse gas and other pollutant emissions. The DOE’s website notes that these laws saved U.S. consumers $63 billion dollars on utility bills and reduced carbon dioxide emissions by 2.6 billion tons.
Economics, operating costs, energy savings, performance, and other factors are considered as part of the rule-making process when efficiency standards are created or amended. The payback of these efficiency rules is real, and end users save energy and money.
Determining exactly how much is saved requires a deeper dive into each application including analysis of motor type, efficiency, operating hours, load range, energy costs, and other factors. Whether it is a replacement motor or a motor on new equipment, payback from higher efficiency motors is likely in just a few years, with additional savings over the lifetime of the motor.
Brian Sisler is drives, motors, and soft start product manager, AutomationDirect. Edited by Chris Vavra, production editor, Control Engineering, CFE Media, email@example.com.
- The Department of Energy (DOE) has regularly refined its standards for improving energy efficiency for motors.
- Implementing new standards must consider several factors including economic impact and estimated energy savings.
- The DOE’s minimum efficiency standards reduce energy demands and save end users money.
What motor types currently need updates and why?
About the author
Bryan Sisler has been involved in the automation and the electrical/electronic field for 35 years. He started in the U.S. Army in cryptographic equipment and then moved into production management and electrical maintenance management. He has been involved in the automation industry for the last 27 years, many of them specializing in drives, motors, and communications technologies at a variety of large industrial manufacturers and distributors. He is now the AutomationDirect drives, motors, and soft start product manager.
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