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November 2009

Factory Automation

What motor users need to know

Motors manufactured in 2011 and beyond must comply with new rules and regs; efficiency is the watchword

By Kitt Butler

Increase production of renewable energy; increase efficiency of products, buildings, and vehicles; and promote research and deployment of greenhouse gas capture and storage are the bottom line.

The aim of the Energy Independence and Security Act (EISA) of 2007 is to hit that bottom line.

The eventual goal is to move the U.S. toward greater autonomy in acquiring resources to meet its energy needs. The one page of the law that focuses on motor efficiency will significantly influence motor design and selection for machinery designers.

Motors manufactured after 19 December 2010 must comply with the new rules defined in EISA, but that is an issue for OEMs. How will this legislation affect the end user?

First, let us understand the new regulations, which will result in a significant jump in motor efficiency. For instance, a 5.0 hp, 4-pole TEFC induction motor required a minimum efficiency of 87.5% under the old legislation, which mainly applied to three-phase general-purpose induction motors; now it requires 89.5% under the new regulations.

Under the old act, the energy efficiency levels for induction motors were its EPAct levels. The new regulation reclassifies them as Subtype I, so these motors, manufactured alone or as part of another piece of equipment, will be required to have nominal full-load efficiencies that meet the levels for NEMA Premium efficiency.

The new EISA law regulating efficiency created a completely new category of motors for motor designs that previous legislation did not cover.

These motors are called out as Subtype II category and defined as motors incorporating design elements of general purpose motors (Subtype I) but are configured as U-frame motors, Design C motors, close-coupled pump motors, footless motors, vertical solid shaft normal thrust motors tested in a horizontal configuration, eight-pole motors (900 rpm), and polyphase motors with less than 600 volts.

Subtype II motors between 1 and 200 hp, as well as NEMA Design B motors with horsepower ratings above 200 hp and not greater than 500 hp, and fire pump motors are all required to have nominal full-load efficiencies.

In addition to these new laws for polyphase motors, small motors in two-digit frame series (including single-phase) are topics of discussion at a series of public meetings held by the U.S. Department of Energy (DOE) throughout 2009. 

These discussions with motor manufacturers, energy efficiency advocates, and other interested parties are expected to establish minimum efficiency standards for small motors (two digit frame series motors) for the first time.

The DOE is proposing test procedures for measuring the efficiency of small electric motors, including single-phase and polyphase, and to update the industry references and clarify the scope of coverage for the DOE’s existing test procedure for electric motors.

For more information on the progress of that initiative, visit http://www.tinyurl.com/sm-elec-motors.

Top of everyone’s checklist

Prior to this legislation, from an OEM designer’s point of view, motor choice focused primarily, in descending order, on price, size, noise-level, and weight. However, a recent survey has shown those OEMs customers believed availability, reliability, and price were the top three issues.

Until the EISA legislation, neither the OEMs nor their customers considered efficiency important enough to factor into a machine’s overall design. Now, rising energy costs and the new legislation are moving efficiency to the top of everyone’s checklist.

End users will not have to replace machinery currently in use, but if they want to replace a motor in an existing machine, they may have to call the OEM, which will supply them with a motor that meets the most current regulations.

The same expectations of fit and form will need to be met—the new motor may match the performance of the one the end user just took off his machine, and even be more efficient, but it may not have the exact same dimensions.

This may require some “engineering on-the-fly” to make it fit. To make a significant impact, the new regulations must affect all motors covered by the legislation, not just a small percentage.

Depending on the application, it may be more cost-efficient to replace the equipment itself rather than just the motor. This is more likely to occur in machinery run by smaller motors, as opposed to simply replacing the component motor because form and fit will pose a greater challenge in more compact equipment.

With larger motors, this is not so much of an issue—speeds may change, and the new motor may require some different control schemes, but the frame sizes will likely remain the same.

From an end-user perspective, these new regulations will influence pricing. There are more active materials, like copper and steel, in these new motors, and it is safe to presume the OEMs will pass this cost along to their customers.

Because of this, more than ever, end users need to carefully evaluate their options in the repair-versus-replace decision-making process.

Advanced Energy helped pioneer the theories of Motor Management (MM) for end users with its first publication of the HorsePower Bulletin for the DOE in 1991 (www.isa.org/link/HP_bulletin). This document is a useful guide to any facility wishing to implement motor management. Electric motors convert approximately 70% of all electric energy delivered to a manufacturing facility into mechanical energy. 

The purchase price for an average motor makes up approximately 3% of the total lifecycle cost to own and operate. Energy costs make up the rest. Managing motors could pay big dividends in reducing energy costs and increasing process reliability. 

Factors that maximize return

MM refers to understanding, tracking, and making planned decisions regarding any motor population. MM theories have not changed since that first HorsePower Bulletin in 1990, and there are now many tools offered by manufacturers, government, and energy efficiency advocates that address them. 

At its core, MM allows for making good, planned decisions in advance of motor failure to determine if a motor should be replaced or repaired, and having an action plan in place that facilitates that decision.

At the heart of the process is making the repair versus replace decision before a motor fails. The best way to do that is to use motor surveys (www.isa.org/link/Motor_Survery).

When repair is the proper choice, making certain your repair vendors can maintain efficiency is critical to long-lasting performance and keeping energy costs low.

When evaluating a motor application, it is important to not only consider purchase price, but other factors including total life cycle cost, energy costs, ROI, and the like.

Factors that maximize ROI in a motor in terms of efficiency include how many hours per year the motor runs and the cost of energy at your location.

The average motor easily consumes 50 to 60 times its initial purchase price in electricity costs in a typical 10-year lifetime. Most importantly, the capital cost of the new motor represents approximately 2 to 3% of its lifecycle cost. 

Another way to maximize ROI is to inventory motors in terms of which ones operate the most hours and are critical to the process, and replace those motors first.

Focus first on motors that would affect overall productivity and revenue if they experienced any downtime. 

Approximately four out of five motors that fail are repaired rather than replaced. Perhaps these new regulations will raise awareness of the issue and help more motor users put an MM plan into action. Not only can it result in increased productivity and energy efficiency, but it can also result in lower operating and maintenance costs.

ABOUT THE AUTHOR

Kitt Butler (kbutler@advancedenergy.org) is director of motors & drives at Advanced Energy. He is president of the Electric Motor Education and Research Foundation.

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