NWE Currents

Wed, Nov 10 2010

This quarter’s newsletter will feature some events we will be attending in the coming months, and introduction to our new sales representatives, an article on the Energy Independence and Security Act effective December 19, 2010, and an article on variable frequency drive speeds. We would like to thank you for subscribing to this newsletter and hopefully it provides you some helpful information to eliminate some headaches.

Coming Events

Northwest Electric’s sales staff will be attending the Dakota Farm Show held at the Dakota dome from January 4 to January 6. We will also be attending the Nebraska Well Drillers show held at the Lancaster Event Center in Lincoln, NE from February 16 to February 17. Please stop by and say hello!

New Sales Representatives

We would like to introduce you to the newest members of our Northwest Electric team.

David Innis joined the team in August of this year as an Outside Sales Representative; he will be serving the Lincoln, Omaha, Council Bluffs, and surrounding areas. David has been working in the electrical industry for over 15 years and has 9 years of experience as an outside sales representative.

Travis Ellis joined the team in October of this year as an Outside Sales Representative and will be serving the Merrill, IA area, including Sioux City, IA, Sioux Falls, SD, and the surrounding areas. Travis has been working in the manufacturing industry for the past 18 years. He brings with him skills in electrical controls, DC motors, engineering, customer service, and sales.

We are very excited to have David and Travis on our sales team. If you have not had the opportunity to meet them yet, please take the time to meet with them the next time they stop at your facility. Please feel free to give them a call David Innis 402-480-0884 for the Lincoln/Omaha area and Travis Ellis 712-560-5508 for the Sioux City/Sioux Falls area.

We would also like to announce that Brad Engelman has moved to the Inside Sales Representative in our Lincoln branch. He has served the Lincoln and Omaha areas for the last 3 years as the Outside Sales Representative and he served as the Inside Sales Representative in our Omaha branch for a year prior to that. He has 5 years of experience in the electric motor industry and is a strong addition to our Inside Sales team in Lincoln.

Our commitment is to find new ways to better serve you!

NEMA Premium™ Motors: The Future is just around the corner

There is a capital investment that can repay many times its original value over the next 20 years. At the same time, it can improve equipment reliability, reduce downtime and repair costs, and result in lower releases of carbon dioxide to the atmosphere.

The investment is straightforward: install electric motors having the highest electrical energy efficiency commensurate with your needs. Energy-efficient motors pay for themselves in a few years or sometimes even a few months, after which they will continue to pile up savings worth many times their purchase cost for as long as they remain in service. That’s another way of saying that operating costs, not just first cost, are what you should look at when buying a new motor.

The rule applies to all motors, although this article is limited to the widely used motors that fall under the requirements of the Energy Policy Act of 1992 (EPAct) and to those that additionally meet or exceed the National Electrical Manufacturers Association’s NEMA Premium™ efficiency ratings. We’ll explain what the ratings mean in a moment.

Background

Until the energy crises in the 1970s, most general-purpose motors were designed to provide rated output and operating characteristics at a reasonable cost, period. The efficient operation was at best a secondary consideration. As energy prices began rising, however, manufacturers began promoting improved motors they called “high-efficiency” and “energy-efficient”, although the terms were not specifically defined at the time.

Old-style “standard-efficiency” motors remained popular because they generally cost less than the new models. Purchasing agents were seldom inclined to spend a little more money upfront in order to save on energy costs later on. Because of the national energy implications of motor efficiency, Congress enacted the Energy Policy Act of 1992, which granted the USA Department of Energy (DOE) the authority to set minimum efficiency standards for certain classes of electric motors. EPAct rules for motors became effective Oct. 24, 1997. All covered motors sold in the USA after that date are required to have efficiency ratings equal to or better than those listed in NEMA MG 1-1993, Table 12.10. EPAct covers general-purpose motors rated from 1 to 200 hp; 2-, 4- and 6-pole (3600, 1800 and 1200 rpm, respectively); horizontal; T-frame; single speed; continuous duty, 230V, 460V or 230/460V; NEMA Designs A and B. Efficiencies of these so-called “EPAct motors” are from one to four percentage points higher than the previous “standard-efficiency” motors.

EPAct did not bring about the manufacture of an entirely new type of motor; it simply set standards for motors that could be sold in the U.S.EPAct also provided grandfather protection to existing standard-efficiency motors no matter how often they were rewound or repaired.

The New Standard

EPAct was a step in the right direction, but its requirements were based on minimum efficiency levels that industry and the DOE agreed were reasonable at the time. In fact, many motors that were available before EPAct became law exceeded the statute’s minimum requirements, and as motor manufacturers continue to improve their products, they are now able to offer significantly more efficient motors, sometimes at little if any cost premium, model for model.

In June 2001, NEMA granted such “better-than-EPAct” motors special recognition by creating a designation called NEMA Premium™. Going a step beyond EPAct, NEMA Premium applies to single-speed, polyphase, 1 to 500hp, 2-, 4-, and 6-pole (3600, 1800 and 1200 rpm) squirrel cage induction motors, NEMA Designs A or B, 600V or less, (5kV or less for medium voltage motors), and continuous rated. Many motors exceed NEMA Premium efficiency ratings; however, some such motors are manufactured by companies that are not members of NEMA and who may therefore not use the NEMA premium trademark. Other manufacturers, while they may be NEMA members, voluntarily choose not to apply the label to their products. The point is that, while the NEMA Premium label assures the buyer of a certain minimum yet high level of efficiency, lack of the label does not necessarily imply that the motor does not meet the high standards. It, therefore, pays to check nameplate efficiencies and use tools such as MotorMaster+, MotorSlide, or other free publications from the Copper Development Association to help identify those motors that do offer high efficiency, possibly even exceeding that of NEMA Premium.

The Energy Independence and Security Act of 2007 (EISA), which restates and broadens the definition of General Purpose Electric Motors, goes into effect on December 19, 2010. Certain motors “manufactured (alone or as a component of another piece of equipment)” will be required to have nominal full-load efficiencies that meet the levels defined in NEMA MG-1 (2006). Motors manufactured after December 19, 2010, must comply with the law.

For the first time, OEMs will be held accountable for the efficiency of motors in their equipment. With the deadline quickly approaching, motor manufacturers should have an action plan for complying with the law. They should be conducting testing in accordance with the regulations and carefully recording the results. OEMs requiring design changes should be reviewing their options. End users should be paying close attention to the amount of energy their motors consume while researching potential cost-saving programs available.

This new legislation, while vast in scope, is designed to “move the United States toward greater energy independence and security, to increase the production of clean renewable fuels, to increase the efficiency of products, buildings, and vehicles, to promote research on and deploy greenhouse gas capture and storage options.” Specifically, the new legislation restates the definition of General Purpose Electric Motors as defined in 10 CFR 431 from the Energy Policy and Conservation Act of 1992 (EPCA) and classifies these motors as Subtype I.

Additionally, the law also defines a new category of General Purpose Motors, Subtype II, as motors incorporating design elements of a general-purpose motor (Subtype I) that are configured as:

  • U-Frame motors
  • Design C motors
  • Close-coupled pump motors
  • Footless motors
  • Vertical solid shaft normal thrust motor (tested in a horizontal configuration)
  • Eight pole motors (900 rpm)
  • Poly-phase motors with voltage less than 600 volts (e.g., 575 volts)

What does this mean for you?

The standard motor you have been purchasing will now have a higher efficiency which will make it more cost-effective to operate and should, as you change out old motors, begin to lower your overall consumption of energy. The downside is the cost of the same horsepower motor you have been purchasing will be higher. To meet the new energy standards the government has put into place has caused the manufacturing cost to go up, which in turn gets passed on to the consumer. The bright side to this, as I stated earlier, in lowering your energy consumption you should get the additional cost of the motor back in energy savings. If you would like additional information please contact your Northwest Electric sales representative or the branch office closest to you.

Controls Spotlight - How Slow Can You Go

A very common question that often arises when dealing with variable frequency drive applications is “What is the speed range my motor is capable of?” in essence, how slow can you go? The most important consideration with reducing the speed of an electric motor is thermal management. For a standard OPD or TEFC motor, there is a fan attached to the shaft that circulates air through or over the motor to help keep it cool. As the speed of the motor is reduced, the cooling capability also decreases. To help guide the user most manufacturers will rate their motors speed capabilities by way of an allowable speed range or turndown ratio. This ratio is the amount of speed reduction that the motor is rated to safely handle the load. Common turndown ratios are 10:1, 12:1 or 1000:1, however, most users do not really understand what this means for their applications. Let’s look at an example of a 1800RPM motor rated for at 10:1 speed ratio. This motor is rated to handle a load down to 180 RPM or down to 6Hz. WEG rates most of their non-vector motors at a 12:1 turndown ratio which means they are suitable to operate a 1800RPM motor down to 150RPM or to 5Hz. A turndown ratio of 1000:1 to one is really a manufacturer’s way of stating that the motor is considered a “Vector” Motor. Many vector motors will have external constant speed blowers to help keep them cool or will have large cooling fins for more effective heat transfer. These motors are used for special applications that require an extremely slow operation or the ability to develop holding torque and zero speed.

To calculate the minimum safe speed for a motor using the turndown ratio use the formula Base Speed / TurnRatio = Minimum Speed, for example, a 1800RPM rated 12:1 it would be 1800/12=150. In order to properly determine the safe operating speed range of a given application, there are several factors to consider. Firstly, what is the application and will the application be such that it determines the minimum and maximum speed range. One common example is in pumping applications, the speed range of the system is often dictated as a result of the pump dynamics and sizing. In pumping applications, the power required increases with the cube of the speed increase. As a result, most pumping applications can only be run a few percents over rated speed without causing an overload condition. On the slow side of a pumping application, below 25-30 Hz a pump will typically not produce enough stable flow to allow for safe operation. In this example, the application will dictate a speed range of approximately 25Hz - 65Hz or 750 - 1950 RPM. With other types of applications such as hoists, web tension and others where slow speed or the ability to hold a load in position at no speed is required the motor and VFD control type need to be carefully specified. These applications will often require a vector motor and closed-loop operation for increased accuracy.

If you have any questions contact our Advanced Controls Group at 402-858- 5560 or visit them online at www.advancedcontrolsgroup.com.


Sincerely,
Northwest Electric

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