Power trip
Petrak, Lynn
PROCESSING
TECHNOLOGY
Motors and drives can save usage and cost with minimal investment and operational impact
Energy costs are rising. Across the country, various power sources have grown unstable, from overtaxed regional power grids to natural resource shortages to uncertainties related to geopolitical upheaval. Government agencies and grassroots groups are urging conservation whenever possible. At the same time, manufacturers are under pressure to maintain or boost throughput, while finding ways to cut expenses, modernize facilities and still play their part in energysaving efforts.
The good news is that one part of the solution to energy-related concerns may be as simple as the equipment that sustains automation and product flow. Motors and drives – the workhorses of many dairy plants – can play an important role in lowering kilowatt hours.
Some have gotten the message and are spreading it. A campaign called “Motor Decisions Matter,” formed with the Boston-based Consortium for Energy Efficiency and various government, business and advocacy groups, aims to boost awareness of motorrelated decisions among industrial energy users. The campaign often repeats an estimate by the U.S. Department of Energy (DOE) that although U.S. manufacturers spend more than $33 billion a year on electricity, only 12 percent of energy customers consider the lower energy operating costs of new motors.
John Morehead, vice president of marketing and sales for Chicago-based Bodine Electric Company, often takes advantage of information provided the by Motor Decisions Matter campaign. Although Bodine Electric produces smaller-scale electric motors that are less than one horsepower (HP), like those used in beverage mixing machines, Morehead believes that even small changes have an effect. “As time goes on, people will start to look for more efficiency improvements and will look at small motors they use,” he says. “And the issue is not only motors, but also about variable speed – the idea that there is no reason to keep a pump operating at full power when it can be adjusted to a lower level.”
Manufacturers have a vested interest in using the most efficient motors and drives, according to Morehead. “I think in every area today, people are looking for smaller, faster, lighter and cheaper. And cheaper not only applies to cost of the appliance, but the operating costs associated with it,” he says.
Likewise, Mark McElhinny, business manager for food and beverage for Rockwell Automation s Reliance Electric and Dodge division, Greenville, S.C., stresses that efficient motors and drives can be a strategic business issue. “Up to 60 percent of energy consumed (in a plant) is typically through the motors,” he says. “What you have is a large amount of energy consumed in industrial motors, yet you also have an opportunity to optimize their efficiency.”
One of the first steps in increasing efficiency through motors and drives is to conduct a thorough energy assessment. “If they want to update their systems from an efficiency standpoint, we can go there and provide an energy study,” suggests Stan Ho, product line manager for Rockwell Automation’s controls division, Mequon, Wis. “We look at things like, What equipment is causing them to pay over the norm in energy usage?’ ‘What are the peak hours?”‘
The Industry Revs Up
Motors, which supply the power used to run manufacturing facilities, and drives, which regulate the speed and efficiency of the motors, can be found throughout a dairy plant. A fluid milk facility with a significant amount of pumping capability generally has more motors. Other operations, such as cheesemaking or ice cream plants, also run a number of motors in varying speeds and sizes.
Compared to other manufacturing environments, dairy facilities have their own set of challenges, for both energy usage and equipment setup. “Most dairy plants are in remote areas, having less than ‘clean’ power,” says John Walker, sales manager for Exlar Corporation, Chanhassen, Minn., a supplier of linear and rotary solutions and servo actuators for motion control. “Dairies typically use caustic chemicals for clean up, as well as vary hot solutions. Many times the temperature of the facility is quote low. This causes a situation where a motor or actuator is quickly taken from a cold temperature to being doused with hot, caustic solution. We spend much of our design time on sealing these environments.”
McElhinny agrees that dairy sites can be unique, and cites some trends affecting the industry’s energy needs. “Consolidation, flexibility and sanitation are three things we see as paramount in talking with folks in the dairy industry,” he says.
According to McElhinny, motors and drives have been impacted by the spate of organizational consolidations over the past few years. “You have major companies buying other companies, and with that you get asset rationalization – they say, ‘We want these plants running between 60 and 85 percent efficiency,”‘ he says. “You also find that they are trying to design their lines to run more flexibly.”
Although not an obvious link to energy savings, sanitation is a major factor in determining what motors or drives to use in a dairy plant. “Sanitation and cleanliness are still a primary priority,” says McEhlinny. “The motor may be in a washdown area that they want to be as cleanable as possible.”
Ho also underscores the importance of sanitation. “Dairy has very strict standards for sanitation requirements and that has forced manufacturers like Rockwell to review products for this industry,” he says.
Indeed, for many dairy customers, the use of motors and drives can hinge on a host of factors. According to Steve Litzau, a soft starter product manager for Rockwell Automation’s industrial components group, Milwaukee, each operation ultimately has its own requirements. “It is dependent on what type of electricity people are using and on the area of the country,” he says. “A power company can say that on their grid, you have to bring up power gently so there won’t be a brownout. Or if it is generator power, the situation in the Middle East could have an effect on their operation.”
Driving Force
Motors may do the work, but drives control their efficiency. At a time when energy costs are up and budgets are tight, suppliers have been working to provide “smarter” drives for optimum energy use.
One example is a line of variablespeed PowerFlex(TM) drives introduced by Rockwell Automation’s AllenBradley division. As Ho points out, a variable frequency drive (a VFD, also known as an inverter drive) can seem like a small change but makes a big difference. “When you start a motor, you typically give it as much juice and power as you can, and that is often not the most efficient way to do it. When a line is running half or three-quarters speed, you end up supplying all that energy and only getting a little work out of it,” he says. “A variable frequency drive provides just enough energy to sustain the load.”
According to Ho, a VFD can save kilowatt hours, and in turn, energy costs. In addition, as dairies continue to consolidate and produce a greater variety of products, such drives can help a manufacturer adjust accordingly. “Flexibility is one feature that a variable frequency drive can bring,” he says. “For example, when you change different products on a line, you have to be able to adapt to have a motor at 1800 RPM and one at 900 RPM.”
Ho cites the PowerFlex 40 as an example of a VFD suitable for a dairy plant. “That is our next generation of product, and will be released in the next few weeks,” he says, adding that one of the attributes of the drive is its ability to calculate digital inputs without the need for a separate logic controller.
Another provider of motor and drive combinations is WEG Electric Motors Corporation, Suwanee, Ga. WEG drives are made to be used with the company’s three phase motors. One of the latest examples is WEG’s Shark(Tm) adjustable speed drive, designed as a companion to the company’s stainless steel Shark motor. According to company spokesman Tom Ristow, the Shark drive offers other benefits relevant for food and beverage processors. “This drive is, as far as we know, the only one offered in a fully stainless steel enclosure, so it will stand up to moisture and washdowns, where those conditions exist,” he says. Other energy-efficient WEG drives include the Vectrue drive, with a variety of efficient control features, and a CFW-08 Plus drive, a “micro drive” designed for use with motors up to 10 HP.
Bodine’s Morehead is another proponent of VFDs. “When you are operating a motor with variable speed you have more flexibility,” he says. “The equipment can have more features; and variable speed can prolong the life of equipment.”
The advent of soft-starter controls has helped make drives even more efficient. Launched only a few months ago, Rockwell Automation’s SMC-Flex (part of the Smart Motor Controller line) is a soft starter that offers a variety of motor starting and stopping methods for customized applications. “We provide a means for soft starting a motor so there isn’t a lot of mechanical or electrical wear and tear on a motor system,” says Litzau. “We also have an energy saver feature; so our products can reduce the amount of current going out to the system. There are a good number of people taking advantage of that.”
Energy-Efficient Motors
If equipment makers are designing soft starters and drives with greater energy efficiency, motors are generating even more attention. As the Motor Decisions Matter campaign emphasizes, premium efficiency motors may be more expensive, but the investment is “insignificant compared to the amount of energy costs the motor will save in the long run.” (By definition, premium efficiency motors exceed the minimum standards required by the federal Energy Policy Act of 1992 by a significant margin.)
WEG offers several premium efficient motors, ranging from one to 500 HP. “These motors are, you might say, beyond high efficiency – they push the efficiency envelope up to levels that qualify for things like utility rebates, in regions of the country where they are available,” says Ristow, adding that the motors are available in both drip-proof and enclosed fan-cooled frames.
In a dairy plant, according to Ristow, premium efficiency motors are most applicable to pumps, fans, conveyors or other applications where motors run for several hours a day. “In those cases, their extra cost can be most easily paid back in energy savings,” he says. For operations with frequent washdowns, WEG also supplies a line of Shark(TM) motors encased in a fully stainless steel exterior.
Exlar also has launched several energy-saving motors, including segmented lamination brushless servo motors. “These motors are more thermally efficient than traditional brushless motors, and allow for the customer to receive higher performance in the same package size,” explains Walker, adding that the motors also include thermally conductive insulating features that conduct heat away from the source.
As one of the nation’s largest motor and drive companies, Rockwell Automation offers highly efficient motors in a variety of sizes and potential applications, in both smooth-frame cast iron and finned surfaces. “If we were to pinpoint just the motors part of our business, we like to talk about our finned products. These motors are our premium efficiency motors, designed for the best efficiencies with variable frequency drives,” says McElhinny. “The fin frame allows the motor to conduct and convect heat, which smoothbody motors don’t do as well. The heavy cast-iron surfaces meanwhile, are among the most robust.”
According to McElhinny, Rockwell Automation is able to provide integrated energy solutions, from starters, drives and motors to gear reducers and synchronous belt drives. “We are a fullline automation supplier. We try to power match, whether it’s an AllenBradley or a Reliance VFD, with the right kind of motor and right kind of reducer,” he says, noting that upgrades are frequently customized by need and priority. “We provide customers with modernization solutions. For example, you may not have to change a pump or conveyor but your HP and speed have changed, so we recommend a different drive solution to manage that.”
The energy situation – while not yet a broad-based crunch – is expected to continue to be sporadically uncertain. As manufacturers seek to save and conserve energy wherever possible, motors and drives are warranting a close look. “They are getting involved in it,” says Ho of dairy operators. “My experience is that plant owners look at it from two ways – one is uptime and one is throughput. When they think of the technology available for more uptime and throughput, they become aware of this.”
Lynn Petrak is a freelance journalist based in the Chicago area.
Copyright Stagnito Publishing Mar 2003
Provided by ProQuest Information and Learning Company. All rights Reserved
