July 2010

On rotating lubricated machinery oil cleanliness, oil sampling, and oil analysis are generally recognized as the cornerstones for what’s known as “reliability centered maintenance.” For this reason most manufacturers of powertrain components and industrial gearboxes specify oil cleanliness levels in their warranty, but few make provisions for implementing the necessary maintenance procedures. That’s why you need to know about kidney-loop filtration.

For installations that work 24/7, the best choice for extending the service life of a critical gearbox is a kidney-loop filtration unit; the oil dialysis machines for lubricated machinery. Most discussions on this system will focus on the filtration unit, and not on the gearbox it services. A more meaningful discussion will start with the gearbox and lubricating oil, ending with the filtration system that best meets the requirements of the job.

The Gearbox
For most gearboxes mechanical reliability starts with an air breather that vents the inside air space to the outer atmosphere. Without a clean and well-functioning air breather daily temperature fluctuations can generate a pressure rise or a vacuum inside the gearbox. Both are a leading cause of premature seal failure, and too often the original air breather is not up to the job. Figure 1

Generally the vent port is also used for the oil fill port, and it is the only access port on top of the gearbox. In addition to this top port there will be one or more bottom drain plugs, and possibly a side port with a sight glass to check the oil level for the safe and continuous operation of the gearbox.

A kidney-loop filtration system is totally independent of the designed lubrication system for the gearbox. It can be turned on or off, or it can run continuously without compromising the lubrication requirements of the gearbox. When turned on the kidney-loop system must insure that the oil removed from the gearbox for polishing is returned at precisely the same rate. To add the benefits of this filtration system to any gearbox there are three prerequisites: a high-quality air breather to protect the air space above the oil; an oil outlet at the bottom of the gearbox for the suction hose to the filtration unit; and an oil inlet on top of the gearbox for the return hose from the filtration unit.

Oil Viscosity and Lubricating Oils
A youngster may not have heard of Sir Isaac Newton or viscosity, but he understands fluid mechanics when he chooses the big straw over the skinny one every time. Viscosity is a measure of fluid friction, and it is resistance to flow within a controlled space at a given temperature. A kidney-loop procedure will be most effective when the lubricating oil is in full circulation, at normal operating temperature, at its lowest viscosity, and with the gearbox operating at full load. Figure 2

Working back from the gearbox, the first consideration for an efficient kidney-loop filtration system is the connecting hoses and fittings. The next challenge is using the fewest connections, with limited twists and turns and the shortest hoses. But the biggest challenge is getting the filter cart as close to the gearbox as possible while keeping safety for the service technician, the machinery, and the environment front and center.

Filtration and filter media technology have improved immensely since inline oil filters were first introduced decades ago. At the time it was well understood that a machine would run longer on dirty oil than it would on no oil. Filter heads were fitted with a bypass mechanism to maintain an uninterrupted flow of lubricating oil even when the filter element was plugged with contamination. Today the filter heads used on most filter carts are essentially unchanged.

True kidney-loop filtration is independent of the machine’s normal lubrication system. The logic of this type of system says that a filter in bypass is no longer part of the solution, it’s part of the problem since unfiltered oil is being circulated back to the gearbox.

Filter Carts
There will always be a debate over the type and number of filters used on a filter cart. The most common filter carts use two 5-inch diameter spin-on oil filters. The first oil filter is called the prefilter, and the second is called the final filter. Each filter head will have a filter condition indicator and a bypass mechanism, usually rated for 25 psi. When the bypass valve begins to open in the prefilter, unfiltered oil passes through to the final filter. At this point the filter cart is effectively a single-filter unit.

The gearboxes that keep a facility up and running are not in the maintenance shop. They are on a crowded operating floor, on an overhead catwalk, at the end of ship loading boom, or 200 feet straight up in a wind turbine. The filter cart has to be pushed, pulled, or dragged to wherever the gearbox is located. Figure 3

Changing out an oil filter is a messy business and best done in the maintenance shop, not on the operating floor. Back in the maintenance shop the real question is more than the time and cost of changing out just the prefilter or both filters; change only one and there is the risk of cross blending oil grade specifications if the filter cart is used on other applications. And then there is always the cost of the waste and disposal of a gallon or more of lubricating oil.

The Kidney-Loop Filtration Unit
For lubricating oils with a wide range grade specifications and viscosities, pump selection becomes an important consideration. The heart of a kidney-loop filtration system is the pump, and the heart of a pump is the rotating group. Figure 4

A fluid can only flow downhill, or move to fill a vacuum. The pump’s rotating group is turned by an electric motor to create a partial vacuum on the suction side of the pump. The vacuum draws lube oil out of the gearbox through the suction hose to the inlet port of the pump, where it fills the cavities of the rotating group. The rotating group carries the oil over to the pressure side of the pump, forcing it through the filter and the return hose back into the gearbox. The performance and efficiency of the pump is determined by the amount of oil that reaches the pump and completely fills each cavity in the rotating group. With the viscosity of the oil specified by the gearbox manufacturer, the four external factors that influence the performance and efficiency of the pump are: the inside diameter of the suction hose; the length of suction hose and number of connections; the type and configuration of the pump’s rotating group; and the speed of the pump’s rotating group.

The most common pump is the gear pump. It works well with hydraulic oil and lighter lubricating oils. By design, it has a limited range for lube oils. The small cavities created by the internal spur gears, the close tolerances required for higher pressure, the knife-edge gear tooth form, and the fixed outer gear housing all combine to severely limit its suitability for the higher-viscosity oils.

The rotating group of a gerotor pump—sometimes called a crescent pump—is better suited for higher-viscosity lube oils. The motor-driven internal gerotor drives the external rotating gerotor to create larger and fewer cavities with rounded corners. This rolling action of the two gerotors creates cavities that open and close more smoothly. This significantly reduces the shearing of the lube oil in the pump, reducing noise, aeration and cavitation, and delivering a ripple-free oil flow. This puts less stress on the filter media, increasing the dirt-holding capabilities of the filter media. Turning the rotating group at a lower rpm improves all aspects of the pump’s performance, particularly at the higher end of the viscosity curve. Figure 5

The most important feature, however, is having an adjustable relief valve built into the pump housing. This eliminates the need for a bypass valve in the filter head and insures that only polished oil can be returned to the gearbox. When the relief valve is set at 60-80 psi it significantly increases the dirt-holding capacity for an oil filter that would otherwise bypass at 25 psi.

Workplace Productivity
For the service technician, maximizing productivity is essential. One feature of a kidney-loop filtration system that can pay huge dividends is a secondary output flow path. Some gearboxes will have to be drained and the oil transferred to secondary containment, allocated to different applications, or disposed of. By selecting the secondary flow path the used oil can be drained off without fouling the main oil filter. The second outlet can also be fitted with a backup oil filter on the operating floor to continue with kidney-loop filtration without the need to retune the filter cart to the maintenance shop for servicing.

The idea of harnessing the power of the wind continues to grow in popularity, presenting a viable source of clean, emissions-free power and leading to an increase in the number of installed wind power projects each year. As a result, quality installation locations with sufficient wind power are getting harder to come by.

According to the AWEA Small Wind Turbine Global Market Study for 2010, “Despite an economic downturn, the U.S. market for small wind turbines—those with rated capacities of 100 kilowatts (kW)1 and less—grew 15 percent in 2009 with 20.3 megawatts (MW) of new capacity and $82.4 million in sales. This growth equates to nearly 10,000 new units and pushes the total installed capacity in the U.S. to 100 MW.2.” Figure 1

Whether you are planning a shopping mall or a wind farm, one of the most important factors to take into consideration is the location. With a growing number of companies cashing in on subsidies and tax incentives, there is a greater demand for quality wind project installation sites. There are several factors to consider when deciding on a location for a small wind turbine including local design wind speeds, soil conditions, geographic location, the size, shape, and distance of surrounding objects within 500 feet, site excavation/preparation needed, accessibility of the site, and the overall distance that generated power will be transmitted. Each of these factors can play a critical role in determining the feasibility of a location supporting a wind turbine.

For example:
• The size and shape of surrounding objects may prevent sufficient wind from reaching the turbine, thereby reducing productivity and thus the ROI on the project;
• Some potential sites may be very difficult for concrete mixer trucks to access to pour the foundation;
• Some potential sites may have a ground surface that is impenetrable such as environmentally sensitive sites or mountainous, rocky regions where ground excavation is not practical.

While some of these factors can be reason enough to look somewhere else for a suitable location, some locations are worth the effort involved in getting the turbine installed in the right place. In some wind shear sites the wind speed can increase by 20 percent, and the power output by 34 percent for every 10 meters in elevation. The right location can make all the difference.

Small and community wind turbine systems can be supported by a variety of different foundation types depending on the soil, turbine height, and regional wind loads. Some of these support methods include driven piles, concrete piers, single piece poured in-place foundations, single piece precast foundations, and modular precast foundations. Figure 2

Of these foundation methods, the one foundation system that has been getting the attention of designers and developers of wind turbine installations is the precast modular foundation. This is happening for several reasons, primarily because they are non-ground penetrating and can simply be placed in location with minimal site preparation. This makes them perfectly suited for use in locations where ground penetration is either not allowed—such as landfill or environmentally sensitive applications—or impractical due to hard to penetrate ground conditions.

Besides the previously mentioned subsidies and tax incentives the EPA has announced that they are behind the push for renewable energy projects on environmentally sensitive sites, such as landfills or Superfund sites. The following statement was issued by the White House in 2009: “President Obama and Congress are pushing to identify thousands of contaminated landfills and abandoned mines that could be repurposed to house wind farms, solar arrays, and geothermal power plants.”

The Environmental Protection Agency (EPA) made this statement the same year: “The EPA is encouraging renewable energy development on current and formerly contaminated land and mining sites. The EPA has identified thousands of properties that could potentially host solar, wind, or biomass energy production facilities. The EPA used information on properties from several land cleanup programs, including abandoned mine lands and lands under EPA’s Superfund, Brownfields, and Resource Conservation and Recovery Act programs.” Figure 3

Environmentally sensitive sites such as landfills and contaminated Superfund sites are ideal candidates for renewable energy because they are considered already disturbed lands and thereby relieve the pressure associated with developing on undisturbed or uncontaminated lands. However, many of these sites do not permit or allow ground penetration for obvious reasons. Once you get past the three feet of top cap soil you reach the contaminated soil below. This is one of the main benefits to using precast modular foundations on these types of sites: they never penetrate the soil. Additional areas where precast modular foundations are finding success include installations going in over bedrock—where penetration is difficult, if not impossible—installations with high water tables, and installations with adverse soil conditions such as corrosive soils or soils with poor passive earth-pressure characteristics. In addition to not penetrating the ground, precast modular foundation systems offer a variety of other benefits such as:

• Can be installed in remote locations where mixer trucks typically are unable to reach;
• Reduced site excavation/preparation needed;
• Speed of delivery and installation;
• Eliminates the need for cast in place concrete and all associated issues including forming, pouring, and dry time which can dictate the pace of the installation process;
• Accommodates most site locations and conditions;
• Design performance is based on turbine asset weight, which is known precisely (on the contrary, driven piles rely on assumed passive soil pressures and other assumptions).

To meet the growing demand for precast modular foundations, a new and innovative foundation system has been developed for small and community wind turbines that will allow the harnessing of wind power on sites like landfills and contaminated Superfund sites, as well as those found in remote locations once thought unreachable.

Cell Block™ modular foundation systems—developed by Cell Blocks, Inc,. and Oldcastle Precast, Inc., for small and community wind turbines—are a precast post tensioned block system that can be assembled in a variety of configurations on site with minimal site preparation. They are designed to meet stringent manufacturing specifications for quality control and mix consistency. Cell Block modular foundation systems offer several key benefits not found in the other turbine foundation methods. One such benefit is scalability, which means the foundation can be enlarged or added onto in order to accommodate additional assets such as control buildings or shelters without interrupting the use of the turbine system. Another key benefit is that it can easily be delivered and installed within the same day without requiring the labor, prolonged site prep, forming, and dry time associated with other methods such as poured in place. Figure 4

Cell Block modular foundation systems can also be decommissioned and reused in a different location. The post-tensioned method of connection allows the blocks to be disconnected from each other and relocated or repurposed in the event that the wind turbines they support are moved or decommissioned. This results in a tremendous environmental advantage over poured in place concrete foundations, which either require a labor-intensive effort to break up and remove the buried concrete or, more likely, leaving the concrete in place long after the turbines have been removed.

Each Cell Block modular foundation system is designed and engineered specifically for the location of the installation. The size, quantity, and configuration of the blocks are engineered based on a number of critical considerations including soil bearing pressures, regional wind design speeds, factored loads, uplift potential, buoyancy loads, and stress loads on all materials, as well as many other factors that must be considered during the design and engineering process.

Cell Block modular foundation systems offer an innovative alternative to driven piles, concrete piers, and single piece poured in place foundations. Designers and developers of wind turbine foundations are no longer constrained by the limits and labor intensive efforts that are often associated with attempting to put wind turbines in environmentally sensitive or remote locations. Having precast modular foundations as an option for supporting their wind turbines give the designers and developers more freedom to do what they do best—to go wherever the wind blows.

As readers of this magazine undoubtedly know, renewable sources such as wind and solar currently supply less than 10 percent of the energy consumed in the United States. But what if the production of this renewable resource was more efficient, enabling companies to see improved results in the bottom line and help drive the usage of wind energy?

Increasing efficiency in the conversion, delivery, and utilization of energy is an essential part of a comprehensive national energy policy. It would only make sense that alternative energy resources such as wind turbines utilize highly efficient generators or motors to create the power to the grids. The Energy Independence and Securities Act goes into effect in less than one year and specifically addresses raising the efficiency levels of industrial electric motors. A few startling statistics:

• An electric motor consumes approximately 65 percent of generated electrical energy;
• The cost of operating an electric motor can run up to 25 times the motor’s purchase cost per year;
• Only about 5 percent of electrical motors have a variable speed drive to control the motor speed depending on the demand [1].

And if those numbers aren’t reason enough to look at the motor in your wind turbines federal, state, county, and local governments are offering rebates and incentives to end users to help offset the cost difference between a premium efficient motor and an EPAct efficient motor. How can a wind-turbine OEM generate more power from the wind using already well-developed equipment and more efficiently convert wind to power?

All energy sources require conversion of energy to electrical power. Obviously, the higher the efficiency of conversion, the more energy we can use productively [2]. This is where a more efficient motor can make a difference. Unfortunately, price is often the barrier. What is not realized, however, is that a motor’s initial purchase price represents only 2 percent of its total lifetime costs. And while premium efficiency motors can save a lot of money, regrettably the purchase is often based initially on price rather than considering operating costs.

Premium vs. Standard Motors
According to the U.S. Department of Energy, electric motors consume a large percentage of the electricity used in American industry. On average, approximately 63 percent of industrial electricity is consumed by electric motors, and it can reach 75 percent or more in certain industries. Also, motors can consume five to 12 times their initial purchase cost in energy per year. If you consider that a 25-horsepower motor running 24/7 can consume up to $15,000 in energy per year, and a 100-horsepower motor can consume up to $56,000 in energy per year, even small reductions in energy consumption per motor could result in substantial savings. Additionally, in the case of motors up to approximately 50 horsepower, the savings difference between using a standard efficient vs. a premium efficient motor could pay for the premium motor in one year. Every year after that would be money in your pocket.

So what is the difference between a standard motor and a premium efficient motor? Because of the superior designs and better materials used, premium efficiency motors tend to run at lower operating temperatures resulting in longer life for the motor’s insulation system, copper windings, and bearings. Another advantage is that by generating less waste and less heat in the space around the motor ventilation requirements are reduced, resulting in additional energy savings.

The difference between a standard and a premium efficiency motor’s cost can be paid off in a few months. Premium efficiency motors will always save money vs. lower efficiency units, and the savings go on for as long as the motor is in operation. In many cases this could be 25-30 years. And, not only do energy efficient motors help reduce maintenance time and costs, but they can significantly increase energy produced from wind turbines, which is a winning combination.

Research in Action

Researchers at Indiana’s Purdue University recently developed a technique that uses sensors and computational software to consistently monitor forces exerted on wind turbine blades, a step toward improving efficiency by adjusting for rapidly changing wind conditions. “Wind energy is playing an increasing role in providing electrical power, according to Doug Adams, a professor of mechanical engineering, director of Purdue’s Center for Systems Integrity, and co-lead on this research project. “The United States is now the largest harvester of wind energy in the world,” he says. “The question is, what can be done to wind turbines to make them even more efficient, more cost effective, and more reliable?” [3]

A wind turbine’s major components include rotor blades, a gearbox, and generator. The aim is to operate the generator and the turbine in the most efficient way, especially since the wind towers can be 200 feet tall or more, making it very expensive to service and repair damaged components [4].

When Clemson University was awarded $45 million under the American Recovery and Reinvestment Act for a wind energy test facility, U.S. Department of Energy Secretary Steven Chu said, “Wind power holds tremendous potential to help create new jobs and reduce carbon pollution. We are at the beginning of a new Industrial Revolution when it comes to clean energy.”

Introduced more than 100 years ago, electric motors resulted in enormous efficiency improvements and energy use, and revolutionized the very nature of work. Today, innovative motor engineering and manufacturing are playing an important role in increasing the productivity of the nation’s energy systems, positioning themselves at the cusp of this new Industrial Revolution.

Economic Stimulation

Your involvement in wind energy means you are probably aware that in 2008 the U.S. Department of Energy (DOE) published a report that examines the technical feasibility of using wind energy to generate 20 percent of the nation’s electricity demand by 2030. Titled “20% Wind Energy by 2030: Increasing Wind Energy’s Contribution to U.S. Electricity Supply,” the report examines the costs, major impacts, and challenges associated with producing 20 percent wind energy or 300 GW of wind generating capacity by 2030. Let’s take a look at what a few states are mandating to comply with the DOE and increase their economic growth. Figure 1

Michigan: Michigan’s Renewable Portfolio Standard mandates that 10 percent of Detroit Edison’s power generation be sourced from renewables such as wind and solar by 2015. Since this mandate was enacted, more than two-dozen companies have started or diversified into manufacturing wind turbine components. To support this Governor Jennifer Granholm proposed investing more than $100 million over the next three years to increase demand, expand production, and encourage research and development of new technologies in Michigan. One example is Global Wind Systems, which will be opening a new wind turbine assembly plant in Novi. The plant expects to hire 250 skilled trades people in May, with an additional 150 or more expected within two years, to assemble 1.5 MW wind turbines. Although many of the components will have to be initially sourced from Europe, the goal is to shift that to in-state suppliers. Figure 2

Ohio: In a unanimous vote, the Ohio legislature passed a new bill two years ago requiring 12.5 percent of Ohio’s energy to be generated from renewable sources like wind and solar. At that time Ohio became the 26th state to adopt renewable energy portfolio standards (RPS), tough new laws that are creating one of the most dramatic shifts in the delivery of energy to American consumers ever [5]. The American Wind Energy Association estimates Ohio’s new RPS law on its own will result in at least $10 billion of new wind energy project investments [6]. The DOE estimates Ohio’s electric generation capacity at 33,877 megawatts. Ohio’s total online wind generation capacity is only 7.4 megawatts [7]; this is a miniscule 0.02 percent. There is obviously tremendous potential for growth in this state.

The Bottom Line

Conserving energy is a great idea, but companies want to see results in the bottom line: How much money can be saved by improving efficiency? High efficiency premium motors save more than $1 million per turbine for wind farm developers and wind turbine OEMs over the life of a turbine. Their unique design offers high performance at low wind speed. As mentioned, premium motors are significantly more efficient than conventional motors and they incur lower operating costs, again positively affecting the bottom line.

In these challenging economic times it is particularly important that wind farm developers and wind turbine OEMs achieve maximum ROI through new innovation, minimizing costs, and harnessing wind energy at efficient and reliable levels. Utilizing and investing in premium motors is one factor that will help achieve this.

Wind power is currently the world’s fastest growing energy technology, reaching $40 billion, and the market continues to grow. As engineers create ever-more efficient models, it makes economic and environmental sense that the engine be as efficient and robust as the turbine. We are in the midst of a global recession and a decades-long slump in American manufacturing. However, as President Obama said in a speech last year at a wind energy manufacturing facility in Newton, Iowa, “The nation that leads the world in creating new sources of clean energy will be the nation that leads the 21st century global economy.”

References:

1) Ruddell, Steve “Energy efficiency – Government pushes variable speed drives as top way to cut CO2,” Electrical Review, March 3, 2010
2) www.choosetocompete.org/downloads/Article_Energy_Efficiency_2009.pdf
3) “Smart Turbine Blades Could Improve Wind Power Efficiency,” by Emil Venere, May 6, 2009. www.renewableenergyworld.com
4) Ibid
5) “New Ohio Renewable Energy Law Has National Importance,” staff writer, April 30, 2008. www.energy-daily.com
6) Ibid
7) www.awea.org/projects/ohio.html

At sea there is significantly more wind than on land. That means the installation is constantly in motion so that torsion in cables, vibration, and points of abrasion can occur. The cables must be protected, naturally, so the cable protection products from PMA are employed. In system construction there is successively less space available for electrical components. Cramped cable ducts, junction boxes full to the bursting point, and extensive EMC protection elements (e.g. EMC shielding) can cause cables and wiring to experience abrasion or chaffing on the edges of electrical components, cabinets, etc., above all when vibration and permanent movement are involved. Cable protection is therefore necessary.

Polyamide Cable Protection

The PMA conduit PCS was specially developed for external applications exposed to high mechanical stress. The conduit is very flexible, allowing it to be formed around sharp angles and curves.

Additionally, metal conduits must be sawn to length, whereas the polyamide conduits can in next to no time be trimmed to the correct length with a pair of scissors or a pocket knife. It is manufactured from specially modified PA12 raw material supplemented by additives to improve the already excellent weathering resistance of the PA12 material. This provides a life expectancy in predominantly static applications such as those in excess of 25 years. PCS also has very good low temperature characteristics, which is very important because the system is exposed to the elements in summer and winter. Polyamide is hygroscopic, absorbing and giving up water to the surrounding air depending upon the humidity. With PA12 this effect is less pronounced, ensuring that even with low humidity the material retains very good impact resistance.

In order to produce the right product for the right application it takes a state of the art production facility that carries out intensive R&D activities using the latest production technologies. Intensive research and development also consist of intensive product testing, which includes dynamic reverse bending, impact strength, compression strength, system pull-out strength, peak load, self-extinguishing flammability resistance, thermal aging, and cold bending, etc. Not only is the test important, so are the test methods themselves.

Test methods consist of Reversed Bending Test with Swinging Movements. This standard is based on a cyclic reversed bending test (pivoting) of conduits under various conditions (temperature). The conduits are dynamically loaded and evaluated at the upper and lower application temperature limits. The test is performed based on IEC EN 61386. The minimum requirement corresponds to the specifications of IEC EN 61386. For PMA, the test is not considered completed for final evaluation until cracking or fracture. The number of cycles to fracture determines the fatigue strength of the conduit.

The next test is Reversed Bending Test. This standard describes a cyclic reversed bending test with additional tensile loading (lifting) on flexible conduits under standard ambient conditions (23°C/73°F @ 50 percent relative humidity). The conduit is loaded until fracture. The number of cycles to fracture determines the fatigue strength of the conduit. In addition to the lifting reversed bending test there is a Rotation or Oval Reversed Bending Test. This standard describes a cyclic bending test (rotation in an oval pattern) on flexible conduits under standard ambient conditions (23°/73°F @ 50 percent relative humidity). The conduit is tested until failure. The number of cycles to fracture determines the fatigue strength of the conduit. Figure 1

The next test is Peak Load Test. This standard describes the peak load test on conduits under standard ambient conditions (23°C/73°F @ 50 percent relative humidity). The conduit is deformed by a defined amount between two plates. The restoring force established over a specific time by relaxation of the conduit describes the crushing pressure or compression strength.

A Pull-Out Test defines the system pull-out test on conduits and connectors under standard ambient conditions (23°C/73°F @ 50 percent relative humidity). The conduits are mounted with the appropriate system connectors. The pull-out strength of the system is determined in a tensile test.

Next is the Impact Test. This standard describes the impact strength test on conduits at various temperatures. The conduit sample is placed on a steel plate and centered under an impact head with a defined profile. The impact head impacts the center of the conduit surface. In contrast to international specifications, deformation behavior (buckling) is determined rather than fracture behavior. The impact test has been passed if no fracture or cracking can be detected after the impact, as well as no excessive permanent deformation of the conduit in accordance with PMA specifications.

A Cold Bending Test describes one performed on conduits at low temperatures. The conduits are stored in a controlled climate cabinet at the specified test temperature. Loading is achieved by winding the conduit around a test mandrel with a defined diameter. The various products are classified based on the mandrel diameter that can be achieved.

Thermal Aging Tests are used on thermally aged conduits. The test conduits are stored in a controlled climate oven at the specified test temperature. After removal from the oven they are cooled to room temperature. Loading is achieved by winding the conduit around a test mandrel with a defined diameter. The various products are classified based on the mandrel diameter that can be achieved.

One of the final tests is known as Self Extinguishing. This standard describes a flame test on conduits based on international specifications. The conduit is exposed to a defined flame from a standard burner. The time of ignition and flame propagation behavior—as well as time of extinguishing after removal of the flame source—are significant parameters for evaluating the flame behavior of the products. Figure 2

In addition to R&D, PMA products need to conform to worldwide standards and regulations. As a pioneer in the field of cable protection, PMA has always given high priority to our own testing facilities and have consciously introduces stringent in-house standards as described previously. This approach has enabled PMA to exercise a significant influence on the development of international standards. Standard committees with responsibility for cable protection systems regularly ask our company to provide advice or participate as an active member.

Armed Against the Elements

A failure in the electronic monitoring system of a wind energy plant can have fatal consequences. PMA specialists for high quality cable protections systems have designed a simple but effective component, manufactured from specially formulated polyamide, which can be applied in addition to a standard lock nut on the thread of a fitting, increasing the outlet radius and thus preventing potential abrasion damage caused by tight bending radii and vibration. The anti-abrasion lock nut is available in a divisible form for retrofit applications or as a one-piece element for applications in new designs from conception onwards.

Cable protection can generally be seen as a dispensable element. If a cable is laid without a conduit around it, it is exposed to the prevailing environmental conditions around it. Cable protection is used to protect the cables from external factors. That means that if through a particularly inauspicious collection of circumstances or some extraordinary mechanical stress damage occurs, it is “only” the cable protection that is damaged and the cable function is not affected. The cable protection may be replaced.

Through the excellent basic characteristics of the specially modified polyamide 12 material used for PCS, this conduit type is particularly suitable for use in applications that are permanently exposed to intensive sunlight (UV). Additionally, PCS possesses very good resistance to chemicals. Given that for an average installation of 100 measuring points with three components each to be installed, the time saved can add up to between 20 and 50 hours comparing the polyamide system with conventional protection using armored metal pipes. Figure 3

For the installation at Alpha Ventas wind park there was no specific requirements placed upon the cable protection system from the wind energy segment regarding certification. The PCS product being used there possesses all relevant certificates for worldwide applications in the highest safety categories.

Being an installation at sea, and having the same needs and requirements as the marine industry, the use of PCS and other PMA products are approved for the shipping industry by Bureau Veritas, Det Norske Veritasl and Lloyds Register. In addition to these approvals PMA products are also approved by UL and CSA for installations in the United States and Canada.

Wind turbine systems are a network made up of motors, controls, lighting, sensors, and numerous devices located throughout the tower, nacelle, and hub. If any one of these devises fails due to damaged cables, costly repairs and service are inevitable. As Hoger Stoven says, “In wind energy installations, particularly offshore, cable protection is indispensable. The products from PMA offer everything today which is necessary for correct cable protection.”

The Hatchet Ridge Wind Farm is a 101.2-megawatt (MW) wind farm owned by Pattern Energy Group, LP. It is located in Shasta County, California, near Mount Shasta on a ridge overlooking the town of Burney and is the first large-scale wind farm in the area. The wind farm construction was announced in October 2009 with Renewable Energy Systems Americas, Inc., as the constructor. With anticipated generation to power nearly 44,000 California homes annually, the project is expected to finish and reach commercial operation before the end of 2010.

The project was delayed several months from its anticipated start date of March 2009 due to financial turbulence when Australian-based Babcock and Brown filed for bankruptcy and had to be reorganized. The North American development branch, which is the operating company that will run the Hatchet Ridge project, was sold off as part of the reorganization. The newly formed Pattern Energy had only been in existence for four months when they announced the construction start date for their first project; the Hatchet Ridge Wind Farm.

Pacific Gas and Electric Company (PG&E) will purchase the power, along with the renewable attributes, under a 15-year power purchase agreement. There are 44 Siemens 2.3 MW turbines, which stand on towers more than 20 stories tall that are being erected for this project. The Siemens SWT-2.3-93 wind turbine has more than 2,000 operating turbines worldwide, and it is well regarded throughout the industry as proven technology.

In comments made to the press Mike Garland, CEO of Pattern Energy, had the following to say about the project: “We are pleased to close financing and commence construction on the Hatchet Ridge Wind Farm,” he said. “This project is the result of years of dedication and collaboration with RES Americas, Siemens, PG&E, local government, project property owners, and the community. We are very appreciative for the local support we received that helped make this project a reality.”

Andrew Fowler, senior vice president of construction for RES Americas, said that “California is one of the top states in generating wind power capacity, and we are excited to continue to bring clean, renewable energy to the region and working with the local businesses in completing the project. Renewable energy brings economic benefits to the community and provides a secure and sustainable future for all.” Figure 1

Pattern Energy Group LP describes itself as an independent, fully integrated energy company that develops, constructs, owns, and operates renewable energy and transmission assets across the United States, Canada, and Latin America. With a long history in wind energy the group’s highly experienced team of scientists, engineers, construction experts, and legal and financial professionals has developed, financed, and placed into operation more than 2,000 MW of wind power in 11 states, including the 283.2 MW Gulf Wind project in Texas; a premier wind farm utilizing a ground-breaking wildlife monitoring system. Pattern’s development pipeline exceeds 4,000 MW of renewable energy projects, including the 101.2 MW Hatchet Ridge wind project in Northern California and the 138 MW St. Joseph wind project in Manitoba, Canada, that is currently under construction.

RES is one of the fastest growing renewable energy companies in the world, and it has been at the forefront of the wind industry since it was founded in 1982. It has been active in North America since 1997, and during this time it has either developed or constructed more than 10 percent of the installed capacity in the United States. As RES continues to grow it is beginning to apply its capabilities and experience in wind energy to solar energy and other emerging renewable systems. RES currently has 3,836 megawatts of operational renewable power, with 410 megawatts under construction.

Dashiell Corporation worked extensively with RES Americas in the months leading up to the official start date on the negotiation of the collector substation and the utility interconnect switchyard. Dashiell initially bid the project in early March 2009 and was given their first limited notice to proceed on the project in early June, 2009. As the financial turbulence discussed above progressed, Dashiell and RES were finally able to reach a full contract in October, 2009. At this time Dashiell was awarded the Hatchet Ridge 230kV/34.5kV collector substation and the Carberry 230kV switchyard on an engineering, procurement, and construction (EPC) basis.Figure 2

The Hatchet Ridge Collector substation consists of one 230kV, 2000A gas circuit breaker; one 230kV/34.5kV, 75/100/125 MVA power transformer; five 38kV, 1200A vacuum circuit breakers; and two 34.5kV, 10 MVAR capacitor banks. The substation has four incoming 34.5kV underground circuits from the wind farm and one outgoing 230kV overhead transmission line to the Carberry switching station. The Carberry switchyard consists of five 230kV gas circuit breakers and three incoming 230kV overhead transmission lines. One of the incoming transmission lines is from the Hatchet Ridge Wind Farm collector substation while the other two lines tie the new switching station into the PG&E power grid. Dashiell’s ability to design and construct these facilities to utility specifications proved valuable, as the Carberry switchyard will be owned and operated by PG&E once it is energized.

One of the many advantages that Dashiell can provide to these large scale wind farm projects is the coordination efforts that are required between the owner (Pattern Energy), the general contractor (RES), and the utility (PG&E) so that both the collector substation and the utility interconnect substation are built successfully and on time to meet the needs of the project. Dashiell has dealt with many utilities throughout the United States. Figure 3

With this wind farm being located near Mount Shasta, at high elevations in the Cascade Mountain range in Northern California, inclement weather has proven to be a major hurdle. The PG&E tie-in date for the Carberry switching station is this summer. With the high amount of snowfall that accumulates in the area late into the spring, the construction schedule has had numerous delays and has resulted in an accelerated construction schedule to meet project deadlines. Due to Dashiell’s substantial experience and resources in the substation construction industry, the Carberry switching station is still on target to meet its tie-in service date, and it is anticipated that the Hatchet Ridge Collector Substation will be ready for energization within that same time frame.

Some of the larger substation material items that go into wind farm projects are the primary voltage breakers, control houses, transformers, and steel structures, and each item requires its own foundation pad. These foundation pads are the first step in the substation construction efforts. After all of the concrete foundations have been laid and cured, the erection process can begin. This starts with setting the larger scale material items on their individual concrete foundation pad. A crane is set up and utilized to lift these heavy items off of the shipment crates and place them onto the poured concrete foundations. The control house at the Hatchet Ridge substation is approximately 50 feet in length. Figure 3 shows some of how this building eventually gets set. Figure 4

The transformers associated with these wind farm projects are generally quite big, both in terms of size as well as capacity. For the industrial projects that involve new substations you’ll typically see a 40 or 50 MVA max transformer. For this particular project the transformer has a base MVA rating of 75 and a full load MVA rating of 125—and this is a 101.2 MW wind farm. We see some wind farms that have 250 MW capacity. Also keep in mind that as the wind farm grows in capacity size, it starts to make more sense to utilize more than one transformer. But generally speaking, the transformers that are included with these wind farm collector substations are very large. Figure 5

Throughout the many phases of this project it has been obvious that without the hard work and coordination of Pattern Entergy, RES Americas, PG&E, and Dashiell working together during difficult financial times and bouts of extreme weather conditions, completion would not have been possible. In addition to providing clean, renewable energy for Californians, Hatchet Ridge has created approximately 100-200 construction jobs during the construction activities and will create as many as eight permanent jobs during operations. Pattern has also stated that they expect “an economic ripple effect in the area from the purchases of goods and services for the wind farm and the increased business for service industries.” In addition, “Hatchet Ridge will invest $5 million in the local community over the life of the project through the Shasta County General Fund, the Burney Regional Community Fund that will be administered by the Shasta Regional Community Foundation, and the Burney-Fall River Education Foundation, as well as pay substantial local taxes.” The benefits of this successful project are clear, and they are many.

The chaotic variability in wind speed, direction, shear, and turbulence makes monitoring and analyzing modern wind turbines a challenge. Wind operators must squeeze out every watt they can when the wind is blowing. To do so, wind projects must be reliable and maintained with minimum cost. With variable winds, high costs, and slim margins, everything has to work right to make sure that wind is an attractive alternative power and a sound economic investment. So if a turbine is to work 20 years or more before retiring, it had better be properly designed and maintained.

Traditional Procedures

Most wind turbines are maintained by a combination of traditional schedule-based preventive maintenance and threshold-based alarm systems. A problem with scheduled maintenance is that the standard six-month interval between inspections may be too long to detect an emerging problem. And fixed-threshold alerts, typically set by OEMs, activate too late to support proactive maintenance. That’s because the alerts are intended to protect equipment from catastrophic damage and can’t take into account a wide range of normal wind-turbine operating conditions and unit-to-unit manufacturing variances. As a result, typical fixed-threshold-alert systems do not detect problems until after a failure occurs.

Likewise, traditional condition-monitoring and predictive maintenance tools such as vibration analysis, oil analysis, and thermography are limited because of the difficulty in accessing the typical wind-turbine nacelle, the variable nature of the machine, and the time limitations and analytic capabilities of the technicians using them.

Ideally, equipment maintenance should only be performed when something needs fixing. Most preventive maintenance works on the idea of regularly inspecting or servicing equipment to address potential failures before they progress. However, given the huge variations in operating profile and environment, it’s easy to see that the regular, fixed inspection interval of traditional preventive maintenance may not catch critical emerging problems in the wind environment.

The conventional power industry, however, leads the industrial world in predicting impending equipment problems before they occur. And it is doing so using a technology directly applicable to the wind industry. In fact, several wind companies already use this technology to get early warnings, avoid surprises, and improve control of their operations. They reduce risk exposed by existing condition-monitoring tools and leverage SCADA data to remotely detect emerging problems by using SmartSignal predictive diagnostics.

Briefly, SmartSignal precisely identifies impending problems by detecting subtle changes in equipment operation. It finds problems earlier than OEMs’ alerting systems or other condition monitoring approaches, and well within traditional alarm limits.

SmartSignal Advantages

Recognizing that wind is unpredictable in predictable ways, SmartSignal predictive diagnostic software works by analyzing SCADA data once every five to 10 minutes. It compares real-time data to software models of equipment when operating in good condition and compensates for normal variations due to load and ambient conditions. Further, SmartSignal uses software models customized for individual pieces of equipment to provide the earliest possible warning of emerging problems. SmartSignal readily integrates with an existing data infrastructure, and it’s quick and easy to deploy, maintain, and use.

This method needs no new sensors, and analysts need not review masses of SCADA data. Instead the software analyzes data and alerts analysts only when it detects an exception, providing ample time to plan and respond. And by using algorithms to identify pattern changes, the analysis is highly accurate.

For wind applications the software uses models customized for each individual turbine, which compensate for fluctuations in wind speed, direction, and ambient conditions. In real time the software compares data collected in the nacelle to the models—literally tens of thousands of data points every five to 10 minutes across a fleet—and notifies maintenance and engineering of impending problems. Owners then focus on fixing problems early, before catastrophic damage occurs.

Take a gearbox, for example. During the initial system configuration a gearbox model would be “trained” using representative data provided from a data historian such as OSI PI (a data historian is a database for storing time-series data from instrumentation). Typically, one year of data would be used to train the model. In live operation data from relevant sensors on the gearbox such as for vibration and temperatures, along with operational state information such as power output and ambient temperature, would be compared to the model. The model would then provide an “estimate” of what each value should be, based on how it was trained from the historical data. If the actual value statistically differed from the model estimate, the system would generate an alert. Technicians would review the sensors in alert and develop a preliminary diagnosis of the problem. A next step would typically be further on-machine investigation or use of other techniques, such as oil sampling. Note that SmartSignal even provides a full-service solution, in which its own engineers monitor customer wind farms from SmartSignal’s in-house Availability and Performance Center (see Figure 1).

Competitive Edge

A recent Wind Energy Operations & Maintenance Report cited that approximately 79 percent of wind turbines in operation are still under warranty. That will soon change, leaving many owner-operators vulnerable to equipment failure. Gearbox reliability consistently falls short of OEM projections. Designed for a 20-year life, many gearboxes are failing after six to eight years of operation. O&M costs for wind power are exceptionally high in the United States, and often double or triple budgeted projections.

Given the high capital intensity of the wind-power business reliable, long-term operation of the equipment is critical for generating positive returns and continued industry growth. It won’t take many major equipment failures before the long-term profitability of a farm is lost. As assets age, performing major work only when needed will be critical to maintaining economic viability.

Remote monitoring and condition-based maintenance approaches will be required to maintain financial returns because wind turbines are hard to access and don’t receive the same “walk-around” monitoring typical of industrial plants. Although wind has unique characteristics, wind turbines are just another kind of machine and successful operators will take advantage of best practices from other industries to outstrip their competition.

Efficient wind-farm management presents distinct monitoring challenges. Schedule-based maintenance and other traditional techniques have been ineffective in the dynamic environment of wind generation. Ambient conditions vary widely, and wind turbines don’t offer a constant load but rather cycle up and down, presenting a unique wind regimen and set of data points. Each turbine has 60 or more analog sensors, with data reporting every few seconds. SmartSignal analyzes in real time all the data that is collected by a programmable logic controller in the nacelle—literally tens of thousands of data points daily on a typical wind farm—and detects and notifies wind farms of impending problems, allowing owners to focus on fixing problems early and efficiently.

SmartSignal helps improve turbine reliability and availability and reduce maintenance costs across a wind farm or an entire fleet by helping to prioritize tower inspections and optimize crane usage. It avoids surprises of equipment failure, while maximizing resources and reducing risks. The chart in Figure 2 illustrates wind farm components protected by SmartSignal and the faults identified. These assets span both rotating and non-rotating equipment, including transformers, across major OEMs.

The Ironworker Progressive Action Cooperative Trust (IMPACT) is a non-profit, labor-management organization devoted to improving the ironworking industry. One of the ways that the IMPACT trustees deliver on this mission is by always looking for new and innovative ways of making ironworkers and the contractors they work for more competitive. There is no better method of doing this than through workforce training.

Ironworkers and the contractors they work for have been erecting wind turbines for many years. To meet the needs of the industry, the International Association of Bridge, Structural, Ornamental and Reinforcing Iron Workers has always maintained a wind turbine training strategy, ensuring that ironworkers had the needed knowledge and skills to safely and efficiently erect wind turbines. That strategy, still in place, includes the following training components:

• Information on wind turbine erection in the “Structural Steel Erection” training package;
• Information in the “Structural Steel Erection” training package focusing on bolt torqueing and tensioning (although not focusing specifically on wind turbines);
• “Rigging for Ironworkers” training package to teach heavy rigging procedures;
• “Cranes” training package to teach to the use of cranes (including signaling).

This training strategy has provided ironworkers with not only wind turbine erection market share, but also the necessary knowledge and skills to safely and efficiently erect wind turbines for decades.

In 2008 and 2009 there were a lot of wind turbines being erected in the United States. Most projections were that the upward trend of the construction of wind farms would continue, and most likely increase, into the foreseeable future. Because of this increased amount of work, and the anticipated further increase, according to input from many of IMPACT’s signatory contractors there was a growing need for ironworkers to have third party, nationally recognized training certifications in several areas. These areas include wind turbine tower climbing and rescue, as well as bolt torque and tension training.

In June of 2009 two things happened that shaped wind turbine training for ironworkers. First a team traveled to Oklahoma to evaluate a wind turbine training program, and second the Department of Labor (DOL) released several grant solicitations as part of the American Reinvestment and Recovery Act of 2009 (ARRA). A team representing the Ironworkers International—referred to as “Ironworkers” from this point forward—IMPACT, and several local unions visited the Wind Turbine Technician Training program at the Francis Tuttle Technology Center (FTTC) in Oklahoma City.  Team members included: Tad Kicielinski, general vice president; Mike Gravette, Texas and Mid-South States District Council; Ron Smitherman, business manager for Local 263 in Dallas; Randy Palumbo, apprenticeship coordinator from Local 48 in Oklahoma City; Rick Sullivan, IMPACT director of education and training; and myself.

FTTC is a non-profit, accredited technology training center in the state of Oklahoma and a member of the American Wind Energy Association’s (AWEA) education committee, as well as a member of the Wind Energy Training Consortium (WETC). The WETC is a group of training institutions that is recognized by AWEA as promoting the skill training essential for wind turbine technicians.

The wind turbine technician training program in place at FTTC was found by the team to address all three areas of interest to the Ironworkers, with a very strong hands-on focus. The FTTC program had industry partnerships with HYTORC, Snap-on Industrial, and Capital Safety (DBI/SALA) so that program completers receive certificates from these three nationally recognized organizations. FTTC was also willing to partner with IMPACT and train ironworkers on demand. Figure 1

The Ironworkers team made a recommendation to the IMPACT trustees that a partnership be developed with FTTC in order to rapidly meet the demands of this growing sector of the ironworking industry. The trustees then formed a training partnership with FTTC to train ironworkers and deliver only the segments of the wind turbine technician course that were pertinent to the erection and heavy maintenance of wind turbines. These courses are comprised of training in two major areas of the wind turbine industry: tower climbing and rescue, as well as bolt torque and tension.

The tower climbing and rescue training portion of the course covers the different forms of fall protection, rescue and evacuation techniques, types of equipment, and the proper use, care, and maintenance of the type of safety and rescue equipment used in the wind energy workplace. Upon successful completion of this component of the course participants receive a nationally recognized certification from Capital Safety.

The bolt torque and tension certification component of the course will certify participants in all aspects of bolt torque and tension. Topics include basic fasteners and safety, and mechanical, electronic, and hydraulic torque. This portion of the course uses a tremendous amount of hands-on learning, application, and three certifications from industry leaders Snap-on Industrial and HYTORC.

The goal of these courses is to rapidly train ironworkers to get them onto wind turbine erection sites; it is not a “train the trainer” course. These courses cover 36 hours of related classroom and hands-on instruction, and the course spans four days. Because the course is delivered in a highly accelerated manner, only journeymen ironworkers with a minimum of three years field experience who already have the OSHA 10, Subpart R, and First Aid/CPR/AED training will be eligible to register in one of these courses. Figure 2

IMPACT and FTTC jointly arrange for one wind turbine course to be held each calendar quarter at FTTC’s Portland campus; one of FTTC’s three campuses in the Oklahoma City metro area, this campus is the site for FTTC’s wind turbine technician training. Ironworkers are signed up for and registered for these courses through the IMPACT office at the request of either a local union or a signatory contractor. However, if a local union or a signatory contractor has anywhere between six and 10 ironworkers who need this training in order to work on a wind turbine erection or maintenance project, IMPACT will work with FTTC to arrange for a “private” course to be conducted within 45 days of the request.

Once participants complete the training and are issued the certifications—since these are third-party certificates, some may take three to four weeks to come back from the industry vendor—the IMPACT office receives an electronic copy of the certifications. The Apprenticeship and Training Department then updates the Apprentice Tracking System (ATS) to show the certifications that the ironworker received and places an electronic file of the certificate on the ATS, as well. Since the ATS is a Web-based secure system, this allows any local union to verify that an ironworker has these certifications and can meet the needs of the contractors. Figure 3

When the DOL announced large grants under the ARRA, there were several meetings at the Ironworkers International to discuss whether or not it would pursue any of the available grant money. It was decided that International, through IMPACT and the National Training Fund, would submit a grant proposal. It was understood that the competition would be tough and the amount of awardees limited, but they were confident that they could develop a competitive proposal. After reading the announcement in the Federal Register in detail, it was easy to see that a national entity was required to work with at least two but no more than five of its local affiliates in order to implement training.

The National Training Fund and IMPACT decided to write a grant that would allow the Ironworkers to take the IMPACT wind turbine partnership training (developed with FTTC and described above) and replicate it at five existing local training centers.

In order to identify these five local training centers, IMPACT looked at the projections for wind farms for the coming two years (also the term of the grant). The five regions of the country projected to have the most wind turbine erection work were identified, and the district council presidents of those regions then identified which training center in that region was best suited to be involved in the grant. The five local training centers chosen to participate in the grant were the training centers for the following Ironworkers local unions: Buffalo, New York; Salt Lake City, Utah; Dallas/Ft. Worth, Texas; Los Angeles, California; and Joliet, Illinois. Some of the other stipulations in the DOL grant solicitation required that each of the local training centers do the following:

• Work with contractors involved in wind turbine erection and to have those contractors supply a letter of support;
• Partner with the state and/or local Workforce Investment Boards (WIB) and get a letter of support;
• Establish or have a relationship with the “one-stops” in the local area.

The Ironworkers grant proposal was written during the summer and then submitted to the DOL in September of 2009. In January of 2010 the DOL announced the grant awards and the Ironworkers was one of the successful organizations. The wind turbine training will be delivered at the five local training centers by instructors who received specific instruction at the FTTC from certified industry partner trainers. The National Training Fund will then equip each of the local training centers with their industry partners’ tools and equipment so that those trainers can begin to conduct wind turbine training for Ironworkers. Each training center will also receive a mobile training trailer to be pulled either directly to wind farm sites or other local training centers to conduct this certification training. By taking the training “on the road,” not only will a wider geographical region be serviced with DOL grant funds, but more ironworkers can receive training. This will ensure that each training center will be able to provide at least 102, including the two instructors trained at FTTC, trained ironworkers with industry recognized certificates by the end of the grant, for a total of at least 510 trained and certified ironworkers under the DOL grant funded training. Figure 4

The two wind turbine training developments forged under the supervision of the IMPACT trustees and with the partnership of the Francis Tuttle Technology Center and the Department of Labor are examples of what can happen when both labor and management work together towards a common goal. These two progressive training programs are providing ironworkers with certifications that will enable employers to secure projects and put more people to work. Figure 5Figure 6