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1. INTRODUCTION
Wind power is viewed as the new alternative energy. It is regarded as the cheapest
and affordable source of energy available, even more favorable than the solar and nuclear
energies. Actually, this type of energy has been used around the world for a long time,
but not in the form of energy transformed into electrical power. For centuries, farmers
harvested the energy of the wind to power wind mills to do tasks like gridding corn to
produce flour. There is basically no change in the concept of harvesting wind energy
now and then: use a propeller like structure to transfer the wind energy into work.
Currently, this concept is used to transfer the wind energy into electric power by means
of large gearboxes and electric generators.
These units require very large and complex mechanical components to produce
enough electricity to power homes and cities. The concept of developing complex
engineering marvels began during the industrial revolution where such complex and
powerful machineries could embark on major functions. During such time, mechanical
applications development would take an exponential climb much like the computer era in
the nineties. It was a time to build larger and stronger machines. This was possible
because there was a need for these types of machines and strength. Slowly the mentality
began to change and it was necessary to understand other areas where it could help make
machines better and affordable. One of the areas was efficiencies. Developing a machine
was no longer just about building it and make sure it would work, it was necessary to
understand the purpose and where the input would maximize the output.
Wind turbines could have been built years ago; however, the lack of knowledge
and tools to build these mega machines would take almost a century to acquire such
capabilities. Designing these complex machines would require a great deal of
understanding the types of components needed and the best material required to build
them. This type of understanding would be required to work well together and provide
the main purpose of maximizing the output.
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Currently manufactures and operators are evaluating the cost of running wind
turbines successfully by developing maintenance methods to prevent failure instead of
running these applications until they break down. Both the manufactures and owners
understand the significance of the variable “cost” which can determine the success of the
product. There are significant costs when dealing with wind turbine operations and
maintenance. The key is to understand the purpose of maintenance and to determine
when to schedule maintenance (Milborrow). It is a considerable aspect of preventive
maintenance as well as important understand these types maintenances to forecast major
failures. This can be done by performing critical tests to identify the areas where failure
can occur by the use of automated systems to monitor and alert malfunctions. This can
also be used to disable the application from operations to avoid catastrophic failure.
Failure analysis is fundamental to determine the areas of impact as well as identifying the
critical components of the application. This type of analysis is commonly performed by
manufactures to distinguish critical components and establish key gages to be monitored.
Usually these components are selected because it will have a serious impact in the
operation of the system in case they are damaged.
In order for parts to work well in motion, it is necessary to understand fluid
dynamics. It will be better if you refer it to a book instead of Wikipedia As defined in
Wikipedia,
“Fluid dynamics is a sub discipline of fluid mechanics that deals with fluid flow—
the natural science of fluids (liquids and gases) in motion.”
Basically, the purpose of fluids is to assist in the motion of moving parts in a particular
system. It is necessary to analyze critical characteristics that make these fluids work well
for various systems. The role of these fluids is to lubricate, seal, clean, cool, and protect.
As fluids are manufactured to achieve all these functions, it requires a critical
understanding of the mechanical purpose of the system and its components. Fluid
dynamics has evolved greatly in the recent years, primarily with the development of
synthetic lubricants. Such products have been developed to provide stability and increase
the life of the lubricant. The constant search and research for better and long lasting
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products is the main purpose of lubricant manufactures to maintain the consistency of
mechanical output. However, in order to keep the lubricants performing at the highest
level it is necessary to maintain and monitor the product during in-service performance.
For wind turbines it is critical to have a good preventive maintenance established.
This will ensure the life of the application. There are two key ingredients that need to be
achieved and balanced to obtain optimal performance: maintenance and cost. It is
necessary to analyze these two topics in order to develop the necessary tools to achieve
optimal performance.
Being exposed to condition monitoring analysis, I had a chance to analyze and
provide technical services to many wind turbines throughout the United States. This
helped me conclude that these systems need better monitoring systems which I will
support by identifying significant aspects that can be improved as well as save cost.
Condition monitoring is a system in which mechanical systems can be monitored and
when necessary determine the type of services and repairs required. I will demonstrate
that using an automated condition monitor systems to analyze critical properties of
lubricants can help wind turbine performance by predicting optimal service times and
conduct repairs before reaching catastrophic failures and reduce maintenance cost.
FIGURE-1 Current wind turbine systems
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2. HISTORY
Wind turbines have been in use for many years. The concept of transferring the
energy of the wind into work began early ancient time. It was then that ancient sailors
notice it could use the pressure cause by wind to move their boats. Even though they
didn’t understand its physics, they used the technique for everyday tasks. Later on this
concept was transferred to other applications on land. The early Persian windmills (500900 A.D.) had vertical shafts. Later on the western world, Europe transformed the design
by adapting a new concept of a shifting the shaft horizontally and adding gear like wheels
to transfer the load from horizontal to vertical. As history describes below,
FIGURE-2 Old wind mills
“Grain grinding was the first documented wind mill application and was very
straightforward. The grinding stone was affixed to the same vertical shaft. The mill
machinery was commonly enclosed in a building, which also featured a wall or shield to
block the incoming wind from slowing the side of the drag-type rotor that advanced
toward the wind.”
“The development of bulk-power, utility-scale wind energy conversion systems
was first undertaken in Russia in 1931 with the 100kW Balaclava wind generator. This
machine operated for about two years on the shore of the Caspian Sea, generating
200,000 kWh of electricity. Subsequent experimental wind plants in the United States,
Denmark, France, Germany, and Great Britain during the period 1935-1970 showed that
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large-scale wind turbines would work, but failed to result in a practical large electrical
wind turbine.” (Pozner, Year)
FIGURE-3 Early wind turbines
As humans noticed this concept of using wind to perform essential tasks, it was
also necessary to keep wind mills from breaking down. It was then the maintenance most
likely started to become an important task of keeping the windmills operating efficiently
and longer. Much like now, the type of maintenance was dedicated to keep the windmill
components from breaking and causing major damages. The most common maintenance
was to keep the wood components from breaking.
The technology has evolved immensely since the introduction of computerized
components; however the industry still uses primitive techniques when performing
regular maintenance. This type of mentality can lead wind power farms to extensive and
expensive maintenance programs. There is a need to study and address the factors that
can be improved as well as provide efficient results to minimize significant maintenance
cost. The best way to understand reliability of wind turbines is to establish testing
conditions. This type of testing can be done on lubricants to determine the application
conditions to analyze its performance.
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3. TYPES OF TESTING
It is critical to understand how the different lubricants and their properties impact
the functions of the application. Most lubricant specifications are published by the
manufactures to determine the optimal lubricant for the application. There are various
types of lubricants; however, specific lubricants have been design for wind turbine
applications. The key to obtain the optimal lubricant for the application is to determine
the critical characteristics and analyze them on a regular basis. It is also necessary to find
the means to test these characteristics and apply conditional limits that can be used to
alert the condition of the lubricant. By establishing these types of tests and guidelines,
one can now built a preventive maintenance or conditioning monitor program. These
types of programs are very common for mechanical applications. There are several
critical analyses that are used to determine the lubricant stability and condition. These
analyses can help minimize mechanical failure and improve efficiency. These tests are
used to determine oxidation levels, contamination, and viscosity for wind turbine
lubricants.
Oxidation
Oxidation is a chemical reaction that occurs between the hydrocarbons and
oxygen. This type of reaction accelerates when various variables are introduced to the
reaction such as temperature, water, acids and metals (copper and iron). It is necessary to
examine different types of tests to understand the impact of oxidation has on mechanical
applications and lubricants. The tests that should be considered are oxidation stability,
Ruler, FTIR, and D664. These tests assist in determining guidelines as well as understand
how lubricant additives behave under oxidation stress.
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FIGURE-4 ASTM D2272 graphical analysis for turbine oil
Oxidation stability test, ASTM D2272, is designed to determine the life of lubricating oils.
This test is significant because it can measure the performance of the in-service lubricant against
the neat product. This test can be used to establish maintenance frequency or determine the time
left in-service products as well as provide reference data for new products (figure-1). The method
D2272 is a test that can determine the ability for lubricants to resist against oxidation (ASTM
D2272). Lubricant manufactures formulate specific additive packages to accommodate the
different types of applications. The data obtained with this test can be used to evaluate expected
life of the lubricant by comparing against the reference product (neat lube). This test is essential
to determine the life of used lubricants before anti-oxidant additives no longer can provide
adequate protection and it should be removed or sweeten (add fresh lube to the in-service) to
recover its stability. The recommended caution for such recovery maintenance is usually provided
when the life of the oil is less than 25% of the neat oil. Under these conditions it is advisable to
perform adequate maintenance to avoid major failures.
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FIGURE- 5 ASTM D664 graphical analysis
Another test that analyses the oxidation levels of lubricants is the ASTM D664. This test
uses the pH value by a titration method to determine the stability of lubricants. The
method is used to determine the acids constituents in petroleum products and lubricants.
It is widely used by petroleum analysis laboratories to obtain preventive maintenance
data for turbine oils. It uses a potentiometric probe to measure the endpoint of the
titration reaction. This is done by measuring the various changes in pH concentration
until the reaction is saturated and measurable result is obtained.
Contaminants
Contamination is a critical aspect of failure analysis of mechanical applications.
The most common contaminations are due to water and wear particulates. This kind of
analysis is significant not only for the lubricant but also for the condition of the moving
parts. There several types of contaminations, however, only water and particulate will be
reviewed here.
Water contamination most likely will occur in wind turbines two ways, externally
or internally. In order to determine the type of water contamination, it is necessary to
understand how it finds its way to lubricants in the system. Let us first look at external
conditions which is most likely due to system failure. It is directly related to seals,
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gaskets or part failure. This is type of water contamination is commonly observed for
wind turbine applications that have cooling systems or exposed to high moisture
locations. Water contamination that occurs due to internal conditions is directly related to
temperature conditions. If high water contamination is observed, this is commonly due to
high friction which increases the temperature causing moisture to form and further
accelerate oxidation. Today’s wind turbine lubricants are equipped with additives to
retain some water while in service; however it becomes an issue when going over the
limit levels. The industry cautious for levels above 500 ppm and for critical above 1000
ppm. For example, some manufactures warranties will not cover failures if water
contamination is over 1000 ppm.
The test widely used to analyze water contamination in lubes is ASTM D6304.
This test is similar to method D664 as mentioned before. The method consists of titration
by the use coulometric analysis. This method measures the amount of water present in
petroleum products by titrating the product and measuring the content using an electrode.
The significance of this test method is described in ASTM D6304 as,
“A knowledge of the water content of lubricating oils, additives, and
similar products is important in the manufacturing, purchase, sale, or
transfer of such petroleum products to help in predicting their quality and
performance characteristics.
For lubricating oils, the presence of moisture could lead to premature
corrosion and wear, an increase in the debris load resulting in diminished
lubrication and premature plugging of filters, an impedance in the effect
of additives, and undesirable support of deleterious bacterial growth.”
(ASTM D6304)
Based on the significance of this test, it seems significant to develop a measuring device
to monitor the water contamination in the lubricant. This moisture analyzer could assist in
setting up adequate and efficient maintenances, and alarm operators when critical
conditions exist.
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Another type of contamination is particulates and they are introduced into the
system either externally or internally. There are two types of contaminants that require
attention, foreign matter (dirt) and wear debris (metallic particles). Foreign contaminants
or dirt are commonly introduced to the system via external ducts while wear debris
consist of particulates generated from degradation of the component parts. These types of
particulate contamination can cause extensive damages to components if not controlled
and monitored which is necessary to study both types. Foreign contaminants or dirt is a
type of particulate contamination that is commonly introduce into system through
breathing vents or poor maintenance. Particulate contamination testing is very common
analysis done on wind turbine lubes. In order to prevent large particulate from entering
the system, manufactures design and develop filtration systems to prevent contamination
to occur. However many of the wind turbines today are not equipped with filtration
systems, especially the older models. These particulates are hard enough to cut and be
abrasive to metal. This can cause wear particulates as shown in figure-4. The other kind
of particulate is called metallic debris.
Figure - 6 Picture of various wear particles
These particles can be classified in various categories as fatigue, severe sliding, spherical
and oxides (see figure 4). These different types of particles can tell a lot about the
condition of the application components and lubricant in order to determine the kind of
maintenance should be performed. As described in the standard ASTM D7690 for
evaluation of particulate contamination,
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“Without particulate debris analysis, in-service lubricant analysis results often
fall short of concluding likely root cause or potential severity from analytical
results because of missing information about the possible identification or extent
of damaging mechanisms.” (ASTM D7690)
It is crucial to develop tools that can assist in measuring particulate contamination while
the system is in use or offline. This tool would control and monitor the turbine working
condition and could help prevent critical failures.
Viscosity
Viscosity is a critical physical property of lubes and is defined as measure of
fluids resistance to gradual deformation by shear stress or tensile stress. Understanding
the purpose for which the type of lube will be used for plays a crucial role in dedicating
the correct lubricating product for the specified application. Wind turbines are very large
systems that work under high loads. The gearboxes support the loads of the giant blades
which are used to generate electrical power.
Figure-7 Drawing example of a viscosity method
These gearboxes require a high viscosity lube to use in order to sustain the high loads.
The most common method used to analyze and calculate lubricant viscosity is ASTM
D445. By having the ability to monitor viscosity levels, it can help identify possible
failures and assist establish the appropriate maintenance frequency. In situations where
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viscosity will decrease below acceptable limits can lead to catastrophic damages which
can be very costly. Per the ASTM method,
“Many petroleum
products, and some non-petroleum materials, are used
as lubricants, and the correct operation of the equipment depends upon the
appropriate viscosity of the liquid being used. In addition, the viscosity of
many petroleum fuels is important for the estimation of optimum storage,
handling, and operational conditions. Thus, the accurate determination of
viscosity is essential to many product specifications.” (ASTM D445)
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4. RELIABILITY
FIGURE-8 Diagram of wind turbine system components
Increase of performance and durability of these components can positively affect
the economic outcome of wind energy projects. However, this continuous improvement
will depend on maintenance efficiencies and economics. A significant aspect of these
applications maintenance is lubrication. Currently sampling is the main technique used to
determine the performance as well as whether additional services or repairs are required.
This type service is usually provided by external services, private companies. These
samples are sent to laboratories for analysis to determine the reliability of the lubricant as
well as the component; identify possible failure. It is necessary to understand the type of
reliability wind turbines have currently and by having remotely advanced monitoring
systems can further increase its reliability.
FIGURE-9 Offshore wind turbine farm
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There are two expects to these wind farms that can affect how maintenance is
performed. They may have the same type of components; however the location of these
systems can have an impact on the type of maintenance required. These farms consist of
both in-land and offshore operations. For example, offshore locations (figure 7) wind
turbine farms are common in countries where land is limited (i.e. Europe and Asia). This
is the opposite for countries with sufficient land space exist to support these large
systems.
FIGURE-10 In-land wind turbine farm
In addition to the location, the size of these turbines (electrical output) can significantly
impact the reliability. This is true as the size of turbine increases; however technology
has also evolved significantly throughout the years to support turbine design and output
requirements. The significance of having an application that can provide real-time
analytical data will only increase the reliability of these giant systems. Figure 9 compares
the relation between each component reliability versus the down time failure. It is
obvious the large components like gearboxes will have a significant impact on the system
if major failure occurs.
“Gearboxes, with some well-publicized failures, only account for about
1.5 incidents every ten machine — years, according to the data. But when
a gearbox fails, the outage time is much longer, at over six days.”
(Gebarin)
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FIGURE-11 Wind turbine reliability diagram
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5. APPLICATION CONCEPT
Designing a tool to monitor the lubricant condition while in use will improve
wind turbine components performance and decrease maintenance cost. The conceptual
tool would consist of several applications to measure critical characteristics of lubricants
in use. These critical characteristics consist of oxidation levels, contaminants, and
viscosity. These measureable characteristics were chosen because they are critical to the
lubricant life and to the condition of the system components.
By establishing these tests as the condition monitoring, one can conceptually
design an electronic monitoring system that could be attached system components sump.
The monitoring system will include applications that can measure these critical
characteristics of the lubricant. These tests are currently being performed by laboratories
to monitor the lubricant condition and identify abnormal conditions. However, it may
some time to reach the lab, extending the time of identifying a major failure and by
raising the repair cost.
The concept would operate much like a testing laboratory kit stationed in
significant components of the wind turbine components; gearboxes and hydraulic
systems. It will include four analyzing systems capable of analyzing oxidation levels,
measure types of contamination, and determine the viscosity for in-service lube oils.
FIGURE-12 FTIR instrument diagram
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Oxidation Application Concept
Oxidation as mentioned before is a critical characteristic of lubes. This property
determines how the lube performs under specific conditions and gives the ability to
measure its life. This is crucial to avoid major damages that can lead to long term
failures. The concept will consist of using an infrared analyzer and oxidation inhibitor
electrode. By having these two methods of measuring oxidation gives the operator the
ability to measure the lubricant oxidation inhibitors additive usage as well as the rate of
decaying of the product. The infrared analyzers have been used in the industry to analyze
characteristics about lubricants for some time; they are Fourier transform infrared
spectroscopy (FTIR). FTIR instruments (figure 12) are commonly used in laboratories to
evaluate and determine characteristics about hydrocarbons, basically providing a
fingerprint. This type of analysis is important in determining the oxidation levels (figure
11), plus it can also provide additional data about contaminants such as water and acids.
FIGURE-13 FTIR scan and oxidation peak
Determining oxidation stability of lubricant is critical to the quality of the lubricant,
however it is also important to know how stable are the oxidation inhibitor additives
found in lubricants. These additives are designed to keep lubricants stable under specific
conditions and differ based on the type of the application and the kind of conditions they
are expected to perform. The industry uses the test called Ruler to analyze these oxidation
inhibitors. Currently the type of inhibitors used in wind turbine applications, gearbox and
hydraulic lubes, are amines and phenols (figure 12). Certain unique gearbox lubes also
use Zinc additive as a strong inhibitor. The analysis is performed using an electrode that
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can measure the stability of these additives.
FIGURE-14 Ruler graphical analysis for Phenols and Amines (oxidation inhibitors).
Contaminants Application Concept
Contaminants are the enemy of maintenance operations, primarily particulates.
They are two types of particulates metallic and non-metallic. Both play a distinguish role
in the maintenance of mechanical applications. Metallic particulates are usually related to
wear debris. Wear debris are generated from different areas on the component; moving
parts syndrome. In wind turbines systems, these parts are critical in gearboxes and
hydraulic systems when generating type of wear debris (figure 4). Depending on the type
of wear debris, it can assist the type of maintenance or repair.
For example, metallic debris generated during the break-in period impose a
different impact to particulate generate during optimal operations. Break-in particulate is
expected to occur (assuming all parts are installed correctly) and it is common to notice a
significant increase in wear rate during this stage. This will normalize as the system
enters the optimal stage, where all parts have had time to adjust and are now in a stable
operation motion. From the maintenance point of view, the break-in period is critical.
This is the period where the maintenance of the unit requires significant monitor because
of large particulate being generated; usually greater than 50µm. The size particle is
visible to the normal eye. As these particulates are being generated, it is necessary to
calculate drainage intervals to remove them.
“Wear debris analysis is essential to effectively gauging machinery life.
When machine components begin to wear, the evidence can usually be
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found in the lubricant flowing through the machine. For example, as parts
undergo sliding, fatigue or creep, pieces of metal will begin to break off
the components and show up as wear debris in the lubricant.”(Wind
Measurement International)
The non-metallic particulates are not generated by mechanical applications.
Silicate particulate, commonly known as dirt particulates, can find their way into the
system components and cause significant damage. This type of particulate is tough
enough to scrape metal and generate metallic chips. This type of wear is known as three
surface contacts, where the silicate particulate as settled in between the moving parts
causing mechanical stress failure. This particulate is usually introduced to the system
externally via air ducts used to cool the components. Most of these components have
filters to prevent large particulate to enter the system however if not maintained or
installed properly will find its way into the system. Having a system that can monitor the
particulate contamination in real-time can prevent major wear failure by assisting with
the maintenance intervals as well as proper maintenance parts are installed.
FIGURE-15 Field particle counter analyzer
The particulate analyzer application concept (see figure 8) would have the ability
to measure a range of particle size. The industry considers particle size below 4µm to
have low impact on wear failure. The known standard used to classify particle size is
ISO11171. This standard provides various methods on how to calibrate laser beam
components to read a range of particulate size. The method ISO4406-1999 describes the
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procedure on how to calibrate these components to measure particulate ranges acceptable
for wind turbine applications. These ranges are ≥4µm, ≥6µm, ≥14µm, ≥25µm, ≥50µm
and ≥100µm.
FIGURE-16 Diagram of particle counter laser analyzer
Best practices for particle contamination control in wind turbines include
the use of inline and offline particle filters and breathers on vents. With
rigorous particle contamination control, bearing life can increase 2.6 to
3.7 times, resulting in greater gearbox reliability, uptime and energy
production, extended warranty periods and a higher return on investment.
To keep gear oil clean, contaminants should be reduced to negligible
amounts. Many gearbox manufacturers and bearing experts believe that to
eliminate the negative effects of particle contamination oil, cleanliness
levels should be maintained at ISO
14/12/10 max, which could bring gearboxes closer to a 20+-year design
life. (ISO 14/12/10 is code based on ISO 4406, shorthand notation for
particle counts, where the first number is a code for the number of
particles greater than 4 μm per mL of fluid, not the actual number; the
second number is the count of particles >6 μm; and the last number the
count of particles >14 μm.”(Clark)
This type of technology (figure 14) is currently being used by lube laboratories
and in the field by operators around the world. Since this tool is available, it would be
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efficient to adapt this technology at the component level. It would require two
applications one to measure particle size and the other to identify particle type; ferrous
vs. nonferrous. The application measuring particle size would utilize a laser as the
method, plus would need to compact. The other would use magnetic sensors to measure
the concentration of ferrous particulate. Currently there are various products on the
market that can be used to measure particulate contamination.
The ability to determine particulate size at real-time and monitor locally would
significantly increase maintenance efficiency and minimize failure due to particulate
contamination. The data would introduce new methods of understanding how these
systems operate and they are impacted by these particulates. Identifying these impacted
areas of the components early can prevent major failure and help maintenance operators
to take specific actions (i.e. filtration systems, vibration analysis, etc.).
“Wear is the inevitable consequence of surface contact between machine
parts such as shafts, bearings, gears, and bushing...even in properly
lubricated systems. Equipment life expectancies, safety factors,
performance ratings and maintenance recommendations are predicated
on normally occurring wear. However, such factors as design complexity,
unit size, intricate assembly configurations, and variations in operating
conditions and environments can make maintenance or repair needs
(ordinary or emergency) difficult to evaluate or detect without taking
equipment out of service.”(Barris)
Viscosity Application Concept
Viscosity is a very critical characteristic of lubricants. This lubricant property is
needed to help manufactures and engineers design mechanical applications. By having
this type of information engineer can assign proper guidelines for loads and speed. This is
the reason why today there is vast of different types of viscosities and lubricant types.
Viscosity depends on two elements temperature and resistance. For example, the higher
the temperature the lower the viscosity will be and the higher the load applied it will
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cause higher resistance which will require higher viscosities. These wind turbines are
gigantic systems for which require lubes with high viscosities to handle its components.
FIGURE-17 Viscometer instrument
The concept would use sensors to measure the viscosity, much like the current
viscometers used on the field and laboratories, except it would be mounted on the
component. Most of the lube industry use automated viscometers to determine the
viscosities for their products. Basically, the concept here would use the same type of
design to measure viscosity (figure 15). The viscosity is determined by measuring the
resistance of some fluid to travel a specified distance. This feature would be helpful to
evaluate the lubricant performance and condition of the component.
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6. ECONOMICS
Economics is one of the most important aspects of success. Every successful
company depends on economic decisions and how they are applied. This concept is the
same when designing a maintenance program for wind turbine farms. Many of these
farms consist of numerous turbines each unit of which has a considerable price tag. The
maintenance price tag on average for these units per year is about 3% of the actual price
of the unit (Dalley). This number tends to increase as the unit ages, which is mainly due
to wear and tear of the different components. We will focus mainly gearboxes and
hydraulic components. These components’ performance are driven by the type of
maintenance program established as well as the economical factor. As we become more
dependable in alternative energy applications, wind turbines are definitely the best cost
affective applications available today. The wind farm industry is growing significantly on
a global scale, primarily among countries where natural fuel resources are limited.
Introducing an application that can monitor the quality of the lubricants and
extend life of the product will help the owners save in maintenance cost and extend its
frequency. Wind turbine maintenance requires significant amount of manpower which
can be very expensive. Monitor the frequency of lubrication is very important to
maintenance operators and it is required to keep the system working in good conditions.
Currently, the method for which these systems lubricants and components conditions are
evaluated is by analyzing the lubricant condition. This method is still being done by using
maintenance operators to climb these towers and collect samples for each component.
Implementing an application that can reduce man labor can result in a significant cost
savings for owners. This type of concept is being introduce in Europe, primarily because
most of Europe’s wind farms are located off-shore; contrary to the farms in the United
States.
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7. CONCLUSION
In the recent years wind power energy has become one of fastest growing
industries in the world. As this industry continues to grow and larger wind turbines are
required to generate more power, it will also require a better and more efficient
maintenance. With technology advancements being developed to support these
applications, it is also necessary to have tools that can support and monitor the condition
of the components used in these systems. Good lubrication conditions are fundamental to
the success of these components. Even though lube manufactures are constantly trying to
improve their recipes to better serve mechanical applications, there is still a need to
monitor the lube condition and determine the optimal service time. Implementing the
concept described here will provide conditions needed to measure and evaluate the
condition of the system and its components. Furthermore, this type of tool will also have
the ability to reduce maintenance cost considerably. The types of analyses described here
were selected to provide the best data to evaluate the condition of both the lube and
machinery.
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REFERENCES
Pozner, M. (2001). Illustrated History of Wind Power Development, Part 1 - Early
History Through 1875. Retrieved from http://telosnet.com/wind/early.html
American Society for Testing and Materials, ASTM D6304 Determination of Water in
Petroleum Products, Lubricating Oils, and Additives by Coulometric Karl Fischer
Titration
American Society for Testing and Materials, ASTM D2272 Oxidation Stability of Steam
Turbine Oils by Rotating Pressure Vessel
American Society for Testing and Materials, ASTM D7690 Microscopic Characterization
of Particles from In-Service Lubricants by Analytical Ferrography
American Society for Testing and Materials, ASTM D445 Kinematic Viscosity of
Transparent and Opaque Liquids (and Calculation of Dynamic Viscosity)
American Society for Testing and Materials, ASTM D664 Acid Number of Petroleum
Products by Potentiometric Titration
Clark, D. (2010, September 23). Windpower Engineering and Development, What to
expect from oil sensors and sampling. Retrieved from
http://www.windpowerengineering.com/design/mechanical/lubricants/what-toexpect-from-oil-sensors-and-sampling/
Fisher, M. (2012). AMSC, Integrated Condition Monitoring - Reliability1(PDF)
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Barris, M., LaVallee, G., Needelman, W. (2009). Power Engineering, Contamination
Control for Wind Turbine Gearboxes. Retrieved from
http://www.donaldson.com/en/ih/support/datalibrary/068309.pdf
Dalley, R. Trico Corporation, Lubricant/Wear Particle Analysis. Retrieved from
http://www.tricocorp.com/pdf-files/oilandwear.pdf
Wind Measurement International, Operational and Maintenance Costs for Wind
Turbines. Retrieved from http://www.windmeasurementinternational.com/windturbines/om-turbines.php
Gebarin, S. (2003). Machinery Lubrication, On-line and In-line Wear debris Detectors:
What’s Out There? Retrieved from
http://www.machinerylubrication.com/Read/521/in-line-wear-debris-detectors
Milborrow, D. (2010, June 15). Windpower Monthly, Breaking down the cost of wind
turbine maintenance. Retrieved from
http://www.windpowermonthly.com/article/1010136/breaking-down-cost-windturbine-maintenance