Holes Book Review: Themes Within the Novel Essay

Twist of fate play major roles in the lives of the main characters in Holes. In â€Å"Holes†, the whole story is based around Stanley’s situation in the present and it’s connection to the past. Stanley’s bad luck is the result of his â€Å" No good rotten-pig- stealing-great-great-grandfather,† who failed to fulfill his promise of carrying Madame Zeroni up the mountain where the stream runs uphill. His situation at Camp Green Lake was connected to the history of ‘Kissin’ Kate Barlow, a schoolteacher turned bandit who robbed his great-grandfather and buried her treasure somewhere on the lake. The boys are forced to dig holes because of this and the person overseeing them is the Warden, who is the granddaughter of Mr. Charles Walker who was, in a way, responsible for Kate Barlow’s death. Stanley meeting Zero, Zero turning out to be Madame Zeroni’s great-great-great-grandson and Stanley helping to carry him up God’s thumb was not a coincidence, but it was fate that brought them together so they could complete the cycle and end Stanley’s curse. Fate has the power to alter lives and change them into a game of chance. The actions of one’s past may affect the situation of one’s future and therefore I agree that fate had played a major role in the novel. In the story, one of the themes are to always respect ones promises and to fulfill them or you had to face the consequences. This is shown when Elya Yelnats does not fulfill his promise to Madame Zeroni and soon after, pays the price. In the novel, Madame Zeroni warns Elya â€Å" That if he failed to do so, he would be cursed for eternity.† And at the time â€Å"†¦he thought nothing of the curse and as a boy he was carefree.† This shows that all people should fulfill their promises so we do not suffer the consequences. This positions the readers to feel sorry for Stanley because the actions of his great-great-grandfather has affected Stanley’s life even if he has done nothing. Stanley’s destiny is explained throughout the novel, because there are many clues, which point towards his destiny and the situations, which lead to the present. When Zero tells Stanley that his named was Hector Zeroni or how his great grandfather found refuge under God’s thumb and it’s relation to the mountains at Camp Green Lake because they provide a connection to Stanley’s past and destiny. This explains the situation to the reader and provides insight to the storyline. Fate plays a major part in the story because it intertwines both the past and the present, giving a connection between Stanley and his great-great-grandfather. This is shown throughout the story because all the problems Stanley faces in the present situation is caused by certain situations which his family was connected to by fate. For example, such scenes like Stanley Yelnats the 1st was robbed by Kate Barlow and her treasure being his suitcase, which Stanley digs up in the end of the book. This shown that the events of ones past may affect ones future. This positions the readers to feel pity for Stanley because he does not know the bigger picture happening to him. Friendship plays a key role in Stanley’s fate as he becomes friends with Zero during his stay at Camp Green Lake and this disrupts X-ray’s sense of superiority and threatens his position of power at camp. The friendship is beneficial for Stanley at the start and the end of the novel because by becoming friends and carrying him up the mountain, Stanley finally breaks his families curse. Stanley carrying Zero up the mountain shows us the true meaning of friendship. This positions the reader to connect to the characters at a human level. In the novel, the story tells us the importance of keeping a promise, having a strong friendship, of destiny and it’s connection to the past and that fate always plays a major role in any situation. Nothing is ever a coincidence and all the events in the novel are linked to Stanley’s history, which affected his present situation. All this could have been avoided if Elya Yelnats have had more common sense and if he had been more mature.

Yevtushenkos Babi Yar Essays - The Holocaust In Ukraine, Free Essays

Yevtushenkos Babi Yar Essays - The Holocaust In Ukraine, Free Essays Yevtushenko's Babi Yar Babi Yar, a poem written by Yevgeny Yevtushenko, tells the story of the Nazi invasion into a small part of Russia, in which, throughout the duration of World War II, over one-hundred thousand Jews, Gypsies and Russian POW's were brutally murdered. However, what is unique about this particular perspective is that the narrator is not a Jew, but a mere observer who is aghast at the atrocities that took place during the Holocaust. It is through allusions, as well as other literary devices, that Yevtushenko elucidates caustically the absurdities of the hatred that caused the Holocaust, in addition to the narrator's identification with the Jews and their history of oppression. Perhaps, the most effective literary device used in "Babi Yar" is the allusion. The first clear allusion seen in the poem is the one concerning Egypt(line 6). This reference harks back to the Jews' enslavement in Egypt before they become a nation. In line 7, the narrator makes reference to how so many Jews perished on the cross. The reason for these initial allusions in the first section is clear. Yevtushenko is establishing the history of the Jewish people, being one of oppression, prejudice, and innocent victims. The next illusion in the poem is a reference to the Dreyfus Affair, a more modern display of irrational and avid anti-Semitism. It is in the Dreyfus affair that an innocent man is accused of espionage and is sent to jail for more than ten years, notwithezding an overwhelming amount of evidence pointing to his innocence, simply because he is a Jew. Yevtushenko uses these allusions to lead up to his referral to a boy in Bielostok who is murdered by the Russian common-folk. Clearly, The narrator is teaching a lesson with a dual message. Firstly, he is informing the reader of the horrors that took place in Russia during the Holocaust. Perhaps even more of a travesty, however, is the fact that humankind has not learned from the past in light of the fact that this "episode" is merely one link in a long chain of terrors. Yevtushenko goes on to allude to Anne Frank, a young Jewish teenager who left behind a diary of her thoughts and dreams, and how the Nazis strip her of any potential future she has when she is murdered in the death camps. Clearly, the allusion creates images in the mind of the reader that mere descriptions via the use of words could not. Another effective literary device used in the poem is the first person narrative in which the narrator identifies with those victims which he describes. This is seen in the case where the narrator says "I am Dreyfus", or "Anne Frank, I am she." The narrator does not claim to underezd what the feelings and thoughts of these people are, but rather, he is acknowledging the fact that they are feeling, "detested and denounced" and that unlike the rest of the world who turned its head, or the Russians who actually abetted such heinous crimes, this gentile narrator can not empathize, but does sympathize with his Jewish "brethren." Another extremely powerful device used by Yevtushenko is the detail of description and imagery used to describe events and feelings that are in both those whom he identifies with, as well as himself. "I bear the red mark of nails"(line 8) seems to include much of the suffering that the Jews have to endure. The statement is almost one of a reverse crucifixion in which the Jews are crucified and now have to suffer with false accusations, blood libels, and Pogroms for the duration of time. The poet describes very clearly the contempt most people have for the Jewish people and how many of these people aided in the barbarity . In line 13, for example, the poet speaks of "shrieking ladies in fine ruffled gowns" who "brandish their umbrellas in my face." In addition, Yevtushenko also depicts explicitly how the "tavern masters celebrate" at the sight of "(a Jewish boy's)blood spurt and spread over the floor." The contrast of age in "Babi Yar" is also quite effective. In the last three sections, the reader finds out that the narrator is remembering the past, mourning those who have perished.

Income Tax and Corporation Tax Essay Example | Topics and Well Written Essays - 2250 words

Income Tax and Corporation Tax - Essay Example Under the finance act 2010/2011, there are three types of rate bands, basic rate, higher rate and additional rate. Every type of income has its own tax rate. These are illustrated in the table below: Basic High Additional Rate Band (?1-?37,400) (?37,401-?150,000) (?150,001 and over) Non-Saving Income 20% 40% 50% Saving Income 20% 40% 50% Dividends Income 10% 32.5% 42.5% If a savings income fall into the basic rate band, then the rate, till the amount of ?2,240 is 10%. Above that the rate of 20% is implied. Any income over and above the individual’s allowance is taxable. There are different kinds of allowances for example personal allowance, old age allowance, married couple allowance, maintenance payment relief, or blind person’s allowance. Personal allowance depends upon the age and income limits, Allowances for the year 2010/2011 are shown below: Age ? Personal Allowance Standard 6,475 Personal Allowance 65 to 74 9,490 Personal Allowance 75 and above 9,640 Income Limi t for age-related Allowances 22,900 Income Limit for standard personal allowance 100,000 The blind person’s allowance is 1,890 pounds for the year 2010/2011, there are no age or income limits, and this allowance is in addition to the personal allowance of the entitled individual. Other allowances like married couple’s allowance or maintenance payment relief are entitled to a couple where both the partners are born before 6 April 1935, or either of the partners or formal partners is born before 6 April 1935, respectively. Married couple’s allowance is ?6,965 for the year 2010/11. Tax Period: The relevant tax period for the year 2010/2011 is from 6 April 2010 to 5 April 2011. All the taxes are computed for this period. Corporation Tax: Scope:... The paper tells that income tax is charged on the income of all UK residents. Income tax is basically charged to all the individuals. That will include employed, self-employed or un-employed individuals. For employed individuals, the basic source of income will be their salaries along with other sorts where as the self employed individuals will be charged on their trading income. Un-employed individuals may have their income coming from savings or investments. There is no maximum age limit for any individual to be exempt from income tax. Corporation tax is payable by limited companies or some other unincorporated businesses, which are UK resident. Such UK resident companies pay tax on their comprehensive income. A company is called a UK resident; if it’s incorporated in UK or even if it isn’t incorporated in UK then it is centrally managed and controlled in UK. In determining where the company’s central administration is positioned, the HM Revenue and Customs wil l focus on the highest level of the company. Especially where the board is located and where all the meetings of the board are carried out. If a company is a non-resident then it is not liable for corporation tax. But if it carries out its trade through a permanent institution like a branch or agency which is a UK resident, then in that case the profits from that institution are liable for tax. From the paper we will see that though rates related to income tax are constantly being increased and the allowances being decreased, no such progressive changes are seen in the corporation tax strategy.

Critical Analysis of a Historical Science Assignment

Critical Analysis of a Historical Science - Assignment Example In DNA data is stored in codes consisting four chemical elements: adenine (A), guanine (G), cytosine(C) and thymine (T) (Watson, 2004). However, we realize that, in human beings, DNA consists of more than a billion elements, which are mostly similar in all humans. The order in which these elements appear determines the availability of elements to build and sustain a being. This can be likened to the order of letters that forms different words and sentences. The four DNA elements combine in a predetermined sequence, that is, A binds with T while C binds with G. This results in the arrangement of elements called base pairs. The ratio of adenine to thymine, and guanine to cytosine govern the pattern of DNA. Further, each element attaches itself to a sugar molecule and phosphate molecule to form a nucleotide. These nucleotides are then aligned in two strands to form a double helix, which is spiral in shape running in an anti-parallel manner. These arrangements are referred to as chromoso mes, which during the process of DNA replication, divide and are copied or replicated to develop more chromosomes. This results in all cells consisting enough chromosomes to support life fully. The key element of DNA is that it is capable of replicating itself to make millions of copies. A DNA strand in a double helix is the prototype for copying the series of bases. This is of paramount importance in cell division as the newly created cells need to obtain a similar DNA trait as the old cell. DNA together with macromolecules such as proteins, lipids and carbohydrates are essential in the establishment and maintenance of any life form, RNA viruses being the exception. The genetic code is the system used in reading the material contained in DNA. The genetic code spells out plan of amino acids which form proteins in the body and is studied by replicating existing DNA strands to RNA acid. This is done through a process referred to as transcription. Beings such as animals, fungi and plan ts, also referred to as eukaryotic organisms gather their DNA in the nucleus, mitochondria or chloroplast of their cells. On the other hand, beings such as bacteria and other single celled organisms commonly referred to as prokaryotes collect their DNA in the cytoplasm. The organization and packing of DNA in cells is tasked upon alkaline based proteins referred to as chromatin. These proteins include histones. Hydrogen bonds between nucleotides help to stabilize DNA; however, we note that interfacing nucleobases in a process referred to as base-stacking is also essential in steadying the DNA helixes. There are two classes of nucleobases, these are: purines which are formed when A and G are combined in the ratio of five to six and pyrimidines formed when six C and T bases combine (Watson, 2004). Biotechnicians examine the characteristics if nuclear based acids through a technology referred to as nucleic acid analogues. These techniques are typically used by medical and biology resear chers. Furthermore, we note that the arrangement of DNA is referred to as sense which is copied to its RNA and, on the other hand, antisense is the term used to refer to the arrangement of DNA on the reverse side. However, it is common for both sense and antisense to appear in a single strand of DNA. RNA antisenses are churned out in prokaryotes and eukaryotes, these RNA antisenses are mandated with controlling gene expression in the process of RNA-RNA base pairing which is quite similar to the base pairing process in DNA

Deepening Essay Example | Topics and Well Written Essays - 1750 words

Deepening - Essay Example This has been interpreted differently, while there are some that have assimilated, some did not have the capacity to go through the assimilation process. This kind of individuals, eventually gave up and held up to their familiar ways of life. We begin with a story comprising of two close friends, Amy and Jeehynum, who have had similar experiences in high school. At the beginning, the two friends separated, and one travelled to Korea. It is apparent that the two have been friends from their childhood days, and their friendship culminates in high school, at a stage where their lives are close together. The future is uncertain, and the two do not know what to expect when they relocate to a different environment. For Amy, she has a different experience in regards to her college life, which makes her get filled up with mixed reactions, as events unfold. However, she starts off nicely, gets new friends and finally begins to catch up with the new environment. For Jeehyun, college years have been tough, and most of the times she would often try to assimilate into the environment with no much progress. It is evident that the two friends are experiencing culture shock; a situation in which a person feels disoriented as a result of being exposed to a new way of life. There are many causes, of this scenario, the notable and most familiar one being, when an individual is exposed to a foreign land (Ward, Bochner, and Furnham). Culture shock is addressed in four defining stages, these are honeymoon, negotiation, adjustment and mastery. The honeymoon stage comprises of a healthy view of the differences that are evident in the subjects. The strange land at this stage seems to be good and at times adventuress. It is at this stage, where the subjects would find nationals that are familiar and at times speak their language. This stage does not last for long, after a short period, it can take about two to three months. The next stage

American Tool Works Essay Example for Free

American Tool Works Essay This course focuses on improving the performance of the firm and its supply chain through coordination among multiple sites, functions, and economic actors (customers and suppliers). Students will know how to design and implement strategies for structure and management, both cross-functionally, with the firm, and across an industry value chain among interacting firms. These strategies include restructuring supply chain facility networks, coordinating information and materials flow, managing supplier relations, and managing customer order fulfillment processes. The theme of the course is that strategies that enhance integration throughout the supply chain can lead to improved performance (in terms of efficiency, effectiveness, quality, customer satisfaction, cost, flexibility, etc. ), providing firms with a source of competitive advantage. TEXTBOOK: D. Simchi-Levi, P. Kaminsky, and E. Simchi-Levi, Designing and Managing the Supply Chain: Concepts, Strategies, and Case Studies, 3rd ed. , McGraw Hill/Irwin, New York, 2008, ISBN 978-0-07-298239-8. READINGS:Additional articles and cases will be made available through WebCT and http://cb. hbsp. harvard. edu/cb/access/5023124 SOFTWARE:The Beer Game simulation software is available on the web and will be used for real-time ordering, planning, forecasting decisions in the supply chain. The Risk Pool Game is available on the CD that comes with the text. The Global Supply Chain Management Simulation is available through harvardbusinessonline. com and allows students to manage product design, procurement, and production for four simulated years. Excel will be used for inventory management, supply contracts, and for optimal resource allocation and distribution network configuration. PREREQUISITES: Second year standing COURSE OBJECTIVES: 1. Recognize salient challenges and opportunities for managing supply chains. 2. Become familiar with supply chain strategies that have been adopted by leading companies. 3. Learn to use several analytical tools to assess tradeoffs and support decision making. METHOD: This course stress those models, concepts, and solutions methods that can be applied to the design, control, operation, and management of supply chain systems. The course includes lectures, case discussions, presentations, and hands-on, practical exercises and games to provide both a sound base of learning and an opportunity to test and develop skill. Students should do all of the assigned readings and cases before coming to class, and prepare for, and contribute to, class discussions. Excel is used to support the quantitatively intensive topics. STUDENT TEAMS: Teams will consist of about five students who will work together as the presenting and questioning teams for cases and articles as described below. The teams may allocate the work as desired, as long as all team members agree with the allocation. The team should let a member know if they are not performing at an appropriate level, and should contact the instructor if problems persist. Each team member will provide the instructor with an evaluation of their team members’ performance at the end of the term by allocating 100 total points (no self-allocation) between the other members. This information will be used to adjust team work grades. CASE PRESENTATIONS: Each student team will have the opportunity of serving as the â€Å"presenting team† for two of the cases and the â€Å"questioning team† for one of the cases that we will discuss in class. The â€Å"presenting team† will provide the background and content of the case, an analysis of what the company did correctly or incorrectly, and suggestions about what the company should do in the future. They should also address any questions given as part of the case write-up or indicated by the instructor. The â€Å"questioning team† will be responsible for questioning the presenting team, offering alternative solutions, and for leading the rest of the class in a discussion of the case. The questioning team will submit a written list of questions prior to the presentation. The members of the class will be asked to assess the performance of both teams. The instructor will incorporate the class evaluations into the presentation grades.

Transformer Oil Or Insulating Oil Engineering Essay

Transformer Oil Or Insulating Oil Engineering Essay CHAPTER 2 LITERATURE REVIEW 2.1 Introduction Transformer is one of the most useful appliances ever invented. Transformer can raise or lower the voltage or current in alternating current (AC) network, the circuit can be isolated from one another, and to increase or decrease the apparent value of a capacitor, inductor, or resistor. Furthermore, the transformer allows us to transmit electricity long distances and to circulate safely in factories and homes. (Electrical Machines, Drives, and Power Systems, 6th Edition). The cost of a transformer is high. The failure of one transformer resulted in a loss in terms of the price of one transformer or in terms of energy supply disruptions to consumers. Therefore, to monitor the transformer oil is one the right way and good for detecting the causes of damage to transformers. 2.2 Transformer Transformer is one of the most important electrical devices. Transformer is widely used in power systems and electronic devices. Transformer can also raise and lower voltage levels and the alternating current to suit application. Transformer can transfer power from one section to another on the same frequency but different voltage levels and currents. Transformer basically consists of two coils of a conductor which acts as an inductor electrically separate but magnetically attached. Transformer consists of two loops wrapped around the core base, core and coil which are a part of the transformer structures. Figure 2.1 shows the general structure of a transformer. When alternating current connected to the transformer primary windings, current will flow through the primary winding. Alternating current flows will create an alternating magnetic flux in the transformer core. The magnetic flux can flow to the secondary winding of the transformer through the transformer core. http://www.electricityforum.com/images/electrical-transformer-design.jpg Figure 2.1 General Structure of Transformer According to the Faraday law, the electromotive force or voltage is induced in the coil-winding transformer when the flux is changes in value. Because of the magnetic flux in the transformer core is an alternating flux whose value is constantly changing over time, the electromotive force or voltage is always induced in the coil-winding transformer. Electromotive force in the primary winding is known as the self-induced electromotive force is due to the flux generated by the coil itself. While the electromotive force induced in the secondary winding is known as mutual induction electromotive force due to the induced electromotive force is caused by magnetic flux generated from the primary winding. In an ideal transformer, the induced voltage in the secondary winding (Vs) is in proportion to the primary voltage (Vp), and is given by the ratio of the number of turns in the secondary (Ns) to the number of turns in the primary (Np) as follows: (Equation 2.1) By appropriate selection of the ratio of turns, a transformer thus allows an AC voltage to be stepped up by making Ns greater than Np, or stepped down by making Ns less than Np. There are many types of transformer are designed to meet the specific industrial applications. These include autotransformer, control, current, distribution, general-purpose, instrument, isolation, potential (voltage), power, step-up, and step-down. To avoid rapid damage of the insulating materials inside a transformer, sufficient cooling of the windings and the core must be provided. Indoor transformers below 200 kVA can be directly cooled by the natural flow of the surrounding air. The metallic housing is equipped with ventilating louvres so that the convection currents that can flow over the windings and around the core. Large transformers can be constructed in the same way, but the forced circulation of fresh air must be provided. Such as a dry-type transformers are used inside the building, away from the hostile atmosphere. Distribution transformers below 200 kVA are usually immersed in mineral oil and sealed in a steel tank. Oil carries the heat away to the tank, which it is lost by radiation and convection to the outside air. Insulating oil is much better than air, consequently, it is often used in high voltage transformers. As the power rating increased, external radiators are added to increase cooling surface of the tank contains oil. Oil circulates around the transformer windings and moving through the radiator, where heat released into the surrounding air. For still higher levels, cooling fans blow air over the radiators. For transformers in the megawatt range, cooling can be effected by the oil-water heat exchanger. Hot oil drawn from the transformer tank is pumped into the heat exchanger where it flowing through the pipes that are in contact with cold water. Such as heat exchanger are very effective, but also very expensive, because water itself must continuously cool and recirculated. Some large transformers are designed to have multiple ratings, depending on the cooling method used. Thus, the transformer may have triple ratings depending on whether it is cooled by: the natural circulation of air (AO) for 18000 kVA, or forced-air cooling with fans (FA) for 24000 kVA, or the forced circulation of oil accompanied by forced-air cooling (FOA) for 32000 kVA. These elaborate cooling systems are nevertheless economical because they enable a much greater output from the transformer of a given size and weight. The type of transformer cooling is designated by the following symbols: AA dry-type, self-cooled AFA dry-type, forced-air cooled OA oil-immersed, self-cooled OA/FA oil-immersed, self-cooled/forced-air cooled AO/FA/FOA oil-immersed, self-cooled/forced-air cooled/forced-air, forced-oil cooled The temperature rise by the resistance of oil-immersed transformers is either 55 °C or 65 °C. The temperature must be kept low to preserve the oil quality. By contrast, the temperature rise of dry-type transformer may be as high as 180 °C, depending on the type of insulation used. TEMCo offers the largest selection of High Voltage Transformers.GE Ventilated Dry-type Transformer Figure 2.2 Dry-Type Transformer Figure 2.3 Oil-Immersed Transformer 2.3 Transformer Oil Transformer oil or insulating oil is usually a highly-refined mineral oil that is stable at high temperatures and has excellent electrical insulating properties. It is used in oil-filled transformers. Transformer oil is likened to be the blood within the transformer body. It must be periodically tested to monitor condition of the transformer. Transformer oil serves three basic functions which are to insulate, to cool and maintain the transformer functions at all times. To keep these functions the industry has agreed on certain standards. The two leading transformer oil specifications in the world are IEC 60296 and ASTM D 3487. In these standards there are many specific requirement and limits based on physical and chemical properties. Many of these properties and their limitations stem from the chemistry of refined mineral oils in combination with application specific requirements of electrical insulation. In an age when alternative to mineral oil being developed, it is important both to know what is desirable and what is likely to achieved in technical terms. Whereas some brands of transformer oil could only meet the specifications, the others excel. In the end, transformer oil consumers should decide which properties are most important to their intended use. Technical specifications also have an impact on issues such as asset management, maintenance planning and investment budget. To aid decisions in these fields it is helpful to have a basic understanding of the science underlying specifications and limitations. In Malaysia, mostly used transformer oil is mineral crude oils (uninhibited mineral oils) which contains Paraffic, Naphteric or mixed. It is supplied by Hyrax Oil Sdn. Bhd. 2.3.1 Transformer Oil Properties The main function of transformer oil is insulating and cooling of the transformer. It should have the following properties: High dielectric strength and good dielectric properties resulting in minimum power loss. Low viscosity improves cooling. Freedom from inorganic acids, alkali, and corrosive sulphur. Resistant to emulsification. Rapid settling of arc products. Low pour point. High flash point resulting in low evaporation losses due to high thermal stability. High resistivity gives better insulation values between windings. Excellent interfacial tension for quick water separation. Proven resistance to electrical stresses. High electrical strength. Remarkably low sludge and acidity formation in both ageing and oxidation tests gives longer life to oil and equipment during storage and service. 2.3.2 Theory of Transformer Oil Parameters Water Content The standard for measuring water contain in oil is IEC 60814. (Marcel Dekker, 1990). The important function in transformer oil is to provide electrical insulation. When oil has higher moisture content, it can reduce the insulating properties of the oil, which may result in dielectric breakdown. This is the particular importance with fluctuating temperatures because, transformer will cools down if any dissolved water will become free and this oil become poor insulating power and fluid degradation. (Azliza binti Mohd Jelan,2009). Breakdown Voltage Dielectric strength is one of the important properties in insulation field. Breakdown voltage in insulating material is the maximum electric field strength that it can be withstand intrinsically without breaking down and without experiencing failure of its insulating properties, dielectric strength also means that a certain configuration and electrode dielectric material that produces minimal damage to the electric field. (Rohaina bt Jaafar, 2003). Breakdown strength in liquid according to various factors influenced in the experiment which is electrode material and surface state, geometry electrode, the presence of chemical pollutants, the presence of physical pollutants, oil molecular structure, temperature and pressure. There also various factors in the theory of voltage breakdown which is like electronic theory, suspended particle theory, cavitations theory and bubble theory were postulated. (Olive Oil from the Tree to the Table). Dielectric strength is also very dependent on the time and method of tension, purity materials, the type of tension as well as experimental and environmental parameters, until set of dielectric strength unique to the specific material is difficult, a range of values can be found and used for application purposes. (Noraniza binti Toriman, 2003). Figure 2.4 Heating / Cooling Curve of Oil (Ahmad Norhakimi bin Ibrihim @ Ibrahim, 2010) 2.3.3 Types of Transformer Oil Mineral Transformer Oil (Mineral Based Oil) A mineral oil or liquid petroleum is a liquid by-product of the distillation of petroleum to produce gasoline and other petroleum based products from crude oil. A mineral oil in this sense is a transparent, colourless oil composed mainly of alkenes (typically 15 to 40 carbons) and cyclic paraffin, related to petroleum jelly (also known as white petrolatum). It has a density of around 0.8 g/cm3. Mineral oil is a substance of relatively low value, and it is produced in very large quantities. Mineral oil is available in light and heavy grades, and can often be found in drug stores. There are three basic classes of refined mineral oils: Paraffinic oils, based on n-alkenes. Naphthenic oils, based on cycloalkanes. Aromatic oils, based on aromatic hydrocarbons (not to be confused with essential oils). Table 2.1 Properties of Mineral Transformer Oil (http://www.substech.com) Property Value in metric unit Value in US unit Density at 60 °F (15.6 °C) 0.880 *10 ³ kg/m ³ 54.9 lb/ft ³ Kinematic viscosity at 68 °F (20 °C) 22 cSt 22 cSt Kinematic viscosity at 212 °F (100 °C) 2.6 cSt 2.6 cSt Fire point 170  °C 338  °F Pour Point -50  °C -58  °F Flash point 160  °C 320  °F Auto ignition point 280  °C 536  °F Specific heat capacity 1860 J/(kg*K) 0.444 BTU/(lb* °F) Thermal conductivity at 20 °C (68 °F) 0.126 W/(m*K) 0.875 BTU*in/(hr*ft ²* °F) Thermal expansion at 20 °C (68 °F) 7.5*10-4  °Cˆ°Ã‚ ¹ 4.2*10-4 in/(in*  °F) Breakdown strength min.70 kV min.70 kV Dielectric dissipation factor at 90 °C (194 °F) max.0.002 max.0.002 Permittivity at 20 °C (68 °F) 2.2 2.2 Silicon Transformer Oil (Polydimethylsiloxane based fluid) Polydimethylsiloxane (PDMS) belongs to a group of polymeric organosilicon compounds that are commonly referred to as silicones. PDMS is the most widely used silicon-based organic polymer, and is particularly known for its unusual rheological (or flow) properties. PDMS is optically clear, and, in general, is considered to be inert, non-toxic and non-flammable. It is occasionally called dimethicone and is one of several types of silicone oil (polymerized siloxane). Its applications range from contact lenses and medical devices to elastomers; it is present, also, in shampoos (as dimethicone makes hair shiny and slippery), caulking, lubricating oils, and heat-resistant tiles. Table 2.2 Properties of Silicon Transformer Oil (http://www.substech.com) Property Value in metric unit Value in US unit Density at 60 °F (15.6 °C) 0.960 *10 ³ kg/m ³ 59.9 lb/ft ³ Kinematic viscosity at 68 °F (20 °C) 55 cSt 55 cSt Kinematic viscosity at 212 °F (100 °C) 15 cSt 15 cSt Fire point min.350  °C min.662  °F Pour Point max.-50  °C max.-58  °F Flash point min.300  °C min.572  °F Auto ignition point 435  °C 815  °F Specific heat capacity 1510 J/(kg*K) 0.360 BTU/(lb* °F) Thermal conductivity at 20 °C (68 °F) 0.15 W/(m*K) 1.019 BTU*in/(hr*ft ²* °F) Thermal expansion at 20 °C (68 °F) 10.4*10-4  °Cˆ°Ã‚ ¹ 5.8*10-4 in/(in*  °F) Breakdown strength 50 kV 50 kV Dielectric dissipation factor at 90 °C (194 °F) max.0.001 max.0.001 Permittivity at 20 °C (68 °F) 2.7 2.7 Synthetic Transformer Oil (Organic Esters Based Fluid) Synthetic oil is a lubricant consisting of chemical compounds which are artificially made (synthesized) using chemically modified petroleum components rather than whole crude oil. Synthetic oil is used as a substitute for lubricant refined from petroleum when operating in extremes of temperature, because it generally provides superior mechanical and chemical properties than those found in traditional mineral oils. Table 2.3 Properties of Synthetic Transformer Oil (http://www.substech.com) Property Value in metric unit Value in US unit Density at 60 °F (15.6 °C) 0.970 *10 ³ kg/m ³ 60.6 lb/ft ³ Kinematic viscosity at 68 °F (20 °C) 70 cSt 70 cSt Kinematic viscosity at 212 °F (100 °C) 5.3 cSt 5.3 cSt Fire point 322  °C 612  °F Pour Point -60  °C -76  °F Flash point 275  °C 527  °F Autoignition point 438  °C 820  °F Specific heat capacity 1880 J/(kg*K) 0.448 BTU/(lb* °F) Thermal conductivity at 20 °C (68 °F) 0.144 W/(m*K) 0.98 BTU*in/(hr*ft ²* °F) Thermal expansion at 20 °C (68 °F) 7.5*10-4  °Cˆ°Ã‚ ¹ 4.2*10-4 in/(in*  °F) Breakdown strength min.75 kV min.75 kV Dielectric dissipation factor at 90 °C (194 °F) max.0.006 max.0.006 Permitivity at 20 °C (68 °F) 3.2 3.2 2.3.4 Transformer Oil Testing Regular sampling and testing of insulation oil taken from transformers is a valuable technique in a preventative maintenance program. If a proactive approach is adopted based on the condition of the transformer oil, the life of the transformer can be extended. Hence, transformer oil must be periodically tested to ensure its basic electrical properties. These tests can be divided into: Liquid Power Factor The IEC standard method for this test is IEC 247. This involves measuring the power loss through a thin film of liquid test. Water, contamination, and the decay products of oil oxidation tend to increase the power factor of oil. The new oil has very low power factor less than 0.1% at 25  ° C and 1.0% at 90  ° C. As the oil ages and moisture accumulates, or if the unit is contaminated, the liquid power factor tends to increase. Many owners make the mistake of having this transformer testing at only one temperature. While the test is more sensitive to 90  ° C, both the temperature should be used. The relationship between 25  ° and 90 ° values can assist in making the diagnosis as to whether the problem of moisture, oxidation, or contamination. (A Guide to Transformer Oil Analysis, by I.A.R. GRAY) Dielectric Breakdown Strength The dielectric breakdown voltage is a measure of the ability of the oil to withstand electric stress. Dry and clean oil showed the inherent high breakdown voltage. Free water and solid particles, especially the latter in combination with high levels of dissolved water, tend to migrate to areas of high electric stress and dramatically reduce the breakdown voltage. The measurement of breakdown voltage, therefore, serves primarily to indicate the presence of contaminants such as water or conducting particles. A low breakdown voltage can be indicating that one or more of these are present. However, a high breakdown voltage does not necessarily indicate the absence of all contaminants. This test was conducted in accordance with IEC 156. (A Guide to Transformer Oil Analysis, by I.A.R. GRAY) Moisture The purpose of dielectric tests are conducted is to ensure the monitoring moisture can be done directly. IEC 733 is a well established and can measure the moisture down to the low part of the million levels. While the acceptable values have been set by the voltage class for moisture, these are somewhat misleading. A truer picture of moisture in the transformer must be taken into account so that percentage saturation of the oil by moisture and percentage moisture by dry weight of the solid insulation can be calculated. A transformer at 20  ° C that containing 20 ppm moisture in oil is considerably wetter than a same unit, with a similar 20 ppm moisture, but it is operating at 40  ° C. The new transformer must be less than 0.5% moisture by dry weight. Anything more than 3.0% (or 30% saturation) is considered very wet. Many owners dehydrate transformer when the moisture level exceed 1.5 to 2.0% moisture by dry weight. (A Guide to Transformer Oil Analysis, by I.A.R. GRAY) Neutralization Number (Acidity) This value, measured by IEC standard method IEC 1125A reported as mg KOH / g sample, reports the relative amount of oil oxidation products, especially acids, alcohol and soap. As oil continues to oxidize, the acid increased gradually, generally over the years. Running the acid number regularly provides guidance as to how far oxidation of the oil has proceeded. The acceptable limit by the test is usually used as general guidelines to determine when the oil should be replaced or reclaimed. Acceptable values for acid number are 0.20 and lower. Unacceptable values are over 0.20.These are the values that are used by TNB. (A Guide to Transformer Oil Analysis, by I.A.R. GRAY) Interfacial Tension The test methods for interfacial tension (IFT), IEC 6295, measuring the strength in mN/m from the interface that will form between service aged oil and distilled water. Because the decay products of oil oxidation are oil and water soluble, their presence would tend to weaken the interface and reduce the interfacial tension value. Brand new oil is often 40-50 mN/m. A value that is acceptable for the in-service oil is greater than 25 mN/m or greater; unacceptable results are below 28 mN/m. (A Guide to Transformer Oil Analysis, by I.A.R. GRAY) Colour/Visual Field inspection of liquid insulation (IEC 296) includes examination for the presence of cloudy or sediment and the general appearance as well as a colour inspection. As oil ages, it will be darken gradually. Very dark oil or oil that changes drastically over a short period of time may indicate a problem. Any cloudiness or sediment indicates the presence of free water or particles that may be harmful to continued the equipment operation. Taken alone, without considering the past history or other test parameters, the colour is not very important to diagnose transformer problems. If the oil has an acrid or unusual odor, consideration should be given to carrying out further tests. (A Guide To Transformer Oil Analysis, by I.A.R. GRAY) Sludge/Sediment The IEC 296 test distinguishes between the sediment and sludge. Sediment is an insoluble substance present in the oil. Sediment may consist of insoluble oxidation or degradation products of solid or liquid materials, solid products such as carbon or metallic oxide and fibres or other foreign matter. Sludge is polymerized oxidation products of solid and liquid insulating material. Sludge is soluble in oil up to a certain limit. At sludge levels above this, the sludge comes out of the solution contributing an additional component to the sediment. The presence of sludge and sediment can change the electrical properties of the oil and prevent the exchange of heat, so encouraging damage to the insulating material. (A Guide to Transformer Oil Analysis, by I.A.R. GRAY) Inhibitor Content Inhibited oil deteriorates more slowly than uninhibited oil so long as active oxidation inhibitor is present. However, after the oxidation inhibitor is consumed, the oil can be oxidized at a higher level. Determination of oxidation inhibitor remaining in the in-service transformer oil is based on IEC 666. (A Guide to Transformer Oil Analysis, by I.A.R. GRAY) Dissolved Gas Analysis In contrast to the tests and the methods discussed to this point, the dissolved gas analysis (DGA) did not measure the gradual changes in the quality of oil. DGA has a very limited utility in determining the continued suitability of the transformer oil. The purpose and functions of the DGA is to provide an indication as to whether there may be an active or incipient transformer fault affecting the operation and continued health of the equipment. DGA is used to detect and measure nine of dissolved gases which are Hydrogen, Oxygen, Nitrogen, Methane, Carbon Monoxide, Carbon Dioxide, Ethan, Ethylene, and Acetylene. (A Guide To Transformer Oil Analysis, by I.A.R. GRAY) Dissolved Metals Analysis Analysis of dissolved metals (in particular, for the three metals: iron, copper, and aluminium) can be used in further identifying the location of transformer faults discovered by dissolved gas analysis. For example, the dissolved metal analysis indicating the presences of conductor metals may indicate a fault is occurring in the winding or at a connection while the presence of iron indicates involvement of the core steel. (A Guide To Transformer Oil Analysis, by I.A.R. GRAY) Furanic Compounds When paper breaks down, the cellulose chains are broken and glucose molecules (which serve as the building blocks of the cellulose) are chemically changed. Each of the glucose monomer molecules that are removed from the polymer chain becomes one of a series of related compounds called furans or furanic compounds. Because these furanic compounds are partially soluble in oil, they are present in both the oil and the paper. Measuring the concentration of the oil can tell us a little more about the paper. The standard method typically tests for five compounds that are normally only present in the oil as a result of the paper breaking down. Those five compounds, and their probable causes, are 5-hydroxymethyl-2-furaldehyde, 5H2F (typically formed by oxidation of paper), 2-furyl alcohol, 2FOL (typically formed in connection with a high moisture content), 2-furaldehyde, 2FAL (very common, formed by all overheating and aging conditions), 2-acetyl furan, 2ACF (very rare, may be related to elec trical stress), and 5-methyl-2furaldehyde, 5M2F (typically formed as a result of overheating). (A Guide To Transformer Oil Analysis, by I.A.R. GRAY) 2.3.4 Instrument / Device for Transformer Oil Testing Oil Test Set (Megger OTS 60 PB) The OTS 60PB is a 0 60 kV, battery powered portable dielectric strength oil test set. Its size and weight make it suitable for on-site assessment of insulating oil quality. The dielectric strength test it performs is an important deciding factor in knowing whether to retain or replace the oil. Breakdown voltage is measured, averaged and displayed under the control of built-in programmed sequences. Go/no-go testing is available. Figure 2.4 Oil Test Set (Megger OTS 60 PB) OTS 60PB follows the oil testing sequences described in many national and other specifications among which are: British BS 148, BS 5730a (automatic proof testing), BS 5874; International IEC 156, American ASTM D877 ASTM D1816, German VDE 0370, French NFC 27, Spanish UNE 21, Italian CEI 10-1, Russian GOCT 6581, South African SABS 555, Australian AS 1767 and Institute of Petroleum IP 295. Two types of withstand (proof) testing of an oil sample are available. The principle with these tests is to subject the oil sample to a specified voltage for a defined length of time (1 minute) to see if it will withstand that voltage. In one of the tests the voltage is removed after a minute, in the other test, the voltage continues to rise after the minute until breakdown or the maximum value is reached. Withstand (proof) tests can be set up to the users own requirements, and then repeatedly called up to quickly test oil under known fixed conditions. The OTS 60PB is used for determining the dielectric strength of liquid insulants such as insulating oils used in transformers, switchgear, cables and other electrical apparatus. It is portable and suitable for testing on site as well as in the laboratory. The test set is fully automatic. The operator has only to prepare the test vessel, load it with sample oil, place it in the test chamber, select the appropriate specification for the tests and then start the test sequence. The test set carries out automatically (and if necessary unattended) the sequence of tests as defined by the pre-selected national specification. Oil testing specifications, for which the set is pre-programmed, are as follows:- Figure 2.5 Oil testing specifications A 5 minute test sequence is also provided so that the operator may quickly obtain an idea of the breakdown value of an oil sample. Two types of semi automatic withstand (proof) testing of an oil sample are available. The principle with these tests is to subject the oil sample to a specified voltage for a defined length of time (1 minute) to see if it will withstand that voltage. In one of the tests the voltage is removed after a minute, in the other test the voltage continues to rise after passing for one minute until breakdown or the maximum value is reached. Withstand (proof) tests can be set up to the users own requirements, and then repeatedly called up to quickly test oil under known fixed conditions. The test results can be reviewed on the LCD or printed via the RS232 interface. An optional, battery operated printer is available to obtain a hard copy of the results. The safety features incorporated in the test sets design include two forced break switches used as described in B S 5304. These are interlocked with the oil vessel loading door. Volumetric titration system Metrohm Titrino SM 702 An automatic potentiometric titration system Titrino SM 702 with Exchange Unit 806 made by Metrohm measured the acidity of the oils. Here the Total Acid Number (TAN) was determined by a volumetric titration with potash to neutralize the carboxylic acids. The titration took place as follows: At first 10 g of the oil were dissolved in 40 ml of solvent toluene / ethanol in a ratio of 5 to 4. Potash (KOH, 0,1 mol/l) was added as titre with volume increments of 0.001 ml or 0.005 ml depending on the expected acidity. The system detects, when the acid-base-equivalence-point EP is reached by a voltage measurement in the solution. From the volume of potash at the EP equation below calculates the acidity as TAN: TAN total acid number EP1 equivalent point C31 blind value of the solvent toluene/ethanol CO1 0.1 mol/L, concentration of titre CO2 1 CO3 56106 g/mol, molar mass of titre CO0 weight of the oil sample Figure 2.6 Volumetric itration systems Metrohm Titrino SM 702 Kelman TRANSPORT X Portable DGA Unit And Moisture In Oil Dissolved Gas Analysis (DGA) is an established technique and is recognised as the most important test in monitoring power transformers. It is now being successfully extended to other oil filled equipment such as tap changers and circuit breakers. The TRANSPORT X unit has been designed to be very rugged and user friendly with an emphasis placed on field operation. The unit is used by over 200 companies and utilities and has sold in excess of 600 units worldwide. Figure 2.7 Kelman TRANSPORT X Portable DGA Unit And Moisture In Oil The TRANSPORT X test uses state of the art infrared measurement technology to give accurate, reliable results in a matter of minutes. The TRANSPORT X product represents an invaluable tool for Asset Management and will increase the power of any DGA program. Extensive field and laboratory use worldwide has proven that the TRANSPORT X test gives highly reliable results and that it is genuinely suitable for field conditions. The TRANSPORT X equip