Chemical and Physical Changes Lab Report

Also, be cautious as to not inhale the chemicals. Because the glassware is glass, they may break and as such must be handled gently. All glassware should be inspected for cracks before starting the lab. Ill. Pre-Lab Questions- 1 . Identify the following as either chemical or physical changes: A. Striking a match- Chemical B. Food Spoiling- Chemical C. Breaking a Glass- Physical D. Mowing the Grass- Physical E. Leaves Decaying- Chemical F. Boiling Water- Physical 2.In your own words, state the Law of Conservation of Mass: The Law of the Conservation of Matter says the matter can be neither created nor destroyed. 3. List he indicators of a chemical change: Chemical change can be illustrated in many forms such as rust, decay, light being produced, heat being given off or cold being given off, and color change. These are simply a few and are not all of them. 4. Identify each as an element, compound, or mixture: A. Alarm- Compound B. Sulfur- Element C. Hydrogen Gas- Element D. Salad- Mixt ure E.Water- Compound F. Sodium Bicarbonate- Compound G. Fruit Punch- Compound H. Sodium Chloride (table salt)- Compound ‘V. Procedure- Experiment 1- Combine a few iron filings along with sulfur powder on an unused piece of paper. Mix the samples well with a scoopful. Examine the mixture with a magnifying glass and record your observation. Next, move the magnet under the mixture and reexamine It with a magnifying glass once again and record the observations. Discard the sample. Experiment 2- Fill a small beaker half way with cold water.Obtain a test tube with warm bath water and add the warm bath water with the cold water in the water and placing it in the trash can and dump the water down the sink. Experiment 3- Place a piece of magnesium in a clean, dry test tube. Next, add 10 drops of MM HCI. Record observations. Carefully touch the bottom of the test tube to check for the change in temperatures. Flush contents down the sink with plenty of water. Experiment 4- Transfer smal l amounts of sodium bicarbonate into a clean, dry test tube.Add 10 drops of MM HCI individually. Touch the bottom of the test tube and record all observations. Wash all the leftovers down the sink. Experiment 5- Mix 10 drops of barium chloride solution in a test tube with sodium sulfate solution. Record all observations in the data table and then pour down the sink. Experiment 6- Mix a small scoop of sodium chloride with 2 ml of water in a test tube. Record all observations and wash down the sink. V. Data and Observations- Experiment # Mass and Observations Chemical or Physical?When the magnet was held under the piece of paper, the iron stood up and followed the magnet physical 2 The warm water became a solid when added to the cold water physical 3 When the MM HCI was added, the liquids began to bubble and heat up, which is exothermic chemical 4 When the MM HCI was added, the liquids began to bubble once again and the liquids lolled, which was endothermic chemical 5 When the barium chloride was added, the color changed and the consistency changed to a more milky consistency physical 6 When the small scoop of sodium chloride was added to the water, nothing could be observed as happening physical VI.Calculations- VI'. Post Lab Questions- 1. In which lab did you observe a precipitate? A precipitate was observed in experiment number 2. 2. In which did you observe energy change? An energy change was observed in experiment number 1 when potential energy changed to mechanical energy. . In which did you observe a color change? A color was observed in experiment was observed in experiment number 5 when it became a milky color. 4. In which did you observe the formation of a gas? Gases of any sort. VIII.Conclusion- The purpose of this lab was to identify what a chemical change and what a physical change is. A chemical change is when bonds are broken and new ones are forced to form. Some indicators are a change are exothermic (heats up), endothermic (cools of, precipitate (solid forms), and color change. In the first experiment when the agent was under the sheet of paper with the iron filings, the iron filings stood up on their end and followed the magnet around, changing from potential energy into mechanical energy.In the second experiment performed, a precipitate formed, a solid was formed out of the warm water when it was added to the cold water. In experiment three, an exothermic change occurred when the magnesium and MM HCI where combined, resulting in bubbling of the two and then the test tube heating up. Then in experiment four, an endothermic change occurred when the sodium carbonate and MM HCI were combined in the test tube and the test tube cooled down.In experiment five, there was a color change when the barium chlorine and sodium sulfate were combined resulting in a new milky color which also now had a milky consistency. In the sixth experiment, as far as I could tell, nothing happened in the sixth experiment. ‘X. Error Analysis- T he only possible error I can see is if my group made an error of some sort of error in experiment number 6 when nothing happened, and it Just seems like something should have happened in the experiment.

The relationship between individuals mirrors the relationship between nations

In the light of this statement, M. Butterfly, a film about a French diplomat, Rene Gallimard, being seduced by the Chinese opera actor, Song Liling, who masqueraded as an Oriental ideal woman, evolves into a tale exposing the East-West misconceptions by using the intricacies of male-female relations. Relationship between eastern nations and western nations, and that among western nations, is mirrored by the two relationships between individuals respectively: the relationship between Rene Gallimard and Song Liling, and the relationship between Rene Gallimard and Lady Baden. Relationship between Eastern nations and Western nations is mirrored by the relationship between Rene Gallimard and Song Liling. Many after watching the film have asked, â€Å"how is it possible for Gallimard to be in love with a man for twenty years, and believe all the time that he is a woman? The answer to this question is Gallimard's misunderstanding of the East. The Western misconceptions of the East and the Western fantasies of protective masculinity towards the East can be seen from the relationship of Gallimard and Song. The misunderstanding of the West towards the East is foregrounded when Gallimard met Song after Song's performance of Madame Butterfly. Seeing Song on stage as Cio Cio San in Madame Butterfly, an Oriental woman who kills herself for the white man Pinkerton, Gallimard assumed that Song would be an equivalent of the submissive Oriental perfect woman. Gallimard's ignorance of the culture of the East is clearly seen as it is Chinese tradition that, in Peking opera, the female characters are played by men, which is also later pointed out by Song in the film. After the performance, Gallimard had a conversation with Song, in which the indifference of the West to distinguish the national and cultural tradition of the Eastern nations is shown. During the conversation, Gallimard said that Song was convincing to be Cio Cio San in Madame Butterfly. Song's reply signified that Gallimard has conflated China and Japan, † Convincing? Me as a Japanese woman? Read also Intro to Public Relations Notes Do you know the Japanese used thousands of our people for medical experiments during the war? But I gather such an irony is lost on you. † The Western fantasies of the Orients with submissive, obedient femininity is also reflected when Gallimard commented on the death of Cio Cio San in Puccini's play, â€Å"†¦ her death†¦ it's pure sacrifice. He's not worth it, but what could she do†¦ She loves him so much. It's very beautiful. † The West sees the East as stereotype, as western men desire the submission of the delicate, obedient Oriental women, which western women can never satisfy. When the relationship of Gallimard and Song further developed, Gallimard was blinded by his ignorance and misunderstanding towards the East. During the night when Gallimard visited Song after he has got promoted to vice-consul, Song said to Gallimard, † please let me keep my clothes on†¦ modesty is so important to the Chinese. † Gallimard believed it and respected Song's â€Å"modesty†, and he did towards the end of the relationship, which was also pointed out by Song, who has unmasked himself as a man in the court, â€Å"he was very responsive to my ancient Oriental ways of love, all of which are invented by myself, just for him. This reflected that the West believes that the East is exactly like the image in their own fantasies. The conflation of the China and Japan of the West is also disclosed at the end of the film, where Gallimard painted his face with pure white. In the Japanese theater, white is a symbol of ideal white complexion of the noble, while in the Chinese opera, white symbolizes treachery. This further highlighted the stereotyping of the East by the West, to conclude all Eastern nations as one single conventional â€Å"Orient†. The Western fantasy of protective masculinity is also mirrored by the relationship between Gallimard and Song. In the relationship of Gallimard and Song, Gallimard enjoyed discovering that he could treat Song with cavalier neglect, and this further strengthened his sense of masculinity, which is parallel with the Western belief of controlling the East, as they believe that the East, deep down, desire submission to the masculine West. Song has written in her letter to Gallimard that she has already given Gallimard her shame, and Gallimard used it against Song to force her to tell him that she is his butterfly. This is exactly an act of protective masculinity of male and at the same time that of the West. The West think that the East is inferior and need to be taught by the West, this is shown by the conversation of Song and Gallimard when they were at the Great Wall. Song asked Gallimard, â€Å"why did you pick a poor Chinese with a chest like a boy? † and Gallimard's answer showed his view of Song as an innocent Orient, â€Å"not a boy-like†¦ girl-like†¦ a young innocent school-girl†¦ waiting for her first lessons. † The Western superficial idea of slave and master is also shown between Gallimard and Song's dialogue after he had sexual intercourse with Lady Baden. Gallimard made use of the idea of slave and master, which he thought himself as master and Song as the slave, to force Song to remove her clothes for his will. The relationship among Western nations can also be mirrored by the relationship between Gallimard and Lady Baden. When Gallimard's relationship with Song is going on smoothly and his career has got a boost, Gallimard also had a rather short-term relationship with Lady Baden. This somehow showed that Gallimard has the ambition to conquer Lady Baden, who was described by the men in the party as â€Å"†¦ uilt like the Forbidden City. Everyone can look but no one gets inside. † This is a reflection of the ambition of the Western nations to conquer each other. Lady Baden, as a western woman, is portrayed as strong as the men, she was already naked when Gallimard hid himself in the bathroom, and this is again the idea of masculinity of the West. To conclude, the relationship between Gallimard and Song mirrors the misconceptions between the West and the East, while the relationship between Gallimard and Lady Baden shows the ambition among the Western nations.

6 Rules of Authoritative Leaders

6 Rules of Authoritative Leaders Authoritative Leaders are really good at setting the vision and painting an appealing picture of where we are going. The authoritative leader will not tell you how to get there, but will be inspiring you to follow. So he or she will say ‘Come with me’, ‘Look at where we are going’. When we catch someone we don’t tell them what to do, but we help people to find their own answers. A coaching style is really good to help the individual to unlock their potential. Some of the questions that we may ask in a coaching style is ‘What are you trying to achieve?’, ‘How can you get there?’. Democratic means that we share the problem space and in that sense a democratic leader will almost take a step back and denounce their leadership roles. They will ask people what they feel is the right thing to do. It has been proven that decision making by consensus is not most effective way of finding a good decision. Affiliative style is all about the harmony. It’s a very heart based style. People come first. If you are working with a team that feels a bit unsettled. Maybe, because two organizations have merged or something has happened. In that case people may not be ready to focus on the job because they are too much in the emotional part of the brain. In that case affiliative style can be really effective. As a pace setter I set a standard. ‘I will show how the job is to be done’. so I am not afraid of getting in there and really working with my team to show them how it must be done. In a long run that can be quite an exhausting style because I am here as a leader. I do it and I expect you to follow it. This is the old fashioned. Command and control management style where ‘It is my way’ or ‘No way’ or ‘You do as I tell you’. Coercive style, as you can probably imagine is not very effective in the long run because it doesn’t leave a lot of room for an individual to perform well and its not very empowering. But there is a time and place where it is appropriate. For example: In a crisis situation when a building is burning, I give you the direction to get out but we shouldn’t abuse this style because we think there is always crisis going on.

Aging Theories Assignment Example | Topics and Well Written Essays - 250 words

Aging Theories - Assignment Example The medical implication of old age is despair and unease resulting to high vulnerability to diseases (Miller 2009). Effectiveness of medication is achieved when individuals accept their health situations. It is implicit that the desperation that comes with old age lowers the resolve to live and disengages the unconvinced older individuals from the society (Alexander 2009). The trickledown effect of failure to accept the signs of old age exacerbates the susceptibility to infections. Nursing advice importantly empowers the old to remain socially active and engaged within the societal activities. Aging is a state of mind when individuals become nostalgic of their past, become less economically productive and disengaged from the active societal activities. The interplay of age determinants results in increased desperation and hopelessness. Hopelessness and desperation results in the survival battle for at old age due to the inescapability of death (Alexander 2009). The administration of medication to the aging individuals has to serve to re-engage the old with the society and at the same time alleviate their ailments. Dual practice of nursing involving the social reunion of the disengaged aged patients and the psychological support to foster the effectiveness of medication causes a challenge to the nursing

Tort law Essay Example | Topics and Well Written Essays - 1250 words

Tort law - Essay Example Thus, this essay will support the notion that corrective justice and providing compensation should be priorities of the law rather than raising protection for public authorities. In considering these issues, one should consider some cases that have clarified these arguments. Firstly: the case of Smith v Ministry of Defense, which deals with claims brought against the Ministry of Defense on the basis of negligence for failing to protect the soldiers involved in a friendly fire by failing to provide them with safe vehicles and equipment for patrolling. The allegations also involved the alleged breach of Article 2 of the ECHR that gives the right to protection of human life. On the other hand, the defendants claimed that they should not be held liable for the incidents that occurred based on the concept of â€Å"combat immunity† which encompasses that â€Å"There is no common law liability for negligence in respect of acts or omissions which occur during combat operations against the enemy and there is no duty to establish a safe system of work during such operations, whether those issues are analyzed from the perspective of combat immunity or under the fair, just and reasonable test. The principle of combat immunity exists because the court cannot realistically or reasonably be required to resolve whether injuries suffered by soldiers could have been avoided by different tactics and if so how to apportion blame.† Nonetheless, the Supreme Court did not agree with the defendants’ arguments and found that the negligence that occurred in this case fell outside the scope of combat immunity. Thus, it was held that it was â€Å"fair, just, and reasonable`’ for the Ministry of Defense to be held liable for such acts of negligence. The ministry of Defense failed on their part to give the soldiers the needed training and equipments and so breached their duty of care against article 2 ECHR1. The soldiers are employees who

Comparing two electroinics Essay Example | Topics and Well Written Essays - 250 words

Comparing two electroinics - Essay Example Therefore, this paper aims at contrasting the two devices in order to make a good decision of the favorable electronic to buy. The both devices have similar Bluetooth capabilities, memory, and hard drive (Miser 5). They have internal wireless LAN cards of 802.11, with the same speed at ay given distances, although the MacBook has connections that are more reliable. In addition, the Vaio sonny consumes a lot of power, as compared to Apple Mac book pro since it has NVIDIA Card that generates a lot of heat. Fortunately, Vaio sonny has two graphic cards NVIDIA and Intel while Apple Mac book pro has only Intel GMA 950. In terms of software comparison, the Vaio sonny uses Windows XP while MacBook have both OSX10.4.8 through a BootCamp And can be set to boot with Win XP. The OS X is more stable that Win XP (Warren, web). In conclusion, if I were to select one device from the two, I would buy a MacBook since it is more favorable to my requirements. It will be supportive to my travel since it saves energy, have connection that is more reliable in many environmental areas (Barr 10-30). The selection is guided by my purpose for the device, although the Vaio Sony has more features than MacBook, but is unfavorable for travelling

When and why did historians become interested in the history of women Essay

When and why did historians become interested in the history of women - Essay Example This is of course due to the fact that it took a fundamental shift with regards to the way in which colonized people were understood and appreciated in order for the history of this particular. To be analyzed through a different lens. Naturally, it cannot be understood that the particular unit of focus that has been utilized throughout the current era is the most effective. For purposes of this analytical research project, the author will discuss the way in which why and when historians came to be interested in women’s issues and history that these stakeholders had participated/endured. Naturally, in order to answer such a research question, a fundamental and full-bodied approach to women’s issues and the manner through which historians began to integrate with them, as well as the causal factors for why this took place, must be analyzed. Accordingly, this student will present the reader with a greater level of understanding with regards to the impact that movements conc erning egalitarianism, equality, liberty, self-determination, and eventually women’s suffrage had with respect to the way in which these determinants were eventually accepted by historians as a valuable means of determining the way in which past history had taken place and the inference that could be drawn from it (Osterud 267). Firstly, it must be argued that merely because historians did not pay a close level of attention to the way in which women impacted history and their overall contributions to it, the reader should not come to the conclusion that these interpretations of history were correct. Rather, since the beginning of recorded history, and long before this time, women continue to represent fully half of the extent human population. As such, these women were vital stakeholders with respect to the way in which societies grew and cultural interpretations/legends/myths/religion were inferred and imparted to subsequent generations (Tharne 34). Accordingly, seeking to d istance oneself from the fact that women only recently began to have an impact upon history and the means through which it is understood is and oversight of the most severe degree. Even though women within early modern and pre-modern society were most certainly constrained by a great litany of patriarchal norms, they nonetheless were able to have profound levels of impact with regards to the way in which these societies evolved and furthered themselves (Schwarts 775). Few historians argue that the past several hundred years have evidenced a rapid degree of change and growth with regards the way in which society is organized and integrated with other societies. Yet, it must not be understood that the change with regards to how women were viewed and how historians and scholars came to view their contributions to history was something of a watershed moment (Wenming 74). Instead, the process was gradual; punctuated by key events throughout several decades. It is the ultimate premise an understanding of this author that the increased level of development, both technological and philosophical, is the main determinant for why women studies, the impact of women in history, and a general focus upon women’s roles and world affairs has shifted of late (McDermid 254). Although it is difficult and somewhat dangerous to delineate a specific time in which this shift ultimately occurred, it must be noted that the core precursors to this happening can be

War in Vietnam, The Opium War, and World War I Essay

War in Vietnam, The Opium War, and World War I - Essay Example In the 1970s, the globe averaged 31 wars each year. In the 1980s, the globe averaged more than 40 wars each year. In the 1990s, the globe averaged more than 40 wars each year. In 1992, the world hit a peak of 51-armed conflicts going on simultaneously. In 2002, there are 38-armed conflicts under way.Most of these conflicts since 1945 have been in the Global South and most have been civil wars (Kegley and Wittkopf 2004). The Vietnam War, Opium war, and the World War 1 were some of the bloodiest and most complicated war in human history. The people and governments involved in these conflicts found it hard to resolve the war easily because of their underlying deep-rooted causes. Some of the countries involved resort to conflict for varied reasons, but mostly fought for nationalism. Most North Vietnamese fought for their national interest while the U.S. fought for the preservation of Democracy. During the Opium War, the Chinese fought to defend their country from the harsh effects of opium trade while the British fought to preserve their colonial and economic interest. Moreover, the underlying causes of World War 1 were the intense nationalism that permeated Europe throughout the 19th and into the 20th century, the political and economic rivalry among nations, and the military buildup that occurred after 1871, when Germany emerged as a great world power (Harvey 2005). The differences in the goals for g oing into war of these countries contributed to the difficulty in achieving peace among them. The main reason why the war in Vietnam is difficult to contain is that it was caused by many conflicts in the past. The American involvement and the Vietnam War did not happen overnight. The Vietnam War developed as a sequel to the struggle (1946-54) between the French, who were the rulers of Indochina before World War II, and the Communist-led Viet Minh, or League for the Independence of Vietnam, founded and headed by the revolutionary leader. Ho Chi Minh. Having emerged as the strongest of the nationalist groups that fought the Japanese occupation of French Indochina during World War II, the league was determined to resist the reestablishment of French colonial rule and to implement political and social changes (Harvey 2005). Following the surrender of Japan to the Allies in August 1945, Viet Minh guerrillas seized the capital city of Hanoi and forced the abdication of Emperor. Bao Dai. On September 2, they declared Vietnam independent and announced the creation of the Democratic Republic of Vietnam, commonly called North Vietnam, with Ho Chi Minh as president. France officially recognized the new state, but the subsequent inability of the Viet Minh and France to reach satisfactory political and economic agreements led to armed conflict beginning in December 1946. With French backing Bao Dai set up the state of Vietnam, commonly called South Vietnam, on July 1, 1949, and established a new capital at Saigon (now Ho Chi Minh City) (Harvey 2005). In most wars, the North Vietnamese were fighting for their nationalism and defending their land while the

Unitarian Universalism Essay Example | Topics and Well Written Essays - 1250 words

Unitarian Universalism - Essay Example It then establishes the historical and philosophical connection between Buddhism and UU. Unitarian Universalism emerged primarily from Christian roots but has drawn extensively from other beliefs and faiths, a practice that has grown to include practically all religions throughout the years. The Unitarians formed in Britain in the 1500’s during the time of the Protestant Reformation, an era of religious enlightenment at least in the context of that period in history (Hamilton, 2005). The Unitarian philosophy introduced people to new ways of thinking including the concept that Jesus was only a man, not a god or the son of God. Instead they maintained, much the same as the Jewish viewpoint regarding Jesus, that he was an important prophet and teacher. Instead of blindly following the Christian or any other religious doctrine, according to the Unitarians, people should employ reasoning and reject superstition with regards to their personal spirituality. It is not only acceptable but preferable to question the authority of the church, its dogma and beliefs but their own beliefs as well. John Murray introduced Unitarianism to America in the early nineteenth century (Hamilton, 2005). His church’s membership consisted predominantly of middle and upper-class intellectuals. The Universalist religion was formed during the eighteenth century based on the belief that all people, not just Christians, receive salvation and emphasized the significance of being compassionate and helping others in need. As opposed to the Unitarian Church in the U.S., Universalism was a populist movement that drew its membership more from the middle and lower-classes. However, both groups were very much alike in that they had disassociated themselves with the traditional Christian doctrines which prescribed dogmatic trials of faith. In addition, â€Å"they emphasized individual freedom of personal belief, individual responsibility to synthesize

To what extent has globalization influenced one or more aspects of the Essay

To what extent has globalization influenced one or more aspects of the culture in your country illustrate your answer with examples - Essay Example But likewise, as economies become more intertwined, we find that they can also become more vulnerable to unexpected shifts and new forms of opaqueness. This isn’t a reason to turn away from globalization, but it is a reason to be vigilant. This essay will look at the way Russia has become more dependent on other countries through the process of globalization and it will suggest that this has mostly been for the best. Although the exact moment of globalization occurring in Russia is a debatable question considering the length of Russia’s history and its extensive involvement in world affairs, it could be send that most of the post-Soviet period has been marked by the rapid acceleration of Russia’s integration into the world economy. Boris Yeltsin, Russia’s first post-Soviet leader, led the country through a kind of economic shock therapy that involved deregulating markets, selling off state assets, and making Russia a better place to do business. It took awhile for these changes to help make Russia into a stable place to do business, but this began to happen under the premiership of Vladimir Putin. He was helped of course by rising world demand for Russia’s energy and other commodities. Prices for have been increasing a lot in recent years (before collapsing recently), and this helped Russia look to the rest of the world as a good place to do business. Britain decided to go full steam ahead with economic global integration. Of course, with current economic events shaking the world economy, we begin to see some of the potential negative effects of globalization for Russia. The problems point to one of the serious drawbacks of globalization: when you open your economy up to the other economies of the world you can get very rich as long as they do well—but you also become very vulnerable to their problems too. But in the course of this important debate it is vital to remember the benefits that have come with globalization. These changes have not

Physically Challenged Community in the Workplace Essay Example for Free

Physically Challenged Community in the Workplace Essay A person is physically deemed physically challenged when he or she has a physical disability or impairment. This is especially true if such impairment is one that limits mobility of the person. Disability on the other hand is defined as a condition or function judged to be significantly impaired relative to the usual standard of an individual or their group. The term is often used to refer to physical impairment, sensory impairment, and intellectual impairment. Whatever physical disability one has, he or she has the same right to be treated as a normal human being. The United Nations has argued that persons with disabilities should have equal rights to education and employment. People with disabilities also have the right to own and inherit property; not be discriminated against at home or in the workplace. The 21st century workplace is a virtual jungle. Those who are physically challenged may, at first, find it difficult to cope with the extra stress of working despite their disabilities. In today’s fast-paced and hectic world, opportunities abound for those who have complete bodies and mind. However, if one is physically challenged, such as being a dwarf (too short), finding a job in this cutthroat world is a very slim possibility. If one has speech impairment, it would be difficult to land a job which main responsibility involves verbal communication. If one is to do machinist’s work, it is almost impossible to apply as a single-armed person. The point being that if one is physically challenged, finding a job that would suit your special needs requires great patience and endeavor. That is just in terms of applying for a job. How about keeping one’s job even one is physically challenged. That requires a lot of grit and determination. For one to survive such an ordeal is already a great accomplishment; and, we should congratulate such persons for their courage and bravery in withstanding the pressures of working in a hectic environment despite their disabilities. An individual who is physically challenged may find it almost impossible to survive alone in a workplace where everybody else is not. Thus, it is very much beneficial for such a physically challenged person to find a job in a workplace where there is a community full of physically challenged persons like him or her. This is because the feeling of belonging to a group gives one the motivation to succeed in every endeavor. It inspires even the most physically disabled to work very well in a company of his peers. In terms of communication, a community inside a workplace whose members all are physically challenged could even develop their own styles of communication that is specially suited to their needs. That makes them feel more confident and secure, and it has a sizable effect on their performance. There are many effective strategies adopted by people who are physically challenged to communicate with their peers. This often involves special non-verbal signals, especially in cases where there is speech impairment, or when mobility of such a person is restricted due to the loss of arms or legs. The advantage of such special communication tools is that it oftentimes enables the physically disabled workers to be more effective and efficient. A special bond of understanding develops between workers who share common disadvantages. This special bond, extends beyond misunderstanding. The only advantage that can be observed in this type of communication strategy between physically challenged persons is that other â€Å"normal† persons might think negatively of it, wrongly assuming that they are being stabbed in the back through this special type of â€Å"language† that only physically challenged persons can understand.

Alcohol Beverage Essay Example for Free

Alcohol Beverage Essay Throughout the history of television, viewers have raised many questions about alcohol advertising. How is advertising affecting us? Does it have an impact on alcohol abuse or alcohol related disease and death? Does advertising influence alcohol consumption? In this essay, I will mainly concentrate on why such alcoholic advertisements should be restricted; and to what extent should any governments be able to control advertising. My personal opinion that I maintain is that I agree with having restrictions on alcoholic beverages’ advertisements on TV, by focusing more on responsible drinking and on problems that drinking causes every year because of irresponsibility of its consumer. I also stand by my opinion because young people are negatively affected by those ads, since there are no messages for responsible action while drinking. Moreover, statistics show that alcohol-related admissions to hospital in United States have reached 20% in 1995. With other words, most of cases sent to our hospitals were alcohol related, which potentially leads to violence, accidents and health issues. Alcohol is thought to cause thirty thousand premature deaths a year. Therefore, it may cause physical and mental harm to its consumers. The two main media tools that help advertising for alcohol are Televised programs and radio channels. These giant corporations make millions of dollars advertising for alcoholic beverages with having minimal advices on responsible drinking and reckless behaviors that can be caused primarily because of it. My personal believe is that too excessive exposure to alcoholic advertisement can increase consumption and influence peoples attitudes towards alcohol especially for youngster as they have not formed the correct understanding of it. In order to prevent the large amount of alcoholic advertising that appears on media, over the last few decades, government have set far stricter guidelines and regulations concerning alcohol. Some of these limitations and restrictions are particularly made for advertising for alcoholic drinks. Some of these restrictions include limiting the timing of advertisements on television and allow alcohol related ads to be displayed only after 10:00pm, which will avoid youth exposure to it. Nowadays, Alcohol advertisement is at its peak on sport events. This is why prohibiting the liquor company from being the official sponsor in sport must be considered. As Professor Gilmore said, limitations should include alcohol sponsorship in sport, as the alcohol was being advertised 24 hours a day. Besides, the contents of advertisement should be restricted, images like violence and potential crime should be forbidden, as it is easy for young people doing the same things that show on television. On the other hand, both in public and private sectors are responsible in joining their efforts to help to set out limitations and restrict alcohol promotion and sales through ads. For instance, clubs should abolish the unlimited drinks to a certain time only with fixed amount of money, and restrict underage people from being exposed to a place where alcohol is heavily consumed. Besides, the price should be increased to reduce the alcohol consumption and alcohol producers should develop a new production line, as an alternative to replace alcohol. Now, alcohol has spread in our culture and society and became the symbol of fun and pleasure. Its consumption has increased more than ever did in mankind history and their effects are increasing with it as well. Advertising for alcohol is not only encouraging our youth to drink more which will affect their health but also promotes reckless and irresponsible behaviors associated with its consumption. Our government is more aware of the seriousness of this issue than ever, however further laws and restrictions must take place in the future in order to decrease its negative effects.

Zara Marketing Mix and Strategy Analysis

Zara Marketing Mix and Strategy Analysis Pardeep Singh Sangwan Introduction Zara is a Spanish clothing and accessories retailer located in arteixo, Galicia. The company was founded in 1975 by amancio Ortega and rosalia mera. It is the main brand of the inditex group, the worlds largest clothing retailer. The fashion groups also have some popular brands like oysho, Massimo dutti, oysho, etc. Their first store features products which are popular and high end clothing fashions at very low prices. In 1980 they opened other stores throughout Spain. In 1988 they started their international expansion by opening store at Porto, Portugal. Zara opened their store in Australia in 2011.ÂÂ   Now in 2016 they have 2,100stores located in 88countries. Zara has remarkable logistics and they produce new products in 2-4 week. Zara is known for their fast fashion, which means latest products may disappear off the shelf within days, forcing customers to come back constantly to check for new designs. Zara has very unique marketing. Zara spends only 0.3% of their revenue on d oing promotion thats why they do not appears on television or any other advertisements. Instead of promotion Zara focuses more on their product, place and pricing. Zara rarely advertises any store sales or have sales promotions other than sale items unlike other retailers. They have very unique thing that they do not put their brand or logo on their products. In contrast to other local retailers Zaras sales associates do not focus on personal selling. Their customer service within the store is rather weak but their products and affordable prices make customer to come back to stores to do shopping. Their product quality, price own advertises it. Zaras Vision Zara through its one of a kind plans of action and stores has demonstrated business can be effective with next to zero promoting. This business is conceivable just through unrivaled client benefit encouraged by proceeded with capacity to restock and react to client needs inside days. This gives Zara the aggressive edge. Thus, keeping in the mind the mission, they generally inventive their items to upgrade shopping knowledge and give new plans at moderate costs produced using quality materials which take after most recent patterns. Zaras Strategy for Growth and Positioning Zara has confidence in zero promoting. It would preferably spend on store development than to publicize. In any case, the insignificantly promote in design magazines. The method of reasoning behind this is the brisk turnaround of store show, which is around 4 weeks, which renders publicizing a superfluous cost. Likewise, Zara focuses on productive outline to market cycle and concentrate on displaying vast number of plans every year. The workforce in Zara is fundamental to its prosperity appropriate from the creation to the store level as to put the input produced about mold execution at store is permeated to the architect and generation and inventory network puts the most recent styles in 2 weeks time. Segments Market segmentation is a marketing strategy which involves dividing a broad target market into subsets of consumers, businesses, or countries that have, or are perceived to have, common needs, interests, and priorities, and then designing and implementing strategies to target them. Demographic Segment- Zara is focusing on youthful purchasers with extra cash. This will be fundamentally in creating nations and created nations. This presents them with a sizeable populace. As indicated statistical surveying, the clients in these nations will attempt new brands however in the meantime are cost and quality cognizant. Economic Segment- Because of low currency, low work expenses and chance to be nearer to clients, Zara need to consider techniques to take profits by other area. Since the opposition has as of now entered the more up to date showcase and is always attempting to use the advantages related with these business sectors. Legal Segment- Owning to increasing work costs and stringent work laws, the production forms in the present nations dont paramount as they will build the generation costs. In the event that, Zara does not have any desire to decentralize these capacities, there are no laws administering their choices as mold industry is not under controls. Technological Segment Zara uses unique technology know as IT to manage their supply chain which gets to low cost in operating. Zara can use IT to extend their distributing and manufacturing activities outside Spain. Global Segment Owing globalization and fast progression in advancements, a few minimal effort generation focuses have come up. With a specific end goal to lessen the expenses significantly further and look after quality, Zara can have seaward generation offices to minimal effort area keeping in mind the end goal to bring down the expenses. Zara being in center form industry with quick cycles have a novel where it provides food just on the main edge of the item cycle which empowers it to convey the guarantee of Moment Fashion. Opportunities Expansion plans- The gathering contributed more than 2.8 billion to open new stores universally in nations it as of now has a nearness and couple of new markets too. The rate of development of stores has been high as 640 stores for each yr. Zara mold will be made accessible in Korea, Ukraine, Egypt .A very much characterized development plan is basic to the corporate goal of worldwide extension with maintained income development later on. Growing Online Sale- Online retailing has been growing at a singing pace in the most recent decade and considering UK showcase, more than 14 billion has been spent online shopping. Zara ought to attempt to open online retail shops oblige the gathering of people who need to look for institutionalized adaptation items. This additionally introduces a chance to show the whole product offerings from Zara and can be effectively sought. Threats Internal Analysis- Zara attempt the asset view and study the inward investigation. Zaras principle resources are the planners, the coordinations procedure, in store sales individuals and the store feeling. These designers are responsible for producing new outlines in a limited capacity to focus time. In the wake of getting the input, they have roughly 2 weeks to convey the article of clothing to the store. Each of the creators is a significant and expensive asset and this speedy turnaround time is not imitable subsequently misused by Zara without limitations. Competitor Analysis- Zara main competitors are HM, GAP, UNIQLO, etc. boasts of large network of stores and has a strong financial leverage as it aims to tap into growing online retail segment and into franchising to expand into new market. On the other hand, HM are matching Zara in terms of designing and also have strong procurement practices. Unlike Zara, they collaborate with designs and have much wider presence as compared to Zara. Products Zara stores have mens clothing and womens clothing, each of these subdivided in Lower Garment, Upper Garment, Shoes, Cosmetics and Complements, as well as childrens clothing. Toxic Free Production- In 2011, Greenpeace began an exchange with Zara to prohibit hurtful poisons from the dress creation. In November 2012, Greenpeace distributed the Harmful strings: the huge mold line up report, in which Zara was distinguished as the most exceedingly awful. In 6 of the 10 garments that were inspected, nonylphenol ethoxylates were found, and in 2 cases malignancy initiating amines from azo colors were found. After this distribution, Zara was picked for instance as greatest retailer on the planet to bring issues to light. Different dissents were held at Zara shops everywhere throughout the world, requesting Zara to think of an aggressive arrangement to detox its garments and esteem .Some of the most harming poisons will be abstained of before, for instance PFCs will be prohibited by 2015. Zara additionally guaranteed to make data about its providers releasing of poisons freely accessible for no less than 100 providers (no less than 40 of which are situated in China) before the finish of 2013. Controversial Products- Zara pulled back a purse from their racks after a client saw a swastika on the sacks plan. The pack originated from an outside provider and Zara said the image was not unmistakable when the tote was picked. Zara representative Susan Suett said had they saw the satchel highlighted the image; they would not have sourced it. When educated of the swastika image, they quickly pulled back the thing from their racks. Zara got feedback for offering a little child T-shirt for nearly looking like garbs worn by Jewish death camp prisoners. The T-shirt was striped and included a yellow star fundamentally the same as the Star of David. Zara said that the plan of the shirt was propelled by the sheriffs stars from the great western movies. After being on sale for a couple short hours, Zara quickly expelled the shirt and apologized. The shirt was sewed in Turkey and sold in Zaras Albanian, French, Israeli, and Swedish online stores. Zara got substantial feedback for offering the T-shirt in Israel si nce Israel does not have sheriffs. Furthermore, Sheriff is sketched out in straightforward letters on the brilliant yellow star. Hana Levi Julian wrote in the Jewish Press that the outline of the word makes it hard to see. The organization said that the sales got from the T-shirts were peripheral and any outstanding T-shirts would be devastated. The Anti-Defamation League reaction to the shirt was The shirt embellished with the yellow star is in poor taste and is profoundly hostile to Jews and Holocaust survivors. To any individual who knows their history, this sort of symbolism ought to be beyond reach. We respect Zaras acknowledgment of the shirts possibly hostile symbolism and expulsion from sale. Strategies Corporate Level Strategies- The Corporate level techniques of Zara can be like that of its parent, Inditex Group. Its procedures can be grouped in view of three structures -Ansoffs Matrix, BCG Matrix and GE-Directional Policy Matrix. In view of the Ansoffs Matrix, Zara takes after the accompanying vital Directions: Market Consolidation and Product Development by getting the most recent in vogue outlines from the plan stage to the dissemination inside 2-3 weeks, much shorter than the business normal. Zara is working in an industry of high development of around 405 while having a high piece of the pie in the vast majority of the nations. This puts Zara as a star for Inditex Group in the Growth-Share BCG Matrix. Likewise the quality of its business is high, hence placing it in the Investment and Growth course of the Directional Policy Matrix. Business Level Strategies- Zara characterizes its objective market as Youthful, instructed one that preferences design and is delicate to mold. This objective is extremely expansive on the grounds that it is not portioned by ages and ways of life. In this way the extent of Zaras business is expansive. Zara likewise takes after both the cost initiative and Differentiation techniques. Functional Level Strategies- Zara changes their designs every week and it is easy for them because of their manufacturing systems. Their technology helps to reduce the time for equipments, increases utilization of machines within the scheduling time and improves quality of products at every stage of processing. Global Strategy- Zara did not follow nay localization in the counties where it was available and given just institutionalized items. Additionally it put stock in giving the most recent design at low expenses. Along these the Global Strategy Grid it can be seen that Zara follows a Global Standardization Strategy. By doing as such it wanted to expand its benefit by lessening costs and accomplishing economies of scale. Conclusion In conclusion, Zara has maintained an upper hand over its competitors by the response to the changing market trends and fashion and by vertical integration. Zara is a successful international retailer which, in less than 30 years, has transformed itself from a Spanish local brand into truly global brand. Zara, with its present IT infrastructure has been effective and able to be consistent with its core business. However, depending on an unreliable change from the supplier side, obsolete OS will not be compatible for future improvements or growth. Although, there no immediate need to change the current system, Zara should not invest more in the current obsolete IT infrastructure. It should adopt the change to the new OS eventually. Making a gradual change to the new system will increase Zaras efficiency, without facing the sudden setback of implementing the change at once.

Synesthesia and the Nature of Perception Essay example -- Biology Essa

Synesthesia and the Nature of Perception Although scientists do not fully understand the workings of the brain and perception, the basic concept seems fairly simple on an intuitive level. The brain interprets one set of stimuli in a specific way. Certain people with synesthesia, however, can experience a single stimulus in different ways. Are they naturally predisposed to hear red? Do these people have extra neural connections allowing them to taste green? Some scientists claim that all humans begin their lives as synaesthetes until they learn to differentiate their senses. It brings into question the nature of perception, and how the brain perceives reality. Synaesthetes experience "cross-modal" associations involuntarily, so that the feeling of one sense stimulates the sensations of another (1). Five features for clinical synesthesia exist (1): People with the rare condition of synesthesia experience it passively, but it requires a certain stimulus to elicit a response. The individual projects the sensations into his peri-personal space. The sensations do not change over time, and are generic, unelaborated sensory perceptions. In addition, the experiences are very memorable; one subject said that "he was merely a passive observer as the reminiscence unfolded itself" (1). Experiments with a single synesthetic subject show perfect consistency for colour descriptions of words, compared to a 17% consistency rate of a control subject with similar intelligence and memory levels (3). Not only did the subject seem genuine, based on her high level of consistency, but she gave far more detailed and vivid descriptions of the associated colours than the control subject. In a larger group of nine subjects, the consistency rate fo... ...until the brain learns to separate sensations. The source of the connections, the limbic brain, still serves as an emotional guide to the rational objective world, giving reality different perspective for each individual. Internet Sources 1)http://psyche.cs.monash.edu.au/v2/psyche-2-10-cytowic.html, in Psyche 2)http://www.psychiatry.cam.ac.uk/isa/whatis.html, Overview on the ISA homepage 3)http://www.psychiatry.cam.ac.uk/isa/expinv.html, Experiments on the ISA website 4) http://www.ozemail.com.au/~ddiamond/synth.html,paper on Synesthesia 5)http://psyche.cs.monash.edu.au/v2/psyche-2-27-baron_cohen.html, in Psyche 6)http://www.cnn.com/HEALTH/9511/synesthesia/, article on CNN 7)http://www.ad-i.com/viral/what/synes2.html, paper by Kamel 8)http://www.healthlink.usa/synesthesia.html,health information about synesthesia from Healthlink

Against Illegal Downloading Essay -- Argumentative Persuasive Peer Pir

Against Illegal Downloading At the dawn of the internet, many things such as books and text became obsolete, due to insufficient monitoring of internet activity and sites. Individuals were able to gain free access to books and publications that normally needed to be bought, or required a fee. This is something that has caused problems for booksellers and publishers. Now, as technology advances, it also begins the decline of music, software, and television industries—but something can be done before it’s too late. Illegal downloading is a problem that affects us all, either directly or indirectly. Many people do not take it too seriously. They have not realized that it is an epidemic; like a disease that keeps growing as people become more knowledgeable about computers and learn more about how software runs. People openly burn music CDs and download music and movies for friends who in turn give it to their friends; it’s a never-ending cycle on illegal practices. The problem started when Nap ster came out and should have ended when it was shutdown. Unfortunately, not enough has been done to stop the illegal transfer of files. It’s time someone takes full action and ends this detrimental offense.   Ã‚  Ã‚  Ã‚  Ã‚  Napster is a company that developed the so-called peer-to-peer technology that lets people search and retrieve music files directly from one another's personal computers. When Napster first came out, millions of internet users worldwide were illegally downloading and distributing copyrighted music, videos, images, and software for free. After being vilified by the entertainment industry, which claims that Napster and any similar programs could make piracy of almost any digital work unstoppable, and many court battles, Napster was ordered by court to be shutdown in 2000. The technology has been praised as a revolutionary development for the Internet—unaware of the problems that would arise from such practices. However, the termination of Napster was not enough, months later, dozens of new, like programs were being developed and used. And since Napster, not much has been done to stop these latest downloading programs. Although there was a period where the Recording Industry Association of America (the RIAA), an organization that investigates the illegal production and distribution of sound recordings, went after a few users, including a twelve year old ... ...ement a chip into the motherboards to scan and analyze people’s online activities. The motherboard is the main system component of computers and all the hardware such as hard drives, video cards, sounds cards and anything else that you connect to your computer must be run through the mother board. So essentially all your activities could be monitored—especially the transfer of large files, such as songs and movies.   Ã‚  Ã‚  Ã‚  Ã‚  As explained above, illegal downloading is a great problem affecting the entertainment industry and could soon be an even bigger problem for consumers. Downloading copyrighted material illegally is just as unlawful as stealing from a store or someone’s personal item. To prevent shutting down businesses and industries, internet pirates must be stopped and actively sought after. So if one is downloading material illegally take in to mind what harm it can do to and who is being hurt in the process. Free does not mean that it’s moral or fine; one must analyze and see the consequences of such actions before they continue—otherwise, it could be the end of something great because people were stealing and driving companies out of business, with no force stopping them.

Simplicity in a Clean Well Lighted Place Essay -- essays research pa

Ernest Hemingway is known as one of the best writers of our time. He has a unique writing style in which he manipulates the English language to use the minimum amount of words and maximize the impression on the reader. A Clean, Well-Lighted Place is a prime example of this. Here, Ernest Hemingway uses his writing style to reinforce the theme of â€Å"Nada†. The setting is simple, the characters are plain, and the dialogues among them are short and to the point. It is with the absence of similes and metaphors that the reader is able to appreciate the work for what it is. Ernest Hemingway does not feel the need to give much detail on the setting. The reader knows that it is late and that these men are in a cafà ©. The main character is sitting in the shadow and he is drinking brandy. Hemingway leaves out details from the setting but does make it clear that this cafà © is, like the title suggest, clean and well-lighted. He only states important aspects of the setting demonstrating that details are nothing: nada. Through his writing Hemingway implies that this old man feels that little details in the world mean nothing. When the older waiter asks the younger waiter why this drunken man had tried to commit suicide a week before, the younger waiter simply answers â€Å"Nothing. He has plenty of money.† In the young waiters mind this old man has everything. Obviously, this old man feels that things like money are nothing and thus not worth living over. Ernest Hemingway, through the lack of deta...

Restricted Earth Fault Protection

A Comparison Between High-Impedance and Low-Impedance Restricted Earth-Fault Transformer Protection Casper Labuschagne, Schweitzer Engineering Laboratories, Inc. Izak van der Merwe, Eskom Enterprises Abstract—Restricted earth-fault (REF) protection on a transformer is a subject for which there has been little attention and, compared to other types of protection, very little literature exists. Depending on the method of transformer earthing and fault location, some transformer earth faults result in only a small increase in phase current, which transformer differential protection may not detect.Conversely, the amount of current in the neutral may be sufficient to detect most or all earth faults, again depending on the earthing method. By connecting an REF relay to CTs installed in correct locations on the transformer, one can use REF protection to complement differential protection in detecting transformer earth faults. Obtaining maximum benefit from REF protection requires tha t one consider many factors, including whether to select high-impedance REF or lowimpedance REF relays. In making this selection, one should understand the theory behind each option.Historically, only high-impedance REF protection was available, because of equipment and technology limitations. Today, numerical protection relays include low-impedance REF elements for transformer protection. Both types of protection have advantages and disadvantages; the relays do not perform equally well in all applications. One key advantage of low-impedance REF protection included in a numerical relay is the ability to use CTs with different ratios and specifications without the need for interposing CTs.One key advantage of high-impedance REF is proven immunity (relay security) to CT saturation for external faults. Key to either type of protection is the ability to provide maximum winding coverage against earth faults. There is also speculation, as yet unsubstantiated, that a high-impedance REF ele ment provides superior sensitivity and coverage against earth faults. This paper summarizes the theory of classical high-impedance REF protection and new low-impedance REF protection.It also discusses issues such as relay sensitivity requirements, transformer fault current distribution, impact of fault location on relay performance (winding coverage), CT requirements, the impact of CT saturation response on REF protection elements, and application considerations for the two protection methods. current changes very little, but large current flows in the neutral conductor [1] [2]. REF takes advantage of the large current in the neutral conductor to provide sensitive and fast protection for transformer faults close to the earth point.REF protection applied to transformers may be referred to as â€Å"unit earth-fault protection,† and the â€Å"restricted† part of the earth-fault protection refers to an area defined between two CTs. Generally, REF protection can be applied in one form or another to all transformer windings, even delta-connected windings (see Delta Winding—NEC/R Earthed). On solidly earthed star windings, we will show that fault coverage is possible from the first turn above the star point, provided the REF element connects to a CT in the transformer neutral.This high winding coverage is possible because the relay operates on the high fault current in the neutral conductor instead of on the small fault current in the phase. On an unearthed star winding or a delta-connected winding without a neutral earthing compensator (NEC), winding coverage is reduced because of the lack of a neutral CT. Unearthed star windings or delta-connected winding installations provide phase CTs only (see Delta Winding—NEC/R Earthed), and the REF element operates on the change in phase current only. II. EARTH-FAULT CURRENT AND IMPACT ON SENSITIVITY A.Earth-Fault Currents in a Transformer for Different Connections When operating from the neutral C T, REF protection provides more sensitive earth-fault protection than does biased current differential protection. However, many setting engineers are uncertain as to the exact increase in sensitivity that REF protection provides. It is therefore necessary to quantify what one means by â€Å"more sensitive. † In the following discussion, we investigate the available fault current for star windings (solidly earthed, impedance earthed, and unearthed) and delta windings. ) Star Winding—Solidly Earthed For a solidly earthed star winding, an earth fault anywhere on the winding is similar to an autotransformer with a fault on the secondary side. Fig. 1 explains the phenomenon. I. INTRODUCTION Power transformers constitute the single most expensive item of primary plant in a substation. To protect this investment properly, transformer protection schemes contain a combination of protection elements, with biased differential protection widely used. Although biased ifferential p rotection provides excellent protection for phase-to-phase and most phase-to-earth winding faults, this element is less sensitive for single-phase-to-earth faults close to the earth point in solidly earthed transformers [1], [2], and [3]. For these faults, phase 2 NS x 14 Current (per unit) x Nc In In 12 10 8 6 4 Neutral Current Phase Current Fig. 1 Solidly Earthed Star-Connected Windings With Earth Fault X Per Unit From the Neutral 2 10 20 30 40 50 60 70 80 90 From Fig. 1, it can be seen that the turns ratio (TR) is as follows: TR = and In N + Ns 1 = c = Ip Nc xDistance of fault from neutral (percent of winding) Fig. 2 Neutral Current vs. Distance From Star Point in a Solidly Earthed HV Star Transformer (1) I n = I p †¢ TR = Ip x (2) Where Nc = the number of turns on the common winding (on the shorted part of the winding) NS = the number of turns on the series winding (on the healthy part of the winding) x = the distance from the neutral (p. u. ) Ip = primary side current In = fault current Therefore, for faults close to the neutral (when x is very small, on the order of 0. 1 p. u. ), the current flowing in the neutral is In = Ip/0. 1 = 10 †¢ Ip.Clearly, the change in neutral current is much greater than the change in phase current. Fig. 2 shows the difference in neutral current and phase current, plotted as a function of the fault distance from the neutral point [1] [2] [3] [4]. This curve was obtained from tests that were performed on a solidly earthed star transformer. (Because results vary for different transformer designs, the authors were unable to locate a formula that accurately describes the theoretical earth-fault current for all transformers). Fig. 2 shows that the neutral current (that also flows through the neutral CT) is always very high, in excess of 5 to 6 p. . For faults closer to the phase terminal of the star winding, there is reduced current contribution from the transformer neutral. Relay sensitivity is still not compromised, be cause the operating current through the relay is the sum of the neutral and phase current, with the phase current now higher than for faults near the neutral. Therefore, in the case of a solidly earthed star winding, relay sensitivity is not a problem for faults near the neutral because there is always sufficient current flowing in the neutral CT and through the relay and varistor to ensure relay operation. ) Star Winding—Resistance Earthed In the case of a resistance-earthed star winding, the relationship between fault location and fault current is linear, and the value of the earthing resistance determines the amount of fault current. From Fig. 1, assuming that the neutral is earthed through a resistor, we can see that the following is true: In = x †¢V 3†¢R (3) Where In = fault current x = the distance from the neutral V = the healthy phase-to-phase voltage R = the value of the earthing resistor Equation 3 presents a linear relationship between the fault location and the neutral current available to operate the relay.For small values of x, In is small and there may not be sufficient current to operate the relay. Therefore, for a resistanceearthed star winding, relay sensitivity is important for faults near the neutral. The value of x where the relay will begin operation is related directly to the relay operating current and the CT characteristics, i. e. , how much magnetizing current the CTs on the healthy phases will require. 3) Delta Winding—NEC/R Earthed In the case of a delta winding, there is always sufficient voltage to drive fault current through the fault and NEC/R.In theory, there is always at least half the phase-to-earth voltage available to drive the fault. This results in sufficient fault current, and relay sensitivity is not an issue [3]. 3 Because delta-connected windings do not have a star point, you can use the so-called balanced earth-fault connection or hybrid REF protection function in cases where the source is on the delta side of the transformer. In this case, the neutral CT is excluded from the circuit and the three-phase CTs are all connected in parallel with the relay element.The zone of protection is still only the delta winding of the transformer. The balanced earth-fault connection may also be applied to an unearthed star winding. III. RESTRICTED EARTH-FAULT PROTECTION THEORY To apply REF protection on star-connected transformers, connect the three-phase CTs in star, and connect this combination to a CT in the neutral leg of the transformer, NER or NEC, as shown in Fig. 3. These CT connections provide a path for the zero-phase sequence currents to circulate in the CTs during external faults, but they force the current through the relay for internal faults.Therefore, the REF relay provides protection for all earth faults that fall in the area between the phase and neutral CTs. Any fault outside this area should be covered by alternative protection functions. Red White Blue IFp Inp Ins Relay Ins Fig. 5 Internal Fault Indicating Operation on a Delta Winding With NEC A hybrid REF protection function may also be applied to a delta winding without an NEC. The hybrid REF excludes the neutral CT from the circuit and the three phase CTs are all connected in parallel with the relay element. This is called a balanced earth-fault connection.The zone of protection is still only the delta winding of the transformer. The hybrid REF function can also be applied to an unearthed star winding. A. High-Impedance REF Relay Element The high-impedance REF relay is normally a currentoperated relay with a resistor in series that provides stabilization. Generally, it may be one of two different types. The first type has internal resistors and has a voltage setting. In this type, the resistors are effectively switched in and out to change the setting and therefore the value of the stabilizing voltage.The second type has an external variable resistor where the setting is calculated in ohms and applied by changing the resistance of the variable resistor. 1) Design Considerations A number of design considerations must be taken into consideration when designing a high-impedance REF scheme. The most important considerations are described here: †¢ The ratio of the phase and neutral CTs must always be the same. †¢ In general, the CTs should have the same saturation characteristics. †¢ The kneepoint voltage must be higher than the stabilization voltage for external faults. The voltage across the relay and CTs (all in parallel) should be kept at safe levels while still being sufficiently high to allow operation of the relay when required. The magnetizing current of the CTs depends on the voltage across it, but too high a voltage results in higher magnetizing current that leads to a less sensitive scheme. †¢ In most cases, a metal oxide varistor (MOV) or surge arrestor is connected across the parallel connection of the CTs and relay to clamp the voltage to a safe limit, without affecting relay operation.The MOV protects the relay against high voltages developed during inzone faults. Sufficient current still flows through the relay to ensure operation [5]. Relay Relay Fig. 3 Basic Design of an REF Function Fig. 4 shows an external earth fault on the star (source) side of a transformer, and Fig. 5 shows an in-zone fault on the delta side of a transformer. Currents are in per unit. In Fig. 4, the zero-sequence infeed for an upstream red phase-to-earth fault circulates between the neutral CT and the red-phase CT, and no operating current can flow through the relay element.In Fig. 5, in the case of the in-zone fault on the delta winding, it is clear that all the fault current flows through the neutral CT (IFp = Inp) and nothing flows in the phase CT. Therefore, the secondary CT current has to flow through the relay element for this element to operate. At this stage, we simplify the scenario by not taking into account the magnetization of the other CTs. Red White Blue IF Relay IF – Inp Inp Ins Inp Inp Ins Fig. 4 ing External Fault Indicating Relay Stability on a Star-Connected Wind- 2) Setting Considerations The high-impedance REF scheme is set such that it is stable for a maximum through fault with one of the CTs completely saturated. Calculate VS, the stabilizing voltage, as follows: Vs = I f max †¢ ( RCT + RL ) n (4) Another important factor in the design of an REF scheme is the minimum allowable knee-point voltage of the phase and neutral CTs. This value is necessary during the design phase of the high-impedance REF scheme to ensure adequately specified CTs.To ensure that the CT does not saturate at the operating voltage, many engineers use a safety factor of 2. The knee-point voltage can be calculated as follows: Where Vs = the stabilizing voltage Ifmax = the maximum through-fault current detectable by the relay RCT = the winding resistance of the CT RL = the total lead resistance of the longest cond uctor between the relay and neutral or phase CTs n = the turns ratio of the CT In cases where the earth-fault current is limited through an NER or NEC/R, use the three-phase fault current as the maximum condition.With all four CTs of the same ratio, we expect the phase CTs (not the neutral CT) to saturate for external faults, because the three-phase fault current is higher than the earth-fault current. Therefore, we can ignore the resistance of the leads between the saturated phase CT and the relay. (The saturated phase CT and the relay are not necessarily near each other, so the lead resistances between them are not negligible). Phase CTs are generally located in close proximity to one another, so lead resistances between these CTs are negligible.VS is the value of the stabilizing voltage across the relay for maximum through-fault current and one saturated CT. The relay setting, Vset, is still unknown. If the voltage applied to the relay exceeds Vset, we expect the relay to operate . The most sensitive setting that can be applied is Vset = VS. Because network parameters change (higher fault current for example), Vset is usually selected higher than VS to allow for a safety margin. To ensure greater stability, one would select relay operating current greater than the sum of the healthy phase CT magnetizing currents at the set voltage.This ensures that the largest part of the secondary side fault current is used for the purpose of operating the relay and that less current is used for magnetizing the CTs on the healthy phases. Any mismatch in CT ratio will result in spill current, part of which will flow through the relay. Spill current cannot be related to current that flows on the primary side and flows on the secondary side. It may, therefore, cause the flow of â€Å"fictitious† current that results from CT inaccuracy.Not all spill current will necessarily flow through the relay; some of the current also flows through CTs (phase and/or neutral) not carr ying primary fault current. Effectively, the spill current flowing through the relay raises the voltage across the relay and CTs, causing more magnetizing current to flow. In the case of a through fault, equilibrium is reached between the voltage, relay current, and magnetizing current. Generally, relay current is far less than the operating current, as explained in the calculation of the stabilizing voltage. Vk = 2 †¢ Vs (5)Where Vk = the kneepoint voltage of the CT Calculate Iop, the minimum primary operating current (primary sensitivity) that causes the relay to operate, as follows: I op = n †¢ ( I R + m †¢ I m + I v ) (6) Where IR = the relay operating current m = the number of CTs needing magnetization (generally three) Im = the magnetizing current at the set voltage (to be obtained from the magnetizing curve test results of the CTs) Iv = the varistor current at Vs [5] From this discussion, it should be clear that the desensitizing factors are the magnetizing cur rent Im and the varistor current Iv.Use Equation 7 to calculate the actual impedance of the REF element. Because Vset is the voltage above which the relay operates, and because the relay resistance is much greater than RCT and RL, you can calculate the relay resistance as follows: RR = Vset IR (7) Where RR = the relay resistance Vset and IR are as defined above To verify correct calculation of operating current, it is possible to calculate the voltage across the relay for a specific inzone fault current. If the voltage is above the set voltage, consider this as confirmation that the relay will operate.You can calculate the operating voltage as follows: (8) n Because the relay is set to be stable under conditions where one CT saturates, it needs no additional time delays to improve security or its operation. B. Low-Impedance REF Relay Element Low-impedance REF protection is provided with new numerical or microprocessor-based protection relays. Generally, relay manufacturers employ di fferent methods to provide REF protection. In most cases, operation of the low-impedance REF protection is based on the fundamental current, after filtering removes all harmonic currents [3]. Vop = ( I op ? †¢ n †¢ I m ? I v ) †¢ ( RCT + RL + RR ) 5 The most important difference between classical highimpedance REF protection and new low-impedance REF protection is the input impedance. As with all numerical relays, the input impedance of the low-impedance REF is very low compared to high-impedance relays. For example, a lowimpedance relay typically has an input impedance of 0. 1 VA. At 1 A nominal rating, this computes to 0. 1 W. On the other hand, for a high-impedance REF relay with a voltage setting of 100 V and a 20 mA operating current, the input impedance is 5 kW. This is a significant difference.Low-impedance REF protection does not have the same inherent stability against CT saturation for external faults as does high-impedance REF protection. A second significa nt difference is that the operating current of the low-impedance REF protection is not realized by CT connection. With low-impedance REF, the relay measures all four CTs necessary to realize the element. Fig. 6 and Fig. 7 show the wiring and CT connections of the low-impedance REF elements. Fig. 6 shows the fault currents for an external fault on the primary star-connected side of a transformer, and Fig. shows an external fault on the secondary deltaconnected side of the transformer. Inp Red White Blue Ins IF + A Red White Blue Ins + A Inp Ins + Fault IF + B + C N Ins Inp IF – Inp Inp Fig. 8 Low-Impedance REF Connections With Internal Earth Fault on a Star-Connected Winding Red White Blue + + C B A IF Fault IF Ins N Ins Fig. 9 Low-Impedance REF Connections With Internal Earth Fault on a Delta-Connected Winding With NEC + B + C + IF – Inp Inp Fault Location B N Ins Inp Fig. 6 Low-Impedance REF Connections With External Earth Fault on a Star-Connected WindingA very impor tant advantage of low-impedance REF protection is the fact that the CT ratios for the phase CTs and neutral CTs do not have to be the same. Most low-impedance REF relays use an operating and a restraint current. The difference between different relays from different manufacturers lies in the way these relays determine the restraint quantities and in the CT saturation detection algorithm of each relay. Note that, in the case of low-impedance REF protection, there is no inherent immunity to CT saturation, as is the case with high-impedance REF protection.The following different methods are used to determine the restraint and operating current: Use of the residual current Ir = Ia + Ib + Ic as the restraint current and the differential current Id = Ia + Ib + Ic – In as the operating current. (9) 2. Use of the residual current Ir = Ia + Ib + Ic as the operating current and the neutral current In as the restraint current. (10) From Fig. 7, it may be seen that Ia = Ib = 0 for a blue -phase out-of-zone fault on the delta side of the transformer. From this, it is clear that |Ic| = |IF| = |Ins|.From Equation 9 above, one can see that the differential current can be defined as follows: Id = Ia + Ib + Ic – In = 0 + 0 +(–Ins) – (–Ins) = 0 and Ir = Ia + Ib + Ic = –Ins This shows clearly that there is restraint current but no differential or operating current for an external fault. From Equation 9 it can be shown that the following relationships are true: Id = Ins and Ir = 0 1. Ins C + B + A Ins IF N IF Fault Location Fig. 7 Low-Impedance REF Connections With External Earth Fault on a Delta-Connected Winding With NEC Fig. 8 and Fig. 9 show the same relay and CT connections for a low-impedance REF relay.They also show the current flow for in-zone faults on the primary star-connected and secondary delta-connected sides of the transformer, respectively. 6 This means that, while there is a large amount of differential or operating current , there is no restraining current. This can be shown similarly for in-zone and external faults on the star side of the transformer. Because of the nature of the protection, classical lowimpedance REF protection cannot be used as a balanced earthfault protection on an unearthed transformer or on a transformer with only three phase CTs and no neutral CT.In short, it is because the low-impedance REF protection requires a restraint and an operating current, at least one of which is also derived from the neutral CT. When a neutral CT is not provided, a low-impedance REF protection cannot be used to protect an unearthed transformer. However, most numerical relays provide a number of protection elements for each winding. To realize balanced earth-fault protection on an unearthed star-connected transformer or a delta-connected transformer, connect the CTs as explained under Delta Winding—NEC/R Earthed, and associate the CT input with an earth-fault element in the relay. ) Design Cons iderations Because of the inherently unstable nature of the lowimpedance REF element, it may misoperate during external faults, especially in the case of faults not involving earth as phase-to-phase and three-phase faults, when one of the phase CTs saturates. Various manufacturers of REF protection relays have each developed additional supervision elements to improve security during external faults while improving sensitivity during in-zone faults. All these relays scale the CT ratios automatically between the phase and neutral CTs to compare the different values on an equal basis. ) Product A [6] [7] This relay makes use of the direction change of the operating current for in-zone and external faults. It derives a zerosequence operating current from the phase CTs (Ir = Ia + Ib + Ic) and a polarizing current from the neutral CT (In). It then compares the direction of operating (Ir) and polarizing (In) currents. CT saturation logic is necessary to determine whether any existing zero- sequence operating current is from saturation of one or more CTs during a three-phase fault, or from an actual earth fault. CT saturation detection comes from a positivesequence restraint factor supervising the REF operation.The relay compares the positive-sequence current multiplied by the positive-sequence restraint factor (generally set to approximately 0. 1) with the zero-sequence operating current. For earth faults, the positive-sequence and zero-sequence currents are equal, so the result of this comparison will always be a logical 0, indicating no CT saturation. If zero-sequence exists as a result of CT saturation, CT saturation detection asserts whenever the ratio of zero-sequence to positive-sequence current is less than the positive-sequence restraint factor.Using the reasoning that current must flow in the transformer neutral for an earth fault, the relay enables the REF element only if the neutral current exceeds a threshold. Supervising the REF element with the neutral c urrent provides additional security against zero-sequence current in the line CTs resulting from CT saturation. Therefore, the relay enables the REF element only if the line CTs measure zero-sequence current and if the current in the neutral CT exceeds a pickup setting. The zero-sequence current pickup setting is therefore also the relay sensitivity.The zero-sequence pickup must be set higher than any natural zero-sequence current caused by load, CT mismatch/spill current, or any other unbalance. The minimum operating current of the relay is 5 percent of rated current (In). The directional element then compares the operating (residual phase current) and polarizing (neutral) currents and indicates a forward or reverse direction. A forward direction indication is for an in-zone fault, and a reverse direction is for an external fault.The fault is said to be in-zone when the residual and neutral currents are in phase; it is reversed if the residual and neutral currents are 180 ° out o f phase. b) Product B The basic principle of operation for this relay is to compare the residual (restraint) current Ir = Ia + Ib + Ic with the differential current Id = Ia + Ib + Ic – In, Where Ia, Ib, and Ic = the respective phase currents the neutral current flowing in the transIn = former as a result of the fault The relay compensates internally for the difference in CT ratios between phase and neutral CTs.In addition, the relay has a biased differential characteristic that you can set in such a way that the relay is desensitized for big differences in CT specifications and subsequent quiescent spill current under normal load conditions. In this case, the relay achieves stability for a through fault by increasing the restraint current when it detects a fault. The bias setting should still be set as sensitive as possible to ensure relay operation for most faults. The biased differential characteristic of this relay has a fixed slope of 1. 05 p. u. The relay will trip if 1) Id / Ir exceeds 1. 5 and 2) Id exceeds the Id pickup or threshold setting. The purpose of the restraint function is to compensate for CT errors and mismatches and to ensure stability during maximum through-fault conditions. The latter may cause CT saturation, and the bias characteristic provides additional stability against CT saturation. The relay has a minimum operating current of 5 percent of nominal current, or 0. 05 In. c) Product C [8] Similarly to Product A above, this relay uses the residual current calculated from the three phase CTs where Ir = Ia + Ib + Ic and the neutral current In for the REF protection.During an in-zone fault, neutral current will always flow irrespective of the transformer winding connection and earthing arrangement. The residual current depends on the transformer winding connection and earthing arrangement. In this case, if residual current exists, it will be in phase with the neutral current. During an external fault, the neutral and residual curren ts will be equal in magnitude and 180 ° out of phase. The relay uses In only as the operating current, and this current is always present during an in-zone fault. The relay pro- 7 ides a stabilizing method for CT saturation for through faults. Both the current magnitude and phase of the residual and neutral currents stabilize the REF protection. The stabilizing or restraint current is defined as follows: I res = k †¢ (| 3I n ? 3I r | ? | 3I n + 3I r |) (11) Where k = a stabilization factor In and Ir are as defined previously An examination of Equation 11 for both internal and external faults reveals that there is no effective restraint for internal faults because the value of restraint is always negative for internal faults.Therefore, the relay has maximum sensitivity, and small earth-fault currents can cause tripping of REF protection. The restraint for external faults is always positive and larger than the operating current, if the operating and restraint quantities are eit her in phase or 180 ° out of phase. During CT saturation, these angles may be different, resulting in reduced restraint for external faults. To prevent reduction of restraint, the relay calculates the angle between the operating and restraint quantities and then allows operation for a certain angle range and blocks operation for another angle range.For this specific relay, the angle is fixed at 110 °. No operation is possible if the angle between the operating and restraint quantities is greater than 110 °, irrespective of any other values of operating and restraint current magnitude. The stabilizing factor (k) is equal to 2 and is fixed. The relay provides further supervision by comparing the neutral current with the sum of the magnitudes of the three phase currents and the neutral current. The relay provides a settable pickup and slope and allows tripping above the characteristic.The relay has a minimum operating current of 5 percent of nominal current, or 0. 05 In. d) Produ ct D [9] The supplier markets this product as an â€Å"earth differential function† with an additional directional check. The relay, therefore, uses a typical biased differential earth-fault characteristic supervised by a directional element. The relay calculates the bias and differential current, where the differential current is the vector difference between the neutral current (measured by the neutral CT) and the residual current where Ir = Ia + Ib + Ic.The bias current is the highest of the three phase currents and the neutral current. The relay has a base sensitivity range of 5 percent (maximum sensitivity) to 50 percent (minimum sensitivity) for the differential current. This sensitivity value is valid from 0 to 1. 25 p. u. bias current. The bias characteristic has two slopes. The first slope is fixed at 70 percent, and the second is fixed at 100 percent. The first slope is valid from 1. 25 p. u. to a point corresponding to a 1 p. u. differential current. The second slo pe is valid beyond 1. 25 p. u.The directional element uses the neutral current as a reference because direction for this current is always the same for both in-zone and external faults. The relay compares the residual current with the neutral current in the vector plane. For an internal fault, the residual and neutral currents are out of phase. For an external fault, the residual and neutral currents are in phase. For the directional element, the relay compares the second harmonic current in the neutral CT with the fundamental component. If the second harmonic current is greater than a pre-set value, the REF element is disabled.This is a form of second harmonic blocking that provides additional security against operation during inrush but increased dependability during inzone faults. The relay has a minimum operating current of 5 percent of nominal current, or 0. 05 In. e) Product E [10] This relay calculates the differential current as Id = Ia + Ib + Ic + In and the residual curren t as Ir = Ia + Ib + Ic. Restraining current is the maximum of the positive-sequence, negativesequence, or zero-sequence current in the residual current. During external faults, the zero-sequence component of the residual current provides maximum restraint.The relay calculates the zero-sequence component as the amplitude of the vector difference between the neutral and residual current. During an external fault, the neutral and residual currents are in phase, so the resulting bias will be twice the neutral current. For an in-zone fault, the residual and neutral currents are out of phase so the restraint will be less than the neutral current. As previously stated, an external phase-to-phase fault can cause misoperation because of CT saturation. The negativesequence restraining quantity provides maximum restraint during such an external phase-to-phase fault.This relay uses a method where the level of restraint increases after a number of cycles. This method ensures the most sensitive r elay operation upon energization of a faulty transformer. When the restraint increases, security improves for external faults. The positive-sequence restraining quantity is intended to provide maximum restraint during symmetrical conditions such as three-phase faults and load. The relay uses a complicated algorithm to determine the value of the positive restraint component. Discussion of this algorithm is beyond the scope of this paper.The relay has a conventional bias characteristic with a pickup setting and slope setting. Both settings can be modified. 2) Setting Considerations for Maximum Sensitivity Some product-specific setting considerations have been discussed previously in this paper. Most relays have a minimum pickup level of 50 mA. Although all low-impedance REF relays this paper discusses have additional supervision for improved security, many manufacturers recommend a pickup setting greater than the steady-state neutral current resulting from load unbalance (quiescent ze ro-sequence current).This ensures that the relay picks up for actual faults, not for load unbalance. This practice reduces scheme sensitivity, because a greater operating current setting increases the minimum primary operating current. In cases where a biased earth differential protection is provided, the bias setting serves mainly to prevent the relay from operating for external faults resulting from CT saturation and other lesser important factors. These characteristics are fairly 8 fixed, and security against operation for external faults is almost guaranteed. IV.SENSITIVITY ISSUES This paper stated previously that relay sensitivity is not of great concern for faults on either solidly earthed star windings or impedance-earthed delta windings. There is always sufficient current to drive the operating element of the relay to ensure operation. Factors affecting REF scheme sensitivity are CT quality or specification, the magnetizing current the healthy phase CTs draw during a fault, the relay operating current, and the resistance earthing of the star-connected transformer. CT performance impacts greatly the sensitivity of the REF element.Lesser-quality CTs can make low-impedance REF protection more sensitive, because the operating voltage is lower and the CTs on the healthy phases draw less magnetizing current. Equation 6 provides relay sensitivity for both highimpedance and low-impedance REF, with slight variations between the two. The equation is valid for the high-impedance REF sensitivity calculation. In the case of low-impedance REF sensitivity, the varistor current is excluded and the relay does not have an operating voltage. Therefore, the magnetizing current is not the current the healthy phase CTs would draw at the operating voltage.A voltage equal to the sum of the lead and relay resistances multiplied by the fault current would appear across the healthy CTs. The magnetizing current of all CTs at this voltage should be added to the relay operating cur rent to determine the relay sensitivity. The lowimpedance REF measuring element will develop a much lower voltage across the healthy CTs and the magnetizing current necessary for those CTs will be substantially less than for the high-impedance REF case. Although the low-impedance REF relay minimum operating current is as much as 50 mA, the reduction in magnetizing current compensates for the greater pickup threshold.For example, assume that the CTs in a high-impedance REF scheme draw 15 mA magnetizing current at the operating voltage, and the relay operating current is 20 mA. It follows then that the total secondary current should be 4 †¢ 15 + 20 = 80 mA. The corresponding primary current must drive sufficient operating current through the relay to produce the magnetizing current necessary for the CTs to operate the relay. With a 200/1 CT ratio (impedance-earthed transformer), there is an implied minimum primary operating current of 16 A.For a typical 355 A NER, the only part o f the winding that is not covered, assuming zero fault resistance, is the bottom 16 / 355 †¢ 100 = 4. 5 percent. Taking the same example, assume that the CTs in a lowimpedance scheme draw only 2 mA magnetizing current because of the lower voltage across the CTs and the relay draws 50 mA. It follows then that the total secondary current should be 4 †¢ 2 + 50 = 58 mA. With the same CT ratio and NER as in the previous example, the minimum primary operating current is 11. 6 A. Clearly, the low-impedance REF function is more sensitive in this case. However, if the CTs used with the high- mpedance REF were of better quality and the magnetizing current were also 2 mA, the high-impedance REF relay would be more sensitive. In this case, (assuming zero fault resistance) the bottom 11. 6 / 355 †¢ 100 = 3. 3 percent of the winding is not covered. The transformer protection philosophy [11] of Eskom Distribution Division requires that the REF sensitivity for resistance-earthed star -connected windings be such that it can be set to pick up for faults between 10 percent and 25 percent of the maximum available earth-fault current for an earth fault on the transformer terminals.With this in mind, one can perform the necessary calculations to determine an adequate CT ratio and whether to apply high-impedance or low-impedance REF protection. As a general rule of thumb for high-impedance REF protection, the relay operating current should be greater than the sum of the CT magnetizing currents at the set voltage, i. e. , more fault current should be used to operate the relay than to magnetize the CTs on the healthy phases. This generally ensures greater stability. V. APPLICATION ASPECTS As we concluded previously, sensitivity becomes a concern only on resistance-earthed star windings.It is only in this case that the application of high-impedance vs. low-impedance REF protection must be considered. There are two important factors that may influence the decision. A. The Quality and Specification of the Available CTs Good-quality CTs with a very steep and linear magnetizing curve indicate CTs that require very little magnetizing current throughout most of the operating range. Poor-quality CTs require more magnetizing current. Perform calculations according to the specific CTs in use for a specific installation to determine the suitability of high-impedance vs. ow-impedance REF protection for the application. Perform this calculation as described under sensitivity issues. B. The Availability of Matching CT Ratios If the existing equipment is of such a nature that the same ratios are not available for both phase and neutral CTs, you should use low-impedance REF protection, because this type of protection can handle different CT ratios for phase and neutral CTs. However, if the same ratios are available for both phase and neutral CTs, further investigation should reveal whether high-impedance or low-impedance REF is the most suitable for the applicatio n.VI. CONCLUSIONS There is a general belief among many engineers that the fault current for faults close to the neutral point of a starconnected transformer is very small and insufficient to operate the REF protection. This is true only for resistance-earthed star-connected transformers. This paper makes no ruling on whether low-impedance or high-impedance REF protection is the better method, but it 9 provides the information and methods for choosing the more appropriate relay for a particular application.REF scheme sensitivity is a problem only on star windings with resistance earthing, because the fault current is a function of fault position, phase-to-neutral voltage, and earthing resistance value. For faults close to neutral, the fault current is very small. The relay operating current and CT magnetizing current are important in determining the winding coverage. In cases where there is always sufficient fault current to operate the REF relay, the choice between high-impedance an d low-impedance REF is not important.Issues such as available CT ratios for the phase and neutral CTs may dictate the choice. For poor-quality CTs that require larger magnetizing current than a better-quality CT at the same voltage, the lowimpedance REF element is more sensitive. Where you use good-quality CTs, however, the high-impedance REF relay is more sensitive. VII. ACKNOWLEDGEMENTS The authors wish to thank the following persons for their valuable contributions: Paul Gerber for his sensitivity calculations. Mike Everton for various discussions on the topic. Veronica van Zweel for the drawings.VIII. REFERENCES GEC Alsthom Measurements Limited, Protective Relays Application Guide, 3rd edition, 1990. [2] D. Robertson, ed. Power System Protection Reference Manual, Reyrolle Protection, Chapter 6, Stockfield: Oriel Press. [3] P. Bertrand, B. Gotzig, and C. Vollet, â€Å"Low Impedance Restricted Earth Fault Protection,† in Developments in Power System Protection, Conference P ublication No. 479, IEE, 2001. [4] SEL-387 Relay Training, Restricted Earth Fault Protection, Schweitzer Engineering Laboratories Inc. , Rev 0. 0, July 2001. [5] P. E.Sutherland, PE (SM), â€Å"Application of Transformer Ground Differential Protection Relays,† presented at the Industrial and Commercial Power Systems Technical Conference, Sparks, NV, 1999. [6] A. Guzman and L. S. Anderson, â€Å"Restricted Earth Fault Protection for Auto-Transformers Using a Directional Element. † Available at www. selinc. com [7] SEL-387-0, -5, -6 Instruction Manual, Current Differential Relay, Overcurrent Relay, Data Recorder, Schweitzer Engineering Laboratories, Date Code 20040628. [8] SIPROTEC, Differential Protection Manual, 7UT612, V4. , C53000– G1176–C148–1, Siemens. [9] Application Manual, ProtectIT Transformer Protection Terminal, RET521*2. 5, 1MRK 504 037-UEN, ABB. [10] T60 Transformer Management Relay, UR Series Instruction Manual, T60 Revision 4. 0x, Man ual P/N: 1601-0090-G1 (GEK-106490), GE Multilin, 2004 [11] P. A. Gerber, SCSAGAAG0 Rev 3, Transformer Protection Philosophy, Eskom Distribution Division, 2001. [12] Mini APPS Course (Analysis & Protection of Power Systems), vol 1, Section 9, Transformer Protection, 25 February to 1 March 1996. 1] Protection Field Engineer. He is currently a Chief Engineer: Protection Specialist in Resources and Strategy, a Corporate Division of Eskom Holdings Limited. He is responsible for Distribution Division National Contracts for protection schemes and equipment, general protection technology direction setting and technology management, and the implementation of Distribution Automation and Substation Automation in Eskom’s Distribution Division.He has authored a number of protection and substation automation related papers. He is a Registered Professional Engineer in South Africa. Casper Labuschagne earned his Diploma (1981) and Masters Diploma (1991) in Electrical Engineering from Vaal Tr iangle Technicon, South Africa. After gaining 20 years of experience with the South African utility Eskom, where he served as Senior Advisor in the protection design department, he began work at SEL in 1999 as a Product Engineer in the Substation Equipment Engineering group.Presently, he is Lead Engineer in the Research and Development group. He is registered as a Professional Technologist with ECSA, the Engineering Counsel of South Africa, and has authored and coauthored several technical papers. IX. BIOGRAPHIES Izak van der Merwe obtained his B. Eng (Electrical) degree from the University of Stellenbosch in 1991. He started to work for Eskom in 1993 as a  © 2005, 2007 by Eskom Enterprises and Schweitzer Engineering Laboratories, Inc. All rights reserved. 20070711 †¢ TP6207-01