Db2 employment recruitment and select Research Paper

Db2 employment recruitment and select - Research Paper Example The other function involves the non essential functions, as the name suggests they are additional duties laid form a major function being presented. They are either caused by some occurrences or used as additional duties to be carried out workers. They done require specialist to perform them so in major organizations they are usually distributed among amongst all employees. According to (Walker, 2003) Essential and non essential functions are executed with respect to the organization of the subject at hand for example the introduction of a new system be it scientific or simple system the need to describe functions of the employs must be kept in mind. In caring out the essential duties the international laws governing the labor sector must be observed. They include the recommend eight hours of working time is observed and that the working conditions are favorable. The issue of overtime pay must be included in performing these duties. Essential duties are major to the organization for instance an account caring out an audit is termed as essential but when he is involved in matters to deal with training of fellow employees then it becomes non

A Dolls house Language Essay Example for Free

A Dolls house Language Essay Ever since reading the text in my own time I have, in many of my past lessons been discussing, acting and re-reading parts of the play as well as researching many other aspects to the play. By doing this I discovered things like the play was firstly written in Norwegian and then translated into many languages along with many more complex things. Back in lessons I was doing tasks that specifically looked at the language in the play. For example before rein acting a scene from the play the whole class gathered in a circle to do a warm up exercise which evolved around the line; What did you do to die today at a minute or two to two, a thing distinctly hard to say but a harder thing to do. I had to say this line in many different accents and characters including a posh upper class character like Nora and Torvold Helmer from the play. The language used in the play not only creates the feel of the 19th century but it also reflects the way the characters are. It does this as the 19th century old English is very formal showing there middle to higher class and well educated. The language also shows the society that the characters live in and is significant as it reveals their inner thoughts, feelings relationships and situations. In one particular part of the play Torvold says: You cant deny it, little Nora now can you? Its a sweet little songbird but it gets through a terrible amount of money you wouldnt believe how much it costs a man when hes got a little songbird like you This rather poetic and metaphoric line compares Nora to a songbird which is petit and shows she can be sweet, innocent and chirpy. It also echos how Torvold belittles Nora and treats her like a child, which in them days was the done thing; men overpowering women and controlling the relationship in addition to this it perhaps shows how he has a fatherly figure and likes to take control over situations. Although in saying that Nora is or should I say acts rather childlike and naive herself but at the same time is manipulative, flirtatious and cunning as it proves on the opening line of the play; Hide that Christmas tree away, Helen. The children mustnt see it before Ive decorated it this evening As well as giving the audience a rough date and establishing shot it shows how Nora seems just as excited about Christmas as the children do. In most houses the children would be helping to set up the Christmas tree but not in the Helmer household Nora is setting up the tree and rather excited about it too. There is some reference to poetry in the text although it is not the rhyming type, its more a usage of poetic words being exchanged. Like in the first quote I made there are countless uses of words like songbird and squirrel being used to describe Nora as well as Torvold (in some parts of the play). There is another quote in Act 1 on page 25 where Nora has just gone out and bought some new things for the family, which Torvold is unhappy about as she has spent so much money which makes Nora unhappy too, it says; Now, now! My little songbird mustnt droop her wings. Whats this? Is little squirrel sulking? (takes out his purse) Nora; guess what Ive got here! This quote to me shows how he just keeps Nora sweet but does not go out of his reach to keep her happy. Also the use of poetic words is very creative and wise it is saying to Nora do not loose hope or become sad. But it says this in a metaphoric way as Nora does not really have wings but a songbird does and this is what Nora is often compared to by Torvold. The majority of the speech used throughout the play is natural from all of the characters as the play itself is done rather realistically and flows well. There are very rare if any uses of Brectian techniques to break any language or any part of the play up for example; there are no placards to make a particular line stand out, this is probably as each line is just as important as the one before. Even though there is reference to use of poetic language I think it gives the play even more of a realistic effect as people do have little pet names for there husband and wife. In addition to this Henrik Ibsen goes that step further and creates for each character there own realm of speech as a quote from the Methuen Student notes verifies: Ibsen creates for each character a habit of speech appropriate to his or her own class and personality With Torvold he is spoken with a rather fatherly/paternal type of speech, Krogstad he always reflects to his training as a lawyer, Mrs Linde speaks direct and could appear a bit bitter and cold, Nora is excitable but finds resolve at the end of the play and Dr Rank speaks in riddles and fondness of using figures of speech. Over all this coursework has made me realise how important the lines actually are in a play and how important it is to deliver them correctly. As well as consistency when delivering the lines in a certain way the character must keep delivering them in that way. I personally believe that this may enhance my skills as a yr 12 drama student.

Procurement of Subcontract Packages

Procurement of Subcontract Packages Purpose The aim of this paper is to investigate how Main Contractor procurement procedures influence value on a project through competitively tendering Sub Contract packages; whereby cost is driven down by competition or single sourcing Sub Contract packages creating value through negotiation and innovation. Design/Methodology/Approach Empirical data was collected through structured questionnaires issued to Sub Contract companies and Main Contractor firms. 1.0 Introduction 1.1 Background What the Study is about When considering the procurement of a Sub-Contract package, the procurer is faced with numerous challenges. First he/she needs to gather all information required to decipher what needs to be procured and how the information can be transposed to potential Sub-Contractors. Secondly a contractual agreement is created including obligations and methods of compensation. Thirdly, the procurer needs to decide how to award the procurement contract between the Sub-Contractors, either through competitive tendering or single source negotiation. Ultimately the award method should result in the selection of a highly competent and desirable Sub-Contractor resulting in a cost effective product. The award method may be appointed to Sub-Contractors in two ways. Either a single Sub-Contractor can be approached to discuss and agree the works (single source tendering), or a number of Sub-Contractors can be invited to compete for it (competitive tendering). With regards to competitive tendering it is important to distinguish the method or form of competition from the criteria used for the selection of Sub-Contractors. Ciria (1994, p15) states that competition may be either: Open, where there is no limit on the number of Sub-Contractors invited to compete for work. Or Selective or restricted, where the number of Sub-Contractors invited to compete is limited. For the purpose of this study open competitive tendering will not be taken into consideration to keep the number of variables to a constant. Where competition is referenced throughout the paper we are to assume selective or restricted competition. 1.2 Research Focus This paper addresss the potential increase of project value generated by detailing a partnering approach based on Sub-Contractor and Main Contractor relationships; compared to that of traditional competitive tendering. Competitive tendering can be described as determining the value of the subcontract; whereas in contrast, negotiation is designed to create the value of the subcontract. Since the Latham Report (1994) and Egan (1998) was published there has been a greater awareness regarding the possible benefits to single source a product or service. In theory if contractors and subcontractors engage and work together would it provide best value? Alternatively would value be added by competition? Competitive tendering is still widely recognised as an attractive procurement mechanism and is strongly advocated as it helps to stimulate and promote competition encouraging many potential suppliers. This subject area has been addressed due to its close relationship with the Quantity Surveying profession. Accurate procuring of goods and services is essential to a projects success, having a direct impact on profit margins. This study is relevant to everyday work for a site based Quantity Surveyor dealing with nominated Sub-Contractors on a daily basis while working closely with the procurement team to procure future packages. Interest has motivated the investigation and address of the thesis question; Single source or competitive tendering; which procurement route gives best value? 1.3 Overall Research Aim and Individual Research Objectives The overall aim of this research is to advance an understanding of the impacts that tendering Sub-Contract packages through negotiation or competition have on a projects value. However, in order to understand tendering methods and its effects on value it is felt necessary to gain an insight into the forces driving Sub-Contractor and Main Contractor relationships and explore the barriers to implementation of both parties achieving maximum value. Further, this research will assess existing practices, exploring the experiences and views of professionals involved with Sub-Contract procurement. In turn two main research vehicles will be exploited to facilitate this study: an in depth review of relevant literature and the collection of and analysis of empirical data. The chapter entitled Methodology contains the details of both research strategy and data collection techniques to be used to obtain empirical data. Specifically, a range of objectives have been developed and unpacked from the central question, the objectives of this research are to: Identify and investigate the forces driving single source and competitive tendering procurement routes. Evaluate critically the construction industries current views and opinions, compiling the attitudes of the experts. Explore and evaluate the advantages and disadvantages for each method of procurement. Formulate and propose recommendations on the procurement route that provides more value to a construction project. 1.4 Value of this research At the risk of oversimplification of the purpose and value of each of the above objectives, objective 1 focuses on methods, reasons and emerging issues. Whereas it is in objectives 2, 3 and 4 is where this research will make key contributions to the field of Sub-Contract package procurement through single sourcing or competitive tendering. Each of the objectives must not be viewed as separate, unrelated issues. The listed objectives are necessarily interlinked. The first objective on investigating procurement routes will cover the strategic drivers and methods associated with the procurement of Sub-Contract packages. For example, it will, in effect, attempt to answer the question are there forces driving companies to procure Sub-Contract packages in certain ways and, if so, what are they and what do they involve? An example of such driver could be perceived as communication, which if the case, may act as a driver to encourage negotiation through single sourcing Sub-Contractors. Obj ective 2 on critically analysing the construction industries views provides an opportunity to gain meaningful insight into the views of professional staff, and management form Sub-Contractor and Main Contractor backgrounds, on what would encourage them to procure Subcontract packages through either negotiation or competition, what would discourage them and how these link to value creation as well as their views on the industries past and current approaches. Objective 3 on the advantages and disadvantages is of obvious relevance to assist in the analysis of each procurement route and links in with objective 4. Finally objective 4 formulating recommendations will, as a result of both a review of literature and the collection and discussion of empirical data, make recommendations. The objectives are not to be seen as independent of each other, but rather as all linked to issues surrounding procurement routes and how they can add value in the construction industry. 2.0 Literature Review 2.1 Introduction This literature review will examine the main issues surrounding the drive for single sourcing and competitive tendering associated with Sub-Contractor selection. Emphasizing current obstacles and potential benefits for each procurement routes from both parties. The study within this review of literature focuses on objectives 1 and 2 as set out in sub-section 1.3 of the Introductory chapter (the third objective will be completed through the vehicle of empirical data collection and analysis, while the final objective objective 4 is derived as a result of findings from objectives 1, 2 and 3): Identify and investigate the forces driving single source and competitive tendering procurement routes. Evaluate critically the construction industries current views and opinions, compiling the attitudes of the experts. Explore and evaluate the advantages and disadvantages for each method of procurement. Formulate and propose recommendations on the procurement route that provides more value to a construction project. By exploring the above areas of literature, a significant contribution will be made to this research. At the end of this chapter it is hoped that a critical understanding of key issues is exhibited, that the reader will be better informed in these areas and that there will emerge a clear focus, and justification, for empirical research in the field of Sub-Contractor procurement methods and their effect on value during a construction project. 2.2 Forces driving single source and competitive tendering procurement routes. 2.2.1 Historical Events Government Legislation Subcontracting became a popular practice in the 1960s and over the years established itself as an integral part of the industries production process. Projects were procured using traditional methods of delivery with main contracts being awarded through competitive tendering (Uher, 2009; Davenport, 2009, p.200). During these years the economy was stable with little inflation and low interest rates, the contractor was seen as the Master Builder due to employing most of its own direct labour and only specialised areas of work such as mechanical and electrical were subcontracted. Since the late 1960s the worlds economies experienced periodic economic downturns, increased inflation and higher interest charges. With the Construction Industry being highly susceptible to economic fluctuations, the adverse economic actions changed the traditional practices of the construction industry; one of the foremost changes being the shift towards subcontracting. Since the early 1990s the Construction Industry has continued its conflict-ridden competitive tendering culture, together with adversarial working relationships throughout its supply chain, (Brindley, 2004). The Construction Industry continued to pressure its suppliers to lower prices, along with delaying payments to them so that it could profit from a level of interest. This tradition placed risk on smaller businesses causing them to cease to exist or execute projects at inferior quality. Authors in the early 1990s were somewhat certain about their view between main contractor and subcontractor relationships; with main contractors driving prices down even if detrimental to quality, not paying subcontractors on time and in some cases forcing smaller companies to cease trading. The UK government, concerned by these facts employed Sir Michael Latham in 1994 and Egan in 1998 to produce two reports. Latham advocated the need for a Code of Practice for subcontractor procurement and for st atutory backing to fair payment terms (Latham, 1994). Consequently in 1996 the Construction Industry Board published and implemented a Code of Practice for the Selection of Subcontractors and the Housing Grants and Regeneration Act. In addition, Egan (1998) pointed out that partnering through the supply chain is a critical approach with which the UK construction industry can drive innovation and sustain incremental improvement in performance. In recent years main contractor supply chain relationships have changed from the traditional adversarial to the joint venture, with tendering experiencing a retreat from traditional methods of procurement towards single source processes. According to Davenport (2009) the contribution of subcontractors to the total construction process can account for as much as 90 per cent of the total value of a construction project. One of the results of this is that main contractors are concentrating their efforts on managing site processs rather than employing direct labour to undertake construction work. Main contractors have recognised the positive impacts that closer working relationships with subcontractors can have on package value and quality. Most work undertaken on construction partnering has been between client and main contractor relationships with little mention of adopting partnering with subcontractors. 2.2.2 The Contracting Framework A central problem in procurement is that both Sub-Contractors and Main Contractors share uncertainty about many important design changes that occur after the contract has been awarded. These changes are usually a consequence of design failures, unexpected conditions and changes in regulations, which have an effect on project costs. This observation suggests that relationships between both parties can become adversarial hindering supply chain relationships. Therefore project design completeness will have an impact on the procurement award method selected. (Tadelis, 2006; Bajari, 2006) argue that simple projects, requiring an uncomplicated design ought to be procured using fixed-price contracts as they have high design completeness. Therefore preventing the need for contract variations, and are best awarded through competitive tendering. In contrast (Tadelis, 2006; Bajari, 2006) state that complex projects demanding large design give rise to surprises throughout the projects due to low levels of design completeness. Implying that there will be a high chance for variations therefore it should be awarded through negotiation. The insight for these thoughts is through incentives to reduce costs that follow on site variations consequently having an effect on a projects overall value. In fixed price contracts, the Sub-Contractor offers the procurer a lump sum price to carry out the works as specified, with any changes being negotiated throughout the contract. The incentives for a Sub-Contractor to reduce tender costs offered by fixed price lump sum tendered contracts will lead to increased costs for the Main Contractor through variations when changes need to be negotiated. This valuable surplus to the Sub-Contractor leads to efficiency loss through the Sub-Contractor wishing to use these changes to his advantage. On the topic of competitive tendering Tadelis (2006, p.4) states: While competitive bidding does have the advantage of unbiased awarding of projects, it fails to respond optimally to ex post adaption. Therefore it appears that competitive tendering stifles coordination between Sub-Contractors and Main Contractors before specifications and drawings have been finalised. After all a Sub-Contractor has no incentive to offer the procurer advice on value engineering or innovative ideas, if anything the Sub-Contractor would benefit from holding any information from the Main Contractor as they would offer a competitive advantage over the rival competitors. Once awarded the contract the anticipated design errors will be discovered and the Sub-Contractor will be in a position to claim excessive variation costs. However In negotiated single source tendering both the Main Contractor and Subcontractor typically spend time discussing the project before construction begins. During these discussions the Sub-Contractor will have better incentives to suggest potential cost saving techniques through design and specification changes. Accompanying this more design pitfalls will be picked up before a p roject begins, potentially adding value. The competitive pressure through negotiating contracts with a single Sub-Contractor is weak with the procurer not achieving all the potential cost savings. 2.3 The construction industries current views and opinions Competitive tendering is widely recognised as an attractive procurement method and is commonly supported for numerous reasons. Largely it is viewed as a means of promoting and stimulating competition amongst Sub Contractors. By its nature open competitive tendering invites potential Sub Contractors from many venues reducing the likelihood for price inflation (Tadelis, 2006; Bajari, 2006). Fair market price discovery is beneficial to this type of tendering with open competitive mechanisms being transparent, making it easier to prevent corruption. (Cira,1994) suggests that competitive tendering has three significant advantages over negotiation which as as follows: Competition encourages a systematic approach which is more likely to yield the right Sub-Contractors than negotiation with a single Sub-Contractor Competition is a transparent process and so helps satisfy the increasing demand for accountability in both public and private sectors. Competition can give clients better value for money, particularly when compared on the basis of both their ability and fees. An interesting point made by CIRA, 1994 pg 14 arguing against competition was that Sub-Contractor input at an early stage cannot be described well enough to allow fair competition. This is because the Sub-Contractor helps define the works needed and bids consist of an element of judgement due to incomplete design. CIRA also mentioned that initially competition is a time consuming and expensive process and costs may outweigh any value saved. However the benefits of selecting the most suitable Sub-Contractor for the job could outweigh this initial investment. Competition can have practical exceptions to its use through complicated packages where only one Sub-Contractor has the specialist expertise needed. Or is services are needed urgently and there is not enough time to undertake the competitive process properly. Competitive tendering, where the lowest bidder gets awarded the contract, is deeply embedded in the construction industry and can be destructive in the long term as the need to minimise transactional costs tends to reduce quality and client satisfaction. The emphasis on cost competition, and the traditional adversarial Main Contractor Sub-Contractor relationships, results in frequent changes in participating firms from one construction project to another. This makes collaboration between them difficult. Partnering leading to single sourcing between Sub-Contractors and Main Contractors has been cited as effective approaches to overcome these difficulties and add value to a project. (Dainty, 2001) identified the following barriers to integration from the subcontractor point of view: Financial/cost-related issues related to competitive tendering based on price, which has developed adversarial relationships that result in serious problems with regard to payments; Planning/time-related issues, such as false expectations on part of the main contractor and unrealistic schedules; and Attitude-related issues, such as arrogant conducts, exclusion of the subcontractor from the early phases, lack of praise for good performance, poor site management practices, and lack of understanding of subcontractors problems. Latham (1994) defines partnering as a contractual arrangement between two parties for either a specific length of time or for an indefinite time period. The parties agree to work together, in a relationship of trust, to achieve specific primary objectives by maximizing the effectiveness of each participants resources and expertise. It is for this reason, that principal contractors are oblivious of the fact that sub contractors can bring added value to the construction project (Dainty et al., 2001). Conversely authors such as (Dimitri, 2006) recognise competitive tendering as an attractive procurement mechanism, stimulating and promoting competition, hampering corruption and inviting more potential subcontractors to price work. Although the single sourcing approach has shown promising results, there are some cases in which subcontractors have considered that it did not add any value, while some main contractors have seen little benefit in forming alliances with firms that they do not regularly work with (Dainty et al. 2001). Egan (1998) feels that sub contractors should be involved in the design team as early as possible. An argument which is echoed by Briscoe et al. (2004), who believes that sub contractors should be procured early, therefore need knowledge and ability to exercise value engineering and other innovation exercises. The primary reason for selecting sub contractors is their innovation and knowledge, not necessarily for the lowest price. However, high performing sub contractors use their innovation and knowledge, and can often deliver a better service at a lesser price. Low performing sub contractors offer only on low price, while high performing contractors offer value (Garrison, T. 2006). The next stage of this research will detail the Research Methods to be used to capture the empirical data, including details on the research strategy to be adopted, data collection techniques, sample selection and management of the researchers role. Ethics Statement When undertaking a research project careful consideration must be taken to ensure that any material contained within the project causes no harm or potential harm to anyone, or organisation. Ethics is the science that deals with conduct, in so far as this is considered as right or wrong, good or bad. (Dewey, 2008) An Ethics Review Checklist has been completed (Appendix A) which has highlighted a potential area for approval. This is due to the methods of research being undertaken which involve human participation. These activities specifically include questionnaires; to ensure they are executed in a morally correct and ethical manner the following steps will be taken. Ensuring that the subjects have the option to grant voluntary consent the questionnaire will be structured in a way that participants can opt out of answering either individual questions or not participate at all. This is honoured by all questionnaires being issued to the subjects via e-mail, permitting candidates to return the document in their own time and at their own will with no pressure to respond, therefore there will be no reason for any of the participants to feel uncomfortable. All questionnaires issued will be sent with a participation consent form and information sheet. The questionnaire refers to this documentation via a disclaimer that by returning the survey the subject agrees to the terms and conditions and privacy statement as disclosed in the consent form. This disclaimer ensures the subject that careful consideration is being taken to ensure that all participants and respective companies remain anonymous, to prevent any possible harm. Subjects will be referred to by job role only with no mention of name or company to eliminate any matters of commercial risk or damage to reputations. Feedback will be issued to subjects that assisted in the research thanking each subject for his/her time and input; including a summary of the findings once all research has been populated. In line with the Data Protection Act 1998 upon completion of the research all completed questionnaires and sensitive data will be destroyed, including any stored on hard disk and in the recycle bin. Two hard copy publications of the finished article will be produced for the university, in addition with one electronic; these publications may be available for public viewing in the university library which is disclosed in the participation information sheet. I intend to conduct a number of case studies for research; therefore it is incredibly important that each case study will be alphabetically referenced, with no mention of any information that could identify the individual, project, location, contractor, client or consultants. All material will remain unidentifiable including any diagrams, illustrations or drawings used. This ensures that all parties involved can be assured that there will be no information detailed in the document which could potentially cause harm. All sensitive material collated will be dealt with due care, and destroyed in the correct manner either by shredding hard copies or deleting the information from hard disk. Any secondary research undertaken will be wholly and correctly recognized to the author and source throughout the dissertation by means of Harvard referencing. Methodology Introduction A valuable aspect to this research relates to Objective 2: the opportunity to study the construction industries current views and implementation in practice in a subject that, although generating much discussion, is in terms of research in its embryonic stages. Research Strategy One research method that will be adopted, related to research strategy, is a questionnaire. What is a questionnaire approach and why is it suitable for this research? Cohen and Manion (2007: 317) describe a questionnaire accordingly: The questionnaire is a widely used and useful instrument for collecting survey information, providing structured , often numerical data, being able to be administered without the presence of the researcher, and often being comparatively straight forward to analyse. According to this definition, a questionnaire is therefore concerned with seeking individuals views, facilitating this researchers drive to probe deeply into answering the thesis question as to which procurement route provides more value by seeking representatives opinions. Cohen and Manions definition also gives merit to a questionnaires practical consideration, aiding the justification for using this researchers chosen research strategy and data collection technique. Data Collection The questionnaire has been structured using primarily qualitative research as it is linked to in-depth exploratory study. Enabling the opportunity for quality responses exist through open ended questions, probing participants thoughts and views. Denzin and Lincoln (2003) hold that qualitative research involves studying things in their natural settings, attempting to make sense of, or interpret, phenomena in terms of the meanings people bring to them. The subjects have been selected through convenience sampling, a non-probability approach to sampling as they have been exclusively targeted. Convenience sampling was used because of its expediency through issuing questionnaires to staff in the organisation for which this researcher works, and to subcontractors whom this researcher has dealt with. Through having a prior association with the subjects a better rate of return has been achieved, with subjects wanting to engage more in the research. In addition to this further time will be spent by each individual on providing more detailed responses further enhancing the thoroughness of this paper. Respondents are construction professionals and range from job roles such as estimators to surveyors and project managers to directors. The wide variety of job roles will give me the levels of unbiased data required to reach a conclusion. This method of research has been selected with the aim that subjects ideas and insights may lead to other, m ore detailed and representative research. Two different questionnaires were issued via electronic mail to a pre populated list of employees with one questionnaire issued to subcontractors and the other to main contractors. The purpose of this was so that the questions could be tailored to suit either the contractor or subcontractor, it was important to collate both views to reach an accurate conclusion. The theory behind using E-mail to distribute and collate the questionnaires was that it is much more reliable than circulation by post, easier to manage and track, whilst being convenient to people encouraging a larger participation as well as being more environmentally friendly and cost effective. Limited background data was requested such as position in company and level of industry experience as I felt other information would be irrelevant and not unpack the central question. There are no more than ten questions asked per questionnaire, it was felt that no further questions were required as a conclusion can be drawn from t he results and that by using fewer questions the participant is more likely to contribute as it will not encroach on their working day. The questions have been structured in a standardised manner so that they can be interpreted and analysed efficiently, there is a balance between open and closed questioning. Framework for Data Analysis Limitations and Potential Problems Convenience sampling suits this area of study because it is industry specific, by targeting known subjects this reduces the limitations of the research as there is only one researcher so manually sourcing or random sampling would be very time consuming with no guarantee of the quality of results. A perceived limitation with using questionnaires for research is that they are limited in number. This is predominantly justified due to the lack of time available as a student. To negate this risk the subjects were carefully selected to ensure a high rate of questionnaire return and an increased level of detailed answers. Methodology Rational Behind the Questions Questions issued to Sub-Contractors Interviews were dismissed as a potential research strategy; the rationale behind this is for the reason that unlike questionnaires they are not anonymous. Therefore interviewees may hold back from their true feelings or not give as much detail in their answers. This researcher has counteracted this by using open ended questions in the questionnaire permitting the subject the opportunity to express concerns and genuine views with the knowledge of total incognito; further substantiating that by using a questionnaire counts as valid empirical research due to its is suitability and relevance to this research paper. This researchers own primary data has been collected due to the lack of previous literature available on this subject; the majority of accessible information is concerned with client and contractor relationships and not contractor/subcontractor relations. Findings Introduction This chapter reveals the results of the survey described in Chapter 3 Methodology. This research concentrates on obtaining the views of Sub-Contractors and Principle Contractors with regards to single sourcing or competitively tendering Sub-Contract packages. Survey Findings; Description, Analysis and Synthesis Main Contractor Question 1.0 The first question Question 1.0 was: Do you feel that repeat work with the same subcontractor improves the working relationship in terms of discussing site issues/valuations? Response 17 (81%) of subjects questioned felt that working with the same Sub-Contractor improves the working relationship with 4 (19%) arguing against the majority. One respondent responded positively: A collaborative working relationship forms the basis of a much stronger approach to on site discussions and subsequent resolution of variations. Another stated: It needs to be two ways, with both parties fully buying into the benefits. One member conjectured that repeat business can improve working relationships however; at times this can be tested due to commercial pressures. No Main Contractor respondents stated a reason behind why repeat work with the same Sub-Contractor does not improve the working relationship. The replies from Main Contractor personnel suggest that there is still a problem with collaborative working. Although 81% of respondents viewed repeat work with the same Sub-Contractor in a wholly positive light, 19% felt differently. Question 2.0 The second question Question 2.0 was: Do you believe that repeat work with the same subcontractor gives a higher quality of workmanship? Response This question gave rise to many mixed views with 57% of the subjects surveyed believing that repeat work with the

Fairness of the SAT :: Standardized Tests ACT SAT Essays

The Scholastic Aptitude Test (SAT) was created to test college-bound students on their mathematical and verbal aptitudes and to thus predict their ability to succeed academically in college. In the United States, the SAT is the oldest and most widely used college entrance test. It was first administered in June 1926 to only 8,040 high school students and is now taken by over 2 million students. Over the years, the SAT has become one of the most important tests of a teenager's life for admission to college. The test is administered seven times a year at thousands of testing centers throughout the United States. Most colleges consider the SAT to be a reliable predictor of academic success in college and is therefore used as a critical tool when selecting applicants. However, the question that has to be confronted is whether the test is fair to all students. Educators have been questioning the validity of the SAT to determine college admission or to predict academic success because the test appears to be discriminatory and biased against women, minorities, and the poor (low income). The Educational Testing Service (ETS), which produces and administers the test, claims that the SAT in its current form "is an impartial and objective measure of student ability" (Owen 272). However, critics of the SAT argue "that tests like the SAT measure little more than the absorption of white upper-middle-class culture and penalize the economically disadvantaged" (Owen 10). The statistical reality of SAT scores is that: students who take coaching/prep courses do better than those who are not coached; men do better than women; whites do better than blacks; and the rich do better than the poor. Based upon my research, the SAT appears to be discriminatory against women, minorities, and the poor, and a test this flawed should not be used as a key factor in c ollege admission or as a predictor of academic success. In March 2005, a "new and improved" SAT will be introduced to theoretically eliminate any questions deemed biased and discriminatory. This revised SAT would appear to be a concession to the out-cry of criticism against the current test. However, since the new test will emphasize achievement rather than aptitude, it will once again favor the student who can afford coaching and attends a high school with a superior curriculum, i.e. the rich and white. An "equal opportunity" college entrance examination is virtually impossible because someone will always have/obtain an advantage.

Single Phase Transformer

Transformer BEE2123 ELECTRICAL MACHINES Mohd Rusllim Bin Mohamed Ext: 2080 A1-E10-C09 [email  protected] edu. my  © MRM 05 Learning Outcomes ? At the end of the lecture, student should to: ? Understand the principle and the nature of static machines of transformer. Perform an analysis on transformers which their principles are basic to the understanding of electrical machines. ?  © MRM 05 Introduction ? ? ? ? A transformer is a static machines. The word „transformer? comes form the word „transform?.Transformer is not an energy conversion device, but is a device that changes AC electrical power at one voltage level into AC electrical power at another voltage level through the action of magnetic field, without a change in frequency. It can be either to step-up or step down. Transmission System TX1 TX1 Generation Station 33/13. 5kV 13. 5/6. 6kV Distributions TX1 TX1  © MRM 05 6. 6kV/415V Consumer Transformer Construction ? Two types of iron-core construction: a) b) C ore – type construction Shell – type construction ? Core – type construction  © MRM 05 Transformer Construction ? Shell – type construction MRM 05 Ideal Transformer ? An ideal transformer is a transformer which has no loses, i. e. it? s winding has no ohmic resistance, no magnetic leakage, and therefore no I2 R and core loses. ? However, it is impossible to realize such a transformer in practice. ? Yet, the approximate characteristic of ideal transformer will be used in characterized the practical transformer. N1 : N2 I1 V1 E1 E2 I2 V2 V1 – Primary Voltage V2 – Secondary Voltage E1 – Primary induced Voltage E2 – secondary induced Voltage N1:N2 – Transformer ratio  © MRM 05 Transformer Equation ? Faraday? s Law states that, ?If the flux passes through a coil of wire, a voltage will be induced in the turns of wire. This voltage is directly proportional to the rate of change in the flux with respect of time. Vind ? Emf ind d? (t ) dt Lenz? s Law If we have N turns of wire, Vind ? Emf ind d? (t ) ? ?N dt  © MRM 05 Transformer Equation ? For an ac sources, ? Let V(t) = Vm sin? t i(t) = im sin? t Since the flux is a sinusoidal function; ?(t ) ? ? m sin ? t Then: Therefore: d? m sin ? t Vind ? Emf ind ? ? N dt ? ? N m cos ? t Thus: Vind ? Emfind (max) ? N m ? 2? fN? m N m 2? fN? m ? ? ? 4. 44 fN? m 2 2  © MRM 05 Emf ind ( rms) Transformer Equation For an ideal transformer E1 4. 44 fN1? m †¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦ (i) ? In the equilibrium condition, both the input power will be equaled to the output power, and this condition is said to ideal condition of a transformer. E2 4. 44 fN 2? m Input power ? output power V1 I1 cos ? ? V2 I 2 cos ? ? V1 I 2 ? V2 I1 ? From the ideal transformer circuit, note that, E1 ? V1 and E2 ? V2 ? Hence, substitute in (i)  © MRM 05 Transformer Equation Therefore, E1 N1 I 2 ? ? ? a E2 N 2 I1 Where, „a? is the Voltage Transformation Ratio ; which will determine whether the transformer is going to be step-up or step-down For a >1 For a E2 E1 < E2  © MRM 05Step-down Step-up Transformer Rating ? Transformer rating is normally written in terms of Apparent Power. ? Apparent power is actually the product of its rated current and rated voltage. VA ? V1I1 ? V2 I 2 ? Where, ? I1 and I2 = rated current on primary and secondary winding. ? V1 and V2 = rated voltage on primary and secondary winding. ? Rated currents are actually the full load currents in transformer  © MRM 05 Example 1. 1. 5kVA single phase transformer has rated voltage of 144/240 V. Finds its full load current. Solution 1500 I1FL ? ? 10. 45 A 144 1500 I 2 FL ? ? 6A 240  © MRM 05 Example 2.A single phase transformer has 400 primary and 1000 secondary turns. The net cross-sectional area of the core is 60m2. If the primary winding is connected to a 50Hz supply at 520V, calculate: a) The induced voltage in the secondary winding b) The peak value of flux densit y in the core Solution N1=400 V1=520V A=60m2 N2=1000 V2=?  © MRM 05 Example 2 (Cont) a) Know that, N1 V1 a? ? N 2 V2 400 520 ? 1000 V2 V2 ? 1300V b) Emf, E ? 4. 44 fN ? m ? 4. 44 fN ? Bm ? A? known, E1 ? 520V , E2 ? 1300V E ? 4. 44 fN ? Bm ? A? 520 ? 4. 44(50)(400)( Bm )(60) Bm ? 0. 976 x10 ? 5Wb / m 2 (T )  © MRM 05 Example 3.A 25kVA transformer has 500 turns on the primary and 50 turns on the secondary winding. The primary is connected to 3000V, 50Hz supply. Find: Full load primary and secondary current b) The induced voltage in the secondary winding c) The maximum flux in the core Solution VA = 25kVA N1=500 V1=3000V N2=50 V2=? a)  © MRM 05 Example 3 (Cont) a) Know that, VA ? V ? I I1FL VA 25 ? 103 ? ? ? 8. 33 A V1 3000 b) Induced voltage, N1 I 2 a? ? N 2 I1 ? 8. 33 ? I 2 ? 500? ? ? 83. 3 A ? 50 ? I1 ? 8. 33 ? E2 ? E1 ? 3000? ? ? 300V I2 ? 83. 3 ? c) Max flux E ? 4. 44 fN ? 300 ? 4. 44(50)(50)? ? ? 27mWb  © MRM 05Practical Transformer (Equivalent Circuit) I1 R1 X1 Ic V1 RC Io I1 ’ Im Load Xm E1 E2 V2 N1: N2 I2 R2 X2 V1 = primary supply voltage V2 = 2nd terminal (load) voltage E1 = primary winding voltage E2 = 2nd winding voltage I1 = primary supply current I2 = 2nd winding current I1? = primary winding current Io = no load current Ic = core current Im = magnetism current R1= primary winding resistance R2= 2nd winding resistance X1= primary winding leakage reactance X2= 2nd winding leakage reactance Rc  © MRM 05= core resistance Xm= magnetism reactance Single Phase Transformer (Referred to Primary) ? Actual MethodI1 R1 X1 Ic Io I2 ’ Im Load RC Xm E1 E2 V2 R2’ X2’ N1: N2 I2 V1 ? N1 ? R2 ‘ ? ? ? N ? R2 ? ? 2? ? N1 ? X2'? ? ? N ? X2 ? ? 2? 2 2 OR R2 ‘ ? a R2 2 ?N ? ‘ E1 ? V2 ? ? 1 ? V2 ? N ? ? 2? I I2 ‘ ? 2 a  © MRM 05 OR V2 ‘ ? aV2 OR X 2 ‘ ? a2 X 2 Single Phase Transformer (Referred to Primary) ? Approximate Method I1 R1 X1 R2’ X2’ Ic V1 RC Io I2 ’ Im Load Xm E1 E2 N1: N2 I2 V2 ?N ? R2 ‘ ? ? 1 ? R2 ? N ? ? 2? ?N ? X2'? ? 1 ? X2 ? N ? ? 2? 2 2 OR R2 ‘ ? a R2 2 OR X 2 ‘ ? a2 X 2 ?N ? ‘ E1 ? V2 ? ? 1 ? V2 ? N ? ? 2? I I2 ‘ ? 2 a  © MRM 05 OR V2 ‘ ? aV2 Single Phase Transformer (Referred to Primary) ? Approximate Method I1 R01 X01V1 aV2 In some application, the excitation branch has a small current compared to load current, thus it may be neglected without causing serious error. ?N ? R2 ‘ ? ? 1 ? R2 ? N ? ? 2? ?N ? X2'? ? 1 ? X2 ? N ? ? 2? 2 2 OR R2 ‘ ? a R2 2 ?N ? ‘ V2 ? ? 1 ? V2 ? N ? ? 2? OR V2 ‘ ? aV2 OR X 2 ‘ ? a2 X 2 R01 ? R1 ? R2 ‘  © MRM 05 X 01 ? X 1 ? X 2 ‘ Single Phase Transformer (Referred to Secondary) ? Actual Method I1 ’ R1’ X1’ Ic Io I2 Im Xm’ R2 X2 V1 a RC’ V2 ?N ? R1 R1 ‘ ? ? 2 ? R1 OR R1 ‘ ? 2 ? N ? a ? 1? ?N ? X 1 ‘ ? ? 2 ? X 1 OR ? N ? ? 1? 2 2 ?N ? V V1 ‘ ? ? 2 ? V1 OR V1 ‘ ? 1 ? N ? a ? 1?  © MRM 05 X1' ? X1 a2Single Phase Transformer (Referred to Secondary) ? Approximate Method I1 ’ R02 X02 Neglect the excitation branch V1 a V2 R02 ? R1 ‘? R2 X 02 ? X 1 ‘? X 2 ?N ? R1 R1 ‘ ? ? 2 ? R1 OR R1 ‘ ? 2 ? N ? a ? 1? ?N ? X 1 ‘ ? ? 2 ? X 1 OR ? N ? ? 1? 2 2 ? N2 ? V ? ?V1 OR V1 ‘ ? 1 V1 ‘ ? ? N1 ? a ? ? I1 ‘ ? aI1  © MRM 05 X1' ? X1 a2 Example 4. For the parameters obtained from the test of 20kVA 2600/245 V single phase transformer, refer all the parameters to the high voltage side if all the parameters are obtained at lower voltage side side. Rc = 3. 3? , Xm =j1. 5? , R2 = 7. 5? , X2 = j12. 4? Solution Given Rc = 3. 3? , Xm =j1. 5? , R2 = 7. ? , X2 = j12. 4?  © MRM 05 Example 4 (Cont) i) Refer to H. V side (primary) E1 V1 2600 a? ? ? ? 10. 61 E2 V2 245 R2 ‘ ? a 2 R2 2 V2 ‘ ? aV2 To refer parameters to primary, Use R2? =(10. 61)2 (7. 5) = 844. 65? , X2? =j(10. 61)2 (12. 4) = 1. 396k? Rc? and X c? becoz parameters were read from secondary side Rc? =(10. 61)2 (3. 3) = 371. 6? , Xm? =j(10. 61)2 (1. 5) = j168. 9 ?  © MRM 05 2nd I I2 ‘ ? 2 X2'? a X2 a Example (What if.. ) 4. For the parameters obtained from the test of 20kVA 245/2600 V single phase transformer, refer all the parameters to the high voltage side if all the parameters are obtained at lower voltage side side.Rc = 3. 3? , Xm =j1. 5? , R2 = 7. 5? , X2 = j12. 4? Solution Given Rc = 3. 3? , Xm =j1. 5? , R2 = 7. 5? , X2 = j12. 4?  © MRM 05 Power Factor ? Power factor = angle between Current and Voltage, cos ? V I ? I ? = -ve Lagging ? V I V ? = +ve Leading ?=1 unity  © MRM 05 Example 5. A 10 kVA single phase transformer 2000/440V has primary resistance and reactance of 5. 5? and 12? respectively, while the resistance and reactance of secondary winding is 0. 2? and 0. 45 ? respectively. Calculate: i. ii. The parameter referred to high voltage side and draw the equivalent circuit The approximate value of seco ndary voltage at full load of 0. lagging power factor, when primary supply is 2000V.  © MRM 05 Example 5 (Cont) Solution R1=5. 5 ? , X1=j12 ? R2=0. 2 ? , X2=j0. 45 ? i) Refer to H. V side (primary) E V 2000 a? 1 ? 1 ? ? 4. 55 E2 V2 440 I1 R01 9. 64 V1 X01 21. 32 aV2 R2? =(4. 55)2 (0. 2) = 4. 14? , X2? =j(4. 55)20. 45 = j9. 32 ? Therefore, R01=R1+R2? =5. 5 + 4. 13 = 9. 64 ?  © MRM X01=X1+X2? =j12 + j9. 32 = j21. 3205? Example 5 (Cont) Solution ii) Secondary voltage p. f = 0. 8 Cos ? = 0. 8 ? =36. 87o 10 ? 103VA Full load, I FL ? ? 5A 2000V From eqn. cct, 1 V1? 0o ? ( R01 ? jX 01)( I1? ? ? o ) ? aV2 2000? 0o ? (9. 64 ? j 21. 32)(5? ? 36. 87 o ) ? (4. 5)V2 V2 ? 422. 6? 0. 8o  © MRM 05 Transformer Losses ? i. ii. Generally, there are two types of losses; Iron losses :- occur in core parameters Copper losses :- occur in winding resistance i. Iron Losses Piron ? Pc ? ( I c) 2 Rc ? Popen circuit ii. Copper Losses Pcopper ? Pcu ? ( I 1) 2 R1 ? ( I 2) 2 R2 ? Pshort circuit or if referr ed , Pcu ? ( I 1) 2 R01 ? ( I 2) 2 R02  © MRM 05 Poc and Psc will be discusses later in transformer test Transformer Efficiency ? To check the performance of the device, by comparing the output with respect to the input. ? The higher the efficiency, the better the system. Efficiency ,? Output Power ? 100% Input Power Pout ? ?100% Pout ? Plosses ? V2 I 2 cos ? ?100% V2 I 2 cos ? ? Pc ? Pcu ? ( fullload) ? ?(load n ) ? VA cos ? ?100% VA cos ? ? Pc ? Pcu nVA cos ? ?100% 2 nVA cos ? ? Pc ? n Pcu Where, if ? load, hence n = ? , ? load, n= ? , 90% of full load, n =0. 9 Where Pcu = Psc Pc = Poc  © MRM 05 nmax ? ? Poc VArated ? P ? ? sc ? ? ? VArated ? ? ? ? Pc VArated ? P ? ? cu ? ?VArated ? ? ? Voltage Regulation ? The measure of how well a power transformer maintains constant secondary voltage over a range of load currents is called the transformer's voltage regulation ?The purpose of voltage regulation is basically to determine the percentage of voltage drop between no lo ad and full load.  © MRM 05 Voltage Regulation ? For calculation of Voltage Regulation, terminologies may be quite confusing, hence you need always think in current, I (A) point of view â€Å"Full-load† means the point at which the transformer ? is operating at maximum permissible secondary current ? When connected to load, current being drawn, hence Voltage drop) ? ? No Load means at Rated At no load, current almost zero, so takes Voltage at rated  © MRM 05 value – think like an open circuit) Voltage Regulation Voltage Regulation can be determine based on 3 methods: a) b) c) Basic Definition Short – circuit Test Equivalent Circuit  © MRM 05 Voltage Regulation (Basic Defination) ? In this method, all parameter are being referred to primary or secondary side. ? Can be represented in either ? Down – voltage Regulation Note that: VNL ? VFL V . R ? ?100% VNL (at Rated Value) VNL ? Up – Voltage Regulation VNL ? VFL V . R ? ?100% VFL  © MRM 05 Vo ltage Regulation (Short – circuit Test) ? In this method, direct formula can be used. V . R ? V . R ? Vsc cos sc ? ? p. f ? V1 ?100% If s/c test on primary side Vsc cos c ? ? p. f ? V2 ?100% If s/c test on primary side Note that: „–? is for Lagging power factor „+? is for Leading power factor Must check that Isc must equal to IFL (I at Rated), otherwise  © MRM 05 can? t use this formula Voltage Regulation (Equivalent Circuit ) ? In this method, the parameters must be referred to primary or secondary V . R ? I1 R01 cos ? p. f ? X 01 sin ? p. f V1 I 2 R02 cos ? p. f ? X 02 sin ? p. f V2 ? 100% 100% If referred to primary side V . R ? ? If referred to secondary side Note that: „+? is for Lagging power factor „–? is for Leading power factor  © MRM 05 assume j terms ~0Comment on VR ? Purely Resistive Load ? > 3 % is considered poor VR Normally poor than Resistive Load ? Inductive Load ? ? Example of application Desired Poor VR ? ? Disc harge lighting AC arc welders  © MRM 05 Example 6. In example 5, determine the Voltage regulation by using down – voltage regulation and equivalent circuit. Question 5 A 10 kVA single phase transformer 2000/440V and V1? 0o ? ( R01 ? jX 01)( I1? ? ? o ) ? aV2 2000? 0o ? (9. 64 ? j 21. 32)(5? ? 36. 87 o ) ? (4. 55)V2 V2 ? 422. 6? 0. 8o  © MRM 05 Example Solution Down – voltage Regulation Know that, V2FL=422. 6V V2NL=440V Therefore, V .R ? VNL ? VFL ? 100% VNL 440 ? 422. 6 ? ?100% 440 ? 3. 95%  © MRM 05 Example 6 (Cont) Equivalent Circuit I1=5A R01=9. 64? X01 = 21. 32? V1=2000V, 0. 8 lagging p. f V . R ? I1 R01 cos ? p. f ? X 01 sin ? p. f V1 ? 100% 5 ? 9. 64(0. 8) ? 21. 32(0. 6)? ? ? 100% 2000 ? 5. 12%  © MRM 05 Example A short circuit test was performed at the secondary side of 10kVA, 240/100V transformer. Determine the voltage regulation at 0. 8 lagging power factor if Vsc =18V Isc =100 Psc=240W Solution Check: 7. I FL2 I FL2 VA 10000 ? ? ? 100 A V 100 ? I sc , Hence, we can use short-circuit method V . R ? Vsc cos sc ? ? p. ? V2  © MRM 05 ?100% Example 7 (Cont) V . R ? Vsc cos sc ? ? p. f ? V2 ? 100% Given p. f ? 0. 8 Hence, ? p. f ? cos ? 1 0. 8 ? 36. 87 o Know that , Psc ? Vsc I sc cos ? sc ? sc ? cos ? 1 ? ? ? Psc ? ? ? ? Vsc I sc ? 18 cos 82. 34o ? 36. 87 o V . R ? ?100% 100  © MRM 05 ? 12. 62% ? ? 240 ? ? ? 82. 34 o ? cos ? 1 ? ? (18)(100) ? ? ? ? Example 8. The following data were obtained in test on 20kVA 2400/240V, 60Hz transformer. Vsc =72V Isc =8. 33A Psc=268W Poc=170W The measuring instrument are connected in the primary side for short circuit test. Determine the voltage regulation for 0. 8 lagging p. f. use all 3 methods), full load efficiency and half load efficiency.  © MRM 05 Example 8 (Cont) V . R ? Vsc cos sc ? ? p. f ? V2 ? 100% Given p. f ? 0. 8 Hence, ? p. f ? cos ?1 0. 8 ? 36. 87 o Know that , Psc ? Vsc I sc cos ? sc ? Psc ? ? sc ? cos ? ?V I ? ? ? sc sc ? ? 268 ? ? ? 63. 4o ? cos ? 1 ? ? (72)(8. 33) ? ? ? ?1 Z sc ? Vsc 72 ? ? 8. 64? I sc 8. 33 ? Z sc ? 8. 64? 63. 4o ? 3. 86 ? j 7. 72 ? R01 ? jX 01 because connected to primary side.  © MRM 05 Example 8 (Cont) 1. Short Circuit method , V . R ? Vsc cos sc ? ? p. f ? V1 ? 100% 72 cos 63. 4o ? 36. 87 o V . R ? ?100% ? 2. 68% 2400 ? ? 2. Equivalent circuit , V .R ? I1 R01 cos ? p. f ? X 01 sin ? p. f V1 ? ? ? 100% 20000 ? 3. 86(0. 8) ? 7. 72(0. 6)? 2400 ? 100% ? 2. 68% 2400  © MRM 05 Example 8 (Cont) 3. Basic Defination , V1 ? I1Z 01 ? aV2 ? 20000 ? 2400 ? o? o 2400? 0 ? ? ? ? 36. 87 ? 8. 64? 63. 4 ? ? ? V2 ? 2400 ? ? 240 ? V2 ? 233. 58? 0. 79 o V o ? ? VNL ? VFL V . R ? ?100% VNL ? 240 ? 233. 58 ? 100% 240 ? 2. 68%  © MRM 05 Example 8 (Cont) ?( full load) (1)(20000)(0. 8) ? ?100% ? 97. 34% 2 (1)(20000)(0. 8) ? 170 ? (1) (268) (0. 5)(20000)(0. 8) ? ?100% ? 97. 12% 2 (0. 5)(20000)(0. 8) ? 170 ? (0. 5) (268) ?( half load)  © MRM 05 Measurement on Transformer ? i. ii.There are two test conducted on transformer. Open Circuit Test Shor t Circuit test ? ? ? The test is conducted to determine the parameter of the transformer. Open circuit test is conducted to determine magnetism parameter, Rc and Xm. Short circuit test is conducted to determine the copper parameter depending where the test is performed. If performed at primary, hence the parameters are R01 and ©X0105and vice-versa. MRM Open-Circuit Test ? ? Voc Ic Measurement are at low voltage side Poc ? Voc I oc cos ? oc From a given test parameters, ? ?1 ? P oc Voc ? oc ? cos ? Voc ? V I ? ? ? oc oc ? I sin? Im Ic oc oc Ioc RcXm ?oc Ioccos? oc Hence, I c ? I oc cos ? oc ? Im I m ? I oc sin ? oc Then, Rc and X m , Voc Voc Rc ? , Xm ? Ic Im Note: If the question asked parameters referred to high voltage side, the parameters (Rc and Xm) obtained need to be referred to high voltage side  © MRM 05 Short-Circuit Test ? ? Measurement are at high voltage side If the given test parameters are taken on primary side, R01 and X01 will be obtained. Or else, viceversa. R01 X01 Psc ? Vsc I sc cos ? sc ? Psc ? ? sc ? cos ? ?V I ? ? ? sc sc ? Hence, Vsc Z 01 ? sc I sc ? 1  © MRM 05 For a case referred to Primary side Z 01 ? R01 ? jX 01 Example 9.Given the test on 500kVA 2300/208V are as follows: Poc = 3800W Psc = 6200W Voc = 208V Vsc = 95V Ioc = 52. 5A Isc = 217. 4A Determine the transformer parameters and draw equivalent circuit referred to high voltage side. Also calculate appropriate value of V2 at full load, the full load efficiency, half load efficiency and voltage regulation, when power factor is 0. 866 lagging.  © MRM 05 [1392? , 517. 2? , 0. 13? , 0. 44? , 202V, 97. 74%, 97. 59%, 3. 04%] Example 9 (Cont) From Open Circuit Test, Poc ? Voc I oc cos ? oc ? 3800 ? ? ? 69. 6o ? oc ? cos ? ? (52. 5)(208) ? ? ? I c ? I oc cos ? oc ? 1 Voc Ic Iocsin? oc IocIoccos? oc ? 52. 5 cos 69. 6o ? 18. 26 A I m ? I oc sin ? oc ? 52. 5 sin 69. 6o ? 49. 2 A ?oc Im ?  © MRM 05 Example 9 (Cont) Since Voc=208V i. e. low voltage side ? all reading are taken on th e secondary side (low voltage side) Voc 208 Rc ? ? ? 11. 39? I c 18. 26 Voc 208 Xm ? ? ? 4. 23? I m 49. 21 Parameters referred to high voltage side, ? E1 ? ? 2300 ? Rc ‘ ? Rc ? ? ? 11. 39? ? ? 1392? ?E ? ? 208 ? ? 2? 2 2 ? E1 ? ? 2300 ? ? ? ? 4. 23? Xm'? Xm? ? ? 517 ? MRM 05 . 21?  © ? 208 ? ? E2 ? 2 2 Example 9 (Cont) From Short Circuit Test, First, check the Isc I FL1 VA 500 ? 103 ? ? ? 217. 4 A V1 2300 Since IFL1 =Isc , ? ll reading are actually taken on the primary side Psc ? Vsc I sc cos ? sc ? 6200 ? ? ? 72. 53o ? sc ? cos ? ? (95)(217. 4) ? ? ? ?1 ?V ? Z 01 ? ? sc sc ? I ? ? sc ? ? 95 ? o o 72. 53 ? 0. 44? 72. 53 ? 217. 4 ?  © MRM 05 ? 0. 13 ? j 0. 42? Example 9 (Cont) Equivalent circuit referred to high voltage side, R01 0. 13? X01 0. 42? V1 Rc 1392? Xm 517. 21? V2? =aV2  © MRM 05 Example 9 (Cont) For V2 at full load, neglect the magnetism parameters, R01 0. 13? X01 0. 42? v1 v2? pf ? cos ? ? 0. 866 ? ? cos ? 1 0. 866 ? 30o  © MRM 05 Example 9 (Cont) Efficie ncy,? ? ? VA cos ? ? FL ? ? ? ?100% ? VA cos ? ? Psc ? Poc ? ? ? 500 ? 103 )(0. 866) ? ? 100% (500 ? 103 )(0. 866) ? 6200 ? 3800 ? ? ? 97. 74% ? ? nVA cos ? ?1 L ? ? ? ? 100% 2 nVA cos ? ? n 2 Psc ? Poc ? ? ? ? (0. 5)(500 ? 103 )(0. 866) ? ? 100% 3 2 ? (0. 5)(500 ? 10 )(0. 866) ? (6200)(0. 5) ? 3800 ? ? 97. 59%  © MRM 05 Example 9 (Cont) Voltage Regulation, ?Vsc cos ? sc ? ? pf ? V . R ? ? ? ?100% E1 ? ? ? (95) cos? 72. 53 ? 30 ? ? 100% 2300 ? ? ? 3. 04% ? ?  © MRM 05 Test Yourself on Final Exam Q ? Following are the test result of a 12 kV A, 415 V / 240 V, 50 Hz, two winding single phase transformer: Open circuit test (reading taken on low voltage side) 240 V 4. 2 A 80 WShort circuit test (reading taken on high voltage side) 9. 8 V ? Determine: i. 28. 9 A 185 W The values of Rp. Rs. Xp, Xs, Xm and Rc, assuming an approximate equivalent circuit. ii. The efficiency of the transformer at full load and 0. 8 lagging power factor. iii. The voltage regulation at full load and 0. 8 lagging power factor.  © MRM 05 Solution i. Solution ? ? ? ? Eff = 97. 3 % ? V. R = 2. 31 % Z = 57. 14 ? Rc = 714. 3 ? Xm = 57. 31 a = 1. 73 R1 = 0. 11 ? R2 = 0. 037 ? X1 = 0. 13 ? X2 = 0. 043 ? ? Refer to Primary, ? ? ? ? ?  © MRM 05 Any Questions Test 1 – coming soon Make sure you prepared for that†¦  © MRM 05

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