The transformer to be used in this lab session is pi ctured in figure 5 a. Revision on exam type questions, on 3 phase transformer calculations. Shortcircuit current calculations singlephase short circuits short circuit calculations on a singlephase center tapped transformer system require a slightly different procedure than 3o faults on 3o systems. Ideal power equation of transformer electrical technology.
November 2019 national examination national examination paper for n2 electrical trade theory. Calculation of kva capacity for a single or three phase transformer, based on winding voltage and amperage information. A single phase transformer has 480 turns on the primary winding and 90 turns on the secondary winding. Basics, maintenance, and diagnostics vii contents continued page 4.
Explain the four standard three phase transformer configurations 2. Buy the complete 9 dvd series with workbook at how to pass the electrical exam. Emf equation of transformer can be established in a very easy way. N2 electrical engineering question papers and memorandums. Singlephase transformers connected into a 3phase bank retain all basic singlephase properties individual voltage and current transformations are based on the singlephase turns ratio phase shift between primary and secondary is zero 3phase transformer banks can introduce a phase shift between the. Introduction a transformer is an electrical device that transfers energy from one circuit to another purely by magnetic coupling. Calculate transformer voltage regulation and efficiency. Compute the load division between parallel transformers.
To study the voltages and currents curves when the operating single phase transformer. Explain the four standard threephase transformer configurations 2. Develop transformer equivalent circuits from opencircuit and shortcircuit test data. Efficiency ratings of low voltage drytype distribution transformers singlephase1 1 single phase ventilated transformer efficiencies remain the same as the 2007 levels.
Department of the interior bureau of reclamation technical service center infrastructure services division hydroelectric research and technical services group. Single phase transformers are manufactured with secondary windings brought out to two, three, or four bushings. A transformer is an electrical device that transfers electrical energy between two or more circuits. A 25 kva single phase transformer has the p rimary and secondary number of turns of 200 and 400, respectively the transformer is connected to a 220v, 50hz source. Transformer designed to be used in general applications. It does this at very high efficiency, at 99% or higher.
Transformers in power stations are generally three phase and double wound, i. Actually in electrical power transformer, one alternating electrical source is applied to the primary winding and due to this, magnetizing current flowing through the primary winding which produces alternating flux in the core of transformer. It is necessary that the proper impedance be used to represent the primary system. How to calculate the required capacity kva rating or amperage. Dec 25, 2010 the transformer interconnects and transfers power between systems at different voltages. Pcbs determination in transformer oil by spe and gas. Purpose this document is to provide guidance to bureau of reclamation reclamation powerplant personnel in maintenance, diagnostics, and testing of transformers and associated. The kn n2 and knn3 enable all types of power measurement with easy installation and easy system construction. One side of the transformer bank is connected to a three phase. Emf equation of transformer turns voltage transformation. Single phase transformers retain their design, ee prefix, and catalog numbering structure.
The rms amplitude of voltage on the primary side is 100 v. For information on single phase products, refer to the energy efficient sin gle. Basic theory of transformers electrical engineering. Square d brand ex low voltage distribution transformers. A read is counted each time someone views a publication summary such as the title, abstract, and list of authors, clicks on a figure, or views or downloads the fulltext. Note that single phase stepdown transformer can also be used as a stepup transformer simply by reversing its connections and making the low voltage winding its primary, and vice versa as long as the transformer. Phasing transformers by susan deats march 28, 2005 on a train layout, if you have two transformers powering two different blocks and theyre out of phase it would be possible to inadvertently run 40 volts through a locomotive when its over the center rail insulating track pin separating the blocks. If we use high efficiency power plants to supply the base load, we can reduce the cost of generation. Massachusetts institute of technology mit opencourseware. Use kfactorrated transformer to solve nonlinear load problems. Sistece 2 coil 1 i1t i2t coil 2 m e1t e2t s1 s2 i1t i2t the transformer primary has n1 turns secondary has n2 turns v2 3. Page 4 all base load power plants have a high load factor. Transformer 37 vector grouping of transformers depending upon the phase shift of lineneutral voltages between primary and secondary.
For more representative collections, this tape not solitary offers it is helpfully baby book resource. We look at models of single phase twowinding, three phase twowinding, and three phase threewinding transformers, as well as auto transformers and regulating transformers. May 15, 2015 this lecture explains the construction,working principle and emf equation of a single phase transformer. It is normally used in the audio frequency band 200 hz to 5 khz.
The other side of the transformer is connected to a three phase residential load of 415. To determine kva you must have at least two pieces of information. Single phase transformer 3rd semester electrical engineering sub. Explain what causes circulating currents in parallel and compute its value. A simple transformer three phase transformers a transformer for use with 3 phase power is constructed by winding three single phase transformers on a single core. Read pdf electrical trade theory n2 question papers 2014 friend in spending the time. Transformer 36 phaseshift between lineline voltages in transformers. Applies to all single and three phase transformers.
If the secondary coil of transformer is attached to a load that allows current to flow, electrical power is transmitted. Shortcircuit current calculations cooper industries. Single phase power transformer lab report shu studocu. After a transformer has been received at its final destination, it is advisable to put it full of oil on its permanent place, even if it is not going to be placed in operation immediately. Aug 14, 2014 learn the single phase and 3 phase calculations with jim lewis easy to understand methods.
Ashok d pateliya prepared by 1 mahendra rajput 140643109030 2 ankur shah 140643109031 3 kaushal rana 140643109021 4 jay prajapati 140643109018 2. For this, a three phase step down transformer is used. A single three phase transformer is cheaper, easier to install, and will operate more efficiently than three single phase units. It can be totally oil filled or with n2 gas cushion or can be equipped with conservator as air interface. Relative motion of the parts of the transformer is not required for transfer of energy. The maximum value of the magnetic flux density is 1. To study the characteristics of the single phase transformer.
Ge 207electrical machines i part a singlephase transformer 2nd year comm. Jun 04, 2015 also at the end of the transmission or distribution, these high voltages are stepdown to levels of 6600, 400, 230 volts, etc. We look at models of singlephase twowinding, threephase twowinding, and threephase threewinding transformers, as well as autotransformers and regulating transformers. Bookmark file pdf n2 electrical engineering question papers and memorandums n2 electrical engineering question papers and memorandums n2 electrical trade theory revision how to pass an engineering exam if youre going into this. The resistor has value ns n1 r 30,000 the transformer turns ratio is 10. Transformer questions and answers electrical academia. A three phase transformer can be built in two ways.
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