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# 1. Introduction to transformers final.pptx

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# 1. Introduction to transformers final.pptx

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### 1. Introduction to transformers final.pptx

1. 1. Introduction to transformers
2. 2. Outline 1. Introduction to Transformers 2. Transformer construction 3. Model of Transformer on no load Performance Management Orientation
3. 3. Transformer • A transformer is a static device comprising coils coupled through a magnetic medium connecting two ports at different voltage levels in an electric system allowing the interchange of electrical energy between the ports • It is used in changing voltage and current levels in electric power systems • Other important tasks include matching source and load impedance for maximum power transfer, and electrical isolation • A transformer, consists essentially of two insulated windings interlinked by a mutual magnetic field established in a core of magnetic material
4. 4. Transformer • When one of the windings, termed the primary, is connected to an alternating-voltage source, an alternating flux is produced in the core • This mutual flux links the other winding, called the secondary. • A voltage is induced in this secondary of the same frequency as the primary voltage but its magnitude depends on the number of secondary turns • The subscript “1”or “p” will be associated with the primary and “2” or “s” with the secondary
5. 5. Transformer • If the secondary voltage is greater than the primary value, the transformer is called a step-up transformer; • if the secondary voltage is less, it is known as a step-down transformer; • if primary and secondary voltages are equal, the transformer is said to have a one-to-one ratio. (these are mostly used for isolation purposes)
6. 6. TRANSFORMER CONSTRUCTION • Construction of transformers will be dependent on a number of factors such as: • Winding voltage • Current rating and operating frequency • Heat removal from the core and windings
7. 7. TRANSFORMER CONSTRUCTION • The primary and secondary coils are wound on the core and are electrically insulated from each other and from the core Two types of cores are commonly used—core-type and shell-type • In core-type construction, the windings are wound around the two legs of a rectangular magnetic core • In shell-type construction, the windings are wound on the central leg of a three-legged core In either case, the core is constructed of thin laminations electrically isolated from each other in order to minimize eddy currents
8. 8. TRANSFORMER CONSTRUCTION • The primary and secondary windings in a core type transformer are wrapped one on top of the other with the low-voltage winding innermost • Half of the low-voltage winding and half of the high-voltage winding is wound on each limb of the core
9. 9. TRANSFORMER CONSTRUCTION • Such an arrangement serves two purposes:  It simplifies the problem of insulating the high-voltage winding from the core. It results in much less flux leakage than would be the case if the two windings were separated by a distance on the core.
10. 10. TRANSFORMER CONSTRUCTION • In shell-type construction leakage is reduced by subdividing each winding into subsections and interleaving LV and HV windings
11. 11. TRANSFORMER CONSTRUCTION • The shell-type construction has better mechanical support and good provision for bracing the windings. However, it requires more specialized fabrication facilities than core-type, • The core type offers the additional advantage of permitting visual inspection of coils in the case of a fault and ease of repair. • In addition, the core type windings can easily be insulated from each other and from the core • For this reason, the core type transformers are commonly used in large high-voltage installations.
12. 12. TRANSFORMER CONSTRUCTION • Transformer windings are made of solid or stranded copper or aluminium strip conductors. • The windings of huge power transformers use conductors with heavier insulation (cloth and paper.) • The winding layers are insulated with pressed boards and varnished cloth