Ch08 Transformers 1s09 - Transformers Transformers Chapter...

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Unformatted text preview: Transformers Transformers Chapter 8 Artemio Artemio P. P. Magabo Magabo Professor of Electrical Engineering Professor of Electrical Engineering Department of Electrical and Electronics Engineering University of the Philippines - Diliman Department of Electrical and Electronics Engineering Direct Current Power System b Steam engine coupled to a 110- volt Direct Current (DC) generator b Underground cable system b All loads were incandescent bulbs b 59 customers within an area 1.5 km in radius The first DC Power System was the Pearl Street Station , built by Thomas Edison in New York City in 1882. Department of Electrical and Electronics Engineering Alternating Current System b First commercial application of transformers b Loads consisted of 150 lamps The first AC system was built by William Stanley, an associate of George Westinghouse, at Great Barrington, Massachusetts in 1886. Department of Electrical and Electronics Engineering AC System vs. DC System Smaller losses and voltage drops Problems with voltage drop and losses Generation capacity can be built to fully utilize available resources Limited power capacity Voltage transformation made possible transport of electric energy over long distances Power delivery is limited to short distances AC System DC System Department of Electrical and Electronics Engineering Distribution Transformer Primary Distribution Feeder Transformers in AC Systems b Generation s Generating Plant b Transmission s Transmission Substation s Transmission Lines s Sub-transmission Lines b Distribution s Power Substation s Primary Distribution Feeders s Distribution Transformers s Secondary Distribution Feeders and Services Department of Electrical and Electronics Engineering Power Substation High Voltage: 500, 230 or 138 kV Low Voltage: 115 or 69 kV Department of Electrical and Electronics Engineering Distribution Substation High Voltage: 69 kV Low Voltage: 13.8 kV Department of Electrical and Electronics Engineering Distribution Transformers High Voltage: 13.8 kV Low Voltage: 220 V Department of Electrical and Electronics Engineering Two-Winding Transformer Consider the two coils shown. Coil 1, which is connected to a voltage source, draws a very small exciting current that produces the magnetic flux ( φ ) that links both coils. Note: In an ideal transformer, i ex = 0. + e 1- i ex Magnetic Flux φ i 2 = 0 Iron Core N 1 N 2 +- v s + e 2- Department of Electrical and Electronics Engineering dt d N e 1 1 φ = From Faraday’s Law, voltages are induced in coils 1 and 2. The induced voltages are dt d N e 2 2 φ = and Dividing the equations, we get 2 1 2 1 N N e e = Note: In an ideal transformer, the ratio of the induced voltages is equal to the ratio of turns....
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Ch08 Transformers 1s09 - Transformers Transformers Chapter...

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