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ECE 316

ECE 316. Introduction to Electric Energy Systems Fall 2014 Mark Patterson TTh 4:30-5:45, KL-351G. Today’s Quote: Cultivate the ability to see each other’s point of view. “The Lord gives wisdom, and from his mouth come knowledge and understanding.” Proverbs 2:6.

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ECE 316

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  1. ECE 316 Introduction to Electric Energy Systems Fall 2014 Mark Patterson TTh 4:30-5:45, KL-351G

  2. Today’s Quote: Cultivate the ability to see each other’s point of view. “The Lord gives wisdom, and from his mouth come knowledge and understanding.” Proverbs 2:6

  3. Major Points from Lecture 4 • Reactive components cause the phase angle of current to either lead or lag voltage. • Steady State AC circuit analysis isn’t really that hard.

  4. AC Nomenclature

  5. Fundamental Assumptions: Steady State AC Circuit Analysis • ALL sources are sinusoidal…..and are often of the same frequency. • ALL transient phenomena have decayed to zero. • ALL circuit elements are linear…..or are approximately so. • ALL currents and voltages are sinusoidal and have the same frequency as the source. • Superposition is VALID. • The MAGNITUDE and PHASE of all voltages and currents completely define the circuit state. • The instantaneous POWER associated with any circuit element IS the product of a sinusoidal voltage and a sinusoidal current. • A COMPLEX NUMBER (or PHASOR) can be chosen to represent a sinusoidal voltage or current where the magnitude or absolute value of the number represents the MAGNITUDE of the voltage or current, and the angle of the number represents the PHASE of the voltage or current relative to an arbitrary reference. • The selection of the reference PHASOR is purely arbitrary. Any reference phasor will yield the SAME circuit solution. • Sometimes, appropriate selection of the reference phasor makes a problem solution more tractable. • Kirchoff’s Voltage and Current Laws and Ohm’s Law can be shown to be valid in AC steady-state. Consequently node and mesh analysis can be applied.

  6. Electric Power

  7. Electric Power

  8. Real Power

  9. Reactive Power

  10. Apparent Power

  11. Power Factor

  12. Power Factor

  13. Power Factor Correction • Load reactance limits the ability of a utility to deliver real power to the customer. • The transmission line capacity is determined by the maximum current capability of the transmission or distribution line – a function of it’s cross-sectional area, the conductor material (copper or aluminum typically) and the insulating material. • Since excess reactive power increases the magnitude of the transmission line current, the spare capacity is reduced.

  14. Power Factor Correction

  15. Electric Energy

  16. Sample Problem 1

  17. Sample Problem 2

  18. Sample Problem 3

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