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EE 458 Electrical Distribution Systems
Books: Sallam, A. A., “Electric Distribution Systems (IEEE Press Series on Power Engineering)”, Wiley-IEEE Press, First Edition, 2011. Gönen, T., “Electric Power Distribution System Engineering”, CRC Press, Second Edition, 2011. Fehr, R. E., “Industrial Power Distribution”, Prentice-Hall, Inc., 2002. Beaty, W., “Electric Power Distribution Systems: A Nontechnical Guide”, Penn Well Pub. Company, 1998
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Basics Power: Instantaneous consumption of energy Power Units
Watts = voltage x current for dc (W) kW – 1 x 103 Watt MW – 1 x 106 Watt GW – 1 x 109 Watt
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Basics Energy: Amount of Work Energy Units (for electrical power)
Wh x 100 Watthour kWh – 1 x 103 Watthour MWh – 1 x 106 Watthour GWh – 1 x 109 Watthour Relationship of power and energy Energy Consumed Average Power Duration
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Sinusoidal Signals Circular rotation of a magnetized rotor in Synchronous Generator produces sinusoidal voltage in stator windings due to FARADAY LAW. (Look at EE 471 Notes)
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Sinusoidal Signals THREE-PHASE SYNCHRONOUS GENERATOR
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? ? Sinusoidal Signals How do you write the mathematical
equation for this periodic function? ? ?
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Sinusoidal Signals Period : 0.01 s. Frequency : 100 Hz.
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Sinusoidal Signals Period : 0.02 s. Frequency : 50 Hz. OR
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Sinusoidal Signals
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? Sinusoidal Signals Peak voltage : 310 V. Period : 0.02 s.
-400 -300 -200 -100 100 200 300 400 0.0000 0.0025 0.0050 0.0075 0.0100 0.0125 0.0150 0.0175 0.0200 Time (seconds) Volts, Amperes Current Voltage Peak voltage : 310 V. Period : s. Frequency : 50 Hz. radian Peak current : 150 A. Period : s. Frequency : 50 Hz.
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Complex Numbers Euler’s Formula : Relates exponential and sinusoidal functions Re Im Rectangular Notation Polar R Attention:
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Complex Numbers Rectangular Polar
Addition and subtraction of complex numbers are easier with the rectangular notation. Multiplication and division of complex numbers are easier with the polar notation. Attention: Rectangular Polar
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Phasors Phasors are complex numbers used to represent sinusoids.
Phasor representation of a sinusoidal function: Phasor If we multiply phasor by and apply Euler’s formula
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Phasors Consider the derivative of sinusoidal signal represented as a phasor Derivative:
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Phasors Examples: Inductor Capacitor
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Phasors Ref. Important: In power systems, RMS values are used for the magnitudes.
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Phasors v(t) i(t)
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