lecture4 - Zpu = Zactual/ Zb HV Zpu = j.1 Z actual (HV...

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EE 740 Professor Ali Keyhani Lecture #4 Homework Problems
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Problem 1: A single phase transformer is rated 100MVA, 127/13.2 kV and ten percent leakage reactance. Compute the transformer impedance from the high voltage side. Problem 2: For problem 1, compute the single phase equivalent circuit from the low voltage side. Problem 3: Compute per unit equivalent circuits for the transformers of problem 1 and 2 based on 100 MVA and the rated voltage. Problem 4: Compute the per unit equivalent circuit of problem 3 based on 200 MVA and voltage base of 130 kV on the high voltage side.
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Problem 1: A single phase transformer is rated 100 MVA, 127/13.2 kV with 10% leakage reactance. Calculate the transformer impedance from the high side. Solution: j16.129 127 kV 13.2 kV HV LV Rated: 100MVA One phase Eq. Ckt. 127/13.2 kV from high voltage side 10% Sbase = 100 x 10 6 Vb HV = 127 kV Zb HV = (Vb) 2 /Sb = (127 x 10 3 ) 2 / 100 x 10 6 = 161.29
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Unformatted text preview: Zpu = Zactual/ Zb HV Zpu = j.1 Z actual (HV side) = j.1 x 161.29 = 16.129 Problem 2: For problem 1 compute the one phase equivalent circuit from the low voltage side. j.17424 Sb = 100 MVA Vb LV = 13.2 kV HV LV Zb LV = (13.2) 2 /100 = 1.7424 Zactual (LV side) = 1.7424 x j.1 = j.17424 One phase Eq. Ckt. from low voltage side Problem 3: Calculate the per unit equivalent circuit of the transformer of problem 1 and problem 2 based on 100 MVA and the rated voltage. Sb = 100 MVA Vb HV = 127 kV Zb HV = 161.29 Zpu HV = Z A / Zb HV = j16.129/161.29 = j.1 pu Sb = 100 MVA Vb LV = 13.2 kV Zb LV = 1.7424 Zpu LV = j.17424/1.7424 = j.1 pu Zpu LV = Zpu HV = j.1 pu j16.129 j.17424 HV LV HV LV 1 Eq. Ckt. from HV side 1 Eq. Ckt. from LV side 100 MVA 100 MVA 127/13.2 kV 127/13.2 kV HV j.01 LV pu Eq. Ckt. Sb = 100 MVA, Vb HV = 127 kV, Vb LV = 13.2 kV (rated voltage)...
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lecture4 - Zpu = Zactual/ Zb HV Zpu = j.1 Z actual (HV...

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