4. A transformer is rated 1000 MVA, 13.8 kV/345 kV with Z=j0.10 pu. If the system base MVA is 500, the corresponding puimpedance becomes(a) j0.10/2 pu(b) j0.10/4 pu(c) j0.10*2 pu(d) j0.10*4 pu5. Ia, Ib and I, are the three current phasors of a load. For a balanced-load condition, which relation is valid?(a) IF - (Ib + I.)(c) la + I = 1.(d) Ia - I = I.(b) la = I, = Ie

Answered: A transformer is rated 1000 MVA kV/345…

Introductory Circuit Analysis (13th Edition)

13th Edition

ISBN:9780133923605

Author:Robert L. Boylestad

Publisher:Robert L. Boylestad

Chapter1: Introduction

Section: Chapter Questions

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Related questions

Question

4. A transformer is rated 1000 MVA, 13.8 kV/345 kV with Z=j0.10 pu. If the system base MVA is 500, the corresponding pu
impedance becomes
(a) j0.10/2 pu
(b) j0.10/4 pu
(c) j0.10*2 pu
(d) j0.10*4 pu
5. Ia, Ib and I, are the three current phasors of a load. For a balanced-load condition, which relation is valid?
(a) IF - (Ib + I.)
(c) la + I = 1.
(d) Ia - I = I.
(b) la = I, = Ie

Expert Solution

Step 1

(4)

Given that

$Z_{p u o l d} = j . 10 M V A_{b o l d} = 1000 K V_{b o l d} = 13.8 K V M V A_{b n e w} = 500$

Assume that the new base voltage is 13.8KV

The formula for Z_{pu new} is given by

${(z_{p u})}_{n e w} = {(z_{p u})}_{o l d} \times (\frac{{(M V A)}_{b_{N e w}}}{{(M V A)}_{b_{o l d}}}) \times {(\frac{{(K V)}_{b}_{o l d}}{{(K V)}_{b}_{n e w}})}^{2} plugging values {(z_{p u})}_{n e w} = j . 10 \times (\frac{500}{1000}) \times {(\frac{13.8}{13.8})}^{2} {(z_{p u})}_{n e w} = \frac{j . 10}{2}$