2.20 The nameplate on a 25-MVA, 60-Hz single-phase transformer indicates that it has a voltage rating of 8.0-kV:78-kV. A short-circuit test from the high-voltage side (low-voltage winding short circuited) gives readings of 4.53 kV, 321 A, and 77.5 kW. An open-circuit test is conducted from the low-voltage side and the corresponding instrument readings are 8.0 kV, 39.6 A, and 86.2 kW. a. Calculate the equivalent series impedance of the transformer as referred to the high-voltage terminals. b. Calculate the equivalent series impedance of the transformer as referred to the low-voltage terminals.

2.20 The nameplate on a 25-MVA, 60-Hz single-phase transformer indicates that it has a voltage rating of 8.0-kV:78-kV. A short-circuit test from the high-voltage side (low-voltage winding short circuited) gives readings of 4.53 kV, 321 A, and 77.5 kW. An open-circuit test is conducted from the low-voltage side and the corresponding instrument readings are 8.0 kV, 39.6 A, and 86.2 kW. a. Calculate the equivalent series impedance of the transformer as referred to the high-voltage terminals. b. Calculate the equivalent series impedance of the transformer as referred to the low-voltage terminals.

Introductory Circuit Analysis (13th Edition)

13th Edition

ISBN:9780133923605

Author:Robert L. Boylestad

Publisher:Robert L. Boylestad

Chapter1: Introduction

Section: Chapter Questions

Problem 1P: Visit your local library (at school or home) and describe the extent to which it provides literature...

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Concept explainers

Single Phase Transformer

A single-phase transformer is a type of power transformer. It is an electrical device that accepts converts the single phase alternating power into single phase alternating power. In this power conversion the voltage is stepped up or down. If the voltage is stepped up, the current will be stepped down and if the voltage is stepped down, the current will be stepped up.

Question

2.20 The nameplate on a 25-MVA, 60-Hz single-phase transformer indicates that it
has a voltage rating of 8.0-kV:78-kV. A short-circuit test from the high-voltage
side (low-voltage winding short circuited) gives readings of 4.53 kV, 321 A,
and 77.5 kW. An open-circuit test is conducted from the low-voltage side and
the corresponding instrument readings are 8.0 kV, 39.6 A, and 86.2 kW.
a. Calculate the equivalent series impedance of the transformer as referred to
the high-voltage terminals.
b. Calculate the equivalent series impedance of the transformer as referred to
the low-voltage terminals.

pr
d.
2.26 (a) Determine the efficiency and voltage regulation of the transformer of
Problem 2.20 if it is supplying rated load (unity power factor) at ratcd voltage
at its low-voltage terminals. (b) Repeat part (a), assuming the load to be at 0.9
power factor leading.

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