Assume that a 250-kVA distribution transformer is used for single-phase pole mounting. The transformer is connected phase-to-neutral 7200 V on the primary, and 2520 V phase-to- neutral on the secondary side. The leakage impedance of the transformer is 3.5%. Based on the given information, determine the following: (a) Assume that the transformer has 0.7 pu A in the high-voltage winding. Find the actual current values in the high- and low-voltage windings. What is the value of the current in the low-voltage winding in per units? (b) Find the impedance of the transformer as referred to the high- and low-voltage windings in ohms. (c) Assume that the low-voltage terminals of the transformer are short-circuited and 0.22 pu V is applied to the high-voltage winding. Find the high- and low-voltage winding currents that exist as a result of the short circuit in pu and amperes. (d) Determine the internal voltage drop of the transformer, due to its leakage impedance, if a 1.2 pu current flows in the high-voltage winding. Give the result in pu and volts.

Assume that a 250-kVA distribution transformer is used for single-phase pole mounting. The transformer is connected phase-to-neutral 7200 V on the primary, and 2520 V phase-to- neutral on the secondary side. The leakage impedance of the transformer is 3.5%. Based on the given information, determine the following: (a) Assume that the transformer has 0.7 pu A in the high-voltage winding. Find the actual current values in the high- and low-voltage windings. What is the value of the current in the low-voltage winding in per units? (b) Find the impedance of the transformer as referred to the high- and low-voltage windings in ohms. (c) Assume that the low-voltage terminals of the transformer are short-circuited and 0.22 pu V is applied to the high-voltage winding. Find the high- and low-voltage winding currents that exist as a result of the short circuit in pu and amperes. (d) Determine the internal voltage drop of the transformer, due to its leakage impedance, if a 1.2 pu current flows in the high-voltage winding. Give the result in pu and volts.

Power System Analysis and Design (MindTap Course List)

6th Edition

ISBN:9781305632134

Author:J. Duncan Glover, Thomas Overbye, Mulukutla S. Sarma

Publisher:J. Duncan Glover, Thomas Overbye, Mulukutla S. Sarma

Chapter3: Power Transformers

Section: Chapter Questions

Problem 3.11MCQ: For a short-circuit test on a 2-winding transformer, with one winding shorted, can you apply the...

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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

Assume that a 250-kVA distribution transformer is used for single-phase pole mounting.
The transformer is connected phase-to-neutral 7200 V on the primary, and 2520 V phase-to-
neutral on the secondary side. The leakage impedance of the transformer is 3.5%. Based on
the given information, determine the following:
(a) Assume that the transformer has 0.7 pu A in the high-voltage winding. Find the actual
current values in the high- and low-voltage windings. What is the value of the current in
the low-voltage winding in per units?
(b) Find the impedance of the transformer as referred to the high- and low-voltage windings
in ohms.
(c) Assume that the low-voltage terminals of the transformer are short-circuited and 0.22 pu
V is applied to the high-voltage winding. Find the high- and low-voltage winding currents
that exist as a result of the short circuit in pu and amperes.
(d) Determine the internal voltage drop of the transformer, due to its leakage impedance, if
a 1.2 pu current flows in the high-voltage winding. Give the result in pu and volts.

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