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 3.9P

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