A 10 MVA three phase load is to be served by a three phase transformer at a line voltage of 13.8 kV. The supply side voltage(line-line) is 138 kV. Various single phase transformers are available in the warehouse but all have windings with voltage ratings under 100 kV and current ratings under 250 A. Is it possible to serve the load using only three single phase transformers? If so, specify the three phase connections and the low and high voltage ratings of the single phase transformers.

A 10 MVA three phase load is to be served by a three phase transformer at a line voltage of 13.8 kV. The supply side voltage(line-line) is 138 kV. Various single phase transformers are available in the warehouse but all have windings with voltage ratings under 100 kV and current ratings under 250 A. Is it possible to serve the load using only three single phase transformers? If so, specify the three phase connections and the low and high voltage ratings of the single phase transformers.

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 3.47P: Consider the oneline diagram shown in Figure 3.40. The three-phase transformer bank is made up of...

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Three single-phase, two-winding transformers, each rated 450MVA,20kV/288.7kV, with leakage reactance Xeq=0.10perunit, are connected to form a three-phase bank. The high-voltage windings are connected in Y with a solidly grounded neutral. Draw the per-unit equivalent circuit if the low-voltage windings are connected (a) in with American standard phase shift or (b) in Y with an open neutral. Use the transformer ratings as base quantities. Winding resistances and exciting current are neglected.
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In per-unit equivalent circuits of practical three-phase transformers, under balanced thr-phase operation, in which of the following connect ions would a phase-shifting transformer come up? (a) Y-Y (b) Y- (c) -
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