Question. Consider a 4 kVA, 200/400 V single-phase transformer supplying full- load current at 0.8 leading power factor. The O.C./S.C. test results are as follows: O.C. test : 200V, 0.8 A, 70 W (L.V. side) S.C. test : 20 V, 10A, 60 W (H.V. side) Calculate efficiency, secondary voltage and current into primary at the above load.

Question. Consider a 4 kVA, 200/400 V single-phase transformer supplying full- load current at 0.8 leading power factor. The O.C./S.C. test results are as follows: O.C. test : 200V, 0.8 A, 70 W (L.V. side) S.C. test : 20 V, 10A, 60 W (H.V. side) Calculate efficiency, secondary voltage and current into primary at the above load.

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 3.63P: A 23/230-kV step-up transformer feeds a three-phase transmission line, which in turn supplies a...

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An ideal transformer has no real or reactive power loss. (a) True (b) False
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A bank of three single-phase transformers, each rated 30MVA,38.1/3.81kV, are connected in Y- with a balanced load of three 1, Y-connected resistors. Choosing a base of 90MVA,66kV for the high-voltage side of the three-phase transformer. spify the base for the low-voltage side. Compute the per-unit resistance of the load on the base for the low-voltage side. Also, determine the load resistance in ohms referred to the high-voltage side and the per-unit value on the chosen base.
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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