A 6.6/33 kV transformer substation receives 5 MVA at 6 kV, 0.85 power factor lagging through a cable with per phase resistance and reactance of 8 and 2.5 Ω respectively. Identical 6.6/33 kV transformer is installed at the other, power station end of the cable as indicated on the figure below. The 6.6 kV side is delta-connected while the 33-kV side is star-connected. The resistance and reactance of star windings are 0.5 and 3.75 Ω and for delta windings are 0.06 and 0.36 Ω. What is the voltage at the generator end? Use per-unit format for your calculations.?

A 6.6/33 kV transformer substation receives 5 MVA at 6 kV, 0.85 power factor lagging through a cable with per phase resistance and reactance of 8 and 2.5 Ω respectively. Identical 6.6/33 kV transformer is installed at the other, power station end of the cable as indicated on the figure below. The 6.6 kV side is delta-connected while the 33-kV side is star-connected. The resistance and reactance of star windings are 0.5 and 3.75 Ω and for delta windings are 0.06 and 0.36 Ω. What is the voltage at the generator end? Use per-unit format for your calculations.?

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 3.36P: Three single-phase two-winding transformers, each rated 25MVA,34.5/13.8kV, are connected to form a...

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Three single-phase transformers, each rated 10MVA,66.4/12.5kV,60Hz, with an equivalent series reactance of 0.1 per unit divided equally between primary and secondary, are connected in a three-phase bank. The high-voltage windings are V-connected and their terminals are directly connected to a 115-kV three-phase bus. The secondary terminals are all shorted together. Find the currents entering the high-voltage terminals and leaving the low-voltage terminals if the low-voltage windings are (a) Y-connected and (b) - connected.
Three single-phase two-winding transformers, each rated 25MVA,34.5/13.8kV, are connected to form a three-phase bank. Balanced positive-suence voltages are applied to the high-voltage terminals, and a balanced, resistive Y load connected to the low-voltage terminals absorbs 75 MW at 13.8 kV. If one of the single-phase transformers is removed (resulting in an open connection) and the balanced load is simultaneously reduced to 43.3 MW (57.7 of the original value), determine (a) the load voltages Va,Vb, and Vc; (b) load currents Ia,Ib, and Ic; and (c) the MVA supplied by each of the remaining two transformers. Are balanced voltages still applied to the load? Is the open transformer overloaded?
Consider the single-Line diagram of a power system shown in Figure 3.42 with equipment ratings given: Generator G1: 50MVA,13.2kV,x=0.15p.u. Generator G2: 20MVA,13.8kV,x=0.15p.u. Three-phase -Y transformer T1: 80MVA,13.2/165YkV,X=0.1p.u. Three-phase Y- transformer T2: 40MVA,165Y/13.8kV,X=0.1p.u. Load: 40MVA,0.8PFlagging,operatingat150kV Choose a base of 100 MVA for the system and 132-kV base in the transmission-line circuit. Let the load be modeled as a parallel combination of resistance and inductance. Neglect transformer phase shifts. Draw a per-phase equivalent circuit of the system showing all impedances in per unit.
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A three-phase two-winding transformer rated 1200 MVA, 14kV/162kV has a leakage reactance of j0.10 pu. A three-phase load operating under balanced positive phase sequence conditions on the secondary side absorbs 1000 MVA at 0.9pf lagging with a terminal voltage of 161kV. Use the given information to answer the following questions: a) Draw a reactance diagram for the circuit. b)Determine the voltage at the primary side of the transformer when it is star connected. c) Determine also the voltage at the primary when the primary side of the transformer is delta connected.
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