1. The one-line diagram of a three-phase power system is shown in the following Figure. V3 j26.459 S2 S3 The transformer reactance is 20% on a base of 100-MVA, 23/115-kV and the line impedance is Z = j26.45 2. The load at bus 2 is S2 = 63 + j5.4 MVA, and bus 3 is j20 MVA. Working in per-unit, 1) Calculate the per-unit values for complex powers S2 and S3. 2) Calculate the magnitude of the line-to- line voltage at bus 1 and bus 2. V₁- V₂ BE

1. The one-line diagram of a three-phase power system is shown in the following Figure. V3 j26.459 S2 S3 The transformer reactance is 20% on a base of 100-MVA, 23/115-kV and the line impedance is Z = j26.45 2. The load at bus 2 is S2 = 63 + j5.4 MVA, and bus 3 is j20 MVA. Working in per-unit, 1) Calculate the per-unit values for complex powers S2 and S3. 2) Calculate the magnitude of the line-to- line voltage at bus 1 and bus 2. V₁- V₂ BE

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 3.33P: Consider the three single-phase two-winding transformers shown in Figure 3.37. The high-voltage...

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(a) An ideal single-phase two-winding transformer with turns ratio at=N1/N2 is connected with a series impedance Z2 across winding 2. If one wants to replace Z2, with a series impedance Z1 across winding 1 and keep the terminal behavior of the two circuits to be identical, find Z1 in terms of Z2. (b) Would the above result be true if instead of a series impedance there is a shunt impedance? (c) Can one refer a ladder network on the secondary (2) side to the primary (1) side simply by multiplying every impedance byat2 ?
The ratings of a three-phase three-winding transformer are Primary(1): Y connected 66kV,15MVA Secondary (2): Y connected, 13.2kV,10MVA Tertiary (3): A connected, 2.3kV,5MVA Neglecting winding resistances and exciting current, the per-unit leakage reactances are X12=0.08 on a 15-MVA,66-kV base X13=0.10 on a 15-MVA,66-kV base X23=0.09 on a 10-MVA,13.2-kV base (a) Determine the per-unit reactances X1,X2,X3 of the equivalent circuit on a 15-MVA,66-kV base at the primary terminals. (b) Purely resistive loads of 7.5 MW at 13.2 kV and 5 MW at 2.3kV are connected to the secondary and tertiary sides of the transformer, respectively. Draw the per- unit impedance diagram, showing the per-unit impedances on a 15-MVA,66-kV base at the primary terminals.
Consider the three single-phase two-winding transformers shown in Figure 3.37. The high-voltage windings are connected in Y. (a) For the low-voltage side, connect the windings in , place the polarity marks, and label the terminals a, b, and c in accordance with the American standard. (b) Relabel the terminals a, b, and c such that VAN is 90 out of phase with Va for positive sequence.
In order to avoid difficulties with third-harmonic exciting current, which three-phase transformer connection is seldom used for step-up transformers between a generator and a transmission line in power systems. (a) Y- (b) -Y (c) Y-Y
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A single-phase, 50-kVA,2400/240-V,60-Hz distribution transformer has the following parameters: Resistance of the 2400-V winding: R1=0.75 Resistance of the 240-V winding: R2=0.0075 Leakage reactance of the 2400-V winding: X1=1.0 Leakage reactance of the 240-V winding: X2=0.01 Exciting admittance on the 240-V side =0.003j0.02S (a) Draw the equivalent circuit referred to the high-voltage side of the transformer. (b) Draw the equivalent circuit referred to the low-voltage side of the transformer. Show the numerical values of impedances on the equivalent circuits.
A 50 Hz, Scott connected transformer supplies an unbalanced two phase load at ( 400 V) per phase. For the leading phase the load has a resistance of (13.3 ohm) and capacitor of (318) micro farad in series. For the other phase the load consists of resistance (10) ohm and an inductance of (42.3) mH. Calculate both mathematically and graphically the lines currents on 3- phase side. The main transformer primary to secondary turns ratio is (12/1).
A 480V/240V, 60Hz single transformer has Z1 = 0.1+j0.22 ohms and Z2 = 0.035 + j0.12 ohm. Find the equivalent impedance in ohm referred to the secondary. Group of answer choices 0.07+j0.135 0.06+j0.175 0.04+j0.135 0.06+j0.135
The rated voltages of a single-phase transformer are 2000 V and 200 V in its primary and secondary respectively. The shunt impedance can be modelled with a resistance of 14000 ohms in parallel with a reactance of 1100 ohm, both refer to primary side. The primary and secondary series impedances are (0.12+j 0.35) ohms and (0.0012+j 0.0035) ohms respectively. A load is connected to the secondary side of transformer, draws 810 KVA with a lagging power factor of 0.85. The load voltage is same as rated voltage, that is 200 V. ▪ Use per unit method for analysis and find the voltage on primary side in pu.
Given Zo-j407 2, R₁143, R6317 52 and a 0.04, what is the magnitude of the source voltage Vs (in V rms) in the primary of the ideal transformer? Vs R₁ ww Answer: Zc Zc R₁ Use up to 2 digits after the decimal point if necessary in your answer below VL-28020 V TR
Q/A single-phase transformer with a capacity of 100 kVA and a voltage of 2000/400 and the equivalent circuit elements are as follows R1=0.10 x1=0.20 R2= 0.250 X2 = 0.75 RO = 500 XO = 150 It feeds a 90 kVA load at a voltage of 2000 volts and a power factor of 8.0 delayed. Calculate the initial voltage and current? Rogl JXql a Mmm T I', 2₁ Acti Go to
A parallel connection of a RL branch with a C branch is connected across a 100V AC mains. At first R = 10 ohms, L = 20mH and frequency of 1000rad / s, the current measured is 2.2361A at 89.44 leading power factor. A) Determine the initial capacitance. B) However, a fault occurs on the capacitor branch making its capacitance 20% lower and a resistance of 5 ohms is detected. If this faulty circuit is rerun but at a frequency of 500 rad / s, determine the new current that will flow through the circuit.