b) A fault occurs at bus 3 of the network shown in Figure Q3. Pre-fault nodalvoltages throughout the network are of 1 p.u. and the impedance of theelectric arc is neglected. Sequence impedance parameters of the generator,transmission lines, and transformer are given in Figure Q3, where X and Y arethe last two digits of your student number.jx2(1) = j0.1X p.u.jx2(2) = j0.1X p.u.jX2(0)=j0.2Y p.u.=V₁ 120° p.u. V₂ = 120° p.u.V₁ = 120° p.u.jx)=j0.1X p.u.jX2)= j0.1X p.u.jxo)=j0.1Y p.u.jx(1) = j0.25 p.u.2 X (2) = 0.25 p.u. 3jx1(0)=j0.3 p.u.jXT(I)=j0.1Y p.u.jX3(1)=j0.1X p.u.=jXT(2) j0.1Y p.u.jx13(2)=j0.1X p.u.jXT(0) = j0.1Y p.u.jX3(0) = j0.05 p.u.00-Figure Q3. Circuit for problem 3b).(i) Assuming a balanced excitation, draw the positive, negative and zerosequence Thévenin equivalent circuits as seen from bus 3.(ii) Determine the positive sequence fault current for the case when a three-phase-to-ground fault occurs at bus 3 of the network.(iii) Determine the short-circuit fault current for the case when a one-phase-to-ground fault occurs at bus 3.

Part 2: ExplanationStep 1: Identify the sequence impedance parameters.- Given: - \( jX2(1) = j0.1X…

Answered: b) A fault occurs at bus 3 of the…

Introductory Circuit Analysis (13th Edition)

13th Edition

ISBN:9780133923605

Author:Robert L. Boylestad

Publisher:Robert L. Boylestad

Chapter1: Introduction

Section: Chapter Questions

Problem 1P: Visit your local library (at school or home) and describe the extent to which it provides literature...

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Draw the fault current direction both in Current transformer and operating relay coils for internal and external double line to line and double line to ground faults. Do the solve for Restricted Earth Fault Protection system for Alternator Stator Winding. Its a topic of Switchgear protection in power system
19
QUESTION TWOo A three-phase 50 Hz, 200 MVA, 220/66 kV transformer has a clock number of Yd11. The transformer winding resistances are 2.0 N and 0.12 N, and the leakage reactances are 10 N and 0.6 N for the high voltage side and low voltage side respectively. (a) Sketch the phase voltage phasor diagrams for the high-voltage side and low-voltage side of the transformer and from the phasor diagrams obtain its connection diagram. (b) Calculate the per-unit impedance of the transformer referred to the high-voltage side. (c) Calculate the full-load copper losses of this transformer. (d) Calculate the efficiency of the transformer when it supplies 90% of full-load at a power factor of 0.85 lagging, if the core losses are equal to 1.6 MW. (e) Suggest the most suitable method of cooling this transformer and explain how the suggested method works. () Why are most power transformers and distribution transformers' tanks oil-filled? To increase the supply capacity, the transformer described above…
A 30kV, 50MVA generator having a solidly grounded neutral and Z1 = 0.25pu, Z2=0.15pu and Z0=0.05pu. a. Calculate the fault current and voltages for a single line to ground fault. b. Sketch the phasor diagram for the fault voltages.
3.8. Three identical 9-MVA, 7.2-kV/4.16-kV, single-phase transformers are con- nected in wye on the high-voltage side and delta on the low voltage side. The equivalent series impedance of each transformer referred to the high-voltage side is 0.12 + j0.82 S per phase. The transformer supplies a balanced three- phase load of 18 MVA, 0.8 power factor lagging at 4.16 kV. Determine the line-to-line voltage at the high-voltage terminals of the transformer.
Q.3 When a line-to-ground fault occurs, the current in faulted phase 'a' is 100A. The zero-sequence current in phase 'c' is
Q2\ The one-line diagram of a simple power system is shown in figure below. All impedances are expressed in per unit (pu) on a common MVA base. All resistances and shunt capacitances are neglected. The generators are operating on no load at their rated voltage. A three-phase fault occurs at bus 1 through a fault impedance of Zf = j0.08 per unit. Using Thevenin's theorem obtain the impedance to the point of fault and the fault current in per unit. Determine the bus voltages and line currents of generators during fault. X₁ = = 0.1 XT-0.1 3 1 to ojo XL=0.2 2 040 X₁ = 0.1
Q: A three phase alternator 100 MVA, 13.5 KV, exposure to types of faults are fallowing: i) Balanced three-phase fault current = 0.437 p.u ii) Line to line fault current = 0.6 p.u iii) Single line to ground fault current = 0.965 The alternator neutral connecting to grounded through the fault reactance j0.15 p.u. Find the x,,x2, xo
If the source impedance at a 13.2 kV distribution substation bus is (0:5 + 1:5) Q per phase, compute the RMS and maximum peak instantaneous value of the fault current, for a balanced three-phase fault. For the system (X/R) ratio of 3.0, the asymmetrical factor is 1.9495 and the time of peak is 7.1 ms (see Problem 1). Comment on the withstanding peak current capability to which all substation electrical equipment need to be designed. Problem 1 Consider the expression for i(f) given by i(t) = v21ms [sin(@t-0-)+ sin 0,.eR/X)] where ez = tan-1 (WL/R). (a) For (X/R) equal to zero and infinity, plot i(f) as a function of (wf). (b) Comment on the DC offset of the fault current waveforms. (c) Find the asymmetrical current factor and the time of peak, tp, in milliseconds, for (X/R) ratios of zero and infinity.
iv. The swing equation can be considered mathematically, as a equation due to the v. The main objects of fault analysis are term.
Q2: A generator supplies motor through a star-delta transformer. The generator is connected to the star side of transformer. A fault occurs between the motor terminals and the transformer. The symmetrical components of the rubtransient current in motor and transformer toward the fault as table below laz(per unit) j2.0 lao(per unit) j3.0 las (per unit) Motof toward the fault Transformer toward the -0.8-j2.6 0.8-j0.4 j1.0 fault Assume X-X,- X2 for both the motor and gencrator. Describe the type of fault. Find (a) the prefault current, in line a, (b) the subtransient fault current in per unit and (c) the subtransient current in each phase of the gencrator in per unit. Gén. Motor
Q3/ For the system shown in figure. The generator is supplying 1.0 pu MW power under prefault condition. When three-phase fault occur at point F. What should the value of fault reactance must be to make the critical clearing angle equal to 58.9. Sc j0.1 j0.1 10.21 BE j0.38 38 j0.21 IEgl-12 pu 10.19 F 10.19 IVI-1.00 pu j0.1 j0.1 Q4/ Figure below shows the one-line diagram

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