COMPUTER NETWORKS (CN)–Nov Dec 2011 Question Paper

Anna University

B.E./B.Tech. DEGREE EXAMINATION

NOVEMBER/DECEMBER 2011.

Sixth Semester

Electrical and Electronics Engineering

CS 2363 — COMPUTER NETWORKS

(Regulation 2008)

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Time : Three hours

Maximum : 100 marks

Answer ALL questions.

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PART A — (10 × 2 = 20 marks)

1. Define a computer network.

2. What is FDDI?

3. What is internet working?

4. What is IPV6?

5. What is queuing?

6. Define congestion.

7. Define cryptography.

8. What is PGP.

9. What is HTTP?

10. List multimedia applications.

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PART B — (5 × 16 = 80 marks)

11. (a) (i) Describe network architecture in detail. (8) (ii) What is Ethernet? Explain in detail. (8)

Or

(b) (i) What is error detection? Explain with examples. (8) (ii) Write a note on bridges. (8)

12. (a) (i) Explain in detail about internet control message protocol. (8) (ii) Describe any one routing algorithm. (8)

Or

(b) (i) What is dynamic host configuration protocol? Explain in detail. (8)

(ii) Write a note on addressing. (8)

13. (a) (i) Explain the user datagram protocol (UDP) in detail. (8) (ii) What is flow control? Explain in detail. (8)

Or

(b) (i) Explain in detail the transmission control protocol. (8) (ii) Write a note on congestion avoidance mechanisms. (8)

14. (a) (i) Write a note on JPEG, MPEG and MP3. (8) (ii) What is IP security? Explain in detail. (8)

Or

(b) (i) Explain fire walls in detail. (8)

(ii) Explain the basic principles of authentication. (8)

15. (a) (i) Describe domain name system in detail. (8) (ii) Write a note on e-mail. (8)

Or

(b) (i) Explain simple network management protocol in detail. (8) (ii) Describe in detail the file transfer protocol (FTP). (8)

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DESIGN OF ELECTRICAL MACHINES (DEM)–Nov / Dec 2011 Question Paper

Anna University

B.E./B.Tech. DEGREE EXAMINATION

NOVEMBER/DECEMBER 2011.

Sixth Semester

Electrical and Electronics Engineering

EE 2355 — DESIGN OF ELECTRICAL MACHINES

(Regulation 2008)

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Time : Three hours

Maximum : 100 marks

Answer ALL questions.

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PART A — (10 × 2 = 20 marks)

1. What are the major considerations in Electrical Machine Design?

2. Write down the classification of magnetic materials.

3. Show how the specific magnetic and electric loadings are interdependent.

4. Mention any two guiding factors for the choice of number of poles.

5. Define the term: ‘Voltage Regulation’.

6. What are the methods by which heat dissipation occurs in a transformer?

7. Write down the equation for output coefficient in an Induction Motor.

8. Define : Stator Slot Pitch.

9. What are the factors that influence the choice of specific magnetic loading in a synchronous machine?

10. Define Short Circuit Ratio of a synchronous machine.

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PART B — (5 × 16 = 80 marks)

11. (a) What are the main groups of Electrical conducting materials?

Describe the properties and applications of those materials. (16)

Or

(b) Describe any two methods used for determination of motor rating for variable load drives with suitable diagrams. (16)

12. (a) Explain the various steps involved in the design of Armature winding of D.C. machine. (16)

Or

	(b)	A design is required for a 50 kW, 4 pole, 600 rpm, d.c. shunt generator, the full load terminal voltage being 220 V. If the maximum gap density is 0.83 Wb/m2 and the armature ampere conductors per metre are 30,000, calculate suitable dimensions of armature core to give a square pole face.
		Assume that the full load armature voltage drop is 3 percent of the rated terminal voltage and that the field current is 1 percent of rated full load current. Ratio of pole arc to pole pitch is 0.67. (16)
13.	(a)	Discuss about temperature rise and methods of cooling in transformers.

Or

	(b)	A 6600 V, 60 Hz single phase transformer has a core of sheet steel. The net iron cross-sectional area is 22.6 × 10–3 m2, the mean length
		is 2.23 m, and there are four lap joints. Each lap joints takes ¼ times as much reactive mmf as is required per metre of core. If Bm = 1.1 Wb/m2, determine
		(i) The number of turns on the 6600 V winding and
		(ii) The no load current. Assume an amplitude factor of 1.52 and that for given flux density, mmf per metre = 232 A/m; specific loss = 1.76 W/kg. Specific gravity of plates = 7.5. (16)
14.	(a)	Describe the steps involved in the design of magnetising current for an induction motor from design data.	(16)

Or

(b) Estimate the stator core dimensions and the total number of stator conductors for a 3 Φ , 100 kW, 3300 V, 50 Hz, 12 pole star connected slip ring Induction motor. Assume : average gap density = 0.4 Wb/m2, conductors per metre = 25,000 A/m, efficiency = 0.9, power factor = 0.9 and winding factor =0.96.

Choose main dimension to give best power factor. (16)

15. (a) Explain the step by step procedure for the design of field winding of Synchronous machine. (16)

Or

(b)	A 1000 KVA, 3300 V, 50 Hz, 300 rpm, 3-phase alternator has 180 slots with 5 conductors per slot. Single layer winding with full pitch
	coils is used. The winding is star connected with one circuit per phase. Determine the specific electric and specific magnetic loadings, if the stator bore is 2.0 m and the core length is 0.4 m. The machine
	has 60° phase spread.	(16)

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DESIGN OF ELECTRICAL MACHINES (DEM)–April / May 2011 Question Paper

Anna University

B.E./B.Tech. DEGREE EXAMINATION, APRIL/MAY 2011

Sixth Semester

Electrical and Electronics Engineering

EE 2355 — DESIGN OF ELECTRICAL MACHINES

(Regulation 2008)

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Time : Three hours

Maximum : 100 marks

Answer ALL questions

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PART A — (10 × 2 = 20 marks)

1. What is specific Electric Loading?

2. How materials are classified according to their degree of magnetism?

3. Name any two methods to reduce armature reaction.

4. What is slot loading?

5. Give the relationship between emf per turn and kVA rating in a transformer.

6. What are the factors affecting the choice of flux density of core in a transformer?

7. How crawling can be prevented by design in an Induction motor?

8. Define dispersion coefficient of an Induction Motor.

9. What is run away speed of Synchronous Machine?

10. Give the need for damper winding in Synchronous Machine.

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PART B — (5 × 16 = 80 marks)

11. (a) Discuss about various duties and ratings of Rotating Machines and give their respective temperature — time curves. (16)

Or

(b) A field coil has a heat dissipating surface of 0.15 m2 and length of mean turn 1 m. It dissipates loss of 150 W, the emissivity being 34 W/m2_°C. Estimate the final steady temperature rise of the coil and its time constant if the cross section of the coil is 100*50 mm2. Specific heat of copper is 390 J/kg° C. The space factor is 0.56. Copper weighs 8900 kg/m3. (16)

12. (a) (i) Explain the effects of choice of number of poles in a DC Machine on (1) Frequency of flux reversal (2) Weight of iron (3) Weight of copper and (4) Length of commutator. (8)

(ii) A 5 kw, 250 V, 4 pole, 1500 rpm DC Shunt Generator is designed to have a square pole face. The specific magnetic loading and specific electric loadings are 0.42 Wb/m2 and 15000 AC/m respectively. Find the main dimensions of the machine. Assume full load efficiency = 0.87 and pole arc to pole pitch ratio is 0.66. (8) Or

(b) (i) Discuss various methods to determine mmf required for teeth of an Electric Machine. (8)

(ii) Determine the apparent flux density in teeth of a DC machine if the real flux density in teeth is 2.15 Wb/m2, slot pitch is 28 mm, slot width is 10 mm, gross core length is 0.35 m, no. of ventilating ducts is 4 each 10 mm wide. Magnetizing force corresponding to flux density of 2.15 Wb/m2 is 55000 AT/m and iron stacking factor is 0.9. (8)

13. (a) (i) Derive the output equation of a three phase transformer. (8)

(ii) The ratio of flux to full load mmf in a 400 kVA, 50 Hz single phase core type transformer is 2.4*10–6. Calculate the net iron area and the window area of the transformer if the maximum flux density in the core is 1.3 Wb/m2, Current density is 2.7 A/mm2 and window space factor is 0.26. Also calculate the full load mmf. (8)

Or

(b) A 250 kVA, 6600/400V three phase core type transformer has a total loss of 4800 W at full load. The transformer tank is 1.25 m in height and 1 m × 0.5 m in plan. Design a suitable scheme for tubes if the average temperature rise is to be limited to 35° C. The diameter of each tube is 50 mm and are spaced 75 mm from each other. The average height of tubes is 1.05 mm. Specific heat dissipation due to radiation and convection is respectively 6 and 6.5 W/bm2_°C. Assume that convection is improved by 35% due to the provision of tubes. (16)

14. (a) Determine the main dimensions, number of radial ventilating ducts, number of stator slots and turns per phase of a 3.7 kW, three phase, 400 V, 4 Pole, 50 Hz squirrel cage Induction Motor to be started by a Star-Delta starter. Given that the average flux density in the air gap = 0.45 Wb/m2; Ampere Conductor per meter of armature periphery = 23000, full load efficiency = 0.85, full load power factor = 0.84 and kw = 0.955. Take L/ τ = 1.5. (16)

Or

(b) (i) Discuss the factors to be considered in estimating the length of air gap of an Induction Motor. (8)

(ii) Discuss the step by step procedure to design the rotor of a squirrel cage Induction Motor. (8)

15. (a) Define Short Circuit Ratio. Explain how it is determined for an alternator. Also discuss its effects on the performance of alternator. (16)

Or

(b) (i) Derive the output equation of an AC machine. (8)

(ii) Determine the main dimensions of a 100 kVA, 50 Hz, three phase 375 rpm alternator. The average air gap flux density is 0.55 Wb/m2 and ampere conductors per metre is 28000. Given that τ / L must be between 1 to 5. The maximum permissible peripheral speed is 50 m/sec. The runaway speed is 1.8 times synchronous speed. (8)

HIGH VOLTAGE ENGINEERING (HVE)–Nov / Dec 2011 Question Paper

Anna University

B.E./B.Tech. DEGREE EXAMINATION, NOVEMBER/DECEMBER 2011.

Sixth Semester

Electrical and Electronics Engineering

EE 2353 — HIGH VOLTAGE ENGINEERING

(Regulation 2008)

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Time : Three hours

Maximum : 100 marks

Answer ALL questions.

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PART A — (10 × 2 = 20 marks)

1. What are the causes of over voltages in power system?

2. What is counter poise wire? Give its use.

3. Write the Paschen’s law.

4. What are two main reasons for long term break down in composite dielectrics?

5. Give the specifications for standard impulse wave.

6. What are the advantages of cascaded transformer method?

7. What is Rogowski coil? Give its limitations.

8. What are the limitations of series resistance micro ammeter method?

9. What are the tests conducted on surge arrester?

10. What is insulation coordination?

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PART B — (5 × 16 = 80 marks)

11. (a) (i) Give the origin and characteristics of switching surges and explain the causes of over voltage due to switching surges in EHV and UHV system. (10)

(ii) Explain the control measures for over voltage due to switching surge. (6)

Or

(b) Elaborate the discussion on protection of power system equipments using protective devices.

(16)

12. (a) Explain in detail the breakdown mechanism in non-uniform fields and phenomenon of Corona. (16)

Or

(b) (i) Describe the ageing and breakdown in composite dielectrics due to partial discharge. (8)

(ii) Describe the thermal breakdown mechanism of solid dielectrics. (8)

13. (a) (i) Explain the operation of simple voltage doubler circuit. (4)

(ii) Discuss the principle of operation of vande graff generator with neat sketch. (12)

Or

(b) (i) How the impulse current is generated using capacitor bank. Explain in detail. (8) (ii) Write a brief note on resonant transformer method. (8)

14. (a) Tabulate and explain the methods used for the measurement of high voltages and high currents. (16)

Or

(b) With neat sketch explain the sphere gap arrangement method of high voltage measurement and give the factors influencing the measurement. (16)

15. (a) Explain the power frequency and impulse voltage test conducted on bushings.

Or

(b) Discuss the dielectric power factor test and partial discharge test conducted on high voltage cables. (16)

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HIGH VOLTAGE ENGINEERING–April / May 2011 Question Paper

Anna University

B.E./B.Tech. DEGREE EXAMINATION, APRIL/MAY 2011

Sixth Semester

Electrical and Electronics Engineering

EE 2353 — HIGH VOLTAGE ENGINEERING (Regulation 2008)

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Time : Three hours

Maximum : 100 marks

Answer ALL questions

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PART A — (10 × 2 = 20 marks)

1. What is known as Isokeraunic Level?

2. A transmission line of surge impedance 250 is connected to a cable of surge impedance 50 at the other end, if a surge of 400 kV travels along the line to the junction point, find the voltage build at the junction.

3. State and explain Paschen’s law.

4. What do you mean by ‘Intrinsic strength’ of a solid dielectric?

5. What are the drawbacks of single stage circuit for the generation of very high impulse voltage?

6. What is a cascaded transformer?

7. What is the effect of nearby earthed objects on the measurements using sphere gaps?

8. An electrostatic voltmeter has two parallel plates. The movable plate is 10 cm

in diameter. With 8 kV between the plates the pull is 5 × 10–3 N. Determine the change in capacitance for a movement of 1 mm of movable plate.

9. List out various tests to be carried out on insulator and give a brief account of each test.

10. What are the significances of power factor tests?

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PART B — (5 × 16 = 80 marks)

11. (a) (i) An underground cable of inductance 0.150 mH/km and of capacitance 0.2 µF/km is connected to an overhead line having an inductance of 1.2 mH/km and capacitance of 0.006 µF/km. Calculate the transmitted and reflected voltage and current waves at the junction, if a surge of 200 kV travels to the junction, (1) along the cable and (2) along the overhead line. (8)

(ii) Describe about various types of shunt protected devices used for overhead lines against lightning stroke. (8)

Or

(b) (i) Discuss about the various control techniques for switching and power frequency over voltages. (8)

(ii) Explain the different theories of charge formation in clouds. (8)

12. (a) (i) Explain clearly various processes which explain electric breakdown in vacuum. (8)

(ii) Discuss about the properties of composite dielectrics. (8) Or

(b) (i) Explain briefly various theories of breakdown in liquid dielectrics. (10)

(ii) Explain the Townsends criterion for a spark. (6)

13. (a) (i) A ten stage Cockraft-Walton circuit has all capacitors of 0.04 µF. The secondary voltage of the supply transformer is 120 kV at a frequency of 150 Hz. If the load current is 1.2 mA, determine

(1) voltage regulation (2) the ripple (3) the optimum number of stages for maximum output voltage (4) the maximum output voltage. (8)

(ii) Explain the Marx circuit arrangement for multistage impulse generators. How is the basic arrangements modified to accommodate the wave time control resistances? (8)

Or

(b) (i) Explain the basic principle of operation of an electrostatic generator. (6)

(ii) Draw a typical impulse current generator circuit and explain its operation and application. (10)

132 132 132

11321 3

14. (a) (i) Explain with neat diagram how rod gaps can be used for measurement of high voltages. Compare its performance with a sphere gap. (8)

(ii) Explain with neat diagram the principle of operation of an Electrostatic Voltmeter. Discuss its advantages and limitations for high voltage measurements. (8)

Or

(b) A Rogowski coil is required to measure impulse current of 8 kA having rate of change of current of 1010 A/sec. The voltmeter is connected across the integrating circuit which reads 8 volts for full scale deflection. The input to the integrating circuit is from the Rogowski Coil. Determine the mutual inductance of coil, R and C of the integrating circuit. (16)

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15. (a) Explain the method of impulse testing of high voltage transformers. What is the procedure adopted for locating the failure? (16)

Or

(b) Explain the different aspects of insulation design and insulation co-ordination adopted for EHV systems. (16)

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SOLID STATE DRIVES (SSD)–April / May 2011 Question Paper

Anna University

B.E./B.Tech. DEGREE EXAMINATION, APRIL/MAY 2011

Sixth Semester

Electrical and Electronics Engineering

EE 2352 — SOLID STATE DRIVES

(Regulation 2008)

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Time : Three hours

Maximum : 100 marks

Answer ALL questions

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PART A — (10 × 2 = 20 marks)

1. What are the types of load torques?

2. Write down the fundamental torque equation of motor load system?

3. List out the drawbacks of ac-dc converter fed dc drive.

4. What is TRC scheme?

5. Write the transfer function of converter.

6. Write the real and reactive power equations of a balanced 3 phase ac system.

7. What are the various applications of stator voltage control scheme?

8. Give the advantages of vector control method.

9. What is the necessity of delay unit in a open loop v/f control of synchronous motor?

10. Define self control of synchronous motor.

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PART B — (5 × 16 = 80 marks)

11. (a) Explain in detail the multi quadrant operation of low speed hoist in speed torque plane. (16)

Or

(b) A motor drives two loads. One has rotational motion. It is coupled to the motor through a reduction gear with a = 0.1 and efficiency of 90%. The load has a moment of inertia of 10 kg-m2 and a torque of 10 N-m. Other load has translational motion and consists of 1000kg weight to be lifted up at a uniform speed of 1.5 m/s. coupling between this load and the motor has an efficiency of 85%. Motor has inertia of 0.2 kg-m2 and runs at a constant speed of 1420 rpm. Determine equivalent inertia referred to the motor shaft and power developed by the motor. (16)

12. (a) Explain the operation of single phase fully-controlled converter fed dc separately excited motor in continuous and discontinuous modes of operation with necessary waveforms and steady state analysis. (16)

Or

(b) (i) Explain the different control techniques of chopper in detail. (8) (ii) Discuss the four quadrant operation of DC-DC converter. (8)

13. (a) Explain the closed loop operation of armature voltage control method with field weakening mode control in detail. (16)

Or

(b) Explain the design procedure of current controller in detail. (16)

14. (a) Explain the theory of v/f control in detail. (16) Or

(b) Explain the principle of vector control in detail with block diagram. (16)

15. (a) (i) Explain the open loop v/f control of synchronous motor in detail. (8)

(ii) Explain the concept of self controlled synchronous motor drive. (8)

Or

(b) Explain the construction and working of permanent magnet synchronous motor. (16)

POWER SYSTEM ANALYSIS (PSA)–Nov / Dec 2011 Question Paper

Anna Univeristy

B.E./B.Tech. DEGREE EXAMINATION

NOVEMBER/DECEMBER 2011.
Sixth Semester
Electrical and Electronics Engineering
EE 2351 — POWER SYSTEM ANALYSIS
(Regulation 2008)

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Time : Three hours Maximum : 100 marks
Answer ALL questions.

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PART A — (10 × 2 = 20 marks)

1. What is single line diagram?
2. How are the loads represented in reactance or impedance diagram?
3. What are the different types of buses in power systems? What are the quantities specified in each bus?
4. How are the disadvantages of Newton–Raphson method overcome?
5. What is the need for short circuit studies?
6. List the various types of shunt and series faults.
7. Define negative sequence impedance.
8. Name the faults which do not have zero sequence currents flowing.
9. Give an expression for swing equation. Explain each term along with their units.
10. State equal area criterion.

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Part B

Download :

PSA - Nov - dec 2011.pdf

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POWER SYSTEM ANALYSIS (PSA)–April / May 2011 Question Paper

Anna University

B.E./B.Tech. DEGREE EXAMINATION, APRIL/MAY 2011

Sixth Semester

Electrical and Electronics Engineering

EE 2351 — POWER SYSTEM ANALYSIS (Regulation 2008)

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Time : Three hours

Maximum : 100 marks

Answer ALL questions

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PART A — (10 × 2 = 20 marks)

1. Draw a simple per-phase model for a cylindrical rotor synchronous machine.

2. What are the advantages of per unit system?

3. What is Jacobian matrix?

4. What is a slack bus?

5. Mention the objectives of short circuit analysis.

6. Write down the balanced and unbalanced faults occurring in a power system.

7. What is sequence network?

8. Write the symmetrical components of a three phase system?

9. Define critical clearing angle.

10. Write swing equation.

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PART B — (5 × 16 = 80 marks)

11. (a) (i) With the help of single line diagram, explain the basic components of a power system. (8)

(ii) Write detailed notes about the per-phase model of a three phase transformer. (8)

Or

(b) Draw the impedance diagram for the electric power system shown in figure 11 (b) showing all impedance in per unit on a 100-MVA base. Choose 20-kV as the voltage base for generator. The three-phase power and line-line ratings are given below. (16)

G1 : 90 MVA 20 kV X = 9%

T1 : 80 MVA 20/200 kV X = 16% T2 : 80 MVA 200/20kV X = 20% G2 : 90 MVA 18 kV X = 9%

Line : 200 kV X = 120

Load : 200 kV, S = 48 MW + j64Mvar

Fig. 11. (b)

12. (a) With neat flow chart explain the computational procedure for load flow solution using fast decoupled method when the system contains all types of buses. (16)

Or

(b) Explain the step by step computational procedure for the Gauss-Seidel method of load flow studies. (16)

13. (a) Explain symmetrical fault analysis using Z-bus matrix with neat flow chart. (16)

Or

(b) A 11 kV, 100 MVA alternator having a sub-transient reactance of 0.25 pu is supplying a 50 MVA motor having a sub-transient reactance of 0.2 pu through a transmission line. The line reactance is 0.05 pu on a base of 100 MVA. The motor is drawing 40 MW at 0.8 p.f. leading with a terminal voltage of 10.95 kV when a 3-phase fault occurs at the generator terminals. Calculate the total current in generator and motor under fault conditions. (16)

14. (a) What are the assumptions to be made in short circuit studies? Deduce and thaw the sequence network for a line to line fault at the terminals of an unloaded generator. (16)

Or

(b) Two 11 kV, 20 MVA, three phase, star connected generators operate in parallel as shown in Figure 14. (b) ; the positive, negative and zero sequence reactance’s of each being, respectively, j0.l8, j0.15, j0.10 pu. The star point of one of the generators is isolated and that of the other is earthed through a 2.0 ohms resistor. A single line to ground fault occurs at the terminals of one of the generators. Estimate

(i) the fault current,

(ii) current in grounding resistor, and

(iii) the voltage across grounding resistor. (16) Fig. 14. (b)

15. (a) Describe the Runge-Kutta method of solution of swing equation for multi-machine systems. (16)

Or

(b) Derive an expression for the critical clearing angle and clearing time. (16)

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