Printed Pages: 03 Subject Code: KEE101 Paper Id: 120101 BTECH

Printed Pages: 03 Subject Code: KEE101Paper Id: 120101 Roll No:

BTECH (SEM I) THEORY EXAMINATION 2018-19

BASIC ELECTRICAL ENGINEERING Time: 3 Hours Total Marks:100

Note: 1.The question paper contains three sections- A, B & C.

2. Read the instructions carefully in each section

3. Course outcome(CO) has been mentioned against each question.

SECTION-A

1. Attempt ALL: [2x10=20]

a. Define with examples: (i) Active and passive element (ii) bilateral and unilateral elements. (CO 1)

b. Explain (i) Ideal current source (ii) ideal voltage source. (CO 1) c. A series circuit has R= 10Ω, L= 0.02H and C= 3µF. Calculate Q-factor of the circuit.

(CO 2)

d. Two ac currents one represented as i1 = 25 sin (314 t + 200) & i2 = 35 sin (314 t +

450). Draw the phasor & show the resultant when they are connected in parallel.

(CO 2)

e. What will happen if the primary of a transformer is connected to dc supply? (CO 3)

f. How can we change the direction of rotation of DC motor? (CO 4)

g. Enlist the various methods of starting of single phase induction motor? (CO 4)

h. Why Earth pin is made thicker and bigger than line and neutral? (CO 5)

i. What are the advantages of auto-transformer over two winding transformer? (CO 4)

j. Calculate the energy consumption per day in a house using 5 CFLs of 20 W each, 3

fans of 60 W each for 3 hrs a day. (CO 5)

SECTION- B 2. Attempt any three parts of the following. Each part carries 10 marks. [3x10=30] (a) Find current through 2Ω resistance using superposition theorem in figure 1 (CO1)

Figure 1

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(b) Derive expression of resonance frequency for series RLC circuit. A series circuit

consists of a resistance of 10Ω, and inductance of 50mH and a variable capacitance in series

across a 100V, 50Hz supply. Calculate-

(i) The value of capacitance to produce resonance. (ii) Voltage across the capacitance. (iii) Q-factor (CO2)

(c) The maximum efficiency of a 100 KVA, 1100/440 V, 50 Hz transformer is 96%, This

occurs at 75% of full load at 0.8 p.f. lagging. Find the efficiency of transformer at 3.4 FL at

0.6 p.f. leading. (CO3)

(d) A 4-pole shunt generator with lap-connected armature has field and armature resistance of

50Ω and 0.1Ω respectively. If supplying power to 100W lamp load for 100 V. Calculate the

armature current and the generated emf. Consider a contact drop of 1V per brush. (CO4)

(e) Draw the characteristics of battery.

Calculate the backup of battery of 100AH connected to load of 100 watts and supply voltage

is 12V. (CO5)

SECTION- C

3. Attempt any ONE question: [10X1=10] (a)Give the statement of Norton’s Theorem. (CO 1)

Find the current in 12 ohm resistance using Norton’s theorem for the given circuit.

Figure 2

(b) Determine current through 15 ohm resistance by node analysis. (CO 1)

Figure 3

4. Attempt any ONE question: [10X1=10] (a)Derive the expression for resonant frequency & quality factor for an ac circuit under the

condition of parallel resonance. (CO 2)


(b)Derive the relation between line current & phase current in case of three phase delta

connected balanced load. Three identical coils of resistance 8Ω and inductive reactance 6Ω

are connected in delta across 400V mains. Determine power, power factor and line current.

Draw phasor diagram. (CO 2)

5. Attempt any ONE question: [10X1=10] (a) Discuss the principle of operation of a single phase transformer. Derive EMF equation for a single phase transformer. (CO 3) (b) What is voltage Regulation in a single Phase Transformer? What should be its value for

an ideal transformer? (CO 3)

6. Attempt any ONE question: [10X1=10] (a) Derive the EMF equation of D.C. Generator. An 8 pole lap wound dc generator has 450

armature turns. It operates at 0.02 wb flux per pole and runs at 1000 rpm at no load. Find the

emf induced by it. (CO 4)

(b)What is the relation between frequencies of stator & rotor currents? A 3-phase, 50Hz

induction motor has 6 poles and operates with a slip of 5% at a certain load. Determine

(i) The speed of rotor with respect to the stator.

(ii) The frequency of the rotor current.

(iii) The speed of the rotor magnetic field with respect to the stator. (CO 4)

7. Attempt any ONE question: [10X1=10] (a)Write short notes on the following: (CO 5)

(i) MCB (ii) MCCB (c) Fuse (d) Types of wires

(b) Explain following: (CO 5)

(i) Need of Earthing

(ii)Battery backup


KEE101 CORRECTION M 15.12.18Kindly read Q.2. as

Q.2.(c) The maximum efficiency of a 100 KVA, 1100/440 V, 50 Hz transformer is 96%, This occurs at 75% of full load at 0.8 p.f. lagging. Find the efficiency oftransformer at 1/2 Full Load at 0.6 p.f. leading.

Page 1


Printed pages: 02 Sub Code: REE101

Paper Id: 120101 Roll No.

B TECH (SEM I) THEORY EXAMINATION 2018-19

BASIC ELECTRICAL ENGINEERING Time: 3 Hours Total Marks: 70 Note: 1. Attempt all Sections. If require any missing data; then choose suitably.

SECTION A

1. Attempt all questions in brief. 2 x 7 = 14 a. Explain linear and non linear circuit. b. Explain ideal voltage and current source with example. c. Give the advantages and disadvantages of 3-phase system. d. Explain Quality factor of series resonance circuit. e. A current wave is represented by the equation i = 20 sin (251t). Calculate the

maximum and RMS value of the current and its frequency. f. Draw and explain torque slip characteristic of three phase induction motor. g. What do you mean by magnetic hysteresis?

SECTION B

2. Attempt any three of the following: 7 x 3 = 21 a. Derive the relation for Star to delta conversion.

b. Using superposition theorem find current in 40 ohm resistance.

c. A star connected balanced load is supplied from a three phase balanced supply with a line voltage of 416 V at a frequency of 50 Hz. Each phase of load consists of a resistance and a capacitor joined in series and the reading on two wattmeters connected to measure the total power supplied are 782 watt and 1980 watt, both positive. Calculate (a) the power factor of the circuit (b) the line current and (c) the capacitance of each capacitor.

d. Give the analogy between magnetic circuit and electric circuit.

e. Explain construction and working principle of three phase synchronous motor.

120102

SECTION C 3. Attempt any one part of the following: 7 x 1 = 7

(a) Find the form factor and Peak factor of the given waveform.

(b) Find current delivered by the voltage source mesh analysis.

4. Attempt any one part of the following: 7 x 1 = 7

(a) Derive the relation for cut off frequencies and bandwidth of a series resonance circuit.

(b) Explain maximum power transfer theorem and find the value of load resistance and amount of power transferred.

5. Attempt any one part of the following: 7 x 1 = 7 (a) Explain construction and working of dynamometer type wattmeter with its

merits and demerits. (b) What is the necessity of a three phase system? Derive the relation between line

values and phase values of a three phase star and delta connected system.

6. Attempt any one part of the following: 7 x 1 = 7 (a) Explain working of a single phase transformer and derive the e.m.f. equation.

Why the rating of transformer is in KVA. (b) In a 50 KVA, 1100/220 V transformer, the iron and copper losses at full load

are 350 W and 425 W respectively. Calculate the efficiency at (i) full load and half load unity power factor (ii) full load 0.8 Power factor (iii) maximum efficiency and load at which maximum efficiency occurs assuming the load to be resistive.

7. Attempt any one part of the following: 7 x 1 = 7 (a) Explain different types of dc motor and give their characteristic. (b) Explain efficiency of a three phase induction motor and derive the condition for

maximum efficiency.

Printed Pages: 03 Subject Code: KEE101Paper Id: 120101 Roll No:

BTECH (SEM I) THEORY EXAMINATION 2018-19

BASIC ELECTRICAL ENGINEERING Time: 3 Hours Total Marks:100

Note: 1.The question paper contains three sections- A, B & C.

2. Read the instructions carefully in each section

3. Course outcome(CO) has been mentioned against each question.

SECTION-A

1. Attempt ALL: [2x10=20]

a. Define with examples: (i) Active and passive element (ii) bilateral and unilateral elements. (CO 1)

b. Explain (i) Ideal current source (ii) ideal voltage source. (CO 1) c. A series circuit has R= 10Ω, L= 0.02H and C= 3µF. Calculate Q-factor of the circuit.

(CO 2)

d. Two ac currents one represented as i1 = 25 sin (314 t + 200) & i2 = 35 sin (314 t +

450). Draw the phasor & show the resultant when they are connected in parallel.

(CO 2)

e. What will happen if the primary of a transformer is connected to dc supply? (CO 3)

f. How can we change the direction of rotation of DC motor? (CO 4)

g. Enlist the various methods of starting of single phase induction motor? (CO 4)

h. Why Earth pin is made thicker and bigger than line and neutral? (CO 5)

i. What are the advantages of auto-transformer over two winding transformer? (CO 4)

j. Calculate the energy consumption per day in a house using 5 CFLs of 20 W each, 3

fans of 60 W each for 3 hrs a day. (CO 5)

SECTION- B 2. Attempt any three parts of the following. Each part carries 10 marks. [3x10=30] (a) Find current through 2Ω resistance using superposition theorem in figure 1 (CO1)

Figure 1


(b) Derive expression of resonance frequency for series RLC circuit. A series circuit

consists of a resistance of 10Ω, and inductance of 50mH and a variable capacitance in series

across a 100V, 50Hz supply. Calculate-

(i) The value of capacitance to produce resonance. (ii) Voltage across the capacitance. (iii) Q-factor (CO2)

(c) The maximum efficiency of a 100 KVA, 1100/440 V, 50 Hz transformer is 96%, This

occurs at 75% of full load at 0.8 p.f. lagging. Find the efficiency of transformer at 3.4 FL at

0.6 p.f. leading. (CO3)

(d) A 4-pole shunt generator with lap-connected armature has field and armature resistance of

50Ω and 0.1Ω respectively. If supplying power to 100W lamp load for 100 V. Calculate the

armature current and the generated emf. Consider a contact drop of 1V per brush. (CO4)

(e) Draw the characteristics of battery.

Calculate the backup of battery of 100AH connected to load of 100 watts and supply voltage

is 12V. (CO5)

SECTION- C

3. Attempt any ONE question: [10X1=10] (a)Give the statement of Norton’s Theorem. (CO 1)

Find the current in 12 ohm resistance using Norton’s theorem for the given circuit.

Figure 2

(b) Determine current through 15 ohm resistance by node analysis. (CO 1)

Figure 3

4. Attempt any ONE question: [10X1=10] (a)Derive the expression for resonant frequency & quality factor for an ac circuit under the

condition of parallel resonance. (CO 2)


(b)Derive the relation between line current & phase current in case of three phase delta

connected balanced load. Three identical coils of resistance 8Ω and inductive reactance 6Ω

are connected in delta across 400V mains. Determine power, power factor and line current.

Draw phasor diagram. (CO 2)

5. Attempt any ONE question: [10X1=10] (a) Discuss the principle of operation of a single phase transformer. Derive EMF equation for a single phase transformer. (CO 3) (b) What is voltage Regulation in a single Phase Transformer? What should be its value for

an ideal transformer? (CO 3)

6. Attempt any ONE question: [10X1=10] (a) Derive the EMF equation of D.C. Generator. An 8 pole lap wound dc generator has 450

armature turns. It operates at 0.02 wb flux per pole and runs at 1000 rpm at no load. Find the

emf induced by it. (CO 4)

(b)What is the relation between frequencies of stator & rotor currents? A 3-phase, 50Hz

induction motor has 6 poles and operates with a slip of 5% at a certain load. Determine

(i) The speed of rotor with respect to the stator.

(ii) The frequency of the rotor current.

(iii) The speed of the rotor magnetic field with respect to the stator. (CO 4)

7. Attempt any ONE question: [10X1=10] (a)Write short notes on the following: (CO 5)

(i) MCB (ii) MCCB (c) Fuse (d) Types of wires

(b) Explain following: (CO 5)

(i) Need of Earthing

(ii)Battery backup


KEE101 CORRECTION M 15.12.18Kindly read Q.2. as

Q.2.(c) The maximum efficiency of a 100 KVA, 1100/440 V, 50 Hz transformer is 96%, This occurs at 75% of full load at 0.8 p.f. lagging. Find the efficiency oftransformer at 1/2 Full Load at 0.6 p.f. leading.

Page 1


Printed pages: 02 Sub Code: NEE101


B TECH

(SEM I) THEORY EXAMINATION 2018-19 BASIC ELECTRICAL ENGINEERING

Time: 3 Hours Total Marks: 100 Note: 1. Attempt all Sections. If require any missing data; then choose suitably.

SECTION A

1. Attempt all questions in brief. 2 x 10 = 20 a. What do you mean by unilateral and bilateral elements? b. Can we apply KVL in a loop containing a current source? Give answer with

reason. c. What do you mean by average value of an alternating quantity? d. Calculate the R.M.S. value of a half wave rectified current. e. Explain phase sequence in a three phase circuit. f. Explain eddy current damping in the measuring instruments. g. What is the necessity of earthling? h. Explain losses in magnetic circuit. i. Explain the principle of Electromechanical energy conversion. j. What is the role of commutator in dc machine?

SECTION B

2. Attempt any three of the following: 10 x 3 = 30 a. Using nodal analysis find current I in the circuit given below.

b. A capacitor of 35 µF is connected in series with a variable resistor. The circuit

is connected across a 50 Hz main. Find the value of the resistor for a particular condition when the voltage across the capacitor is half the supply voltage.

c. Explain two wattmeter methods for the measurement of three phase power. Derive the relation for three phase power with the help of phasor diagram.

d. Draw and explain equivalent circuit of a single phase transformer.

e. A short shunt compound generator supplies 200 A at 100 V. The resistance of armature, series field and shunt field is respectively 0.04, 0.03 and 60 ohm. Find the emf generated.

120105



(a) Find the equivalent resistance between point A and B using star delta conversion

(b) Determine power loss in the 1 ohm resistance across terminal A and B of circuit given in figure using Norton’s theorem.


(a) Explain power factor. What are the causes of low power factor? Explain methods of power factor improvement.

(b) Find the capacitance which must be connected in series with a 100W, 110V lamp in order that the lamp may draw its normal current when the combination is connected to a 230V, 50 Hz supply.

5. Attempt any one part of the following: 10 x 1 = 10 (a) Three inductive coils, each with a resistance of 15 ohm and an inductance of

0.03 H are connected (i) in star (ii) in delta, to 3 phase, 400V 50 Hz supply. Calculate for each of the above case (i) Phase current and line current (ii) total power absorbed.

(b) Explain construction and working of PMMC type instruments also gives it’s and disadvantages.

6. Attempt any one part of the following: 10 x 1 = 10 (a) What do mean by earthling? Explain any methods of earthling. (b) An electromagnet is shown in figure whose area of cross section is 12cm2.

Mean length of iron path is 50cm. It is excited by two coils each having 400 turns. When the current in the coil is 1.0 A, the resulting flux density gives a relative permeability of 1300. Calculate (i) reluctance of iron part, air gap and total reluctance.(ii) total flux(iii) flux density in air gap.

7. Attempt any one part of the following: 10 x 1 = 10 (a) Explain double field revolving theory for single phase induction motor. (b) An 8 pole alternator runs at 750 rpm. It supplies power to a 6 pole, 3 phase

induction motor, which has a full load slip of 3 %. Find the full load speed of the induction motor and the frequency of its rotor emf.


Printed pages: 02 Sub Code: REE101


B TECH (SEM I) THEORY EXAMINATION 2018-19

BASIC ELECTRICAL ENGINEERING Time: 3 Hours Total Marks: 70 Note: 1. Attempt all Sections. If require any missing data; then choose suitably.

SECTION A

1. Attempt all questions in brief. 2 x 7 = 14 a. Explain linear and non linear circuit. b. Explain ideal voltage and current source with example. c. Give the advantages and disadvantages of 3-phase system. d. Explain Quality factor of series resonance circuit. e. A current wave is represented by the equation i = 20 sin (251t). Calculate the

maximum and RMS value of the current and its frequency. f. Draw and explain torque slip characteristic of three phase induction motor. g. What do you mean by magnetic hysteresis?

SECTION B

2. Attempt any three of the following: 7 x 3 = 21 a. Derive the relation for Star to delta conversion.

b. Using superposition theorem find current in 40 ohm resistance.

c. A star connected balanced load is supplied from a three phase balanced supply with a line voltage of 416 V at a frequency of 50 Hz. Each phase of load consists of a resistance and a capacitor joined in series and the reading on two wattmeters connected to measure the total power supplied are 782 watt and 1980 watt, both positive. Calculate (a) the power factor of the circuit (b) the line current and (c) the capacitance of each capacitor.

d. Give the analogy between magnetic circuit and electric circuit.

e. Explain construction and working principle of three phase synchronous motor.

120102


(a) Find the form factor and Peak factor of the given waveform.

(b) Find current delivered by the voltage source mesh analysis.


(a) Derive the relation for cut off frequencies and bandwidth of a series resonance circuit.

(b) Explain maximum power transfer theorem and find the value of load resistance and amount of power transferred.

5. Attempt any one part of the following: 7 x 1 = 7 (a) Explain construction and working of dynamometer type wattmeter with its

merits and demerits. (b) What is the necessity of a three phase system? Derive the relation between line

values and phase values of a three phase star and delta connected system.

6. Attempt any one part of the following: 7 x 1 = 7 (a) Explain working of a single phase transformer and derive the e.m.f. equation.

Why the rating of transformer is in KVA. (b) In a 50 KVA, 1100/220 V transformer, the iron and copper losses at full load

are 350 W and 425 W respectively. Calculate the efficiency at (i) full load and half load unity power factor (ii) full load 0.8 Power factor (iii) maximum efficiency and load at which maximum efficiency occurs assuming the load to be resistive.

7. Attempt any one part of the following: 7 x 1 = 7 (a) Explain different types of dc motor and give their characteristic. (b) Explain efficiency of a three phase induction motor and derive the condition for

maximum efficiency.

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Printed Pages: 03 Subject Code: KEE101 Paper Id: 120101 BTECH