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NEE-101/Mr.Braj Kishor Verma, Mr. Gaurav Sharma, Mrs. Kavya Sharma, Mr. Bhupesh Kr. Pal, Mrs. Pankhuri Kishore

Date: 17/11/2014 Page-1

SHRI RAMSWAROOP MEMORIAL COLLEGE OF ENGG. & MANAGEMENT

B.Tech. [SEM I (EE, EN, EC, CE)]

QUIZ TEST-3 (Session: 2014-15)

ELECTRICAL ENGINEERING

(NEE-101)

Roll No.

(To be filled by the Student) Note: Attempt All Questions.

Part – A (Questions from Tutorial Sheet)

[10 Marks]

Q1) Three identical resistors of 20 ohm each are connected in star to 415 V, 50 Hz three Phase. Calculate:

a) The total power consumed.

b) The total power consumed if they are connected in delta.

c) The total power consumed , if one of the resistors is opened. [Q.7] [3+2]

Q2) A 3 phase balanced load connected across 3 phase 400 V a.c. supply draws a line current of 10A .Two

watt meters are used to measure input power .The ratio of two wattmeter readings is 2:1 . Find the readings

of both watt meters . [Q.15] [2.5+2.5]

Part – B [20 Marks]

Q3). Short Answer type questions: a) State whether a delta connected three phase supply can be fed to a household or not? Give reasons.[1]

b) Why are the iron losses also called fixed losses. [1] c) What is flux density? [1] d) Explain the Lenz law? [1]

e) Explain the condition of maximum efficiency of transformer? [1]

Q4) The efficiency of a 400KVA, single phase transformer is 98.77% at full load 0.8 power factor and

99.13% at half full load unity power factor.

(a) Iron losses at full and half full loads [2.5]

(b) Cu losses at full and half full loads. [2.5]

Q5) State and explain Thevenin’s theorem and mention its important applications. [5]

Q6) A balanced 3-phase star-connected load of 18KW taking a leading current of 60A when connected

across a 3-phase 440V, 50Hz supply. Find the values and nature of the load components and also power

factor of the load. [2+2+1]

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Time: 1 Hour Max. Marks: 30

NEE-101/Mr.Braj Kishor Verma, Mr. Gaurav Sharma, Mrs. Kavya Sharma , Mr. Bhupesh Kr. Pal, Mrs. Pankhuri Kishore

Date: 17/11/2014 Page-1





(NEE-101)

Roll No.



[10 Marks]

Q1) The power input to a 200V, 50Hz, 3 phase motor running on full load at an efficiency of 90% is

measured by two wattmeter which indicates 300KW & 100KW respectively.

Find a) The input power b) power factor c) line current and power output. [Q.3] [2+2+1]

Q2) Three capacitors, each of 150μF, are connected in delta to a 400V, 3-phase, 50 Hz supply. What will be

capacitance of each of the three capacitors such that when connected in star across the same supply, the

line current remains the same? [Q.14] [5]

Part – B

Q3). Short Answer type questions: [20 Marks] (a) What do you understand by power factor of a 3-phase circuit? [1]

(b) If the thickness of the lamination is reduced to half, what effect will it have on the iron and copper

losses for the same load. [1]

(c) What is a B-H curve?

[1] (d) Draw the no-load phaser diagram of the transformer. [1]

(e) Write the formula and unit for active and reactive power for 3-phase. [1]









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Refer/WI/ACAD/18


NEE-101/Mr.Braj Kishor Verma, Mr. Gaurav Sharma, Mrs. Kavya Sharma ,Mr. Bhupesh Kr. Pal, Mrs. Pankhuri Kishore

Date: 17/11/2014 Page-1

SHRI RAMSWAROOP MEMORIAL COLLEGE OF ENGG. &

MANAGEMENT




(NEE-101)

Roll No.



[10 Marks]

Q1) Three similar coils connected in star take a total power of 1.5 KW at power factor of 0.2 lagging from a

3 phase 400 V, 50 Hz supply .Calculate resistance and inductance of each coil . [Q.6] [2+3]

Q2) A 400 V supply is connected across a balanced load of three impedances each consisting of 32 ohm

resistance and 24 ohm inductive reactance. Determine the current drawn from power mains, if three

Impedances are (a) Star connected (b) Delta connected. [Q.11] [2.5+2.5]

Part – B [20 Marks] Q3). Short Answer type questions:

(a) Which torque is not present in an integrating type instrument? [1]

(b) What is the difference between permeability and permittivity? [1] (c) What are the values of leakage reactances of a single phase transformer if the coupling between

primary and secondary winding fluxes is perfect?. [1]

(d) What is meant by Q-factor of parallel resonant circuit? [1]

(e) Explain the term capacitive reactance. [1]







across a 3-phase 440V, 50Hz supply. Find the values and nature of the load components and also

power factor of the load. [2+2+1]

__________X__________

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Refer/WI/ACAD/18


EEE-101/Mr.Braj Kishor Verma, Mr. Gaurav Sharma, Mrs. Kavya Sharma , Mr. Bhupesh Kr. Pal, Mrs. Pankhuri Kishore

Date: 17/11/2014 Page-1





(NEE-101)

Roll No.



[10 Marks]

Q1) A permanent magnet moving coil instrument gives full scale reading of 25mA when a potential difference

across its terminal is 75mV.Show how it can be used a)as an ammeter for a range 0-100A .b)as a voltmeter

for a range 0-75V .Also find multiplying power of the shunt and voltage amplification? [Q.8] [2+3]

Q2) Three 40 ohms non inductive resistances are connected in delta across 400 V 3 phase lines .Calculate the

Power taken from the mains .If one of the resistances is disconnected what would be the power taken from

the mains ?[Q.9] [5]

Part – B

Q3). Short Answer type questions: [20 Marks] a) What is the function of current and voltage coil in a wattmeter? [1]

b) If a pure sin wave is fed to the input of a PMMC instrument, what will be its reading? [1] c) What is the difference between electric and magnetic fluxes?. [1]

d) What is the necessity of Dot convention? [1] e) What is the value of reluctance if the length of the magnetic path is doubled? [1] Q4) The efficiency of a 400KVA, single phase transformer is 98.77% at full load 0.8 power factor and








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Refer/WI/ACAD/18


NEE-101/Mr.Braj Kishor Verma, Mr. Gaurav Sharma, Mrs Kavya Sharma ,Mr. Bhupesh Kr. Pal, Mrs. Pankhuri Kishore

Date: 27/10/2014 Page-1





(NEE-101)

Roll No.



[10 Marks]

Q1) Two branches of parallel circuit draw current i1 and i2 such that i1=10 and

i2=5 . What is the total current drawn by them. [Q.4] [5]

Q2) An R-L-C circuit consists of a resistance of 1000Ω, an inductance of 100mH and a capacitance of 10pF.

If voltage of 100V is applied across the combination, find [Q.15] [1+2+2]

(a) The resonant frequency

(b) Q-factor of the circuit and

(c) The half-power points

Part – B

Q.3 Short Answer type questions: [20 Marks] (a) Differentiate between form factor and peak factor. [1] (b) Draw phasor between voltage and current for RL series circuit [1] (c) Find the instantaneous value of an alternating voltage having frequency 50Hz and

maximum value of 100V at 0.001 sec. [1]

(d) What do you understand by the term bandwidth of a series resonant circuit? [1]

(e) Explain active and reactive power using power triangle. [1]

Q4) Using Thevenin’s Theorem find VTH and RTH for a circuit given in fig.1 and also draw the equivalent

circuit for the same. [2+2+1]

2Ω

16V

4Ω 4Ω

8A

16A6Ω

+

-

P

Q

Fig.1.

Academic/26

Refer/WI/ACAD/18


NEE-101/Mr.Braj Kishor Verma, Mr. Gaurav Sharma, Mrs Kavya Sharma ,Mr. Bhupesh Kr. Pal, Mrs. Pankhuri Kishore

Date: 27/10/2014 Page-2

Q5) For the circuit shown in fig. 2 determine: [1×4]

i) Resonant Frequency

ii) Total impedance of the circuit at resonance

iii) Bandwidth

iv) Quality factor

Fig.2.

Q6) A 3 phase, 400 V supply is connected to a 3 phase star connected balanced load. The line current is 20 A

and the power consumed by the load is 12 kW. Calculate the impedance of the load, phase current and power

factor. [2+2+2]

__________X__________


Date: 27/10/2014 Page-1





(NEE-101)

Roll No.



[10 Marks]

Q1) A metal filament lamp, rated at 750 W, 100 V is to be connected in series with the capacitor across

230 V, 50 Hz supply. Calculate the value of capacitance required. Draw phasor diagram of the circuit. [Q.10]

[3+2]

Q2) A 230V 50Hz a.c. supply is applied to a coil of 0.06 H inductance and 2.5 Ω resistance connected in series

with a 6.8μf capacitor. Calculate [Q.14] [2+1+2]

(a) Impedance, current

(b) Phase angle between current and voltage

(c) Power factor and power consumed.

Part – B

Q3). Short Answer type questions: [20 Marks] a) Draw voltage triangle for RL circuit. [1]

b) Draw phasor between voltage and current for series RLC circuit when XL< XC. [1] c) The equation of an alternating current is given by, i=14.1421sin 100πt. Find the time taken by it to complete three cycles. [1] d) Give the expressions for upper and lower cut off frequencies for series resonance. [1]

e) What is the main cause of low power factor? [1]

Q4) Using Thevenin’s Theorem, find VTH and RTH for a circuit given in fig.1 and also draw the equivalent


2Ω

16V

4Ω 4Ω

8A

16A6Ω

+

-

P

Q

Fig.1.

Academic/26

Refer/WI/ACAD/18



Date: 27/10/2014 Page-2

Q5) For the circuit shown in fig. 2 determine: [1.25×4]



iii) Bandwidth

iv) Quality factor

Fig.2.



factor. [2+2+1]

__________X__________


Date: 27/10/2014 Page-1





(NEE-101)

Roll No.



[10 Marks]

Q1) An ac sinusoidal voltage, v= (160+j120) v is applied to a circuit. The resulting current is I= (-4+j10). Find

the impedance of the circuit and state whether it is inductive or capacitive. Also, find the power factor, active

power and reactive power. [Q.7] [2+1+1+1]

Q2) A series ac circuit has resistance of 15 ohm and inductive reactance of 10 ohm. Calculate the value of

capacitor which is connected across this series combination so that the system has unity power factor. The

frequency of ac supply is 50 Hz. [Q.13] [5]

Part – B

Q3). Short Answer type questions: [20 Marks] (a) What do you understand by power factor of a circuit? [1]

(b) Draw phasor between voltage and current for RC series circuit. [1] (c) The equation of an alternating quantity is v=282.84 sin 100πt, find its r.m.s value. [1] (d) Define series resonance of an RLC circuit and give expression for resonant frequency. [1]

(e) Write the formula and unit for active and reactive power. [1]

Q4) Using Thevenin’s Theorem, find VTH and RTH for a circuit given in fig.1 and also draw the equivalent


2Ω

16V

4Ω 4Ω

8A

16A6Ω

+

-

P

Q

Fig.1.

Academic/26

Refer/WI/ACAD/18



Date: 27/10/2014 Page-2

Q5) For the circuit shown in fig. 2 determine: [1×4]



iii) Bandwidth

iv) Quality factor

Fig.2.



factor. [2+2+2]

__________X__________


Date: 27/10/2014 Page-1

SHRI RAMSWAROOP MEMORIAL COLLEGE OF ENGG. &

MANAGEMENT




(NEE-101)

Roll No.



[10 Marks]

Q1) A two element series circuit is connected across an AC source v=300cos (314t+20

0) volts. The current

drawn is 15cos (314t-200) amp. Determine the circuit impedance, magnitude and phase angle. What is

average power drawn? [Q.6] [3+2]

Q2) One branch of parallel circuit consists of coil of inductance 0.05 H and effective resistance of 5Ω and

the other is 0.1 µf capacitor. Calculate resonant frequency, dynamic impedance and quality factor. [Q.11]

[2+2+1]

Part – B Q3). Short Answer type questions: [20 Marks]

(a) Differentiate between average value and rms value. [1]

(b) Draw phasor between voltage and current for series RLC circuit when XL>XC [1] (c) Find the instantaneous value of an alternating current having r.m.s value of 7.071A at 120º. [1]

(d) What is meant by Q-factor of series resonant circuit? [1]

(e) Explain the term inductive reactance. [1]

Q4) Using Thevenin’s Theorem find VTH and RTH for a circuit given in fig.1 and also draw the equivalent


2Ω

16V

4Ω 4Ω

8A

16A6Ω

+

-

P

Q

Fig.1.

`Academic/26

Refer/WI/ACAD/18



Date: 27/10/2014 Page-2

Q5) For the circuit shown in fig. 2 determine:

[1×4]



iii) Bandwidth

iv) Quality factor

Fig.2.

Q6) A 3 phase, 400 V supply is connected to a 3 phase star connected balanced load. The line current is

20 A and the power consumed by the load is 12 kW. Calculate the impedance of the load, phase current and

power factor. [2+2+2]

__________X__________


Date: 27/10/2014 Page-1





(NEE-101)

Roll No.



[10 Marks]

Q1) Voltage across R, L, and C are 5, 8 and 10 volts respectively. Calculate the value of supply voltage at 50

Hz. Also find the frequency at which this circuit would resonate. [Q.18] [2+3]

Q2) A coil of resistance 8 ohms and inductance 0.12 Henry is connected in series with a capacitance of 140 µF

across 230 volts. Determine impedance of entire circuit, Power factor of circuit and voltage across condenser.

[Q.20] [2+1+2]

Part – B

Q3). Short Answer type questions: [20 Marks] a) What is the effect of frequency on capacitive reactance? [1]

b) Draw phasor between voltage and current for series RLC circuit when XL=XC [1] c) Find the maximum value of a sinusoidal voltage having magnitude of 200 V at 150º. [1]

d) Define current magnification factor of parallel resonant circuit. [1] e) Give two disadvantages of low power factor. [1] Q4) Using Thevenin’s Theorem find VTH and RTH for a circuit given in fig.1 and also draw the equivalent


2Ω

16V

4Ω 4Ω

8A

16A6Ω

+

-

P

Q

Fig.1.

Academic/26

Refer/WI/ACAD/18



Date: 27/10/2014 Page-2

Q5) For the circuit shown in fig. 2 determine: [1.25×4]



iii) Bandwidth

iv) Quality factor

Fig.2.



factor. [2+2+1]

__________X__________

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