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7/31/2019 Basic Electrical Engineering 2009-2-3 0
1/3
B.E. 2nd
Semester
Basic Electrical Engineering
[Maximum Marks:100]
Note: Attempt any 5 questions selecting at least two questions each from Part-A & Part-B.
PART-A
Q1. (a) State & explain the superposition theorem with illustration. (6)
(b) Determine the current through 2 ohm resistor in the network in
figure1: (14)
(i) Thevenins theorem
(ii) Nortons theorem
Q2. (a) A coil of resistance 12 ohm & inductance of 0.05 ohm , inductive
resistor of 20 ohm resistance & a loss free 40 micro farad capacitor are
connected in series across a 240V , 50Hz sinusoidal supply. Calculate: (a) the
current , (b) the voltage across the coil & the capacitor; (c) the power
consumed in the circuit; (d) the power consumed by the coil ; & (e) the
power factor of the circuit. (10)
(b) Define the term rms & average value. Derive expressions for both for
sinusoidal waveform. (10)
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Q3. (a) Explain the advantage of 3-phase system over the 1-phase system.
(10)
(b) Two inductive coils A & B are in parallel across a 100V, 50Hz supply.
Coils A takes 12 A at 0.9 power factor & total current for both the coils is
20A at 0.8 power factor. Determine (a) the equivalent resistance &
equivalent reactance , (b)the individual resistances & reactances of both coils
(c) the power factor of coil B. (10)
Q4. (a) Derive a relations between phase & line voltage for star & delta
connections. (10)
(b) Explain how power factor is measured using 2-wattmeter method? (10)
PART-B
Q5. (a) A mild steel ring of 30 cm mean circumference has crossectional
area of 6 cm square & has a winding of 500 turns on it. The ring is cut
through to provide air gap of 1mm in the magnetic circuit. A current of
4A in the winding produces a flux density of 1T in the air-gap. Find
(i) Relative permeability of the mild steel &
(ii) Inductance of the windings. (10)
(b) Give the detailed comparison of electric & magnetic circuits. (10)
Q6. (a) Define the term voltage regulation. Derive its expression & give its
significance. (10)
(b) At 400V &50HZ the total core loss of a transformer was found to be
2400W. When the transformer is supplied at 200V & 25Hz, the core loss is
800 W? Calculate the hysteresis & eddy current loss at 400V & 50Hz. (10)
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Q7. (a) Derive torque equation of d.c. motor. Explain different methods of
excitation of d.c. machines. (10)
(b) Why single phase induction motor is not self starting? Give working of
split phase induction motor. (10)
Q8. Explain with the diagrams, construction, working & applications of various
stepper motors. (20)
Disclaimer: Well this looks a little stupid but we are not responsible if any portion of this paper
is not relevant with todays syllabus. Due care has been taken to make this paper error free, but
there always remains a chance of error so please ignore any typographical error if present..