basic electrical engineering 2009-2-3 0

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)


2/3

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)


3/3

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..

basic electrical engineering 2009-2-3 0

Documents