Answer any one question from Q1 & Q2

1 (a)
Define Insulation Resistance and derive expression for it of a Cable.

6 M

1 (b)
A single core cable has its conductor diameter as 2 cm and outer diameter as 5 cm. The resistivity of conductor and insulator are 1.73 × 10

^{-8}? -m and 8×10^{12}? -m respectively. Calculate resistance of conductor and insulation for a cable of 100 meter.
6 M

2 (a)
Derive an expression for Energy stored in a magnetic field.

6 M

2 (b)
An iron ring of mean circum ference of 50 cm has an airgap of 2mm cut in it. It has circular cross section with area of 5 cm

^{2}. It carries a coil wound with 600 turns wound uniformly. The relative permeability of iron is 580. If the coil carries a current of 2 amp. Find the Flux in air gap.
6 M

Answer any one question from Q3 & Q4

3 (a)
Derive an expression of Average value of an alternating simusoidal current.

6 M

3 (b)
An inductive coil, having negligible resistance and 0.1 H inductance, is connected across a 200V, 50Hz supply. Find

(i) Inductive reactance.

(ii) RMS value of current drawn. State equations for voltage & current.

(i) Inductive reactance.

(ii) RMS value of current drawn. State equations for voltage & current.

6 M

4 (a)
Compare core type and shell type transformer construction.

6 M

4 (b)
A 25k VA, 2200/20V 50Hz single phase transformer has a primary resistance of 1.8 ? and secondary resistance of 0.02 ?. Calculate the transformer efficiency at half load 0.8 lagging p.f. The Iron Losses are 1000 watt.

6 M

Answer any one question from Q5 & Q6

5 (a)
A circuit, consisting of resistance of 20 ? and inductance of 0.1 H in series, is connected across single phase 220V, 50Hz supply.

Calculate :

(1) Current drawn

(2) p.f. and

(3) Power consumed by ckt.

Calculate :

(1) Current drawn

(2) p.f. and

(3) Power consumed by ckt.

7 M

5 (b)
Define:

(1) Impedance and

(2) Admitance of circuit. Sketch the impedance & admittance triangles.

(1) Impedance and

(2) Admitance of circuit. Sketch the impedance & admittance triangles.

6 M

6 (a)
Three coils each of 5? resistance and 6? inductive reactance are connected in Delta across 3 phase, 440V, 50Hz, A.C. Supply. Calculate current drawn p.f. of system and power consumed by circuit.

7 M

6 (b)
A coil of 2? resistance and 0.01 H inductance is connected in series with a capacitor across 200V supply. What must be capacitance in order that maximum current is drawn at frequency of 50 Hz. Find also voltage across capacitance.

6 M

Answer any one question from Q7 & Q8

7 (a)
State and explain kirchhoff's laws.

8 M

7 (b)
Calculate the equivalent resistance between terminals X and Y for the circuit shown in Fig, 1

5 M

8 (a)
Apply Thevenin's theorem to calculate current flowing in branch A-B as shown in Fig. 2

8 M

8 (b)
State and explain Superposition Theorem.

5 M

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