SPPU First Year Engineering (Semester 1)
Basic Electrical Engineering (BEE)
December 2013
Total marks: --
Total time: --
(1) Assume appropriate data and state your reasons
(2) Marks are given to the right of every question
(3) Draw neat diagrams wherever necessary

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?1012? -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 cm2. 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.
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.
7 M
5 (b) Define:
(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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