B.Tech I Year I Semester (R20) Regular Examinations March-2021

BASIC ELECTRICAL ENGINEERING

(Common to CSE & IT)

Time: 3 Hours

Max. Marks: 70

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Note: 1. Question Paper consists of two parts (Part-A and Part-B)

2. Answer ALL the question in Part-A

3. Answer any THREE Questions from Part-B

PART-A (10 * 2 = 20 Marks)

1. Define Ohm’s Law and its limitations.
2. State Kirchhoff’s Laws.

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3. Define RMS value and Average value of an alternating quantity.
4. Define power factor. What is its importance?
5. List the various losses in a transformer.
6. Why the O.C test is conducted on LV side and S.C test is conducted on HV side of the transformer?
7. What is the function of commutator in a DC machine?

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8. Why a DC series motor never starts without load?
9. List different types of single-phase induction motors.
10. What are the applications of synchronous motors?

PART-B (3 * 16 = 48 Marks)

1. a) Calculate the equivalent resistance between terminals ‘a’ and ‘b’ in the following figure.

   b) Using Nodal analysis, find the current through 2O resistor in the following circuit.

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2. a) Derive the EMF equation of a single-phase transformer.

   b) A single-phase 50 Hz transformer has 35 primary and 350 secondary turns. The net cross-sectional area of the core is 550 cm². If the primary winding is connected to a 230 V, 50 Hz supply, determine i) the EMF induced in the secondary winding ii) the maximum value of flux density in the core.

3. a) Explain the principle of operation of a DC generator.

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   b) A 4-pole, lap-wound DC shunt generator having 800 conductors is running at 1000 rpm. If the flux per pole is 0.03 wb, determine the generated EMF. If the generator is supplying a load of 15A at a terminal voltage of 230V, determine the armature resistance and shunt field resistance.

4. a) Explain the principle of operation of a three-phase induction motor.

   b) A 6-pole, 50 Hz, three phase induction motor running on full load develops a useful torque of 150 N-m. Calculate the rotor frequency if the rotor EMF makes 120 complete alterations per minute.

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5. Write short notes on the following:

   a) Construction and working principle of synchronous motor.

   b) Applications of various electrical machines.

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