B.Tech I Year I Semester (R20) Supplementary Examinations June 2023

BASIC ELECTRICAL ENGINEERING

(Common to ECE & CSE)

Time: 3 hours

Max. Marks: 70

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

2. Answer ALL the question in Part-A

3. Answer any FOUR questions from Part-B

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PART-A (14 Marks)

1. 1. Define active and passive elements. (2M)
   2. State Kirchhoff’s laws. (2M)
   3. Define RMS value and Average value. (2M)
   4. Define phase and phase difference. (2M)
   5. Define the slip of an induction motor. (2M)

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   6. What are the different types of single-phase induction motors? (2M)
   7. List the applications of DC motors. (2M)

PART-B (56 Marks)

1. a) Using Nodal analysis, find the current through 2Ω resistor for the circuit shown in below figure. (7M)

   b) Determine the equivalent resistance Rab for the circuit shown in below figure using star-delta transformation. (7M)

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2. a) Explain the behavior of R, L and C elements in AC circuits. (7M)

   b) A series RLC circuit has R = 10 Ω, L = 0.1 H and C = 100 μF and is supplied with 220V, 50 Hz supply. Find i) Impedance ii) current iii) power factor. (7M)

3. a) Explain the construction and principle of operation of a single-phase transformer. (7M)

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   b) A 200 kVA, 3300/400 V, 50 Hz single-phase transformer has 80 turns on the secondary winding. Assuming an ideal transformer, calculate: i) primary and secondary currents on full load ii) the number of primary turns iii) the maximum value of flux in the core. (7M)

4. a) Explain the construction and principle of operation of a three-phase induction motor. (7M)

   b) A 6-pole, 50 Hz, three-phase induction motor running on full load develops a useful torque of 150 Nm when the rotor emf makes 150 complete cycles per minute. Calculate the slip and rotor input power. (7M)

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5. a) Explain the construction and principle of operation of a DC generator. (7M)

   b) A 4-pole, lap-wound DC shunt generator having 800 conductors is running at 1200 rpm. If the flux per pole is 0.03 wb, determine the generated emf. (7M)

6. Explain the necessity of earthing. Explain different types of earthing. (14M)

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