THEORY EXAMINATION (SEM–II) 2016-17 BASIC ELECTRICAL ENGINEERING

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This document is a B.Tech Electrical Engineering Semester Examination question paper, designed for a total of 100 marks to be attempted within 3 hours. It thoroughly covers fundamental and applied concepts of basic electrical engineering, circuit theory, AC analysis, transformers, machines, resonance, measurement techniques, and power systems. The paper is divided into three structured sections—A, B, and C, ensuring a balanced evaluation of conceptual understanding, numerical ability, and analytical problem-solving skills.

SECTION – A (Short Answer Questions – 10 × 2 = 20 Marks)

This section includes ten short and direct questions, testing basic definitions and essential theoretical knowledge. Topics include:

Unilateral & bilateral elements used in circuit theory

Advantages of three-phase systems over single-phase supply

Reason behind calling series resonance “voltage resonance”

Meaning of acceptor and rejector circuits in AC networks

Need for damping torque in analog measuring instruments

Concept of phase sequence in three-phase systems

Methods to minimize hysteresis loss in transformers

Function of the commutator in DC generators

Names of motors suitable for constant-speed operation

Role of capacitors in ceiling fans for starting and phase splitting

This section evaluates core theoretical knowledge needed before moving to numerical and analytical questions.

SECTION – B (Numerical & Analytical Questions – 5 × 10 = 50 Marks)

Students must answer any five out of eight questions. These involve calculations, circuit analysis, derivations, and detailed conceptual explanations. Major topics include:

Network Analysis:

Solving for current using loop/mesh current method and verifying results using node voltage method.

Parallel AC Circuits:

Finding:

Current through each branch

Total current and power factor

Equivalent impedance

Drawing a phasor diagram

Power Factor:

Definition, causes of low power factor, effects on system efficiency, and methods of power factor improvement (capacitors, synchronous condensers, phase advancers).

Series RLC Circuit:

Given R = 10 Ω, L = 0.1 H, C = 8 μF, determining:

Resonant frequency

Q-factor

Bandwidth

Lower and upper half-power frequencies

Transformer Theory:

Discussing transformer losses (iron & copper), efficiency, and conditions for maximum efficiency.

Measuring Instruments:

Construction, working, advantages, and disadvantages of attraction-type moving iron instruments.

DC Machines:

A 20 kW, 250 V DC shunt machine problem to calculate:

Developed EMF when working as a generator

Developed EMF when working as a motor

Three-Phase Induction Motor:

Working principle, torque–slip characteristics, and explanation of operating, braking, and generating regions.

This section strengthens understanding of practical and theoretical aspects of AC/DC systems, machines, and instruments.

SECTION – C (Long Answer Questions – 2 × 15 = 30 Marks)

This section includes three detailed questions, and the student must attempt any two. These questions require in-depth derivations, numerical computations, and analytical reasoning.