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

This document contains the complete B.Tech Electrical Engineering Semester Examination question paper, designed for 70 marks with a duration of 3 hours. The question paper assesses a student’s understanding of essential concepts in basic electrical engineering, AC/DC circuits, transformers, motors, resonance, power factor, and network theorems. It is divided into three major sections: A, B, and C, covering both theoretical and numerical problem-solving skills.

SECTION A – Short Answer Questions (7 × 2 = 14 Marks)

This section includes seven short questions, each testing a fundamental concept from the syllabus. It ensures that the student understands the basics such as:

Characteristics of active elements

Phase relationship between two sinusoidal voltages

Concept of series resonance in RLC circuits

Norton’s Theorem

Advantages of three-phase systems

Need for damping torque in analog measuring instruments

Definition of Magnetomotive Force (MMF)

Difference between transformer and autotransformer

Applications of synchronous motors

These questions check conceptual clarity and basic definitions that form the foundation for deeper understanding in later sections.

SECTION B – Medium-Length Analytical Questions (3 × 7 = 21 Marks)

Students must attempt any three questions. These questions involve diagrams, phasor analysis, constructional details, derivations, and conceptual explanations.

The topics include:

Network Analysis (Nodal Method)

Calculating current through a specific resistor using nodal analysis, applied to a multi-source network.

Phasor Diagram & Resultant Voltage

Drawing phasor diagrams for several sinusoidal voltages, finding their vector sum, and calculating the resultant RMS voltage.

PMMC Instrument Construction & Working

Explaining the principle, operation, advantages, and disadvantages of the Permanent Magnet Moving Coil (PMMC) instrument.

Magnetic vs Electric Circuits

Drawing analogy between magnetic and electric circuits, explaining B-H curve and its significance related to hysteresis loss.

DC Machine Equations

Deriving the EMF equation and torque equation of DC machines.

This section tests a student’s ability to apply theory to practical circuits and devices through clear understanding and structured explanation.

SECTION C – Long Numerical & Theoretical Questions (5 × 7 = 35 Marks)

This section contains five long-answer questions, from which the student must attempt any five. These questions focus on deeper numerical analysis, derivations, and understanding of electromechanical systems.

Topics include:

Transformers

Efficiency calculations of a 25 kVA transformer at half load and 0.8 pf lagging, and determination of maximum efficiency and its corresponding load.

Single-Phase Induction Motor

Explanation of why it is not self-starting, names of different starting methods, and working principle of a capacitor-run motor.

Series Resonance in RLC Circuits

Deriving expressions for:

Bandwidth

Quality factor (Q)

Lower & upper half-power frequencies

Power Factor Correction

Given an inductive coil, calculating:

Current drawn

Value of capacitance required to achieve unity power factor

Three-Phase Star-Connected Load

Given a balanced load, determining:

Line current

Power factor

Total active power

Total volt-amperes

Phasor diagram

Power Factor Improvement

Definition, reasons for low power factor, and methods to improve it.

DC Shunt Generator & Motor

Calculating speed and torque when the same machine operates as a shunt motor while taking the same power it delivers as a generator.

Maximum Power Transfer Theorem

Statement, proof, and calculation of the load resistor RL for maximum power transfer along with the numerical value of maximum power.

These questions measure deeper problem-solving skills, numerical accuracy, and the ability to derive and apply electrical engineering formulas.