Basic Electrical Engineering (3110005)

BE | Semester 1 
  Winter - 2019|11-01-2020
Total Marks 70

Q1 (a) State Ohm’s law and Kirchhoff’s Laws in context with DC circuits.

 Unit : DC Circuits |  Topic : Kirchoff’s current and voltage laws

Q1 (b) A 100V, 60Watt bulb is to be operated from a 220V supply. What is the resistance to be connected in series with the bulb to glow normally ?

 Unit : DC Circuits

Q1 (c) Derive an expression for equivalent resistances of a star connected network to transform into a Delta connected network.

 Unit : DC Circuits |  Topic : analysis of simple circuits with dc excitation

Q2 (a) State Thevenin’s and Norton’s Theorems.

 Unit : DC Circuits |  Topic : Thevenin and Norton Theorems

Q2 (b) Compare series and parallel resonance in ac circuit.

 Unit : AC Circuits |  Topic : Series and parallel resonance

Q2 (c) A single-phase R-L-C circuit having resistance of 8 Ω , inductance of 80mH and capacitance of 100µF is connected across single phase ac 150 V, 50Hz supply. Calculate the current, power factor and voltage drop across inductance and capacitance.

 Unit : AC Circuits |  Topic : Analysis of single-phase ac circuits consisting of R, L, C, RL, RC, RLC combinations (series and par

OR

Q2 (c) Derive an expression for the voltage across the capacitor during charging through the resistor at any instant VC = V  1 - e- t RC   . Assume that RC series circuit is connected across a DC supply of voltage V.

 Unit : DC Circuits |  Topic : Time-domain analysis of first-order RL and RC circuits

Q3 (a) Define the following terms in connection with AC waveforms : - (1) Q-Factor (2) Power Factor (3) Form factor.

 Unit : AC Circuits |  Topic : Representation of sinusoidal waveforms

Q3 (b) Draw impedance triangle, Voltage triangle, Power triangle for single phase R-L series circuit.

 Unit : AC Circuits |  Topic : Analysis of single-phase ac circuits consisting of R, L, C, RL, RC, RLC combinations (series and par

Q3 (c) Derive the relationship between Phase and Line values of voltages and currents in case of 3-phase Star- connection.

 Unit : AC Circuits |  Topic : Three phase balanced circuits

Q3 (a) Define the terms: - 1. Real power 2. Reactive power 3. Apparent power.

 Unit : AC Circuits

Q3 (b) Derive the EMF equation of single-phase transformer.

 Unit : Transformers |  Topic : Construction and working principle of single phase and three phase transformers

Q3 (c) With neat circuit diagram and a phasor diagram prove that two-watt meters are sufficient to measure total power in 3-phase system.

 Unit : AC Circuits |  Topic : Power measurement in three phase circuits

Q4 (a) Explain working principle of single-phase Transformer.

 Unit : Transformers |  Topic : Construction and working principle of single phase and three phase transformers

Q4 (b) Give Merits, Demerits and Applications of Induction Motor.

 Unit : Electrical Machines

Q4 (c) Explain in detail the construction of an Alternator.

 Unit : Electrical Machines |  Topic : Construction and working of Synchronous generators

OR

Q4 (a) Explain working principle of D.C. Motor.

 Unit : Electrical Machines |  Topic : Construction and working of Separately excited DC motor

Q4 (b) Compare poly phase Induction Motor and single-phase Induction Motor.

 Unit : Electrical Machines

Q4 (c) Explain Generation of Rotating Magnetic Field in 3-phase Induction Motor with diagrams and equations.

 Unit : Electrical Machines |  Topic : Generation of rotating magnetic fields.

Q5 (a) Classify different types of cables with reference to voltage and insulation materials.

 Unit : Electrical Installations |  Topic : Types of Wires and Cables

Q5 (b) Explain the terms : - 1. Residual magnetism 2. Coercive Force.

 Unit : Transformers

Q5 (c) Explain the process of charging and discharging of Lead acid cell.

 Unit : Electrical Installations |  Topic : Types of Batteries, Important Characteristics for Batteries

OR

Q5 (a) Compare MCB and ELCB.

 Unit : Electrical Installations |  Topic : Components of LT Switch gear:

Q5 (b) Write safety precautions for electrical appliances.

 Unit : Electrical Installations |  Topic : Safety precautions for electrical appliances

Q5 (c) Explain different methods of power factor improvement.

 Unit : Electrical Installations |  Topic : Basics of power factor improvement.