F S2028 Page: 2
Reg No.:_______________ Name:__________________________
APJ ABDUL KALAM TECHNOLOGICAL UNIVERSITY
FIRST SEMESTER B.TECH DEGREE EXAMINATION, DECEMBER 2018
Course Code: EE100
Course Name: BASICS OF ELECTRICAL ENGINEERING
Max. Marks: 100 Duration: 3 Hours
PART A
Answer all questions, each carries 4 marks. Marks
1 Explain Kirchhoff’s voltage and current law with example. (4)
2 Compare electric and magnetic circuits. (4)
3 Calculate the RMS and average values of a purely sinusoidal current having peak (4)
value 15A.
4 What is the phase angle relationship between applied ac voltage and circuit (4)
current in a purely inductive circuit? Prove your answer.
5 What factors are taken in to account while selecting the site for thermal power (4)
plant?
6 Distinguish between primary transmission and secondary transmission. (4)
7 Explain the principle of operation of single phase transformer. (4)
8 What is back e.m.f. concerned with DC motors. Write the voltage equation (4)
representing back emf.
9 Calculate the speed of a 6 pole, 50Hz, 400V 3-phase induction motor when it is (4)
operating at a slip of 2%.
10 With neat diagram, explain the working of split phase induction motor. (4)
PART B
MODULE (1-4)
Answer any four questions, each carries 10 marks.
11 Find current in 100 ohm resistor using node analysis. (10)
Page 1 of 2
F S2028 Page: 2
12 a) A ring shaped electromagnet has an air gap of 6mm and cross sectional area of (6)
12 cm2. The mean length of the core (excluding air gap) is 60cm. Calculate the
mmf required to produce a flux density of 0.4 Wb/m2 in the gap. Take the
relative permeability of the material as 400.
b) Derive the expression for energy stored in a magnetic field. (4)
13 A balanced three phase load consists of three coils each having resistance of 4Ω (10)
and inductance 0.02H. It is connected to a 415V, 50Hz, 3-phase ac supply.
Determine the phase voltage, phase current, power factor and active power when
the loads are connected in (i) star (ii) delta
14 a) A 220V, 50Hz single phase sinusoidal voltage produces a current of 2.2A in a (5)
purely inductive coil. Determine (i) inductive reactance of the coil (ii) inductance
(iii) power absorbed (iv) expression for applied voltage and current.
b) With the help of circuit diagram and phasor diagram derive the relation between (5)
line and phase voltages, and line and phase currents in a balanced delta
connected system.
15 Draw a neat schematic diagram of a Thermal power plant and explain its (10)
operation.
16 Explain about any two types of available Non-conventional energy sources. (10)
MODULE 5
Answer any one full question, each carries 10 marks.
17 a) Explain the construction and working of DC generator. (5)
b) A four pole wave connected armature has 1000 conductors and flux per pole is (5)
0.05wb. Calculate the emf generated when the generator is running at a speed of
1200rpm.
18 A 40 kVA transformer has a core loss of 450W and a full load copper loss of (10)
850W. If the power factor of the load is 0.8, calculate (i) full load efficiency
(ii) maximum efficiency (iii) the load at which maximum efficiency occurs.
MODULE 6
Answer any one full question, each carries 10 marks.
19 Explain the constructional details of squirrel cage and slip ring induction motor (10)
20 With suitable diagrams explain the principle of operation of a capacitor-start (10)
induction motor. Compare it with split-phase motor. Give one application.
****
Page 2 of 2
