BASIC ELECTRICAL ENGINEERING 2022

INTRODUCTION TO ELECTRICAL ENGINEERING

[22ESC142]

QUESTION BANK
(only 2-units)

DEPARTMENT OF EEE,DSCEPage 1
 BASIC ELECTRICAL ENGINEERING 2022

Sl. Questions Marks COs BL

No
UNIT-1
1 Explain the conventional and non-conventional energy 10 CO1 2,5
sources
2 List Advantages and disadvantages of conventional energy 08 CO1 1,4
sources
3 Advantages and disadvantages of non-conventional energy 08 CO1 1,4
sources
4 With aid of single line diagram explain the general structure 08 CO1 2,5
of electrical power system
5 Explain Solar power generation with neat block diagram 10 CO1 2,5
6 Explain Wind power generation with neat block diagram 10 CO1 2,5
7 Explain Hydel power generation with neat block diagram 10 CO1 2,5
8 Explain Nuclear power generation with neat block diagram 10 CO1 2,5
9 State and explain Ohm’s law 06 CO1 2,5
10 State and explain Kirchhoff’s law 06 CO1 2,5
11 Illustrate the equivalent resistance of two resistors 06 CO1 2
connected in series is the sum of two resistance value.
12 Illustrate the equivalent resistance of two resistors 06 CO1 2
connected in parallel is the ratio of product of these two
resistances divided by the sum of those two-resistance
value.
13 A circuit consists of two parallel resistors of 20 Ω and 30 Ω 08 CO1 4
respectively, connected in series with 15 Ω. If the current
through 15 Ω resistor is 3A, determine (i) current in 20 Ω
and 30 Ω resistors, (ii) voltage across the whole circuit, (iii)
the total power consumed in all resistances.
14 A current of 20A flows through 2 ammeters A & B in series. 08 CO1 4
The potential difference across A is 0.2V & across B is
0.3V. Determine how the same current will divide between
A&B when they are in parallel.
15 A circuit consisting of three resistors 12Ω, 18Ω,36Ω 06 CO1 4
respectively joined in parallel is connected in series with a
fourth resistance. The whole circuit is supplied at 60V and it
is found that the power dissipated in the 12Ω resistor is
36W. determine the fourth resistance and the total power
dissipated in the group.
16 In a parallel resistive circuit resistors 8ohm,40-ohm,25 ohm 06 CO1 4
and X ohm are connected in parallel. The current in 8-ohm
resistor is 2.5A. The current entering the circuit is 4A.
Determine (i) current in other resistors (ii)resistor X (iii) the
equivalent resistance.
17 A 8-ohm resistor is in series with a parallel combination of 08 CO1 4
two resistors 12-ohm and 6-ohm .If the current in the 6-ohm
resistor is 5A, determine the total power dissipated in the
circuit.

DEPARTMENT OF EEE,DSCEPage 2
 BASIC ELECTRICAL ENGINEERING 2022

UNIT-2
1 Sketch the sinusoidal AC waveform and define the 06 CO1 1
following terms: (1) Time period (2) frequency (3)
amplitude (4) phase (5) phase difference
2 Sketch the sinusoidal alternating current waveform and 06 CO1 1
define the following :(i) Frequency (ii) Average value (iv)
RMS value (v)Form Factor (vi)peak factor
3 Define the following: (1) Voltage (2) current (3) amplitude, 10 CO1 1
(4) phase, (5) phase difference (6), average value (7), RMS
value, (8) form factor (9) peak factor (10) power
4 Justify that a pure Inductor does not consume any power 06 CO1 5
5 Justify that a pure Capacitor does not consume any power 06 CO1 5
6 Illustrate with suitable circuit, phasor diagram and 06 CO1 2
waveforms, that a pure inductor does not consume power
7 Illustrate with suitable circuit, phasor diagram and 06 CO1 2
waveforms, that a pure resistor power is P=VI
8 Illustrate with suitable circuit, phasor diagram and 06 CO1 2
waveforms, that a pure capacitor does not consume power
9 Justify that power consumed in an R-C series circuit is 10 CO1 5
VIcosφ. Draw the waveform for voltage, current and power.
10 Justify that power consumed in an R-L series circuit is 10 CO1 5
VIcosφ. Draw the waveform for voltage, current and power.
11 Justify that the power consumed in an RLC series circuit is 08 CO1 5
VIcosФ. Draw phasor for each case.
12 Draw the power triangle and define the following terms 08 CO1 1
w.r.t AC circuits: (i) True power(ii)Apparent
power(iii)Reactive power.

13 Define phase sequence and list out the advantages of three 06 CO1 1
phase system as compared to single phase system.
14 Illustrate the relationship between the line and phase values 08 CO1 2
of voltage and current in a three phase, delta connected
circuit with relevant phasor diagram and circuit diagram
15 List the advantages of 3-φ systems over a single phase 06 CO1 1
system
16 Illustrate the relationship between the line and phase values 08 CO1 2
of voltage and current in a three phase, star connected
circuit with relevant phasor diagram and circuit diagram
17 Elaborate the difference between balanced and unbalanced 06 CO1 6
3Ф AC system.

18 The instantaneous values of the voltage across a two 06 CO2 5

element series circuit and the current through it is given by v
= 282 sin (314t + 300) volts and i = 7.05 sin (314t - 300)
amps. Determine a) Impedance b) Circuit elements c) power
and d) power factor.
19 A voltage of 200V is applied to a series circuit consisting of 08 CO2 5
a resistor, an inductor and a capacitor. The respective

DEPARTMENT OF EEE,DSCEPage 3
 BASIC ELECTRICAL ENGINEERING 2022
voltages across these components are 170V, 150V, 100V
and the current is 3A. Determine (i) the power factor (ii)
resistance (iii) impedance (iv) inductive reactance and
capacitive reactance.
20 A circuit consisting of a resistance of 10 ohms and an 05 CO2 5
inductance of 12mH and a capacitance of 8µF all in series.
A voltage of 150V at 50Hz is applied across the
combination. Determine i) Impedance ii) current iii) power
and iv) power factor
21 A coil of resistance 10Ω and inductance 0.1 H is connected 08 CO2 5
in series with a 150 µF capacitor across a 200V, 50 Hz
supply. Determine the voltage across the coil and the
capacitor respectively.
22 A series RLC circuit is composed of 100Ω resistance ,1H 08 CO2 5
inductance and 5µF capacitance. A voltage
v(t)=1414.4cos(377t) V is applied to the circuit. Determine
the current and voltages of each element of the circuit.
23 The equation of an alternating current is given by 06 CO2 5
i=42.42sin628t , determine its (i)maximum value
(ii)frequency(iii)RMS value (iv)average value (v)Form
factor .
24 An inductor coil is connected to a supply of 250V, at 50Hz 06 CO2 5
and takes current of 4A. The coil dissipates
725W.Determine power factor, resistance and inductance of
the coil.
25 Given v=200sin(377t) volts , i=8sin(377t-30)A for an AC 08 CO2 5
circuit , determine (i)power factor (ii)active power
(iii)reactive power(iv)apparent power.
26 The equation of an alternating current is given by 06 CO2 5
i=42.42sin628t , determine its (i)maximum value
(ii)frequency(iii)RMS value (iv)average value (v)Form
factor .
27 A 50Ω resistor is connected in series with an inductive 06 CO2 5
reactance of 70Ω to a 240V, 50Hz supply, determine (i)
current through resistor and inductance, (ii) supply current,
(iii) circuit phase angle. Draw the phasor diagram
28 A circuit consists of a resistance of 25Ω and a capacitance 08 CO2 5
of 100µF connected in series. A supply of 200V at 50Hz is
applied across the circuit. Determine the current, power
factor and power consumed by circuit. Draw the vector
diagram.

29 The three arms of a three phase load each comprise of an 08 CO2 5

inductor of resistance of 25Ω, and of inductance 0.15H, in
series with a 120µF capacitor. The supply voltage is 415V,
50Hz. Determine the line current, and total power in watts,
when the 3 arms are connected in delta
30 A balanced 3-φ star connected load of 150kW takes a 06 CO2 5
leading current of 100A, with a line voltage of 1100V,

DEPARTMENT OF EEE,DSCEPage 4
 BASIC ELECTRICAL ENGINEERING 2022
50Hz. Determine the circuit constants of the load per phase
A 3ф, 230V, supply is given to balanced load which is Δ 06 CO2 5
connected. Impedance in each phase of the load is (8+j6) Ω.
Determine the phase current and the total power consumed?
31 The 3 arms of a 3φ load each comprise of an inductor of 08 CO2 5
resistance 20Ω and of inductance 0.10H in series with a
125µF capacitor. The supply voltage is 415V, 50Hz.
Determine the line current and total power in watts, when
the three arms are connected in star?
32 A balanced star connected load of (8+6j) Ω per phase is 10 CO2 5
connected to a 3Ф 230V supply. Determine the line current,
power factor, power, reactive volt-ampere and total VA.
33 A 3Ф delta connected load consumes a power of 60KW 06 CO2 5
taking a lagging current of 200A at a line voltage of 400V,
50Hz. Determine the parameters of each phase. What would
be power consumed, if the load were connected in star.
34 Three similar choking coils each having resistance 10Ω and 06 CO2 5
reactance 10Ω are connected in star across a 440V,3Ф
supply. Determine line current, power factor and power
consumed
35 A 3Ф, Y-connected supply with a phase voltage of 230v is 06 CO2 5
supplying a balanced delta load. The load draws 15KW at
0.8 p.f. lagging. Determine the line currents and the current
in each phase of the load .Also find load impedance per
phase
36 The 3 arm of a 3Ф load comprise of an inductor of 08 CO2 5
resistance 20Ω and of inductance 0.10H in series with a
125µF capacitor. The supply voltage is 415V,50Hz.
Evaluate the Phase current , line current and total power in
watts , when the three arms connected in Delta.
37 A Y-connected load consists of 6Ω resistance and 8Ω 06 CO2 5
inductive reactance in each phase. A supply of 440V at
50Hz is applied to the load. Determine the line current, P.f.
and power consumed by the load.

DEPARTMENT OF EEE,DSCEPage 5
 BASIC ELECTRICAL ENGINEERING 2022

UNIT-3: DC Machines
Sl. No Questions Mark COs BL
s
1 State and explain Faraday’s laws of electromagnetic 06 3 5,2
induction.
2 Explain the working principle of a DC Machine as a 10 3 5,2
generator and motor with suitable diagrams.
3 With neat sketch, explain the construction of a DC machine 10 3 5,2
4 Develop the expression for emf generated in a DC generator. 06 3 4,6
5 Explain the concept of back EMF and its significance 06 3 5,2
6 Explain the classification of DC motors 04 3 2
7 Sketch and explain the various characteristics of DC shunt 10 3 5,2
motor and series motor and also mention their applications
8 Define Torque and develop the expression for armature 10 3 4,6
torque developed in a DC motor
9 List the applications of the following motors. (i) DC shunt 04 3 4,6
motor, (ii) DC series motor

10 An 8 pole generator has 400 armature conductors and has a 10 4 5

useful flux per pole of 0.065Wb. Determine the e.m.f
generated if it is lap connected and runs at 1000rpm and also
evaluate the speed at which it is to be driven to produce the
same e.m.f if it is wave wound.
11 A 6 pole DC generator has a lap connected armature with 06 4 5
480 conductors. The resistance of the armature circuit is
0.02Ω. With an output current of 500A from the armature,
the
terminal voltage is 230V when the machine is driven at
900rpm.Determine the useful flux per pole.
12 A four pole generator having wave-wound armature winding 10 4 5
has 51 slots, each slot containing 20 conductors. Determine
the voltage generated in the machine when driven at 1500
rpm assuming the flux per pole to be 7.0 mWb
13 An 8-pole d.c. generator has 500 armature conductors, and a 10 4 5
useful flux of 0.05 Wb per pole. Determine the e.m.f.
generated if it is lap-connected and runs at 1200 rpm and also
determine the speed at which it is to be driven to produce the
same e.m.f. if it is wave-wound.

14 A 220V series motor is taking a current of 30A. Resistance 10 4 5

of armature 0.5 Ω, resistance of series field is 0.25 Ω.
Determine (i) voltage at the brushes (ii) back emf (iii) power
wasted in armature (iv)power wasted in series field.
15 A 4 pole DC shunt motor takes 22A from 220V supply. The 10 4 5
armature and the field resistances are 0.5 Ω and 100Ω

DEPARTMENT OF EEE,DSCEPage 6
 BASIC ELECTRICAL ENGINEERING 2022
respectively. The armature is lap connected with 300
conductors. If the flux per pole is 20mWb, determine the
speed and gross torque.
16 A 120V D.C. shunt motor has an armature resistance of 0.2Ω 10 4 5
and shunt field resistance of 60Ω. It turns at 1500rpm, when
it takes full load current of 30A. Determine the speed of the
motor while it is operating at half the full load.
17 A 200V, 4 pole, lap wound dc shunt motor has 600 10 4 5
conductors on its armature. The resistance of the armature
winding is 0.5Ω and shunt field winding is 200Ω. The motor
takes a current of 21A, the flux per pole is 30mWb,
Determine the speed and gross torque developed in the motor
18 A 440V dc shunt motor takes an armature current of 20A and 10 4 5
runs at 500rpm. The armature resistance is 0.6Ω. If the flux is
reduced by 30% and torque is increased by 40%.
Determine the new values of armature current and speed.
19 A 20kW, 200V dc shunt motor has armature and field 10 4 5
resistances of 0.05 ohm and 100 ohms respectively.
Determine the total power developed by the armature when it
delivers full output power.
20 A D.C series motor running with a speed of 1000rpm, while 10 4 5
taking a current of 22amp from the supply. If the load is
changed such that the current drawn by the motor is
increased
to 55amp, determine the speed of the motor on new load. The
armature and series winding resistances are 0.3ohm and
0.4ohm respectively. Assume supply voltage as 250V.
21 A DC series motor connected to a connected to a 440V 10 4 5
supply runs at 600rpm when taking a current of 50A.
Determine the value of resistor which when inserted in series
with the motor will reduce the speed to 400rpm, the gross
torque being than half its previous value. Resistance of motor
is 0.2Ω. Assume the flux to be proportional to the field
current.
22 A series motor takes 20A at 400V and runs at 250rpm.The 10 4 5
armature and field resistance are 0.6Ωand 0.4Ω. Determine
the applied voltage and current to run the motor at 350rpm, if
the torque is required varies as the square of the speed.
23 A 4-pole DC shunt motor working on 250V takes a current of 10 4 5
2A when running light (i.e., no-load) at 1000rpm. Armature
resistance and shunt field resistance are 0.2Ω and
250Ω.Determine (1) Back EMF generated (2) Back EMF and
speed if the motor takes 51A at a certain load.

DEPARTMENT OF EEE,DSCEPage 7