Download VTU ((Visvesvaraya Technological University) B.E/B-Tech 2019 July ( Bachelor of Engineering) First & Second Semester (1st Semester & 2nd Semester) 15 Scheme 15ELE15 Basic Electrical Engineering Question Paper
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irstisetond Semester B.E. Degree Examination, June/July 2019
Basic Electrical Engineering
Time: 3 hrs. Max. Marks: 80
Note: Answer any FIVE full questions, choosing
ONE full question from each module.
Module-1
? =
1 a. State Kirchhoff s laws. For the circuit shown in Fig.Q1(a) if
V
a
= 60V, Vb = 20V, R
a
= 200, Rh = 50. Find V, the voltage across K.
gi-
ct
4
?
t .
4)
=
Fig.Q 1(a)
b. Explain statically and dynamically induced EMF's. (04 Marks)
c. Two identical coils of 1200 turns each are placed side by side such that 60% of flux
produced by coil links the other. A current of 10Amps in first coil sets up a flux of 0.12milli
webers. If current in first coil changes from 10 Amps to ?10 Amps in 20 milli seconds. Find :
i) Self inductance of coils
ii) The E.M.F's induced in both the coils. (05 Marks)
OR
2 a. For the circuit shown in Fig. Q2(a). i) Find `IZ' ii) current through an resistance iii) power
supplied by source if power dissipated in 400 is 160 watts. (06 Marks)
2?p A--
I C
0
"
Fig.Q2(a)
b. State Lenz's law and Flemings left hand rule. (04 Marks)
c. For the circuit shown if Fig. Q2(c). Find voltage across AB i) with switch `S' open ii) with
switch 'S' closed. (06 Marks)
QD?i
Fig.Q2(c)
of3
(07 Marks)
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15ELE15/25
1114111111
' TCSociet
y
.,
cHlgoni
n t E .0- ??
irstisetond Semester B.E. Degree Examination, June/July 2019
Basic Electrical Engineering
Time: 3 hrs. Max. Marks: 80
Note: Answer any FIVE full questions, choosing
ONE full question from each module.
Module-1
? =
1 a. State Kirchhoff s laws. For the circuit shown in Fig.Q1(a) if
V
a
= 60V, Vb = 20V, R
a
= 200, Rh = 50. Find V, the voltage across K.
gi-
ct
4
?
t .
4)
=
Fig.Q 1(a)
b. Explain statically and dynamically induced EMF's. (04 Marks)
c. Two identical coils of 1200 turns each are placed side by side such that 60% of flux
produced by coil links the other. A current of 10Amps in first coil sets up a flux of 0.12milli
webers. If current in first coil changes from 10 Amps to ?10 Amps in 20 milli seconds. Find :
i) Self inductance of coils
ii) The E.M.F's induced in both the coils. (05 Marks)
OR
2 a. For the circuit shown in Fig. Q2(a). i) Find `IZ' ii) current through an resistance iii) power
supplied by source if power dissipated in 400 is 160 watts. (06 Marks)
2?p A--
I C
0
"
Fig.Q2(a)
b. State Lenz's law and Flemings left hand rule. (04 Marks)
c. For the circuit shown if Fig. Q2(c). Find voltage across AB i) with switch `S' open ii) with
switch 'S' closed. (06 Marks)
QD?i
Fig.Q2(c)
of3
(07 Marks)
15ELE15/2
Module-2
3 a. Derive Torque equation for a DC motor (04 Marks)
b. Explain with neat diagram the constructional features and operation of an induction type
single phase energy meter. Show that revolution of disc is proportional to energy consumed.
(06 Marks)
c. A 40 KW long shunt compound generator supplies full load current at a load voltage of
400V. The shunt and series field resistances are 10052 and 0.0552 respectiv ely.
Find :
i) Load resistance ii) armature current iii) induced EMF. (06 Marks)
OR
4 a. A 4-pole DC shunt motor working on 250 volts takes a current of 2 amperes when running
at 1000 RPM_ What will be its back EMF, speed if motor takes 51A at certain load?
Armature and shunt field resistances are 0.2Q and 2500 respectively. (06 Marks)
b. Derive EMF equation of a DC generator. (06 Marks'
c. Explain the significance of back EMF and necessity of a starter for a DC motor. (04 Marksr
Module-3
5 a. For circuit shown in Fig.Q5(a) find current in all branches. Draw vector diagram. (06 Marks)
2
00
v
)
Co Hi
5
--
Fig.Q5(a)
b. With neat diagram, explain plate Earthing. (05 Marks)
c. Derive the expression for average power consumed in an R- L series circuit. (05 Marks'
6 a.
b.
c.
OR
Derive RMS value for sinusoidal voltage with definition. (05 Marks)
With suitable circuit diagrams table the operations of two way control of lamps. (05 Marks)
A certain takes a current of (-5 + j10) amperes when applied voltage is (50 + j200) volts. If
the frequency of the supply is 50Hz, Find :
i) Circuit elements ii) apparent power iii) reactive power iv) power factor. (06 Marks)
Module-4
7 a. Show that with necessary circuit and vector diagram the two wattmeters used to measure
power reads equal in a 3-phase balanced star connected purely resistive load. (06 Marks)
b. Derive the EMF equation of an 3 ? phase synchronous generator. (04 Marks)
c. Three identical resistors are connected in star across 400V, 50Hz AC supply. The line
current is lOAmps. Find power consumed when resistors are reconnected in delta with line
current remaining the same.
--:;)
1. 46
o rs
Marks)
:
1
;?s
sl
LIBRAR
FirstRanker.com - FirstRanker's Choice
15ELE15/25
1114111111
' TCSociet
y
.,
cHlgoni
n t E .0- ??
irstisetond Semester B.E. Degree Examination, June/July 2019
Basic Electrical Engineering
Time: 3 hrs. Max. Marks: 80
Note: Answer any FIVE full questions, choosing
ONE full question from each module.
Module-1
? =
1 a. State Kirchhoff s laws. For the circuit shown in Fig.Q1(a) if
V
a
= 60V, Vb = 20V, R
a
= 200, Rh = 50. Find V, the voltage across K.
gi-
ct
4
?
t .
4)
=
Fig.Q 1(a)
b. Explain statically and dynamically induced EMF's. (04 Marks)
c. Two identical coils of 1200 turns each are placed side by side such that 60% of flux
produced by coil links the other. A current of 10Amps in first coil sets up a flux of 0.12milli
webers. If current in first coil changes from 10 Amps to ?10 Amps in 20 milli seconds. Find :
i) Self inductance of coils
ii) The E.M.F's induced in both the coils. (05 Marks)
OR
2 a. For the circuit shown in Fig. Q2(a). i) Find `IZ' ii) current through an resistance iii) power
supplied by source if power dissipated in 400 is 160 watts. (06 Marks)
2?p A--
I C
0
"
Fig.Q2(a)
b. State Lenz's law and Flemings left hand rule. (04 Marks)
c. For the circuit shown if Fig. Q2(c). Find voltage across AB i) with switch `S' open ii) with
switch 'S' closed. (06 Marks)
QD?i
Fig.Q2(c)
of3
(07 Marks)
15ELE15/2
Module-2
3 a. Derive Torque equation for a DC motor (04 Marks)
b. Explain with neat diagram the constructional features and operation of an induction type
single phase energy meter. Show that revolution of disc is proportional to energy consumed.
(06 Marks)
c. A 40 KW long shunt compound generator supplies full load current at a load voltage of
400V. The shunt and series field resistances are 10052 and 0.0552 respectiv ely.
Find :
i) Load resistance ii) armature current iii) induced EMF. (06 Marks)
OR
4 a. A 4-pole DC shunt motor working on 250 volts takes a current of 2 amperes when running
at 1000 RPM_ What will be its back EMF, speed if motor takes 51A at certain load?
Armature and shunt field resistances are 0.2Q and 2500 respectively. (06 Marks)
b. Derive EMF equation of a DC generator. (06 Marks'
c. Explain the significance of back EMF and necessity of a starter for a DC motor. (04 Marksr
Module-3
5 a. For circuit shown in Fig.Q5(a) find current in all branches. Draw vector diagram. (06 Marks)
2
00
v
)
Co Hi
5
--
Fig.Q5(a)
b. With neat diagram, explain plate Earthing. (05 Marks)
c. Derive the expression for average power consumed in an R- L series circuit. (05 Marks'
6 a.
b.
c.
OR
Derive RMS value for sinusoidal voltage with definition. (05 Marks)
With suitable circuit diagrams table the operations of two way control of lamps. (05 Marks)
A certain takes a current of (-5 + j10) amperes when applied voltage is (50 + j200) volts. If
the frequency of the supply is 50Hz, Find :
i) Circuit elements ii) apparent power iii) reactive power iv) power factor. (06 Marks)
Module-4
7 a. Show that with necessary circuit and vector diagram the two wattmeters used to measure
power reads equal in a 3-phase balanced star connected purely resistive load. (06 Marks)
b. Derive the EMF equation of an 3 ? phase synchronous generator. (04 Marks)
c. Three identical resistors are connected in star across 400V, 50Hz AC supply. The line
current is lOAmps. Find power consumed when resistors are reconnected in delta with line
current remaining the same.
--:;)
1. 46
o rs
Marks)
:
1
;?s
sl
LIBRAR
15ELE15/25
OR
8 a. A 3 ? phase star connected alternator on open circuit is required to generate a line voltage of
3600V, 50Hz when driven at 500 RPM. The stator has 3 slots/pole/phase and 10
conductors/slot. Calculate useful flux/pole by assuming full pitched coils. (07 Marks)
b. A certain 3?phase load takes 20KW at 25 KVA. Find the reading of two wattmeters to
measure power. (04 Marks)
c. With neat diagram, explain the construction and working of salient pole alternator.(05 Marks)
Module-5
9 a. Derive the EMF equation of a single-phase transformer. (04 Marks)
b. Derive the condition for maximum efficiency and define voltage regulation for a single
phase transformer. (06 Marks)
c. The EMF in the stator of an 8-pole induction motor has a frequency of 50Hz and that of
rotor is 1.5Hz. Find the speed of the rotor and slip. (06 Marks)
OR
10 a. With neat diagram, explain the star-delta starter for an 3-phase induction motor. (05 Marks)
b. A transformer has a maximum efficiency of 98% at three?fourth load and unity power
factor. The copper loss at this load is 314 watts. Compute the efficiency of transformer at
80% load with same power factor. (07 Marks)
c. Explain the working of an squirrel cage induction motor with neat diagrams. (04 Marks)
3 of 3
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This post was last modified on 01 January 2020