Vocational Training Center
FINAL EXAM–EELW
PRACTICAL
Academic Year:2017-2018
Course Title: Basic Electricity(AC/DC) & Electrical Code
Semester : 2 Year : 1
Course code: EELIW1102
Student name :
ID :
Section No :
Marking Code :
Instructions for the students:
1)
2)
3)
4)
5)
6)
7)
8)
Your students ID cards should be placed on the table
This exam paper consists ( 7 ) pages including the front page.
Time allowed is TWO hours ( 3 hours ) .
Blue and black PEN ONLY is allowed for answering the questions. Pencils shall be used for diagrams,
Problem solving and program writing purposes only.
Dictionary or any electronics gadgets are not allowed.
Switch off your mobile phones.
Exchanging or sharing of resources is prohibited.
Calculators are allowed to be used.
Total Marks Allocated
Total Marks Scored
Remarks
100
Marked by:.........................................
Checked by:........................................
Signature:...........................................
Signature:...........................................
Date :...................................................
Date :...................................................
PART A -1PHASE HALF CONTROLLED RECTIFIER
APPARATUS REQUIRED
Sl.No
1.
2.
3.
4
5.
5.
6.
APPARATUS
AC Power Supply
SCR BT151
Variable Resistor
Resistor
Capacitor
DSO
DMM
RANGE
(0-30)V
-----(0-500) Ω
5KΩ
4.7µf
-------
QTY
1
1
1
1
1
1
1
CIRCUIT DIAGRAM:-
VS=Input Supply Voltage.
PROCEDURE:
1. Connect the circuit as shown in the figure.
2. Draw Input Wave form and Out wave at firing angle 36 degree,72 degree by using DSO.
3. Register output voltage at different firing angle by using DMM and write to the table.
4.Calcuate Vaveage,I average and Vrms and Irms by using calculation and write in tabulation.
TABULATION:
Sl.No
1
INPUT VOLTAGE
OUTPUT VOLTAGE
FIRING ANGLE 36
DEGREE(In Practical)
Vav
Vrms
OUTPUT VOLTAGE FIRING
ANGLE 72 DEGREE(In
Practical)
Vav
Vrms
5V
Sl.No
INPUT VOLTAGE
OUTPUT VOLTAGE
FIRING ANGLE 36
DEGREE(In Calculation)
Vav
1
5V
Manual Calculation:-
Vav= (Vm/2π)*(1+cosα)
Iav = Vav/RL
VRMS=(Vm/2√π)((π-α)+0.5sin2α)0.5
IRMS= VRMS/R
a) At Firing angle 36 degree
a) At Firing angle 72 degree
Vrms
OUTPUT VOLTAGE FIRING
ANGLE 72 DEGREE(In
Calculation)
Vav
Vrms
PART B –3Phase Half Uncontrolled Rectifier
APPARATUS REQUIRED
Sl.No
1.
2.
3.
4.
Apparatus
AC Power Supply
Resistance
Inductor
Oscilloscope
Qty
1
1
1
1
Range
(0-100)V
100Ω
1.3H
CIRCUIT DIAGRAM:
Procedure:
1. Connect the circuit at the figure.
2. By use Oscilloscope device find the following:
A. Complete the empty of the following table:
TABULATION
Sl.No
1
INPUT VOLTAGE
20V
VR
VL
DRAW THE PHASE SHIFT DIAGRAM OF THE CIRCUIT(VR,VL)
Draw Voltage Phasor Diagram
CALULATION:1. Find Power Factor
2. The current through in Circuit (I)
3. Total Impedance
PART C -THEVENIN THEOREM-PRACTICAL
APPARATUS REQUIRED
Sl.No
1.
2.
3.
4.
Apparatus
DC Power Supply
DC Voltmeter
DC Ammeter
Resistance
Range
(0-30)V
(0-100)V
(0-5)Amps
100Ω, 330Ω,1000Ω
CIRCUIT DIAGRAM:-
VS=Input Supply Voltage.
PROCEDURE:
1. Connect the circuit at the figure.
2. By using Thevenin theorem Determine Load current and draw Thevenin equivalent circuit
3. Register measurements to table.
4. Determine the current throw resistance RL.
Thevenin’s EQUIVELENTS CIRCUIT
IL=
TABULATION:
Sl.No
INPUT VOLTAGE
1
2
VTH
10V
15V
Manual Calculation
Result:Il(Manual)=
Il(Practical)=
ASSESSMENT CRITERIA
RTH
IL
ID NO
Student Name:Allotted
Marks
OBSERVATION
A.SAFETY
1.
2.
Did the student wear proper during the
exam ?
Did the student use the tools and
instrument safety ?
B. WORK HABIT
5
5
(80)
Norton’s Equivalent Circuit
5
2.
Manual Calculation
5
Circuit connection
10
4.
Tabulation
5
1.
Circuit Connection and Procedure
5
2.
Tabulation
5
Graph and usage of Oscilloscope
10
4.
Phasor Diagram
5
5.
Calculation
5
1.
Thevenin’s Equivalent Circuit
5
2.
Manual Calculation
5
Circuit connection
10
Tabulation
5
3.
3.
PART A
PART B
PART C
4.
(5)
C.ACCURACY
1.
Read accuracy of Instruments
5
D.TIME OF COMPLETION
1.
Did the student finish the work on time ?
TOTAL
Total
(10)
1.
3.
Earned
Marks
(5)
5
100