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LABORATORY MANUAL Basic Electrical Engineering
Laboratory
Department of Instrumentation Engineering
JORHAT ENGINEERING COLLEGE Assam-785007
Do’s
Ø Be punctual, maintain discipline & silence. Ø Keep the Laboratory clean and tidy. Ø Leave your shoes in the rack outside. Ø Handle the equipment carefully. Ø Save all your files properly. Ø Come prepared with programs/algorithms/related manuals. Ø Follow the procedure that has been instructed. Ø Get the signature on experiment result sheet daily. Ø For any clarification contact faculty/staff in charge only. Ø Log off the system properly before switching off .
Don’ts
Ø Avoid unnecessary chat or walk. Ø Disfiguring of furniture is prohibited. Ø Avoid using cell phones unless absolutely necessary. Ø Do not use personal pen drives without permission. Ø Do not displace monitor, keyboard, mouse etc. Ø Avoid late submission of laboratory reports.
EE102 BEE LABORATORY Semester I
L-T-P 0-0-2
1 CREDIT
Experiment No.
Title of the Experiment Objective of the Experiment
1 Calibration of Ammeter
To compare the readings of an Ammeter (M.C. or M.I.) with those of a substandard one and hence to draw the (a) Calibration curve (b) Correction Curve
2 Calibration of Voltmeter To compare the readings of a voltmeter (M.C. or M.I.) with those of a substandard one and hence to draw the a) Calibration curve (b) Correction Curve
3 Calibration of milli-voltmeter as Ammeter
To calibrate a millivoltmeter as an ammeter with the help of a substandard ammeter and hence to draw the, (a) Calibration curve (b) Correction Curve
4 Verification of Thevenin’s Theorem
To verify the Thevenin’s Theorem with the help of an electronic trainer.
5 Verification of Maximum Power Transfer Theorem
To verify the Maximum Power Transfer Theorem with the help of an electronic trainer.
6 Power and Power Factor (Cos Φ) in a single phase R-L series circuit. (3 voltmeter Method)
To measure the power dissipated in a single phase R-L circuit and to calculate power and also to draw phasor diagram for each reading and have to find the value of power factor from it.
7 Power and Power Factor in a single phase R-L Parallel circuit.
To measure the power dissipated in a single phase R-L parallel circuit and to calculate power factor (Cos Φ) by three ammeter method.
8 Measurement of Power and power factor by wattmeter.
To measure the power dissipated in a single phase R-L circuit with the help of a wattmeter and find power factor by measuring the voltage and current in the circuit.
Text book
Ø Electrical Machines, D P Kothari and R J Nagrath
Student Profile Name Roll Number Department Year
Student Performance Sl. No. Title of the Experiment Remarks
1 Calibration of Ammeter
2 Calibration of Voltmeter
3 Calibration of milli-voltmeter as Ammeter
4 Verification of Thevenin’s Theorem 5 Verification of Maximum Power Transfer
Theorem
6 Power and Power Factor (Cos Φ) in a single phase R-L series circuit. (3 voltmeter Method)
7 Power and Power Factor in a single phase R-L Parallel circuit.
8 Measurement of Power and power factor by wattmeter.
Office Use Checked and found ………………………………………………… Grade/ Marks ………………………………………………… Signature ……………………………………………………
Experiment No: 1(a)
Title: Calibration of Ammeter
Roll No. of the Student:
Date of the Experiment:
Objective: To compare the readings of an Ammeter (M.C. or M.I.) with those of a substandard one and hence to
draw the
(a) Calibration curve
(b) Correction Curve
Circuit Diagram:
AA +-+-
+
-
0-3 A0-3 A
Lamp
Board
35 Ω, 5A
220 V
DC
Supply
List of Apparatus:
Sl. No. Item Range Make Maker’s No
Experimental Observation:
Sl.
No.
Reading of Error
AT-AS
Correction
= - Error Ammeter under test (AT) Substandard Ammeter AS
Report:
i. Draw the Calibration and Correction Curve (AT vs AS) and (AT vs Correction)
ii. What are the various errors in the moving coil and moving iron instruments?
iii. What do you mean by substandard instrument?
_________________________
Signature of the class teacher
Theory:
The various types of measuring standards are given below,
International Standard: These standards are defined by an international agreement. The standards are accurate to
the extent the production and measurement technology of the time allowed. These are periodically evaluated
by absolute measurement in terms of fundamental units. These international standards are kept and
maintained at International Bureau of Weights and Measures at Paris. These are not available to ordinary
users for the purpose of calibration.
Primary/ Basic standards: National standards laboratories are responsible for keeping in maintaining the primary
standards. The primary standards are independently by absolute measurements at each of the national
laboratories. The result of measurements at various national laboratories are compared amongst themselves.
This brings out an average figure for primary standards all over the world. These are available for calibration
purpose outside the national laboratories. However the basic purpose of maintaining the primary standards
remains the verification/ calibration of secondary standards.
Secondary Standards: These are calibrated with the primary standards. They are maintained by involved
industries. They are sent to national laboratories for calibration and certify periodically.
Working standards: These are used to further calibrate the instruments which are made for the users. These types
of standards can be named as sub-standards.
The need of calibration arises out of two reasons. First, because of continuous use of laboratories/
industries any instrument may develop some fault/ detect due to which it start giving wrong results. Second,
the instrument is tested for its quality at the time of procurement. By calibration we mean to record the
actual value of the quantity under measurement (by sub-standard meter) and the value given by the meter
under test. If the two reading are same to the accuracy desired, then the meter under test can be taken is
correct, otherwise, calibration and correction curve are plotted as an outcome calibration.
Procedure: The following procedures may be adopted for calibration of ammeter.
1. Connect the circuit as shown in the figure.
2. Keep the lamp load in off position and also keep the rheostat to its maximum position.
3. Both the meter should be zero initially and then switch-on the supply.
4. Switch on the lamps in steps till the end of the scale of the test ammeter. If full scale not covered then adjust
the rheostat.
5. Note down readings in both the meters by switching off the lamps in different steps until zero.
6. Switch-off the supply.
Experiment No: 1(b)
Title: Calibration of Voltmeter
Roll No. of the Student:
Date of the Experiment:
Objective: To compare the readings of a voltmeter (M.C. or M.I.) with those of a substandard one and hence to
draw the
(a) Calibration curve
(b) Correction Curve
Circuit Diagram:
+
-VSVT
220V DC
Supply
350Ω 1.4A0-150V0-150V
+
-
+
-
List of Apparatus:
Sl. No. Item Range Make Maker’s No
Experimental Observation:
Sl.
No.
Reading of Error
VT-VS
Correction
= - Error Under test (VT) Substandard voltmeter VS
Report:
i. Draw the Characteristic Curve (VT vs VS)
ii. Draw the correction curve (VT vs Correction)
iii. Explain briefly the application of the experiment in practical Field.
_________________________
Signature of the class teacher
Procedure: The following procedures may be adopted for calibration of voltmeter.
1. Connect the circuit as shown in the figure.
2. Keep the potential divider in its minimum potential position.
3. Both the meter should be zero initially and then switch-on the supply.
4. Increase the potential difference gradually till the end of the scale of the test voltmeter.
5. Note down readings in both the meters now by decreasing the potential difference up to zero.
6. Switch-off the supply.
Experiment No: 2
Title: Calibration of milli-ammeter as Voltmeter
Roll No. of the Student:
Date of the Experiment:
Objective: To calibrate a millimeter as a voltmeter and hence to draw
(a) Calibration curve
(b) Correction Curve
Circuit Diagram:
+
-VS
AT
220V DC
Supply
350Ω 1.4A0-150V
0-200mA
1165Ω, 0.6A
+
-
+
-
List of Apparatus:
Sl. No. Item Range Make Maker’s No
Experimental Observation:
Equivalent Constant,
n
n
I
VK
Sl.
No.
Voltmeter Reading,
V (Volts)
Milli-ammeter
Reading, I (mA) Equivalent Volt
Veq=k.In
Error in Volts
Veq-V
Correction in Volt
= - Error
Report:
i. Draw the Calibration Curve (mA vs Veq)
ii. Draw the correction curve (Veq vs Correction)
________________________
Signature of the class teacher
Procedure: The following procedures may be adopted for calibration of millimeter as voltmeter.
1. Connect the circuit as shown in the figure.
2. Keep the potential divider in its minimum potential position and adjust the rheostat in series with the
millimeter in its maximum position.
3. Both the meter should be zero initially and then switch-on the supply.
4. Increase the potential difference gradually and at the same time adjust the series rheostat carefully such that
both the meter show maximum deflection as desired.
5. Note down readings in both the meters by gradually decreasing the potential difference up to zero.
6. Switch-off the supply.
Experiment No: 3
Title: Calibration of milli-voltmeter as Ammeter
Roll No. of the Student:
Date of the Experiment:
Objective: To calibrate a millivoltmeter as an ammeter with the help of a substandard ammeter and hence to draw
the,
(a) Calibration curve
(b) Correction Curve
Circuit Diagram:
+
-
220V
DC
Supply
0-10A
Load
Resistance
230V, 7.5
KW
A
50mV
+-
mV
50mV
+-
List of Apparatus:
Sl. No. Item Range Make Maker’s No
Experimental Observation:
Equivalent Constant,
n
n
V
IK
Sl.
No.
Substandard
Ammeter Reading, I
Millivoltmeter
voltmeter Reading,
V (mV)
Equivalent Volt
Ieq =k. Veq
Error in
current
Ieq-I
Correction in
current
= - Error
Report:
i. Draw the Calibration Curve (mV vs I)
ii. Draw the correction curve (Ieq vs Correction)
_________________________
Signature of the class teacher
Procedure: The following procedures may be adopted for calibration of milli-voltmeter as ammeter.
1. Connect the circuit as shown in the figure.
2. Keep the lamp load in off position.
3. Both the meter should be zero initially and then switch-on the supply.
4. Switch o the lamps in steps till the end of the scale of the milli-voltmeter. The ammeter in series may not
show the full scale deflection.
5. Switch off the lamps in different steps and Note down readings in both the meters up to zero value.
6. Switch-off the supply.
Experiment No: 4
Title: Verification of Thevenn’s Theorem
Roll No. of the Student:
Date of the Experiment:
Objective: To verify the Thevenin’s Theorem with the help of an electronic trainer.
Circuit Diagram: Draw the circuit diagram from the apparatus supplied.
V 6V
+
-
2 kΩ1 kΩ
2 kΩ2 kΩ
RL1=
1 kΩ
RL2=
1 kΩ
A
B
Procedure: (Refer to the network trainer)
1. Connect the voltage source to ‘1’ and ‘2’.
2. Measure the open circuit voltage between A & B.
3. Calculate the Thevenin’s Equivalent resistance.
4. Connect the RL1 to AB and measure the current through it.
5. Repeat step (4) with RL2.
6. Repeat step (4) with RL2 and RL2 in series and parallel.
Experimental Observation:
Open Circuit Voltage (Thevenin’s Voltage) :
Thevenin’s Resistance :
Sl. No. Load Resistance Measured Voltage Calculated Voltage Remarks
RL2
RL1
RL1+RL2
RL1||RL2
Report:
Show the calculations (Add extra pages if needed)
_________________________
Signature of the class teacher
Experiment No: 5
Title: Verification of Maximum Power Transfer
Theorem
Roll No. of the Student:
Date of the Experiment:
Objective: To verify the Maximum Power Transfer Theorem with the help of an electronic trainer.
Circuit Diagram: Draw the circuit diagram from the apparatus supplied.
V 6V
+
-
2 kΩ1 kΩ
2 kΩ2 kΩ
RL1=
1 kΩ
A
B
Procedure: (Refer to the network trainer)
1. Connect the voltage source to ‘1’ and ‘2’.
2. Measure the open circuit voltage between A & B.
3. Calculate the Thevenin’s Equivalent resistance.
4. Connect the RL1 to AB and measure the current through it.
5. Calculate L
thL
R
VP
2
max
6. Calculate 1
2
maxL L LR I P
7. Repeat step (4-6) with RL2.
8. Repeat step (4-6) with RL2 and RL2 in series and parallel.
Experimental Observation:
Open Circuit Voltage (Thevenin’s Voltage) :
Thevenin’s Resistance :
Sl. No. Load Resistance Measured Voltage Calculated Voltage Remarks
RL2
RL1
RL1+RL2
RL1||RL2
Report:
Show the calculations (Add extra pages if needed).
_________________________
Signature of the class teacher
Experiment No: 6
Title: Power and Power Factor (Cos Φ) in a single
phase R-L series circuit. (3 voltmeter Method)
Roll No. of the Student:
Date of the Experiment:
Objective: To measure the power dissipated in a single phase R-L circuit and to calculate power and also to draw
phasor diagram for each reading and have to find the value of power factor from it.
Circuit Diagram:
L
NV1
A
0-300V
35Ω/ 4.5A
0-5 A
Lamp
Board
V2
V3
0-300V
0-60V
230V
50 Hz
List of Apparatus:
Sl. No. Item Range Make Maker’s No
Experimental Observation:
No of
observ
ation
Ammeter
Reading
Voltmeter
Reading
(V1)
Voltmeter
Reading
(V2)
Voltmeter
Reading
(V3)
Power
Dissipated
P=V3I1cos Φ
Power Factor From
Calculation
(cosθ)
Vector
Diagram
(cosθ)
Report:
i. Show the calculation
_________________________
Signature of the class teacher
Procedure: The following procedures may be adopted to measure the power and power factor in a single phase a.c.
circuit using three voltmeters.
1. Connect the circuit as shown in the figure.
2. Keep the rheostat at its maximum position and the lamp load in off position.
3. All the meter should be zero initially and then switch off the supply.
4. Decrease the resistance of the rheostats so that voltmeter V2 gives suitable result as desired.
5. Switch on the loads at different steps and note the readings of all the instruments.
6. Change the position of the rheostat slightly and repeat the step 5 again.
7. Switch-off the supply.
Theory: Since it is a series circuit, the current I should be taken as reference phasor.
From the phasor diagram we can write,
V12=V2
2+V3
2+2V2V3Cos Φ
Hence the power factor of the coil is, Cos Φ = ( V12 - V2
2 - V3
2)/( 2V2V3)
The power consumed by the coil is, P=V3I Cos Φ
Again, Cos θ is the power factor of the total circuit. It can be calculated as follows,
V1 Cos θ = V2 + V3 Cos Φ
Hence, Cos θ = (V2 + V3 Cos Φ) / V1
I
V3V1
V2
Φθ
Experiment No: 7
Title: Power and Power Factor in a single phase R-L Parallel
circuit.
Roll No. of the Student:
Date of the Experiment:
Objective: To measure the power dissipated in a single phase R-L parallel circuit and to calculate power factor
(Cos Φ) by three ammeter method.
Circuit Diagram:
L
N
V1
A2
0-300V
250Ω/
1.5A
0-5 A
Lamp
Board
A3
A2
0-2 A
230V
50 Hz
0-5 A
List of Apparatus:
Sl. No. Item Range Make Maker’s No
Experimental Observation:
No of
observ
ation
Ammeter
Reading,
(I1)
Ammeter
Reading (I2) Ammeter
Reading (I3)
Voltmeter
Reading
(V1)
Power
Dissipated
P=V3I1cos Φ
Power Factor From
Calculation
(Cos Φ)
Vector
Diagram
Report:
i. Draw he vector diagram for each set of reading and find the power factor.
ii. What is Henry? Two solenoids are kept co-axially at a little distance apart and current is sent through
them. What will be the effect of the changing the direction in (a) one of the coil (b) both the coil.
_________________________
Signature of the class teacher
Procedure: The following procedures may be adopted to measure the power and power factor in a single phase a.c.
circuit using three ammeters.
1. Connect the circuit as shown in the figure.
2. Keep the rheostat at its maximum position and the lamp load in off position.
3. All the meter should be zero initially and then switch off the supply.
4. Decrease the resistance of the rheostats so that ammeter A2 gives suitable result as desired.
5. Switch on the loads at different steps and note the readings of all the instruments.
6. Change the position of the rheostat slightly and repeat the step 5 again.
7. Switch-off the supply.
Theory: In D.C. circuit power is given by the product of voltage and current, whereas, in A.C. circuit it is given by
the product of voltage, current and power factor. For this reason, power in an A.C. circuit is normally measured by
wattmeter. However, this method demonstrates that the power is a single phase A.C. circuit can be measured by
using three ammeters.
Power consumes by the load, P=VI3Cos Φ. The phasor diagram of this circuit is given below. Since it is a parallel
circuit, the voltage V is considered as reference phasor.
From the phasor diagram we can write,
I12=I
2 + I3
2+2 I2 I3 Cos Φ
Hence the power factor of the coil is, Cos Φ = ( I12 - I2
2 - I3
2)/( 2I2I3)
Cos θ is the power factor of the total circuit. It can be calculated as follows,
I1 Cos θ = I2 + I3 Cos Φ
Hence, Cos θ = (I2 + I3 Cos Φ) / I1
V
I3I1
I2
Φθ
Experiment No: 8
Title: Measurement of Power and power factor by
wattmeter.
Roll No. of the Student:
Date of the Experiment:
Objective: To measure the power dissipated in a single phase R-L circuit with the help of a wattmeter and find
power factor by measuring the voltage and current in the circuit.
Circuit Diagram:
L
NV1
230V
50 Hz
A
0-300V
0-5 A
Lamp
Board
ML
Com
List of Apparatus:
Sl. No. Item Range Make Maker’s No
Experimental Observation:
Sl. No Voltage across
Load VL Current
through Load,
IL
Reading of
Wattmeter
(div)
Power
Dissipated
(watt)
Power Factor
Cos Φ=W/(I1VL)
With
Core
Without
Core
Report:
i. Show the calculation and draw the vector diagram for each sets of reading
_________________________
Signature of the class teacher
Procedure: The following procedures may be adopted to measure power and power factor in a single phase a.c.
circuit using wattmeter.
1. Connect the circuit as shown in the figure.
2. Keep the lamp load in off position and rotate the wheel of the variable inductor to get with core condition.
3. All the meters should be zero initially and then switch on the supply.
4. Switch on the loads at different steps and note the readings of all the instruments.
5. Switch off all the loads and now rotate the wheel again to get without core position.
6. Switch on the lamps at different steps again and note down the readings.
7. Switch-off the supply.
Multiplying factor of the wattmeter = (current coil rating *voltage coil rating ) / number of scale division
