E3271 Ec Lab
E3271 Ec Lab
E3271 Ec Lab
THIRUKKUVALAI-610204
Department of
Electrical and Electronics Engineering
EE3271
Electric Circuits Laboratory
Laboratory Manual
1ST YEAR – EEE
(REGULATION 2021)
Name :
SPR. No :
Class :
EE3271 ELECTRIC CIRCUITS LABORATORY LTPC0042
LIST OF EXPERIMENTS
1. Simulation and experimental verification of series and parallel electrical circuit using
fundamental laws.
2. Simulation and experimental verification of electrical circuit problems using
Thevenin‟s theorem.
3. Simulation and experimental verification of electrical circuit problems using Norton‟s
theorem.
4. Simulation and experimental verification of electrical circuit problems using
Superposition theorem.
5. Simulation and experimental verification of Maximum Power transfer theorem.
6. Simulation and Experimental validation of R-C, R-L and RLC electric circuit
transients
7. Simulation and Experimental validation of frequency response of RLC electric circuit.
8. Design and implementation of series and parallel resonance circuit.
9. Simulation and experimental verification of three phase balanced and unbalanced star,
delta networks circuit (Power and Power factor calculations).
TOTAL: 60 PERIODS
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Cycle – 1
1. Simulation and experimental verification of series and parallel electrical circuit using
fundamental laws.
2. Simulation and experimental verification of electrical circuit problems using Thevenin‟s
theorem.
3. Simulation and experimental verification of electrical circuit problems using Norton‟s
theorem.
4. Simulation and experimental verification of electrical circuit problems using Superposition
theorem.
5. Simulation and experimental verification of Maximum Power transfer theorem.
Cycle – 2
1. Simulation and Experimental validation of R-C, R-L and RLC electric circuit transients
2. Simulation and Experimental validation of frequency response of RLC electric circuit.
3. Design and implementation of series and parallel resonance circuit.
4. Simulation and experimental verification of three phase balanced and unbalanced star, delta
networks circuit (Power and Power factor calculations).
ADDITIONAL EXPERIMENT:
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S.
DATE TITLE OF THE EXPERIMENT MARKS SIGN
No.
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OBSERVATION TABLE
S.No V I1 I2 I3 I1 = I2 + I3
(Volts) (mA) (mA) (mA) ( mA)
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EXP.NO: 1
DATE:
AIM:
APPARATUS REQUIRED:
1 RPS
2 Resistor
3 Ammeter
4 Voltmeter
5 Bread board
6 Connecting wires
SOFTWARE REQUIRED:
Matlab 7.1
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THEORETICAL CALCULATION
S.No. V I1 I2 I3 I1 = I2 + I3
(Volts) (mA) (mA) (mA) ( mA)
MODEL CALCULATION:
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The term node means a common point where the different elements are connected.
Assume negative sign for leaving current and positive sign for entering current.
PROCEDURE:
1. Connect the circuit as per the circuit diagram.
2. Switch on the supply.
3. Set different values of voltages in the RPS.
4. Measure the corresponding values of branch currents I1, I2 and I3.
5. Enter the readings in the tabular column.
6. Find the theoretical values and compare with the practical values
FORMULA:
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OBSERVATION TABLE:
S.No. V V1 V2 V3 V =V1+ V2
Volts Volts Volts Volts +V3
Volts
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PROCEDURE:
FORMULA:
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THEORETICAL CALCULATION:
S.No. V V1 V2 V2 V =V1+ V2 + V3
Volts Volts Volts Volts Volts
MODEL CALCULATION:
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SIMULATION PROCEDURE:
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VIVA QUESTIONS:
RESULT:
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EXP.NO: 2
DATE:
SIMULATION AND EXPERIMENTAL VERIFICATION OF ELECTRICAL
CIRCUIT PROBLEMS USING THEVENIN’S THEOREM
AIM:
APPARATUS REQUIRED:
SOFTWARE REQUIRED:
Matlab 7.1
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TO FIND Vth:
TO FIND Rth:
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THEVENIN’S THEOREM:
STATEMENT:
Any two-terminal linear network, composed of voltage sources, current
sources, and resistors,
can be replaced by an equivalent two-terminal network consisting of an independent
voltage source in series with a resistor. The value of voltage source is equivalent to
the open circuit voltage (Vth) across two terminals of the network and the resistance
is equal to the equivalent resistance (Rth) measured between the terminals with all
energy sources replaced by their internal resistances.
Rth
Circuit
Vth
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OBSERVATION TABLE
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PROCEDURE:
1. Give connections as per the circuit diagram.
2. Measure the current through RL in the ammeter.
3. Open circuit the output terminals by disconnecting load resistance RL.
4. Connect a voltmeter across AB and measure the open circuit voltage Vth.
5. To find Rth, replace the voltage source by short circuit.
6. Give connections as per the Thevenin‟s Equivalent circuit.
7. Measure the current through load resistance in Thevenin‟s Equivalent circuit.
8. Verify Thevenin‟s theorem by comparing the measured currents in Thevenin‟s
Equivalent circuit with the values calculated theoretically.
SIMULATION PROCEDURE:
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SIMULATION:
TO FIND LOAD CURRENT:
TO FIND Vth:
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VIVA QUESTIONS:
RESULT:
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EXP.NO: 3
DATE:
AIM:
To verify Norton‟s theorem.
APPARATUS REQUIRED:
SOFTWARE REQUIRED:
Matlab 7.1
NORTON’S THEOREM
STATEMENT:
Any two-terminal linear network, composed of voltage sources, current
sources, and resistors, can be replaced by an equivalent two-terminal network
consisting of an independent current source in parallel with a resistor. The value of the
current source is the short circuit current (IN) between the two terminals of the
network and the resistance is equal to the equivalent resistance (RN) measured
between the terminals with all energy sources replaced by their internal resistances.
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Circuit
IN RN
PROCEDURE:
SIMULATION PROCEDURE:
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VIVA QUESTIONS:
1. How do you calculate Norton‟s resistance?
2. State Norton‟s Theorem.
3. Give the usefulness of Norton‟s theorems.
RESULT:
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EXP.NO: 4
DATE:
SIMULATION AND EXPERIMENTAL VERIFICATION OF ELECTRICAL
CIRCUIT PROBLEMS USING SUPERPOSITION THEOREM
AIM:
To verify superposition theorem.
APPARATUS REQUIRED:
SOFTWARE REQUIRED:
Matlab 7.1
SUPERPOSITION THEOREM:
STATEMENT:
In any linear, bilateral network energized by two or more sources, the
total response is equal to the algebraic sum of the responses caused by
individual sources acting alone while the other sources are replaced by their
internal resistances.
To replace the other sources by their internal resistances, the voltage
sources are short- circuited and the current sources open- circuited.
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OBSERVATION TABLE:
Experimental Values: Theoretical Values:
V1 V2 I3 V1 V2 I3
(Volts) (Volts) (mA) (Volts) (Volts) (mA)
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FORMULAE :
I3’ + I3’’ = I3
PROCEDURE :
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SIMULATION PROCEDURE:
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Theoretical:
S.No. I3 I3’ I3’’ I3= I3’ +I3’’
(mA) (mA) (mA) (mA)
VIVA QUESTIONS:
1. State Superposition Theorem.
2. What is meant by a linear system?
3. Give the usefulness of Superposition Theorem.
4. How will you apply Superposition Theorem to a linear circuit containing
both dependent and independent sources?
5. State the limitations of Superposition theorem.
RESULT:
Thus the Superposition theorem was verified.
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OBSERVATION TABLE:
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EXP.NO: 5
DATE:
SIMULATION AND EXPERIMENTAL VERIFICATION OF ELECTRICAL
CIRCUIT PROBLEMS USING MAXIMUM POWER TRANSFER THEOREM
AIM:
To verify maximum power transfer theorem.
APPARATUS REQUIRED:
SOFTWARE REQUIRED:
Matlab 7.1
THEORY:
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MODEL GRAPH:
MODEL CALCULATION:
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PROCEDURE:
1. Find the Load current for the minimum position of the Rheostat theoretically.
2. Select the ammeter Range.
3. Give connections as per the circuit diagram.
4. Measure the load current by gradually increasing RL .
5. Enter the readings in the tabular column.
6. Calculate the power delivered in RL.
7. Plot the curve between RL and power.
8. Check whether the power is maximum at a value of load resistance that equals
source resistance.
9. Verify the maximum power transfer theorem.
SIMULATION PROCEDURE:
VIVA QUESTIONS:
RESULT:
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CIRCUIT DIAGRAM FOR RC TRANSIENT:
MODEL GRAPH:
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EXP NO. : 6
DATE :
SOFTWARE REQUIRED:
PSpice Lite
APPARATUS REQUIRED:
THEORY:
RC CIRCUIT:
Consider a series RC circuit as shown. The switch is in open state initially.
There is no charge on condenser and no voltage across it. At instant t=0, switch is
closed.
Immediately after closing a switch, the capacitor acts as a short circuit, so
current at the time of switching is high. The voltage across capacitor is zero at t= 0 + as
capacitor acts as a short circuit, and the current is maximum given by,
i = V/R Amps
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OBSERVATION TABLE:
S.No. Frequency Time Voltage across the
(Hz) (s) capacitor VC
(v)
MODEL CALCULATION:
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This current is maximum at t=0+ which is charging current. As the capacitor starts
charging, the voltage across capacitor VC starts increasing and charging current starts
decreasing. After some time, when the capacitor charges to V volts, it achieves steady
state. In steady state it acts as an open circuit and current will be zero finally.
Charging current and voltage in capacitor are given as below,
V t t
IC in e RC VC Vin (1 e RC )
R
PROCEDURE:
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SIMULATION DIAGRAM:
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SIMULATION PROCEDURE:
VIVA QUESTIONS:
RESULT:
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OUTPUT WAVEFORM:
Case (i):
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EXP NO. : 7
DATE :
AIM:
SOFTWARE REQUIRED:
PSpice Lite
APPARATUS REQUIRED:
THEORY:
RLC CIRCUIT:
Consider a series RLC circuit as shown. The switch is in open state initially.
There is no charge on condenser and no voltage across it. At instant t=0, switch is
closed.
Immediately after closing a switch, the capacitor acts as a short circuit, so
current at the time of switching is high. The voltage across capacitor is zero at t= 0+ as
capacitor acts as a short circuit, and the current is maximum given by,
i = V/R Amps
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OBSERVATION TABLE:
S.No. Frequency Time Voltage across the
(Hz) (s) capacitor VC
(v)
MODEL CALCULATION:
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This current is maximum at t=0+ which is charging current. As the capacitor starts
charging, the voltage across capacitor VC starts increasing and charging current starts
decreasing. After some time, when the capacitor charges to V volts, it achieves steady
state. In steady state it acts as an open circuit and current will be zero finally.
Laplace transform of current flowing through the circuit is,
V/L
I(s)=
R 1
s2 + s+
L LC
Case (i):
R 2 1
If >
2L LC
The roots are real and distinct. The current is over damped.
Case (ii):
R 2 1
If =
2L LC
The roots are equal. The current is critically damped.
Case (iii):
R 2 1
If <
2L LC
The roots become complex conjugate. The current is oscillatory in nature.
PROCEDURE:
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Case (ii):
Case (iii):
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SIMULATION PROCEDURE:
VIVA QUESTIONS
RESULT:
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OBSERVATION TABLE:
MODEL CALCULATION:
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AIM:
To plot the current Vs frequencies graph of series resonant circuits and hence
measure their bandwidth, resonant frequency and Q factor.
SOFTWARE REQUIRED:
PSpice 9.1 Lite
APPARATUS REQUIRED:
S.No. Name of the Type Range Quantity
Components/Equipment required
1 Function Generator - - 1
2 Resistor - 100 Ω 1
3 Decade Inductance Box - - 1
4 Decade Capacitance Box - - 1
5 Ammeter MI (0-30) mA 1
6 Connecting Wires Single - Few nos
strand
THEORY:
A circuit is said to be in resonance when applied voltage V and current I
are in phase with each other. Thus at resonance condition, the equivalent complex
impedance of the circuit consists of only resistance (R) and hence current is
maximum. Since V and I are in phase, the power factor is unity.
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PSpice SIMULATION:
OUTPUT WAVWFORM:
MATLAB SIMULATION:
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XC = 1/C
At resonance, XL= XC and hence Z= R
BANDWIDTH OF A RESONANCE CIRCUIT:
Bandwidth of a circuit is given by the band of frequencies which lies between
two points on either side of resonance frequency, where current falls through 1/1.414
of the maximum value of resonance. Narrow is the bandwidth, higher the selectivity
of the circuit.
As shown in the model graph, the bandwidth AB is given by f2 – f1. f1 is the
lower cut off frequency and f2 is the upper cut off frequency.
Q - FACTOR:
In the case of a RLC series circuit, Q-factor is defined as the voltage
magnification in the circuit at resonance. At resonance, current is maximum. Io= V/R.
The applied voltage V = IoR
Voltage magnification = VL/V = IoXL
In the case of resonance, high Q factor means not only high voltage, but also higher
sensitivity of tuning circuit. Q factor can be increased by having a coil of large
inductance, not of smaller ohmic resistance.
Q = L / R
FORMULAE USED:
1
Resonant frequency fr = Hz
2 LC
Bandwidth BW = f2 – f1
fr
Quality Factor =
BW
PROCEDURE:
1. Connect the circuit as per the circuit diagram.
2. Vary the frequency and note down the corresponding meter reading.
3. Draw the current Vs frequency curve and measure the bandwidth, resonant
frequency and Q factor.
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Imax
A B
0.707Imax
f1 fr f2
Frequency in Hz
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SIMULATION PROCEDURE:
VIVA QUESTIONS:
1. Define Bandwidth.
2. Define Quality factor.
3. What is meant by selectivity?
4. Give the significance of Q- factor.
5. What is meant by resonance?
6. What are the characteristics of a series resonant circuit?
7. What will be the power factor of the circuit at resonance?
RESULT:
Thus the current Vs frequency graphs of series and parallel resonant circuits
were plotted and the bandwidth, resonant frequency and Q factor were measured.
They were found to be
(a) Series resonance
Resonant frequency =
Bandwidth =
Q- Factor =
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OBSERVATION TABLE:
Imin
fr
Frequency in Hz
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AIM:
To plot the magnitude & phase angle of current for various frequencies for the
given RLC parallel circuit.
SOFTWARE REQUIRED:
1 Function Generator - - 1
2 Resistor - 100 Ω 1
3 Decade Inductance Box - - 1
4 Decade Capacitance Box - - 1
5 Ammeter MI (0-30) mA 1
6 Connecting Wires Single - Few nos
strand
THEORY:
A circuit is said to be in resonance when applied voltage V and current I are in
phase with each other. Thus at resonance condition, the equivalent complex
impedance of the circuit consists of only resistance (R) and hence current is
maximum. Since V and I are in phase, the power factor is unity.
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PSpice SIMULATION:
OUTPUT WAVEFORM:
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Q = L / R
FORMULAE USED:
1
Resonant frequency fr = Hz
2 LC
Bandwidth BW = f2 – f1
fr
Quality Factor =
BW
PROCEDURE:
1. Connect the circuit as per the circuit diagram.
2. Vary the frequency and note down the corresponding meter reading.
3. Draw the current Vs frequency curve and measure the bandwidth, resonant
frequency and Q factor.
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MATLAB SIMULATION:
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SIMULATION PROCEDURE:
VIVA QUESTIONS:
1. Define Bandwidth.
2. Define Quality factor.
3. What is meant by selectivity?
4. Give the significance of Q- factor.
5. What is meant by resonance?
6. What are the characteristics of a parallel resonant circuit?
7. What will be the power factor of the circuit at resonance?
RESULT:
Thus the current Vs frequency graphs of series and parallel resonant circuits
were plotted and the bandwidth, resonant frequency and Q factor were measured.
They were found to be
(a) Parallel resonance
Resonant frequency =
Bandwidth =
Q- Factor =
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SIMULATTION DIAGRAM:
3 Φ BALANCED STAR CONNECTED NETWORK:
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EXP NO.: 9
DATE :
SOFTWARE REQUIRED:
Matlab 7.1
THEORY:
BALANCED THREE- PHASE CIRCUIT:
Balanced phase voltages are equal in magnitude and are out of phase with each
other by 120°.The phase sequence is the time order in which the voltages pass through
their respective maximum values. A balanced load is one in which the phase
impedances are equal in magnitude and in phase.
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VIVA QUESTIONS:
RESULT:
Thus the three phase balanced and unbalanced star, delta network circuits were
simulated and verified.
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CIRCUIT DIAGRAM:
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EXP NO.:10
DATE :
EXPERIMENTAL DETERMINATION OF POWER IN THREE PHASE
CIRCUITS BY TWO-WATT METER METHOD
AIM:
To determine the power in three-phase balanced and unbalanced circuit using
two-watt meter method.
APPARATUS REQUIRED:
SLNO NAME OF ITEM SPECIFICATION QUANTITY
1. 3-phase Auto transformer 20 Amp. 440v 50 Hz 1
2. Ammeter MI(0-10A) 1
3. Voltmeter MI(0-600V) 1
4. Wattmeter 250v, 5A 2
3- phase Load or 3- phase
5. 415V, 5H.P 1
induction motor
6 Connecting wires - Few
THEORY:
Two wattmeter method can be employed to measure power in a 3- phase,3 wire
star or delta connected balance or unbalanced load. In this method, the current coils of
the watt meters are connected in any two lines say R and Y and potential coil of each
watt meters is joined across the same line and third line i.e. B. Then the sum of the
power measured by two watt meters W1 and W2 is equal to the power absorbed By
the 3- phase load
PROCEDURE:
1. Connect the Voltmeter, Ammeter and Watt meters to the load through 3ф
Auto transformer as shown fig and set up the Autotransformer to Zero position.
2. Switch on the 3ф A.C. supply and adjust the autotransformer till a suitable
voltage.
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OBSERVATION TABLE:
Voltmeter Ammeter Total Reactive Power
Wattmeter reading
reading reading power power factor
S. (watts)
VL IL P Q
No
W1 W1 W2 W2
(V) (A) obser Actu Obser actua (watts) (watts)
ved al ved l
MODEL CALCULATION:
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FORMULAE USED:
1. Total power or Real power P = √3VLILCOSф =W1actual+W2actual
2. Reactive power of load= Q=√3(W1actual-W2actual)
3. tan ф= [√3(W1actual-W2actual)]/[ W1actual+W2actual]
4. Power factor=cos ф
PRECAUTION & SOURCES OF ERROR:
1. Proper currents and voltage range must be selected before putting the
instruments in the circuit.
2. If any Wattmeter reads backward, reverse its pressure coil connection and the
reading as negative.
3. As the supply voltage Fluctuates it is not possible to observe the readings
correctly.
VIVA QUESTIONS:
1. What are the various types of wattmeter?
2. How many coils are there in wattmeter?
3. What is meant by real power?
4. What is meant by apparent power?
RESULT:
The power measured in the 3-phase circuit and there corresponding power
factors are in observation table.
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