Electrical circuits and simulation lab manual
Exp - 1
1. THEVENIN’S AND NORTON’S THEOREMS
1(a). VERIFICATION OF THEVENIN’S THEOREM
1.1. OBJECTIVE: To verify Thevenin’s & Norton’s theorems for the given circuit. 15v
1.2. RESOURCES:
S. No
Name of the apparatus
Range
Type
Quantity
1
Regulated power supply
(0 – 30)V/2A
Digital
01
2
Voltmeter
(0-30)V
MC
01
3
Ammeter
(0-200m)A
MC
01
4
Resistors
100Ω
150Ω
200Ω
Carbon
Composition
02
01
01
5
D.R.B
0-10k Ω
---
01
6
Connecting wires
---
----
Required number
1.3. PRECAUTIONS:
1. Initially keep the RPS output voltage knob in zero volt position.
2. Set the ammeter pointer at zero position.
3. Take the readings without parallax error.
4. Avoid loose connections.
5. Avoid short circuit of RPS output terminals.
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Electrical circuits and simulation lab manual
1.4. PROCEDURE:
1.
Connect the circuit as per fig (1)
2.
Adjust the output voltage of the regulated power supply to an appropriate value (Say 30V).
3.
Note down the response (current, IL) through the branch of interest i.e. AB (ammeter reading).
4.
Reduce the output voltage of the regulated power supply to 0V and switch-off the supply.
5.
Disconnect the circuit and connect as per the fig (2).
6.
Adjust the output voltage of the regulated power supply to 30V.
7.
Note down the voltage across the load terminals AB (Voltmeter reading) that gives Vth.
8.
Reduce the output voltage of the regulated power supply to 0V and switch-off the supply.
9.
Disconnect the circuit and connect as per the fig (3).
10.
Adjust the output voltage of the regulated power supply to an appropriate value (Say V = 30V).
11.
Note down the current (I) supplied by the source (ammeter reading).
12.
The ratio of V and I gives the Rth.
13.
Reduce the output voltage of the regulated power supply to 0V and switch-off the supply.
14.
Disconnect the circuit and connect as per the fig (4).
15.
Adjust the output voltage of the regulated power supply to 30V
16.
Note down the response (current, IN) through the branch AB (ammeter reading).
17.
Reduce the output voltage of the regulated power supply to 0V and switch-off the supply.
18.
Disconnect the circuit.
1.5. GIVEN CIRCUIT:
STATEMENTS:
Thevenin’s Theorem
It states that any linear, active network with two open terminals can be replaced by an equivalent circuit
consisting of Thevenin’s equivalent voltage source Vth in series with Thevenin’s equivalent resistance Rth. Where
Vth is the open circuit voltage across the two terminals and Rth is the resistance seen from the same two terminals.
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Electrical circuits and simulation lab manual
1.7. CIRCUIT DIAGRAMS:EXP.SETUP TO FIND IL:
FIG(1)
EXP.SETUP TO FIND VTH:
FIG(2)
TO FIND Rth:
EXP. SET UP TO FIND RTH AND RN
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TO FIND IN:
Fig(4)
1.8. THEORY:
Thevenin’s Theorem:
Statement:
The values of VTh and RTh are determined as mentioned in thevenin’s theorem.
Once the thevenin’s equivalent circuit is obtained, then current through any load resistance
RL connected across AB is given by, I =
Thevenin’s theorem is applied to d.c. circuits as stated below.
Any network having terminals A and B can be replaced by a single source of
e.m.f. VTh in series with a source resistance RRh.
(i)
The e.m.f the voltage obtained across the terminals A and B with load, if any removed i.e., it
is open circuited voltage between terminals A and B.
(ii)
The resistance RTh is the resistance of the network measured between the terminals A and B
with load removed and sources of e.m.f replaced by their internal resistances. Ideal voltage sources
are replaced with short circuits and ideal current sources are replaced with open circuits.
To find VTh, the load resistor ‘RL’ is disconnected, then VTh =
Χ R3
To find RTh,
RTh = R2 +
,
Thevenin’s theorem is also called as “Helmoltz theorem”
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Electrical circuits and simulation lab manual
Norton’s Theorem:
Statement:
It states that any linear, active network with two open terminals can be replaced by an
equivalent circuit consisting of Norton’s equivalent current source IN in parallel with Norton’s
equivalent resistance RN. where IN is the short circuit current through the two terminals and RN is the
resistance seen from the same two terminals.
Nortom’s theorem is applied to d.c circuits may be stated as below.
Any linear network having two terminals ‘A’ and ‘B’ can be replaced by a
current
source of current output IN in parallel with a resistance RN.
(i)
The output IN of the current source is equal to the current that would flow through AB when
A&B are short circuited.
(ii)
The resistance RN is the resistance of network measured b/wn A and B with load
removed and the sources of e.m.f replaced by their internal resistances.
Ideal voltage source are replaced with short circuits and ideal current sources are replaced with
open circuits.
Norton’s theorem is converse of thevenin’s theorem in that Norton equivalent circuit
uses a current generator instead of voltage generator and the resistance RN is parallel with
generator instead of being series with it.
for source current,
II =
=
for short-circuit current,
IN = Χ
=
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Electrical circuits and simulation lab manual
1.9. TABULATION FOR THEVINEN’S THEOREM:
THEORITICAL VALUES
PRACTICAL VALUES
RTH=RL=
RTH=RL=
IL =
IL=
Vth=
Vth=
1.10. TABULATION FOR NORTON’S THEOREM:
THEORITICAL VALUES
RN=RL=
IL =
IN=
PRACTICAL VALUES
RN=RL=
IL =
IN=
1.11. RESULT:-
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Electrical circuits and simulation lab manual
Thevenin’s theorem
Parameter
Norton’s theorem
Theoretical Practical Theoretical Practical
Values
Values
Values
Values
IL in given circuit
Thevenins voltage(vTH)
Thevenins resistance(RTH)/nortons
resistance(RN)
Nortons current IN
IL in Thevinens equi. ckt
IL in Nortonsequi. ckt
1.12. PRE LAB QUESTIONS:1)
The internal resistance of a source is 2 Ohms and is connected with an
External load of 10 Ohms resistance. What is Rth ?
2)
In the above question if the voltage is 10 volts and the load is of 50Ω.
What is the load current and Vth? Verify IL?
3)
If the internal resistance of a source is 5 Ω and is connected with an
External load of 25 Ohms resistance. What is Rth?
4)
In the above question if the voltage is 20V and the load is of 50 Ohms,
What is the load current and IN ? Verify IL ?
1.13. LAB ASSIGNMENT QUESTION:
Calculate the current in 200Ω branch by using thevenin’s & norton’s theorem.
1.14. POST LAB QUESTIONS:
1) Show that Thevenin’s Theorem and Norton’s Theorems are dual to each other.
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Exp - 2
SUPERPOSITION AND MAXIMUM POWER TRANSFER
THEOREM
2. (a) VERIFICATION OF SUPERPOSITION THEOREM
2.1. OBJECTIVE:
To verify the superposition theorem
2.2. RESOURCES:
S. No
Name of the apparatus
Range
Type
Quantity
(0 – 30)
V/2A
digital
01No
1
Dual channel regulated
power supply
2
Ammeter
(0 – 200m) A
MC
01No
3
Resistors
100
150
200
Carbon
Composition
01No
01No
01No
4
Experi mental board
-
-
01No
5
Connecting wires
-
-
Required number
2.3. PRECAUTIONS:
1. Initially keep the RPS output voltage knob in zero volt position.
2. Set the ammeter pointer at zero position.
3. Take the readings without parallax error.
4. Avoid loose connections.
5. Avoid short circuit of RPS output terminals
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2.4. PROCEDURE:
1. Connect the circuit as per the fig (1).
2.
Adjust the output voltage of sources X and Y to appropriate values (Say 30V and20V
respectively).
3.
Note down the response (current, IL) through the branch of interest i.e. AB ammeter reading.
4.
Now set the source Y (20V) to 0V.
5.
Note down the response (current, ILl) through the branch AB (ammeter reading).
6.
Now set the source X (20V) to 0V and source Y to 20V.
7.
Note down the response (current, ILll) through the branch AB (ammeter reading).
8.
Reduce the output voltage of the sources X and Y to 0V and switch off the supply.
9.
Disconnect the circuit.
GIVEN CIRCUIT:
STATEMENT:
Super Position Theorem:
In any linear, bilateral, multi source network the response in any element is equal to the algebraic
sum of the responses obtained by each source acting separately while all other sources are set equal
to zero.
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Electrical circuits and simulation lab manual
2.5. CIRCUIT DIAGRAM:
WhenV1&V2 source acting(To find I):-
WhenV1 Source Acting (To Find I1):-
Whenv2 Source Acting(To Find I2):-
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2.6. THEORY:
Superposition theorem:
The superposition theorem states that in a linear bilateral network consisting N number of
sources each branch current is the algebraic sum of N currents through ( branch voltage), each of
which is determined by considering one source at a time and removing all other sources. In
removing the sources, voltage sources are short circuited or replaced by resistances equal to their
internal resistances for no ideal sources, while the ideal current sources are open circuited.
2.7. TABULAR FORMS:
Tabular Column:
Theoretical
values
Practical
values
When v1 and v2 acting
(20v,10v) current (I)
when v1 acting (20v)
current (I1)
When v2 acting (10v)
current (I11)
.
2.8.RESULT:
Theoretical
values
Practical
values
When v1 and v2 acting
(20v,10v) current (I)
when v1 acting (20v)
current (I1)
When v2 acting (10v)
current (I11)
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Electrical circuits and simulation lab manual
2.9. PRE LAB QUESTIONS:1) What do you mean by Unilateral and Bilateral network? Give the limitations of
Superposition theorem.
2) What are the equivalent internal impedances for an ideal voltage source and for a Current
source?
3) Transform a physical voltage source into its equivalent current source.
4) If all the 3 star connected impedance are identical and equal to ZA,then what is the Delta
connected resistors?
2.10. LAB ASSIGNMENT:
Calculate the current in 200Ω branch by using superposition theorem at 30V & 20V.
2.11. POST LAB QUESTIONS:
Why super position theorem is not applicable for power calculation?
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2(b) VERIFICATION OF MAXIMUM POWER TRANSFER THEOREM
2b.1. OBJECTIVE:
To verify maximum power transfer theorem on D.C circuit.
2b.2. RESOURCES:
S. No
1
Name of the apparatus
Range
Regulated power supply (0 – 30)V/2A
Type
Quantity
digital
01No
2
Voltmeter
(0-30) V
MC
01No
3
Ammeter
(0-1) A
MC
01No
4
Rheostats
5
Connecting wires
100 /5A
50/5A
-
Wound Wire
-
01No
01No
Required number
2b.3. PRECAUTIONS:
→ Avoid loose connections
→ Ammeter should always connected in series with the circuit.
2b.4MODEL GRAPH FOR MAXIMUM POWER TRANSFER THEOREM:
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2B.5. PROCEDURE:
1. Connect the circuit as per the circuit diagram fig(1).
2. Adjust the output voltage of the regulated power supply to an appropriate value (Say 30V).
3. Vary the load rheostat. in steps, and note down the response (current) through the load for
each step (ammeter reading) & load voltage.
4. Reduce the output voltage of the regulated power supply to 0V and switch-off the supply.
5. Disconnect the circuit.
6. Calculate the power absorbed by the load, PL for each step using the formula PL=IL2 RL.
7. Plot the graph by taking ‘RL’ on X-axis and PL on Y-axis.
8. Get the practical value of the load resistance for which it will gain the maximum power from
the source.
STATEMENT:
It states that, maximum power will be transferred from source to load when the load
resistance is the complex conjugate of source resistance.
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Electrical circuits and simulation lab manual
2B.6. CIRCUIT DIAGRAM:
Fig(1)
THEORY:
The statement of maximum power transfer is “ In d.c circuits, maximum power
is transferred from a source to load when the load resistance is made equal to the internal
resistance of the source as viewed from the load terminal with load removed and all e.m.f
sources replaced by their internal resistance.
Consider a voltage source of V of internal resistance R delivering power to aload
RL. We shall prove that when RL = RS the power transferred is maximum.
Circuit current =
Power delivered P = I2 RL
RL
=0
RL+Ri cannot be zero,
Ri – RL = 0
RS ==RL
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Electrical circuits and simulation lab manual
2b.7. TABULATION FOR MAXIMUM POWER TRANSFER THEOREM:
LOAD
SNO.
RESISTENCE
In ohms
VOLTAGE
CURRENT
POWER
VL (in Volts)
IL (in amps)
P=VL*IL(watt)
1
2
…….
2b.8. THEORETICAL CALCULATIONS:
Total current I =
P = I2 RL
=
2. RL
Power is maximum dp/dRL =0
→
=0
→
=0
→
=0
Rs=RL
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Electrical circuits and simulation lab manual
2b.9. RESULT:-
2b.10. PRE LAB QUESTIONS:1. Derive the condition for maximum power transfer theorem.
2. Where and why maximum power transfer theorem is applied?
3. What is the efficiency of the circuit at the maximum power transfer condition & why?
2b.11. LAB ASSIGNMENT:
Prove the maximum power transfer theorem for the given circuit at 30V.
2b.12. POST LAB QUESTIONS:
1. Derive the condition for maximum power transfer theorem for a.c. Circuits.
2. Define a dependent source.
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Exp -4
3. COMPENSATION THEORM
4.1. OBJECTIVE:
To verify compensation theorem for the given circuit.
4.2. RESOURCES:
S. No
1
2
Name of the apparatus
Range
Regulated power supply (0 – 30)V/2A
Ammeter
Type
Quantity
digital
01No
MC
2No
(0-200)mA
100 
150K
200
100 
01No
01No
01No
01No
Carbon
Composition
3
Resistors
4
Connecting Wires
----
----
Required number
5
Experimental Board
----
-----
01No
4.3. PRECAUTIONS:
→ Avoid loose connections
→ Ammeter should always connected in series with the circuit.
4.4. PROCEDURE:
1. Connect the circuit as per the fig (1).
2. Adjust the output voltage of source X to an appropriate value (say 30V).
3. Note down I1 and I2 by using ammeters A1 & A2. Now set the source X(30V) to 0V.
4. And connect the circuit as per the fig (2). If 100Ω resistance is charged to 150Ω then find the
charge in 200Ω connect the circuit as shown in fig.
5. By applying ΔE = I2ΔR using R.P.S find the current in 200Ω.
6. Note down the response (current, I200) through AB branch (ammeter reading).
7. Disconnect the circuit.
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GIVEN CIRCUIT:
STATEMENT:
It states that in a linear bilateral network any element may be replaced by a voltage source of
a magnitude equal to the current passing through the element multiplied by the value of its resistance
(provided that the current and voltage in the other parts of the circuit remain unaltered).
4.5. CIRCUIT DIAGRAMS:
To find I100 Ω and I200Ω:
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Electrical circuits and simulation lab manual
To find I200Ω:
To find current in 200 when 100 changed to 150:
4.6. THEORY:
The compensation theorem states that any element in the linear, bilateral network,
may be replaced by a voltage through the element multiplied by the value of the element, provided
the currents and voltages in other parts of the circuit remain unallered. Consider the circuit shown.
The element R can be replaced by voltage source V, which is equal to the current I passing through
R Multiplied by R.
This theorem is useful in finding the changes in current of voltage when the value of
Resistance R is changed M the circuit consider the network containing a resistance R. A small
change in resistance R, that is (R+ΔR) causes a change in current in all branches. This current
increment in other branches is equal to the current produced by the voltage source of voltage I.ΔR
which is placed in series with altered resistance.
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4.7. TABULATIONS:
THEORITICAL
VALUES
PRACTICAL
VALUES
Current in 100 and 200 I
and I200
Current in 200 when 100
changed to 150 I1200
Current in 200 when
ΔE = ΔRI applied I11200
Change in current I200-I1200
4.8. MODEL CALCULATIONS:From compensation theorem:I=
I2 =
I = I1 + I2
I1 = I-I2
I=
I=
I200 =
From the figure (b)
ΔE = ΔR I1
ΔE =
4.9. RESULT:
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Electrical circuits and simulation lab manual
4.10. PRE LAB QUESTIONS:1. State the compensation theorem?
2. Application of compensation theorem?
4.11. LAB ASSIGNMENT QUESTIONS:
Verify compensation theorem for the given circuit at 20V.
4.12. POST LAB QUESTIONS:
1. Advantages of compensation theorem?
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Exp - 5
RECIPROCITY AND MILLMAN’S THEOREMS
5. (a) VERIFICATION OF RECIPROCITY THEOREM
5a.1. OBJECTIVE:
To verify reciprocity theorem for the given circuit.
5a.2. RESOURCES:
S. No
Name of the apparatus
1
Regulated power supply
2
Ammeter
3
Resistors
4
Experi mental board
5
Connecting wires
Range
Type
Quantity
digital
01No
MC
01No
Carbon
Composition
01 No
01No
01No
-
-
01No
-
-
Required
number
(0 – 30)
V/2A
(0 – 200m)
A
100
150
200
5a.3. PRECAUTIONS:
1. Initially keep the RPS output voltage knob in zero volt position.
2. Set the ammeter pointer at zero position.
3. Take the readings without parallax error.
4. Avoid loose connections.
5.Avoid short circuit of RPS output terminals.
6.If voltmeter gives (-) ve reading then interchange the terminals connections of a voltmeter.
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Electrical circuits and simulation lab manual
5a.4. PROCEDURE:
Reciprocity Theorem:
1. Connect the circuit as per the fig (1).
2. Adjust the output voltage of the regulated power supply to an appropriate value (Say 30V).
3. Note down the response (current, IL) through 150 resistor (ammeter reading).
4. Reduce the output voltage of the signal generator to 0V and switch-off the supply.
5. Disconnect the circuit and connect the circuit as per the fig (2).
6. Adjust the output voltage of the regulated power supply to an appropriate value (Say 30V).
7. Note down the response (current, IL1) through 100 resistor (ammeter reading).
8. Reduce the output voltage of the signal generator to 0V and switch-off the supply.
9. Disconnect the circuit.
CIRCUIT:
STATEMENT:
Reciprocity theorem:
In any linear, bilateral, single source network, the ratio of excitation to the response is same even
though the positions of excitation and response are interchanged.
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5a.5. CIRCUIT DIAGRAMS:CIRCUIT – 1(Before Interchanging source and Response):
CIRCUIT -2(After Interchanging source and Response)
5a.6. THEORY:
RECIPROCITY THEOREM:
Statement:
This theorem permits in to transfer source from one position in the circuit to another and may
be stated as under.
In any linear bilateral network, if an e.m.f E acting in a branch causes a current ‘I’ in branch
‘Y’ then the same e.m.f E located in branch ‘Y’ will cause a current I in branch. However, currents
in other branches will not change.
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Electrical circuits and simulation lab manual
5a.7. TABULAR FORM:
For Circuit-1
Applied voltage
S. No
(V1) Volt
Current
IL
(mA)
Applied voltage
S. No
(V2) Volt
Current
IL 1
(mA)
For Circuit-2
5a.8. RESULT:
Theoretical Value
Practical Value
V/I
(Before inter change
source & excitation)
V/I
(After inter change
source & excitation)
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Electrical circuits and simulation lab manual
5a.9. PRE LAB QUESTIONS:1. State the reciprocity theorem?
2. Application of reciprocity theorem?
3. Advantages of reciprocity theorem?
5a.10. LAB ASSIGNMENT:
Calculate the current in 150Ω branch by using reciprocity theorem at 30V supply.
5a.11. POST LAB QUESTIONS:
1. Prove that the given circuit is reciprocal?
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5. (b) MILLMAN’S THEOREM
5B.1. OBJECTIVE:
To verify Millman’s theorem for the given circuit.
5b.2. RESOURCES:
S. No Name of the apparatus
1
2
Range
Dual channel
(0 – 30)V/2A
Regulated power supply
(0-200)mA
Ammeter
(0-0.5)A
Type
Quantity
digital
02No
MC
MC
100
150
200
Carbon
Composition
01No
01No
01No
01No
01No
3
Resistors
4
Experi mental board
-
-
01No
5
Connecting wires
-
-
Required number
6.
Voltmeter
0-30V
MC
01No
5b.3. PRECAUTIONS:
1. Initially keep the RPS output voltage knob in zero volt position.
2. Set the ammeter pointer at zero position.
3. Take the readings without parallax error.
4. Avoid loose connections.
5. Avoid short circuit of RPS output terminals.
5b.4. PROCEDURE:
1. Connect the circuit as per the fig (1).
2. Adjust the output voltage of sources X,andY to appropriate values. (Say 30Vand 25V
respectively).
3. Note down the response (current, IL) through the branch of interest (AB)(ammeter reading).
4. Disconnect the circuit and connect the circuit as per the fig (2).
5. Adjust the output voltage of sources X,andY to appropriate values. (Say 30Vand 25V
respectively).
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Electrical circuits and simulation lab manual
6. Find the voltage across open circuit terminals
7. Connect the circuit as shown in fig
8. Find the current in 200Ω.
GIVEN CIRCUIT:
STATEMENT:
Millman’s theorem:
Statement:
It states that in a linear active network, if number of voltage sources V1,V2,……….Vn with
internal resistances R1,R2,……….Rn are connected in parallel, then this network can be replaced by
a single voltage source V1 in series with single resistance R1.
V1G1  V2 G 2             Vn G n
G1  G 2              G n
1
R1 =
G 1  G 2             G n
Where V1 =
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5b.5. CURCUIT DIAGRAMS:
To find I200Ω:
To find’V’
To find’R’
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To find’I200’
To find I200Ω
5b.6. THEORY:
Millman’s theorem slates that in any network, if the voltage sources V1,V2, --------Vn in
series with internal resistances R1,R2---------RN, respectively, are in parallel, then these sources may
be replaced by a single voltage sources V in series with R as
shown.
where
V =
Here Gn is the conduction of the nth branch , R1=
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Similar theorem can be stated for n current sources having internal conductances which can
be replaced by a single current source I’ in parallel with an equivalent conductance.
where
G1 =
5b.7. TABULATIONS :
TABLE-1(FIG(1):
V (V)
I (Amp)
R1=V/I
V1(V)
V2(V)
VI (V)
Theoretical
Practical
Table-2(fig(2):
Theoretical
practical
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Electrical circuits and simulation lab manual
Table-3(fig(3):
V1
I200
V1
V2
Theoretical
practical
5b.8. RESULT:
Theoretical values
Practical values
Current in 200 Actual
given circuit
Millimans resistance(R1)
Millimans voltage(V1)
Current in 200 (Millimans
Circuit )
5b.9. PRE LAB QUESTIONS:1. State the Millman’s theorem?
2. Advantages of Millman’s theorem?
5b.10. LAB ASSIGNMENT:
Prove Millman’s theorem for the given circuit for load resistance of 300Ω
5b.11. POST LAB QUESTIONS:
1. Application of the Millman’s Theorem?
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Exp - 6
LOCUS DIAGRAMS OF SERIES RL AND RC CIRCUITS
6.1. OBJECTIVE:
To draw the current locus diagrams for series RL and RC circuits by varying resistance and
for series RC circuit by varying capacitance.
6.2. RESOURCES:
S. No
Name of the apparatus
Range
Type
Quantity
(0 – 3M) Hz, (0-20) VPP
-
1No
1
Signal generator
2
Decade Resistance Box
(0-111.11K)
-
1No
3
Decade inductance Box
(0-1.11)H
-
1No
4
Decade Capacitance Box
(0-1.11)F
-
1No
5
Ammeter
(0-2000m)A
MC
1No
6
Connecting wires
-
-
Required number
6.3. PRECAUTIONS:
1. Initially keep the RPS output voltage knob in zero volt position.
2. Set the ammeter pointer at zero position.
3. Take the readings without parallax error.
4. Avoid loose connections.
5. Avoid short circuit of Function Generator output terminals.
34
Dept. of EEE
Electrical circuits and simulation lab manual
6.4. MODEL GRAPHS:
6.5. PROCEDURE:
Series RL circuit (varying resistance):
1. Set the signal generator to be in sine wave mode and adjust the output voltage to 20V peakto-peak, frequency to 200 Hzs.
2. Connect the circuit as per fig (7.1).
3. Vary the resistance in the circuit using DRB in steps and note down the current through the
circuit for each step (ammeter reading).
X 
4. Calculate phase angle  using to formula  = tan-1  L  for each step.
 R 
5. Disconnect the circuit.
6. Plot the current locus diagram by taking current on x axis and voltage on Y – axis.
35
Dept. of EEE
Electrical circuits and simulation lab manual
Series RC circuit( varying resistance ):
1.
Set the signal generator to be in sine wave mode and adjust the output voltage to 20V peak
to peak,frequency to 200 Hzs.
2.
Connect the circuit as per fig(7.2).
3.
Vary the resistance in the circuit using DRB in steps and note down the current through the
circuit for each step(ammeter reading).
4.
X 
Calculate phase angle  using to formula  = tan-1  C  for each step.
 R 
5.
Disconnect the circuit.
6.
Plot the current locus diagram by taking current on Y axis and voltage on X – axis.
Series RC circuit (varying capacitance):
1. Set the signal generator to be in sine wave mode and adjust the output voltage to 20V peakto-peak, frequency to 200 Hzs.
2. Connect the circuit as per fig (7.3).
3. Vary the Capacitance in the circuit using DCB in steps and note down the current through the
circuit for each step (ammeter reading).
X 
4. Calculate phase angle  using to formula  = tan-1  C  for each step.
 R 
5. Disconnect the circuit.
6. Plot the current locus diagram by taking current on Y-axis and voltage on X – axis.
36
Dept. of EEE
Electrical circuits and simulation lab manual
6.6. CIRCUIT DIAGRAMS:
Series RL circuit (R Varying):
Series RC circuit (RVarying):
Set up for series R-L circuit:
37
Dept. of EEE
Electrical circuits and simulation lab manual
Set up for series R-c circuit:
`
6.7. THEORY:
A phasor diagram may be drawn and is expanded to develop a curve; known as a
locus. Locus diagrams are useful in determining the behavior or response of an RLC circuit when
one of its parameters is varied while the frequency and voltage kept constant. The magnitude and
phase of he current vector in the circuit depends upon the values of R,L, and C and frequency at the
fixed source voltage. The path traced by the terminus of the current vector when the parameters R<L
or of are varied while f and V are kept constant is called the current locus.
The term circle diagram identifies locus plots that are either circular or semi circular loci of
the terminus ( the tip of the arrow) of a current phasor or voltage phasor. Circle diagrams are often
employed as aids in analyzing the operating characteristics of circuits like equivalent circuit of
transmission lines and some types of AC machines.
38
Dept. of EEE
Electrical circuits and simulation lab manual
6.8. TABULATIONS:
S.NO Current Voltage
resistance
 Xl 
= tan 1  
in
across
R
circuit
rheostat(v)
(mA)
S.NO Current Voltage
resistance
X 
= tan1  C 
in
across
 R 
circuit
rheostat(v)
(mA)
6.9. RESULT:
6.10. PRE LAB QUESTIONS:1. What is RC circuit
2. What is the Q factor of series circuit
3. What is RL circuits
6.11. LAB ASSIGNMENT:
1. Draw the locus diagram for the given circuit at 30V peak-to-peak, frequency to 150 Hzs.
6.12. POST LAB QUESTIONS:
What is meant by Effective value of an alternating quantity.
39
Dept. of EEE
Exp - 7
SERIES AND PAREALLEL RESONANCE
7.1. OBJECTIVE: To determine the performance of the series and parallel circuit at
resonance.
7.2. RESOURCES:
S. No
Name of the apparatus
Range
Type
Quantity
1
Signal generator
(0 – 1M)Hz,
(0-20) VPP
digital
01No
2
Decade inductance Box
(0-40mH)
----
01No
-
01No
3
4
Capacitor
0.1uf
5
Resistors
30 
Carbon
Composition
01No
6
Ammeter
(0-200m) A
MI
01No
7
Experimental board
-
-
1No
8
C.R.O
30 MHz
-
1No
9
Connecting wires
-
-
Required
Number
7.3. PRECAUTIONS:
1. Meter reading should be taken without parallax error.
2. Connection should be made tight.
01No
Electrical circuits and simulation lab
SERIES RESONANCE
7.4. MODEL GRAPH:
PARALLEL RESONANCE
7.5. PROCEDURE:
1. Connections are made as per the circuit diagram.
2. By varying the frequency note down the corresponding values of current in both cases and
note down f, VC, VL and VR.
3. At a particular value of frequency the current reaches its Maximum /minimum in
Series/Parallel resonance. That instant of frequency VC = VL and VR = VS in series Resonance
circuit.
Dept. of EEE
Electrical circuits and simulation lab
7.6. GIVEN CIRCUIT:
SERIES RESONANCE
PARALLEL RESONANCE
FOR PARALLEL RESONANCE
Dept. of EEE
Electrical circuits and simulation lab
7.7. THEORY:
Resonance is a particular type of phenomenon inherently found normally in every
kind of system, electrical, mechanical, optical, Acoustical and even atomic. There are several
definitions of resonance. But, the most frequently used definition of resonance in electrical
system is studied state operation of a circuit or system at that frequency for which the
resultant response is in time phase with the forcing function.
Series resonance:
A circuit is said to be under resonance, when the applied voltage ‘V’ and current are
in phase. Thus a series RLC circuit, under resonance behaves like a pure resistance network
and the reactance of the circuit should be zero. Since V & I are in phase, the power factor is
unity at resonance.
The frequency at which the resonance will occur is known as resonant frequency.
Resonant frequency, fr =
Thus at resonance the impedance Z is minimum. Since I = V/Z. The current is maximum. So
that current amplification takes place.
The parallel circuit consisting branches with single pure elements R,L & C is an ideal
circuit. How ever the performance of such a circuit is of interest in the general subject of
resonance. This ideal parallel circuit is of interest in the general subject of resonance.
Lower cut-off frequency is above the resonant frequency at which the current is
reduced to
times of it’s minimum value. Upper cut-off frequency is above.
Quality factor is the ratio of reactance power inductor (or) capacitor to its resistance.
Selectivity is the reciprocal of the quality factor.
Dept. of EEE
Electrical circuits and simulation lab
7.8. TABULAR FORMS:
FOR SERIES RESONANCE
S.NO FREQUNCY
V(L)
V(C)
V(R)
I(mA)
1
2
...
7.9. THEORITICAL CALCULATIONS:
For Series Resonance circuit:
1. Resonant frequency fr =
2. Lower cut-off frequency fl =
+
3. Upper cut-off frequency f2 =
4. Band width = f2-f1
5. Quality factor Q =
+
=
6. Current at Resonance Io = VRo/R
TABULAR FORMS:
FOR PARALLEL RESONANCE
S.NO FREQUNCY
V(L)
V(C)
V(R)
I(mA)
1
2
Dept. of EEE
Electrical circuits and simulation lab
For parallel Resonance circuit:
1. Resonant frequency fr =
2. Lower cut-off frequency fl
3. Upper cut-off frequency f2 =
4. Band width =
5. Quality factor Q =
=
6. Current at resonance Io
7.10. RESULT:
Series Resonant circuit
S.No
1
2
3
Parameter
Theoretical
Values
Practical
Values
Parallel Resonant circuit
Theoretical
Values
Practical
Values
Resonant
Frequency (fo)
Lower cut off
frequency(f1)
Upper cut off
frequency(f2)
4
Band width(f2- f1)
5
Quality factor
7.11. PRE LAB QUESTIONS:1. Definition of resonance?
2. Define the series resonance?
3. Define the parallel resonance?
4. Applications of resonance?
5. What is the condition of voltage &current at the resonance condition?
7.12. LAB ASSIGNMENT:
Design the circuit for resonance frequency, f = 10,000 Hz
7.13. POST LAB QUESTIONS:
What is meant by bandwidth?
Dept. of EEE
Electrical circuits and simulation lab
Exp - 8
DETERMINATION OF SELF, MUTUAL INDUCTNCES AND
COEFFICIENT OF COUPLING
OBJECTIVE
To determine the self-inductance, mutual inductance and coefficient of coupling of
the given 1- transformer.
RESOURCES:
S. No
Name of the apparatus
Range
Type
Quantity
1
Single phase transformer
230V / 115V, 3KVA
-
01No
2
1- auto transformer
230V / 0-270V,10A,
Induction
01No
3
Ammeter
(0-2) A
MI
01 No
4
Voltmeter
(0-600) / (0-300) V
MI
01No
5
Ammeter
(0-2) A
MC
01No
6
Connecting wires
-
-
Required number
7
Voltmeter
0-1V
MC
01No
PRECAUTIONS:
1. Ensure the minimum position of autotransformer during power on and off.
2. Set the ammeter pointer at zero position.
3. Take the readings without parallax error.
4. Avoid loose connections.
PROCEDURE:
To find Z1:

Apply rated voltage (V1) i.e 115 to primary winding and note down corresponding
ammeter reading. Then find out Z given
. We use auto transformer to vary voltage.
Dept. of EEE
Electrical circuits and simulation lab
To find Z2:

Apply rated voltage i.e 230 to primary winding and note down corresponding
ammeter reading. Then find out Z2 using the formula
.
To find Rdc1:

Apply low voltage to primary winding i.e 115 V and note down corresponding
ammeter readings. Then find Rdc given by
and from this Rac1 = 1.0 Rdc.
To find Rdc2 :

Apply a low voltage to primary i.e 230V winding and note down corresponding
ammeter readings. Then find Rdc2 given by
and from this Rac2 = 1.6 Rdc2.
To find M :

Apply voltage of primary winding till the voltmeter in secondary reads 115V and note
down corresponding ammeter reading in primary.
CRICUIT FOR FINDING ‘ M’ VALUE:
Dept. of EEE
Electrical circuits and simulation lab
CIRCUIT FOR SELF INDUCTANCE (L1):
CIRCUIT FOR SELF INDUCTANCE (L2):
CIRCUIT FOR RDC1:
CIRCUIT FOR RDC2:
Dept. of EEE
Electrical circuits and simulation lab
THEORY:
A voltage is induced in a coil when there is a time rate of charge of current
through it. The inductance parameter L, is defined in terms of the voltage across it and the
time rate of change of current through it V(t) =
Where V(t) is the voltage across the
coil. I(t) is the current through the coil, L is the inductance of the coil, Strictly speaking, this
definition is of self-inductance and this is considered as a circuit element with a pair of
terminals. Whereas circuit element “mutual inductor” does not exist mutual inductance is a
property associated with two or more coils or inductors which are in close proximity and the
presence of common magnetic flux which links the coils? A transformer is such a device
whose operation is based on mutual inductance. The two coils, or circuits are said to be
inductively coupled, because of this property they are called “
coupled elements “ , are coupled circuits and the induced voltage or emf is called voltage (or)
emf of mutual induction and is given by V2(t) =
volts. Where V2 is the voltage
induced in coil L2 And M1 is the co-efficient of proportionality and is called the co-efficient
of mutual inductance or simple mutual inductance.
The amount of coupling b/wn the inductively coupled coils is expressed in terms of
the co-efficient of coupling which is defined as
K=
where M= mutual inductance b/wn the coils,
L1 = self inductance of first coil,
L2 = self inductance of second coil.
Co-efficient of coupling is always less than unity, and has a maximum value of
1(or100%).
This case, for which K=1 is called perfect coupling when the entire flux of one coil
links the other. The greater the co-efficient of coupling b/wn the two coils, the greater the
mutual inductance between them, and vice-versa. It can be expressed as the fraction of the
magnetic flux produced by the current in one coil that links the other coil.
The co-efficient of coupling k is a non magnetic number and is independent of the
reference directions of the currents in the coils. If the two coils are a great distance apart in
space, and K is also very small. For iron core coupled circuits, the value of K may be as high
as 0.999, for air-core coupled ckts, K varied between 0.4 to 0.8.
Dept. of EEE
Electrical circuits and simulation lab
TABULAR FORMS:
To find Z1:
S.No
V1
(Volts)
I1
(amp)
Z1 
V1
Ω
I1
V2
(Volts)
I2
(amp)
Z2 
V2
Ω
I2
V
(Volts)
I
(amp)
V1
(Volts)
I1
(amp)
R1 
V1
Ω
I1
V2
(Volts)
I2
(amp)
R2 
V2
Ω
I2
1
To find Z2:
S.No
1
To find M :
S.No
M=V/I
1
To find Rdc1:
S.No
1
To find Rdc2 :
S.No
1
Dept. of EEE
Electrical circuits and simulation lab
CALCULATIONS:
XL1 =
XL2 =
XL1 = 2 fL1
XL2 = 2 fL2
=
=
L1 =
L2 =
Co-efficient of coupling K=
Where M =
=
=
RESULT:
PRE LAB QUESTIONS:1. Derive an expression for Mutual coupling coefficient.
2. Explain series aiding & series opposing in coupled circuit.
3. Explain parallel aiding& parallel opposing in a coupled Circuit
LAB ASSIGNMENT:
Calculate the self-inductance, mutual inductance and coefficient of coupling of the given
220V/220V , 3KVA 1- transformer
Exp - 8
DETERMINATION OF Z AND Y PARAMETERS
OBJECTIVE:
To determine open circuit impedance parameters (Z) and short circuit admittance
parameters (Y) of the given two port network.
.
Dept. of EEE
Electrical circuits and simulation lab
RESOURCES:
S. No
Name of the apparatus
Range
Type
Quantity
digital
01
1
Regulated power supply (0 – 30) V/2A
2
Voltmeters
(0-30) V
MC
01
3
Ammeters
(0-200m) A
MC
01
4
Resistors
330 
470
630
Carbon
Composition
01
01
01
5
Experi mental board
-
-
01
6
Connecting wires
-
-
Required
Number
PRECAUTIONS:
1. Initially keep the RPS output voltage knob in zero volt position.
2. Set the ammeter pointer to zero position.
3. Take the readings without parallax error.
4. Avoid loose connections
5. Do not short-circuit the RPS output terminals.
PROCEDURE:
1. Connections are made as per the circuit diagram.
2. Open the port – I i.e, I1=0 find the values of I1,I2, V1.
3.Short circuits the port V2 =0 find the values of V2,I1, I2.
4. Repeat steps 2,3 for port – II and find the values of V1,I1,I2 and V2,I1,I2 respectively.
5. Find all the parameters of two port networks I,e, Z,Y, ABCD, AI BI CI DI, h, g
parameters from the above data
GIVEN CIRCUIT:
Dept. of EEE
Electrical circuits and simulation lab
CIRCUIT DIAGRAMS:
Exp set up When V1=0:
Exp set up When I1=0:
Exp set up When V2=0:
Dept. of EEE
Electrical circuits and simulation lab
WHEN I2=0:
THEORY:
A port is normally referred to a pair of terminals of a network though which we can
have access to network of calculating current in any part of network. Frequently the problem
is move restried in nature and may be that of calculating the response at a terminal pair
designated an input when excitation is applied at another terminal pair designated as input
terminals. It is a problem of terminal through which it is accessible, is called “Two Port
Network.“
If we relate the voltage of one port to the current of the same port, we get driving
point immitance. On the other hand, if we relate the voltage of one port to the current at
another port, we get transfer immittance. Immitance is a general term used to represent either
the impudance or the admittance of a network.
We will consider a general two-port network composed of linear, bilateral elements
and no independent sources. Dependent sources are permitted. It is represented as a black box
with two accessible terminals pairs as shown in. The voltage and current at port -1 are V1 and
I1 and at port =II are V2 and I2. The position of V1 and V2 and the directions of I1 and I2 are
customarily selected. out of four variables, I1I1V2 and I2 only two are independent. The other
two are expressed in terms of the independent variable of network parameters.
Dept. of EEE
Electrical circuits and simulation lab
TABULAR FORMS:
THEORATICAL VALUES
V1
(volts)
I1
(mA)
V2
(mA)
I2
(mA)
V1=0
I1=0
V2=0
I2=0
PRACTICAL VALUES
V1
(volts)
I1
(mA)
V2
(mA)
I2
(mA)
V1=0
I1=0
V2=0
I2=0
THEORETICAL CALCULATIONS:
1. When I1 = 0 (i.e.,) When port is open circuited:
RL =
V2 =
=
I2=
V1 = I2.R =
2. When port -2 is open circuited (I2=0):
V1 =
Rt =
=
I1 =
V2
=
3.
When port -1 is short circuited ( V1=0):
V2 =
Rt =
=
I2 =
Dept. of EEE
Electrical circuits and simulation lab
I1 = I2
4.
When port –II is short – circuited (V2 = 0 ) :
V1 =
Rt
=
I1 = V1/Rt =
I2
=
THEORETICAL CALCULATIONS FOR PARAMETERS:
Z-parameters:
Z11 = / I2=0
=
Z12 = / I1=0
=
Z21 = / I2=0
=
Z22 = / I1=0
=
Y – Parameters
Y11 = / V2=0
=
Y12 =
/ V1=0
=
Y21 =
/ V2= 0 =
Y22 =
/ V1 = 0 =
.RESULT:
S. No
Parameter
1
Z11
2
Z12
3
Z21
4
5
Z22
Y11
6
Y12
7
Y21
8
Y22
Theoretical Values
Practical Values
Dept. of EEE
Electrical circuits and simulation lab
PRE LAB QUESTIONS:1. Write the 2-port network equations in terms of hybrid parameter?
2. Define image impedance?
3. What is Z- parameter?
4. Write the network equations of Y- parameter
LAB ASSIGNMENT:
Determine open circuit impedance parameters (Z) and short circuit admittance
parameters (Y) of the 25Ω, 50Ω, 10Ω T network circuit.
POST LAB QUESTIONS:
Write Y parameters in terms of Z parameters.
Dept. of EEE
Electrical circuits and simulation lab
Exp - 9
DETERMINATION OF TRANSMISSION AND HYBRID PARAMETERS
OBJECTIVE:
To determine transmission parameters and hybrid parameters of the given two port
network.
. RESOURCES:
S. No
Name of the apparatus
Range
Type
Quantity
digital
01
1
Regulated power supply (0 – 30) V/2A
2
Voltmeters
(0-30) V
MC
01
3
Ammeters
(0-200m) A
MC
01
4
Resistors
330 
470
630
Carbon
Composition
01
01
01
5
Experi mental board
-
-
01
6
Connecting wires
-
-
Required
Number
PRECAUTIONS:
1. Initially keep the RPS output voltage knob in zero volt position.
2. Set the ammeter pointer to zero position.
3. Take the readings without parallax error.
4. Avoid loose connections.
5. Do not short-circuit the RPS output terminals
PROCEDURE:
1.
Connections are made as per the circuit diagram.
2.
Open the port – I i.e, I1=0 find the values of I1,I2, V1.
3.
Short circuits the port V2 =0 find the values of V2,I1, I2.
4.
Repeat steps 2,3 for port – II and find the values of V1,I1,I2 and V2,I1,I2 respectively.
5.
Find all the parameters of two port networks I,e, Z,Y, ABCD, AI BI CI DI, h, g
parameters from the above data.
Dept. of EEE
Electrical circuits and simulation lab
GIVEN CIRCUIT:
CIRCUIT DIAGRAMS:
Exp set up When V1=0:
Exp set up When I1=0:
Exp set up When V2=0:
Dept. of EEE
Electrical circuits and simulation lab
WHEN I2=0:
THEORY:
A port is normally referred to a pair of terminals of a network though which we can
have access to network of calculating current in any part of network. Frequently the problem
is move restried in nature and may be that of calculating the response at a terminal pair
designated an input when excitation is applied at another terminal pair designated as input
terminals. It is a problem of terminal through which it is accessible, is called “Two Port
Network.
If we relate the voltage of one port to the current of the same port, we get driving
point immitance. On the other hand, if we relate the voltage of one port to the current at
another port, we get transfer immittance. Immitance is a general term used to represent either
the impedance or the admittance of a network.
We will consider a general two-port network composed of linear, bilateral elements
and no independent sources. Dependent sources are permitted. It is represented as a black box
with two accessible terminals pairs as shown in. The voltage and current at port -1 are V1 and
I1 and at port =II are V2 and I2. The position of V1 and V2 and the directions of I1 and I2 are
customarily selected. out of four variables, I1I1V2 and I2 only two are independent. The other
two are expressed in terms of the independent variable of network parameters.
Dept. of EEE
Electrical circuits and simulation lab
.TABULAR FORMS:
THEORETICAL VALUES
V1
(volts)
I1
(mA)
V2
(mA)
I2
(mA)
V1=0
I1=0
V2=0
I2=0
PRACTICAL VALUES
V1
(volts)
I1
(mA)
V2
(mA)
I2
(mA)
V1=0
I1=0
V2=0
I2=0
THEORETICAL CALCULATIONS:
1.
When I1 = 0 (i.e.,) When port is open circuited:
RL =
V2 =
=
I2=
V1 = I2.R =
2.
When port -2 is open circuited (I2=0):
V1 =
Rt
=
=
I1 =
V2
=
Dept. of EEE
Electrical circuits and simulation lab
3.
When port -1 is short circuited ( V1=0):
V2 =
Rt =
=
I2 =
I1 = I2
4.
When port –II is short – circuited (V2 = 0 ) :
V1 =
Rt
=
I1 = V1/Rt =
I2
=
THEORETICAL CALCULATIONS FOR PARAMETERS:
ABCD parameters:
A = / I2= 0
B=
C=
D=
=
/ V2= 0 =
/ I2= 0
/ V1=0
=
=
H – Parameters:
h11 = / V2 =0 =
h12 =
h21 =
h22 =
/ I1=0
=
/ V2 =0 =
/ I1 =0
=
RESULT:
S. No
Parameter
1
A
2
B
3
C
4
5
D
H11
6
H12
7
H21
8
H22
Theoretical Values
Practical Values
Dept. of EEE
Electrical circuits and simulation lab
PRE LAB QUESTIONS:1. Write the 2-port network equations in terms of hybrid parameter?
2. Define image impedance?
3. What are Transmission parameters?
4. Write the network equations of Hybrid parameters.
LAB ASSIGNMENT:
Determine transmission parameters and hybrid parameters of the given two port network of
25Ω, 50Ω, 10Ω T network ciruit.
POST LAB QUESTIONS:
Obtain the condition for symmetry in ABCD parameters.
Dept. of EEE
Electrical circuits and simulation lab
Exp - 10
MEASUREMENT OF 3-PHASE REACTIVE POWER USING
SINGLE PHASE WATTMETER
OBJECTIVE : To measure reactive power in a three-phase circuit using single phase
wattmeter.
RESOURCES :
Sl.No
1
2
Apparatus
Voltmeter
Wattmeter
3
4
Ammeter
3 autotransformer
5
3 loading inductor
Range
(0-600V)
1,600V,10A,
LPF
0-10A,
415/0-470V,
10A, 8.14KVA
10A, 415V
Type
MI
D.M.T
Qty
1 no.
1 no.
MI
1 no.
1no.
1 no.
PRECAUTIONS:
1. Ensure the minimum position of Three phase autotransformer during power on and off.
2. Set the ammeter pointer at zero position.
3. Take the readings without parallax error.
4. Avoid loose connections.
MODEL GRAPH:
Dept. of EEE
Electrical circuits and simulation lab
PROCEDURE:
1.
Connect the circuit as per the circuit diagram.
2.
Keep the variac of the auto-transformer in minimum position.
3.
Close supply TPST switch and vary the auto-transformer slowly and apply rated
voltage i.e.230V.
4.
Vary the load gradually and at different loads, note down readings of ammeter,
Voltmeter and Wattmeter.
5. Draw the phasor diagram
CIRCUIT DIAGRAM:
Dept. of EEE
Electrical circuits and simulation lab
THEORY:
Reactive power measurement in 3- circuits using 1- wattmeter can be done only for
balanced 3- loads. By connecting the current coil of the wattmeter in one line and the
pressure coil across the other two lines of 3- circuit, current through the current coil and
voltage across the pressure coil are determined. Now as the current in the current coil lags the
voltage by an angle of 90,the wattmeter reads a value proportional to the reactive power of
the circuit.
PHASOR DIAGRAM:
IR
VR
VYB
VBN
VY
OBSERVATIONS:
For ideal inductive load  = 900 --> Sin= 1
Reactive power
Wattmet
Reactive power
(actualvalue)
Qa=
S.
Voltage
Current
er
(measured
No
VL volts
IL amp
reading
value)Qm=
(W)
3W (VAR )
3VL I L sin 
(VAR )
%err
or =
{(QmQa)/
Qa}*1
00
1
2
3
4
5
Dept. of EEE
Electrical circuits and simulation lab
SAMPLE CALCULATIONS:
Load voltage VL =
Load current IL =
Watt meter reading W =
Reactive power (measured value) =
3W =
3VL I L sin  =
Reactive power (actual value) =
measured value - actual value
% error =
x100
actual value
RESULT:
PRE LAB QUESTIONS:1. What is meant by Reactive power?
2. What is the difference between balanced and unbalanced loads?
3. What is meant by complex power?
LAB ASSIGNMENT:
Calculate the active & apparent power for the given circuit
Dept. of EEE
Electrical circuits and simulation lab
Exp - 13
MEASUREMENT OF 3-PHASE POWER BY
TWO WATTMETER METHOD FOR UNBALANCED LOADS
OBJECTIVE:
To measure the 3-phase active and reactive power by 2 – wattmeter method for
(i) resistance load (ii) inductive load.
RESOURCES:
Sl. No.
1
2
3
4
Apparatus
Voltmeter
Ammeter
Wattmeter
Wattmeter
Range
(0-600V) MI
(0-10A) MI
600V, 10A, UPF
600V, 10A, LPF
Quantity
1
1
2
2
PRECAUTIONS:
1) THE TPST switch must be kept open initially. 
2) Load must not be applied while starting. 
PROCEDURE:
(i) – Resistive load
1) Give the connections as per the circuit diagram.
2) Give the supply by closing TPST switch.
3) Vary the resistance load and note down the corresponding readings.
(ii) Inductive load
1) Give the connections as per the circuit diagram.
2) Give the supply by closing the TPST switch
3) Vary the inductive load and note down the corresponding readings.
Dept. of EEE
Electrical circuits and simulation lab
For inductive load
For resistive load
Dept. of EEE
Electrical circuits and simulation lab
Formulae Used:
1.
Real power = w1 + w2
2.
Reactive power = 3(w1w2 )
3.
Tan=
4.
Power factor = cos 

3(w w )
1
2
w1 w2

OBSERVATIONS:
Two Wattmeter Method: Resistive Load
V
(volt)
I
(A)
MF =
Wattmeter
Reading (W1)
OBS
ACT =
(watt) OBS X
MF
(watt)
MF =
Wattmeter
Reading (W2)
OBS ACT=OBS
(watt)
x MF
(watt)
Power
Cos 
Real
Power
(watt)
Reactive
power
(watt)
Dept. of EEE
Electrical circuits and simulation lab
Two Wattmeter Method: Inductive Load
V
(volt)
I
(A)
MF =
MF =
Wattmeter
Wattmeter
Reading (W1)
Reading (W2)
OBS ACT = OBS
ACT=OBS
(watt) OBS x (watt)
x MF
MF
(watt)
(watt)
Power
Cos 
Real
Power
(watt)
Reactive
power
(watt)
RESULT:
PRE LAB QUESTIONS:
1) What are the methods to measure 3 phase power?
LAB ASSIGNMENT QUESTIONS:
1) Explain about two wattmeter method for 3 phase power measurement?
POST LAB QUESTIONS:
1) What is meant by balanced and un balanced loads?
Dept. of EEE
Electrical circuits and simulation lab
Exp - 03
VERIFICATION OF RMS VALUE OF A COMPLEX WAVE
OBJECTIVE:
To calculate the RMS value of a complex wave.
RESOURCES:
Sl. No.
1
2
3
4
5
Apparatus
Function generator
DRB
DLB
Multimeter
CRO
Range
0-20mhz
0-100K
0-1H
0-30mhz
Quantity
1
2
1
1
1
PRECAUTIONS:
1. Take the readings without parallax error.
2. Avoid loose connections.
PROCEDURE:
1. Connect the circuit as per the circuit diagram.
2. Apply the sinusoidal wave as input from the Function Generator.
3. Observe the output waveform in the CRO. Note down the peak value of the output
wave, from the CRO.
4. Switch OFF the supply.
Dept. of EEE
Electrical circuits and simulation lab
CIRCUIT DIAGRAM:
RESULT:
Dept. of EEE