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ELECTRICAL TECHNOLOGY
LAB MANUAL
Subject Code:
Regulations:
Class:
A40215
R13 – JNTUH
II Year II Semester (ECE)
DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING
INSTITUTE OF AERONAUTICAL ENGINEERING
(Autonomous)
Dundigal – 500 043, Hyderabad
1|P age
INSTITUTE OF AERONAUTICAL ENGINEERING
(Autonomous)
Dundigal, Hyderabad - 500 043
Department of Electrical and Electronics Engineering
Program Outcomes
PO1
PO2
PO3
PO4
PO5
PO6
PO7
PO8
PO9
PO10
PO11
PO12
Engineering Knowledge: Apply the knowledge of mathematics, science, engineering
fundamentals, and an engineering specialization to the solution of complex engineering problems.
Problem Analysis: Identify, formulate, review research literature, and analyze complex
engineering problems reaching substantiated conclusions using first principles of mathematics,
natural sciences, and engineering sciences.
Design / Development of Solutions: Design solutions for complex engineering problems and
design system components or processes that meet the specified needs with appropriate
consideration for the public health and safety, and the cultural, societal, and environmental
considerations.
Conduct Investigations of Complex Problems: Use research-based knowledge and research
methods including design of experiments, analysis and interpretation of data, and synthesis of the
information to provide valid conclusions.
Modern Tool Usage: Create, select, and apply appropriate techniques, APPARATUS, and modern
engineering and IT tools including prediction and modeling to complex engineering activities with
an understanding of the limitations.
The Engineer and Society: Apply reasoning informed by the contextual knowledge to assess
societal, health, safety, legal and cultural issues and the consequent responsibilities relevant to the
professional engineering practice.
Environment and Sustainability: Understand the impact of the professional engineering solutions
in societal and environmental contexts, and demonstrate the knowledge of, and need for sustainable
development.
Ethics: Apply ethical principles and commit to professional ethics and responsibilities and norms
of the engineering practice.
Individual and Team Work: Function effectively as an individual, and as a member or leader in
diverse teams, and in multidisciplinary settings.
Communication: Communicate effectively on complex engineering activities with the engineering
community and with society at large, such as, being able to comprehend and write effective reports
and design documentation, make effective presentations, and give and receive clear instructions.
Project Management and Finance: Demonstrate knowledge and understanding of the engineering
and management principles and apply these to one’s own work, as a member and leader in a team,
to manage projects and in multidisciplinary environments.
Life - Long Learning: Recognize the need for, and have the preparation and ability to engage in
independent and life-long learning in the broadest context of technological change.
Program Specific Outcomes
PSO1
PSO2
PSO3
Professional Skills: Able to utilize the knowledge of high voltage engineering in collaboration
with power systems in innovative, dynamic and challenging environment, for the research based
team work.
Problem - Solving Skills: Can explore the scientific theories, ideas, methodologies and the new
cutting edge technologies in renewable energy engineering, and use this erudition in their
professional development and gain sufficient competence to solve the current and future energy
problems universally.
Successful Career and Entrepreneurship: The understanding of technologies like PLC, PMC,
process controllers, transducers and HMI one can analyze, design electrical and electronics
principles to install, test , maintain power system and applications.
2|P age
S. No.
List of Experiments
Page No.
1
Verification Of KVL And KCL
6-7
2
Series And Parallel Resonance
8 - 10
3
Time Response Of First Order RC And RL Networks
11 - 13
4
Z & Y Parameters
14 - 15
5
Transmission And Hybrid Parameters
16 - 17
6
Verification of Superposition Theorem And Reciprocity Theorem
18 - 20
7
Verification of Maximum Power Transfer Theorem
21 - 22
8
Verification Of Thevenin’s And Norton’s Theorems
23 - 25
9
Magnetization Characteristics Of A Dc Shunt Generator
26 - 28
10
Swinburne’s test on DC Shunt machine
29 - 32
11
Brake test o DC Shunt Motor
33 - 35
12
OC & SC test on a Single phase Transformer
36 - 40
13
Load test on a Single phase Transformer
41 - 43
3|P age
ATTAINMENT OF PROGRAM OUTCOMES & PROGRAM SPECIFIC OUTCOMES
Exp.
No.
Experiment
Program Outcomes
Attained
Program Specific
Outcomes Attained
1
Verification Of KVL And KCL
PO1,PO2
PSO1,PSO2
2
Series And Parallel Resonance
PO2,PO3
PSO1,PSO2
3
Time Response Of First Order RC
And RL Networks
PO1,PO2
PSO1,PSO2
4
Z & Y Parameters
PO1,PO2
PSO1,PSO2
5
Transmission And Hybrid Parameters
PO1,PO2
PSO1,PSO2
PO1,PO2
PSO1,PSO2
PO1,PO2
PSO1,PSO2
PO1,PO2
PSO1,PSO2
PO1,PO2,PO5
PSO1,PSO2,PSO3
PO1,PO2,PO5
PSO1,PSO2,PSO3
PO1,PO2,PO5
PSO1,PSO2,PSO3
PO1,PO2,PO5
PSO1,PSO2,PSO3
PO1,PO2,PO5
PSO1,PSO2,PSO3
6
7
8
9
10
11
12
13
Verification of Superposition Theorem
And Reciprocity Theorem
Verification Of Maximum Power
Transfer Theorem
Verification Of Thevenin’s And
Norton’s Theorems
Magnetization Characteristics Of A
Dc Shunt Generator
Swinburne’s test on DC Shunt
machine
Brake test o DC Shunt Motor
OC & SC test on a Single phase
Transformer
Load test on a Single phase
Transformer
4|P age
ELECTRICAL TECHNOLOGY LAB
OBJECTIVE:
The objective of the Electrical Technology lab is to expose the students to the operation of electrical circuits
and give them experimental skill. The purpose of lab experiment is to continue to build circuit construction
skills using different circuit element. It also aims to introduce PSPICE, a circuit simulation software tool. It
enables the students to gain sufficient knowledge on the programming and simulation of Electrical circuits ,
OUTCOMES:
Upon the completion of Electrical Circuit and simulation practical course, the student will be able to
attain the following:
1. Familiarity with DC circuit analysis techniques, resistive circuits.
2. Analyze complicated circuits using different network theorems.
3. Acquire skills of using PSPICE software for Electrical circuit studies.
4. Apply techniques for the analysis and simulation of linear electric circuits, and
measurements of their properties.
5. Analyze the transient and AC steady state behavior of a circuit
6. Demonstrate the ability to work Lab Experimentation effectively to electrical circuit
exercises/problems, circuit measurements, and computer work using PSPICE.
5|P age
EXPERIMENT - 1
VERIFICATION OF KVL AND KCL
1.1
AIM: Verification of KVL and KCL theoretically and practically.
1.2
APPARATUS:
S. No
1.3
Name of the Equipment
1
Multimeter
2
Ammeter MC
3
Connecting wires
Range
Type
Quantity
CIRCUIT DIAGRAM OF KVL:
Figure 1
1.4
CIRCUIT DIAGRAM OFKCL:
Figure 2
6|P age
1.5
PROCEDURE:
1.5.1
KVL:
1. Make connections as per diagram
2. Verify the connections to the lab instructor.
3. Switch on the DC supply with the help of DPST.
4. Note down all meter readings, the sum of VI, V2 and V3 must be equal to the Vs.
1.5.2
KCL:
1. Make connections as per diagram
2. Verify the connections to the lab instructor.
3. Switch on the DC supply with the help of DPST.
4. Note down all meter readings, the sum of A2 and A3 must be equal to the A1.
1.6
CALCULATIONS:
1.6.1
KVL
Total resistance of the circuit R=R1+R2+R3 -- Ω
Total current of the circuit I= Vs÷R -- Amp
The resistance are connected in series so the total current I will flow in every
resistance.
So, Voltage drop in resistance R1= I × R1-------Volts.
Voltage drop in resistance R2 = I × R2-------Volts.
Voltage drop in resistance R3 = I × R3-------Volts.
Now Supply voltage Vs = (I × R1)+(I × R2)+(I × R3).
1.6.2
KCL
3 R2 and R3 resistances are in parallel so effective resistance Re= R2×R3÷ R3+R2-Ω
Now R1 and Re are in series, so total resistance R = R1+Re ---------Ω.
Total current of the circuit I = Vs÷R -- Amp.
Current through R2 resistanceI1 = Total current (I) ×Opposite resistance (R3) ÷
Total resistance (R2) + (R3) ------ Amps.
Current through R3 resistanceI2 = Total current (I)- (I1) ---------- Amps.
Now Total current (I) =(I1)+ (I2) ----Amps.
1.7
RESULT:
1.8
PRE-VIVA:
1. State KVL.
2. State KCL .
1.9
PRE-VIVA:
1. For what types of circuits KVL and KCL are used?
7|P age
EXPERIMENT – 2
SERIES AND PARALLEL RESONANCE
2.1
AIM:
To find the resonant frequency, quality factor and band width of a series and parallel resonant
circuit.
2.2
APPARATUS:
S. No.
2.3
Name of the Equipment
1
Signal generator
2
Decade resistance box
3
Decade inductance box
4
Decade capacitance box
5
Ammeter
6
Connecting wires
Range
Type
Quantity
CIRCUIT DIAGRAM:
2.3.1 Series Resonance
I
Fig - 1
2.3.2 Parallel resonance
Signal
Generator
Fig - 2
2.4
PROCEDURE:
1. Connect the circuit as shown in fig.1 for series resonant circuit & fig.2 for parallel
resonant circuit.
2. Set the voltage of the signal from function generator to 10V.
3. Vary the frequency of the signal from 100 Hz to 20 KHz in steps and note down the
corresponding ammeter readings.
4. Observe that the current first increases & then decreases in case of series resonant circuit
& the value of frequency corresponding to maximum current is equal to resonant
frequency.
8|P age
5. Observe that the current first decreases & then increases in case of parallel resonant
circuit & the value of frequency corresponding to minimum current is equal to resonant
frequency.
6. Draw a graph between frequency and current & calculate the values of bandwidth &
quality factor.
2.5
THEORETICAL CALCULATIONS:
Series Resonance
Resonant Frequency
(fr) = 1/(2∏√LC)
Lower cut off frequency
(f1) = fr-R/4∏L
Upper cut off frequency
(f2) = fr+R/4∏L
Quality factor
Qr = ωrL/R = 1/ωrRC
Band Width
f2-f1 = R/2∏L
Parallel Resonance
2.6
Resonant Frequency
(fr) = 1/(2∏√LC)
Lower cut off frequency
(f1) =fr-1/4∏RC
Upper cut off frequency
(f2) = fr+1/4∏RC
Quality factor
Qr = ωrCR = fr/B.W
Band Width
f2-f1 = 1/2∏RC
TABULAR COLUMN:
S.No.
Frequency
(Hz)
Current
(mA)
1
2
3
4
5
6
7
8
2.7
MODEL GRAPH:
Fig - 3
Fig - 4
9|P age
2.8
PRE LAB VIVAQUESTIONS
1. Define resonance.
2. Give condition for series resonance.
3. What is meant by band width?
4. Define quality factor.
5. What is mean by power factor?
2.9
LAB ASSIGNMENT
1. Define quality factor and give expression for it.
2. Give the application of series and parallel resonance circuit.
2.10
POST LAB QUESTIONS
1. What is the difference between series and parallel resonance?
2. What do you observe from the series and parallel resonance graphs?
3. What is the power factor under resonant condition?
2.10:
RESULT
10 | P a g e
EXPERIMENT - 3
TIME RESPONSE OF FIRST ORDER RC AND RL NETWORKS
3.1
AIM: To determine the time constant of series RL and RC circuits
3.2
APPARATUS:
S.No.
1
2
3
4
5
6
3.3
Equipment
Range
Type
Quantity
Resistor(D.R.B),
capacitor(D.C.B),
Inductor(D.L.B)
C.R.O.
C.R.O.PROBES
Signal Generator
Bread Board
Connecting wires
CIRCUIT DIAGRAM:
Fig - 1
Fig - 2
Fig3
Fig - 3
11 | P a g e
Fig - 4
3.4
PROCEDURE:
3.4.1
SERIES RC CIRCUIT:
1. Connect the circuit as shown in figure (1) with R=1kohm and C=0.1uF.
2. Apply a voltage of 15vp-p from the signal generator at 800 Hz to the circuit.
3. Observe the output waveform i.e. VR (voltage across the resistor) on the CRO and also
input.
4. Connect the CKT as shown in figure (2), this time the capacitor is connected across the
output terminals.
5. Observe the waveform of Vc (voltage across the capacitor) and note down the peak value
of thin voltage, 0.632 times the peak value of thin voltage and note down the time
corresponds to 0.632Vp (This value of time in the time constant value).
6. Calculate the theoretical time constant value by using T=RC and compare with practical
value.
7. Draw the input, VR & VC waveform on the graph sheet.
3.4.2
SERIES RL CIRCUIT:
1. Connect the circuit as shown in figure (3) with R=1kohm and L=50mH
2. Apply a voltage of 15vp-p from the signal generator at 800hz to the circuit.
3. Observe the output waveform i.e. VL (voltage across the inductor) on the CRO and also
input.
4. Connect the ckt as shown in figure (4), and observe the output waveform i.e. voltage
across resistor VR on the CRO and also the input waveform.
5. From the VR waveform, note down the value of peak voltage 0.632times the peak voltage
and time corresponds to 0.632Vp. This time is called the value of time constant.
6. Calculate the theoretical time constant value by using T=L/Rsec and compare with
practical value.
7. Draw the input ,VR & VL waveform on the graph sheet, Indicate time corresponds to
0.632Vr
12 | P a g e
3.5
EXPECTED GRAPH:
Input wave:
Fig - 5
Expected Graph:
Vc = V(1-e-t/RC)
At t=0 Vc=0
t=∞ Vc=V
Fig - 6
VR = V(1-e-(R/L)t)
At t=0 VR=0
t=∞ VR=V
Fig - 7
VL = V(e-(R/L)t)
At t=0 VL=V
t=∞ VL=0
Fig - 8
13 | P a g e
i=V/R(1-e-(R/L)t)
At t=0 i=0
t=∞ i=V/
Fig - 9
3.6
RESULT:
3.7
PRE LAB VIVAQUESTIONS
1. What is time response?
2. Series R-L as --------phase angle.
3. Series R-C as --------phase angle.
3.8
LAB ASSIGNMENT
1. Derive the series R-L circuit with Ac voltage.
2. Derive the series R-Ccircuit with Ac voltage.
3.9
POST LAB QUESTIONS
1. Define time constant.
2. write the time constants of R-L and R-C circuits.
14 | P a g e
EXPERIMENT – 4
Z & Y PARAMETERS
4.1
AIM:
To find the Z & Y parameters of a two port network.
4.2
APPARATUS:
S. No.
4.3
Name of the Equipment
1.
Resistors
2.
Ammeter
3.
Voltmeter
4.
R.P.S
5.
Bread Board
6.
Connecting wires
Range
Type
Quantity
CIRCUIT DIAGRAM:
Fig - 1
4.4
PROCEDURE:
Z – Parameters
1. Connect the circuit as shown in fig.
2. Open circuit port2 that is (i.e I2 = 0 ) and measure I1 and V2 and calculate Z11 & Z21 using
the formulas
𝐕
Z11= 𝐈 𝟏 |I2 = 0
𝟏
𝐕
Z21= 𝐈 𝟐 |I2 = 0
𝟏
3. To Measure Z12 and Z22, open circuit port1 (i.e. I1=0) and measure V1 and I2 and calculate
Z12 & Z22 using the formulas
𝐕
Z12= 𝐈 𝟏 |I1 = 0
𝟐
𝐕
Z22= 𝐈 𝟐 |I1 = 0
𝟐
Y – Parameters
1. Connect the circuit as shown in fig.
2. Short circuit port 2 (i.e V2 = 0 ) and measure V1, I1 & I2 and calculate Y11 & Y12 using the
formulas
15 | P a g e
𝐈
𝐈
Y11=𝐕𝟏 |v2 = 0
Y21=𝐕𝟐 |v2 = 0
𝟏
𝟏
3. To Measure Y12 and Y22, short circuit port 1 (i.e. V1=0) and measure V2, I1 and I2 and
calculate Y12 & Y22 using the formulas
𝐈
𝐈
Y11=𝐕𝟏 |v1 = 0
Y21=𝐕𝟐 |v1 = 0
𝟐
4.5
𝟐
TABULAR COLUMN:
When I2=0
S.No
V1(V)
I1(mA)
V2(V)
V1(V)
V2(V)
I2(mA)
V1(V)
I1(mA)
I2(mA)
I1(mA)
I2(mA)
V2(V)
1
When I1=0
S.No
1
When V2=0
S.No
1
When V1= 0
S.No
1
4.5
PRE LAB QUESTIONS:
1. What are Z parameters?
2. What are Y parameters?
3. What is the other name of Z parameter?
4. What is the other name of Y parameter?
5. What is the reciprocity and symmetry condition for Z parameters
6. What is the reciprocity and symmetry condition for Y parameters
4.6
LAB ASSIGNMENT:
1. Find out Z parameters for 𝜫 network and T network.
2. Find out Y parameters for 𝜫 network and T network.
4.7
POST LAB QUESTIONS:
1. Give the relation between Y and Z parameters.
2. What are the different parameters used to represent two port networks?
3. Represent Z parameter in terms of Y parameter.
4.8
RESULT:
16 | P a g e
EXPERIMENT – 5
TRANSMISSION AND HYBRID PARAMETERS
5.1
AIM:
To find the ABCD and H parameters of a two port network.
5.2
APPARATUS:
S. No.
5.3
Name of the Equipment
1.
Resistors
2.
Ammeter
3.
Voltmeter
4.
R.P.S
5.
Bread Board
6.
Connecting wires
Range
Type
Quantity
CIRCUIT DIAGRAM:
Figure - 1
5.4
PROCEDURE
ABCD – Parameters
1. Connect the circuit as shown in fig.
2. Connect the circuit as shown in figure make I2=0 and note down the values of V1, I1 & V2.
A = V1/V2
|I2=0
= (R1+R3)/R3
C = I1/V2
|I2=0
= 1/R3
3. Make V2=0 and note down the values of V1,I1 & I2.
4.
B = -V1/I2
D = -I1/I2
|V2=0
= (R1R2+R2R3+R3R1)/R3
|V2=0 = (R2+R3)/R3
5. Find the values of A, B, C, D and compare them with the theoretical values.
17 | P a g e
H – Parameters
1. Connect the circuit as shown in fig.
2. Connect the circuit as shown in figure make I1=0 and note down the values of V1, I2 & V2
h12 = V1/V2
h22 = I2/V2
3. Make V2=0 and note down the values of V1,I1 & I2.
H11 = V1/I1
H21 = I2/I1
4. Find the values of H11, H22, H12, H21 and compare them with the theoretical value
4.5
TABULAR COLUMN
When I2=0
S.No
V1(V)
I1(Ma)
V2(V)
When I1=0
S.No
V1(V)
V2(V)
I2(Ma)
When V2=0
S.No
V1(V)
I1(Ma)
I2(Ma)
When V1= 0
S.No
I1(Ma)
I2(Ma)
V2(V)
5.6
RESULT:
5.7
PRE LAB QUESTIONS:
1. What are ABCD parameters?
2. What are H parameters?
3. What is the other name of ABCD parameter?
4. What is the other name of ABCD parameter?
5. What is the reciprocity and symmetry condition for ABCD parameters
6. What is the reciprocity and symmetry condition for H parameters
5.8
LAB ASSIGNMENT:
1. Find out ABCD parameters for 𝜫 network and T network?
2. Find out H parameters for 𝜫 network and T network?
18 | P a g e
5.9
POST LAB QUESTIONS:
1. Give the relation between ABCD and H parameters.
2. What are the different parameters used to represent two port networks?
3. Represent ABCD parameter in terms of H parameter.
19 | P a g e
EXPERIMENT – 6
VERIFICATION OF SUPERPOSITION THEOREM AND RECIPROCITY THEOREM
6.1
AIM:
To Verify Superposition Theorem and maximum power transfer theorem
STATEMENT:
In any linear and bilateral network consisting of number of voltage and current sources, the response
in any element is given as sum of the responses due to individual sources, when one source is active
remaining all other sources are made non-operative.
6.2
APPARATUS:
S. No.
6.3
Name of the Equipment
1
Resistors
2
Multimeter
3
Voltmeters
4
Ammeters
5
R.P.S
6
Bread Board
7
Connecting Wires
Range
Type
Quantity
CIRCUIT DIAGRAM:
Fig - 1
Fig - 2
Fig - 3
20 | P a g e
6.4
PROCEDURE:
1
Connect the circuit as shown in figure (1) and note down the current flowing through R 3
and let it be I.
2
Connect the circuit as shown in figure (2) and note down the ammeter Reading, and let it
be I1.
3
Connect the circuit as shown in figure (3) and note down the ammeter reading, and let it
be I2.
6.4
4
Verify for I=I1+I2.
5
Compare the practical & theoretical currents.
TABULAR COLUMN:
PARAMETERS
WHEN BOTH
V1 & V2≠0
(I)
WHEN
V1≠0 & V2=0
(I1)
WHEN
V1=0& V2≠0
(I2)
Current through R3
(Theoretical Values)
Current through R3
(Practical Values)
RECIPROCITY THEOREM
6.6
STATEMENT:
In any linear, bilateral, single source network the ratio of excitation to response is constant
even when their positions are inter-changed.
6.7
CIRCUIT DIAGRAM:
Fig - 1
Fig - 2
21 | P a g e
Fig - 3
6.8
PROCEDURE:
1. Connect the circuit as shown in fig1.
2. Measure the current I in the branch CB.
3. Inter-change voltage source and response as shown in fig2. and note down the current I1.
4. Observe that the currents I and I1 should be same.
6.9
TABULAR COLUMN:
Parameters
6.10
Theoretical Values
Practical Values
PRE LAB QUESTIONS:
1. What is reciprocity theorem?
2. What is Superposition theorem
3. Reciprocity Is it possible to apply both theorems to ac as well as dc circuit?
4. Reciprocity is applicable for unilateral and bilateral networks
6.11
LAB ASSIGNMENT:
1. State and prove reciprocity theorem.
2. State and prove Superposition theorem theorem.
3.
State application of Reciprocity theorem.
4. State application of Superposition theorem.
6.12
RESULT:
22 | P a g e
EXPERIMENT – 7
MAXIMUM POWER TRANSFER THEOREM
7.1
STATEMENT:
The maximum power transfer theorem states that maximum power is delivered from a source
to
a load resistance when the load resistance is equal to source resistance. (Rs = RL is
the
condition
required for maximum power transfer).
7.2.
APPARATUS:
S. No.
Name of the Equipment
1
2
3
4
5
6
7
7.3.
Range
Type
Quantity
Resistors
Multimeter
Voltmeters
Ammeters
R.P.S
Bread Board
Connecting Wires
CIRCUIT DIAGRAM:
Fig - 1
7.4.
PROCEDURE:
1. Connect the circuit as shown in fig.
2. Vary the load resistance in steps and note down voltage across the load and current
flowing through the circuit.
3. Calculate power delivered to the load by using formula P=V*I.
4. Draw the graph between resistance and power (resistance on X- axis and power on Yaxis).
5. Verify the maximum power is delivered to the load when RL = Rs for DC.
7.5.
TABULAR COLUMN:
S. No
1
RL
VL
IL
P=VI
2
3
4
5
23 | P a g e
7.6.
MODEL GRAPH:
Fig - 2
7.7.
RESULT:
7.8.
PRE LAB VIVA QUESTIONS:
1. What is Superposition theorem?
2. What is maximum power transfer theorem?
3. Is it possible to apply Superposition theorem to ac as well as dc circuit.
4. How to find power using Superposition theorem?
7.9.
LAB ASSIGNMENT:
1. State and prove maximum power transfer theorem.
2. State and prove Superposition theorem.
3. Apply superposition theorem to the circuit having dependent source.
7.10.
POST LAB QUESTIONS:
1. What are conditions for maximum power transfer theorem?
2. Is it possible to apply Superposition theorem to nonlinear circuit?
24 | P a g e
EXPERIMENT – 8
THEVENIN'S AND NORTON'S THEOREMS
8.1.
AIM
To Verify Thevenin's and Norton's theorems
8.2
APPARATUS:
S. No.
Name of the Equipment
1
Ammeter
2
Voltmeter
3
Bread Board
4
R.P.S
5
Resistors
6
Connecting Wires
Range
Type
Quantity
THEVENIN’S AND NORTON’S THEOREM
(A)
THEVENIN’S THEOREM
Statement
Any linear, bilateral network having a number of voltage, current sources and resistances
can be replaced by a simple equivalent circuit consisting of a single voltage source in series
with a resistance, where the value of the voltage source is equal to the open circuit voltage
across the open circuit terminals of the network, and the resistance is the equivalent
resistance measured between the open circuit terminals with all energy sources replaced by
their internal resistances.
8.3
CIRCUIT DIAGRAM
Fig - 1
8.4
PROCEDURE
1. Connect the circuit diagram as shown in fig1.
2. Measure Voc between A and B terminals, by open circuiting AB terminals.
3. Connect the circuit as shown in fig2.
4. The resistance between A and B is obtained by using voltmeter, ammeter method, and the
ratio of V and I gives RTh
5. Draw the Thevenin’s equivalent circuit as shown in fig.3
25 | P a g e
8.5
TABULAR COLUMN
Parameters
Theoretical Values
Practical Values
Voc
Isc
RTH
(B)
NORTON’S THEOREM
Statement
Any linear, bilateral network with current sources, voltage sources and resistances can be
replaced by an equivalent circuit consisting of a current source in parallel with a resistance.
The value of the current source is the current flowing through the short circuit terminals of
the network and the resistance is the equivalent resistance measured between the open
circuit terminals of the network with all the energy sources replaced by their internal
resistances.
8.6
CIRCUIT DIAGRAM
Fig - 2
8.7
PROCEDURE
1. Connect the circuit diagram as shown in fig1.
2. Measure the current Isc (or) IN through AB by short-circuiting the resistance between A
and B.
3. Connect the circuit diagram as shown in fig2.
4. The resistance between A and B are obtained by using. Voltmeter, ammeter method and
the ratio of V and I gives RN.
5. Draw Norton's equivalent circuit by connecting IN & RN in parallel as shown in fig3.
8.8
TABULAR COLUMN
Parameters
Theoretical Values
Practical Values
Isc/ IN (mA)
RN (kΩ)
IL (mA)
26 | P a g e
8.9
PRE LAB VIVA QUESTIONS
1. State Thevenin’s theorem.
2. State Norton’s theorem.
3. Define Rth.
4. Define Vth..
8.10
LAB ASSIGNMENT
1. State and prove Thevenin’s theorem.
2. Derive the value of Rth.
3. Find Norton’s equivalent from the circuit having dependent source?
8.11
POST LAB VIVA QUESTIONS
1. Convert Thevenin’s equivalent into Norton’s equivalent.
2. Is it possible to apply Thevenin’s and Norton’s theorem ac as well as dc circuit?
3. What are the applications of Norton’s theorem?
4. What are the practical applications of Thevenin’s theorem?
27 | P a g e
EXPERIMENT-9
MAGNETIZATION CHARACTERISTIC OF A D.C. SHUNT GENERATOR
9.1
AIM:
To determine experimentally the magnetization or open circuit characteristic of a D.C Shunt
generator and to determine the critical field resistance and critical speed. `
9.2
9.3
APPARATUS:
S. No
Item
1
Ammeter
2
Voltmeter
3
Rheostat
4
Tachometer
Type
Range
NAME PLATE DETAILS:
Motor
9.4
Quantity
Generator
Voltage
Voltage
Current
Current
Output
Output
Speed
Speed
CIRCUIT DIAGRAM:
RFm
20A
Fig – 1
28 | P a g e
9.5
PROCEDURE:
1. Choose the proper ranges of meters after noting the name plate details of the given
machine and make the connections as per the circuit diagram.
2. Keep the motor field rheostat (Rfm) in the minimum position. The jockey [J] of the
potential divider should be at the minimum voltage position [P] and start the MG set.
3. Observe the speed of the generator using a tachometer and adjust to the rated value by
varying the motor field rheostat. Keep the same speed through out the experiment.
4. Note down the terminal voltage of the generator. This is the e.m.f. due to residual
magnetism.
5. Increase the generator field current If (ammeter) by gradually moving the jockey J in the
direction P to Q. for every value of If, field resistance of the generator note down the
corresponding voltmeter reading. Increase the field current till induced e.m.f is about
120% of rated value.
6. Repeat the same procedure for decreasing values of the same field currents (I fg) and
finally note down the emf generated due to residual magnetism.
7. Draw the characteristics of generated emf (Efg) versus field current for both increasing and
decreasing values of field current. Draw the average O.C.C
8. Draw a tangent to the initial portion of average O.C.C from the origin. The slope of this
straight line gives the critical field resistance.
9.6
TABULAR COLUMN:
ASCENDING
DESCENDING
S. No
Field current
(amp)
Generated voltage
(volts)
Field current
(amp)
Generated voltage
(volts)
29 | P a g e
9.7
MODEL GRAPH:
If Decreasing
If Increasing
Fig - 2
9.8
PRE LAB VIVA QUESTIONS:
1. Under what conditions does the DC shunt generator fail to self-excite?
2. OCC is also known as magnetization characteristic, why?
3. How do you check the continuity of field winding and armature winding?
4. How do you make out that the generator is DC generator without observing the name
plate?
5. Does the OCC change with speed?
9.9
POST LAB VIVA QUESTIONS:
1. Define critical field resistance.
2. How do you get the maximum voltage to which the generator builds up from OCC?
3. What does the flat portion of OCC indicate?
4. Why OCC does not start from origin?
5. Why is Rsh >> Ra in dc shunt machine?
6. How do you create residual magnetism if it is wiped out?
7. Why does the OCC differ for decreasing and increasing values of field current
9.10
PRECAUTIONS:
1. The experiment should be done at constant speed.
2. The jockey should be moved only in one direction (i.e., from P to Q or Q to P). It should
not be moved back and forth for obtaining a particular field current.
3. At zero field there would be some emf due to residual magnetism
4. Avoid parallax errors and loose connections
9.11
RESULT:
30 | P a g e
EXPERIMENT - 10
SWINBURNE’S TEST OF A D.C.SHUNT MACHINE
10.1
AIM:
Pre - determine the efficiency and constant losses of a D.C. Shunt Machine by Swinburne’s method.
9.2
10.3
APPARATUS:
S. No
Item
1
Ammeter
2
Voltmeter
3
Rheostat
4
Tachometer
Type
Range
Quantity
NAME PLATE DETAILS:
Motor
10.4
Voltage
Output
Current
Speed
CIRCUIT DIAGRAM:
20A
Fig -1
10.5
PROCEDURE:
1. Choose the proper ranges of meters after noting the name plate details of the given
machine and make the connections as per the circuit diagram.
2. Keep the motor field rheostat (Rfm) in the minimum position, Start the motor by closing
the switch and operating the starter slowly.
3. Run the motor at rated speed by adjusting the motor field rheostat.
4. Note down the voltage, no load current and field current.
31 | P a g e
10.6
TABULAR COLUMN:
S. No.
10.7
V
ILo
If
MODEL GRAPH:
Fig - 2
10.8
CALCULATIONS FOR SWINBURNE’S TEST:
From the no load test results,
Supply voltage = VL Volts.
No load line current = ILo Amperes.
Field current= If Amperes.
Therefore No load Armature Current = Iao = IL-If Amperes.
Resistance cold = Rm
Effective resistance Re = 1.25 x Rm ohms.
No load copper losses are =Iao 2 Re
No load power input=VLIL
Constant losses = (No load power input - No load copper losses). ------------ (1)
10.9
Efficiency as motor:
Efficiency=output/input = (input – total losses)/ input.
Where total losses = constant losses + variable losses.
Constant losses are known value from the equation (1)
Variable loss = Ia2 Re , where Ia = IL-If
Input = VL IL.. VL is rated voltage of the machine
Assume line currents (IL) as 2, 4,6,----20A and find corresponding efficiency
10.10
Efficiency as generator:
Efficiency=output/input = output / (output + total losses).
Where losses = constant losses + variable losses
Constant losses are same for both motor and Generator
32 | P a g e
Armature Current = Ia = IL + IF
Variable loss = Ia2 Re
Output power = VL IL . VL is rated voltage of the machine
Assume load currents (IL) as 2, 4,6,----20A and find corresponding efficiencies
10.11
TABULAR COLUMN:
As a Motor:
S.
IL
No.
Rated voltage VL =
VLIL
Constant
Copper
INPUT
losses
losses
Power
W const.
Wcu = Ia2 Re
As a Generator:
S. No
IL
VLIL Out
power
Rated voltage VL =
Total losses
=
(Wcons. +
Output power =

(input power –
losses)
Wcu)
Rated speed N =
Constant
Copper
Total loss =
Input power =
losses W
losses Wcu =
(Wcons. +
(output power +
Wcu)
losses)
const.
10.12
Rated speed N =
2
Ia Re

PRE LAB VIVA QUESTIONS:
1.
Will the values deduced from the Swinburne’s method exactly coincide with the values
realized by direct loading on the machine? Why?
10.13
2.
Why are the constant losses calculated by this method less than the actual losses?
3.
Can we conduct Swinburne’s test on dc series motor?
4.
What are the drawbacks of Swinburne’s test?
POST LAB VIVA QUESTION:
1. Why Swinburne’s is used to find efficiency of high rating motors?
2. How you can say that the wattmeter reading in the experiment is constant losses?
3. Why constant losses are constant irrespective of load?
4. Advantage of this test
33 | P a g e
10.14
PRECAUTIONS:1. The experiment should be done at constant speed.
2. The jockey should be moved only in one direction (i.e., from P to Q or Q to P). It should
not be moved back and forth for obtaining a particular field current.
3. At zero field there would be some emf due to residual magnetism
4. Avoid parallax errors and loose connections
10.14
RESULT:
34 | P a g e
EXPERIMENT - 11
BRAKE TEST ON A D. C. SHUNTMOTOR
11.1
AIM:
To obtain the performance characteristics of a D.C. shunt motor by conducting brake test.
11.2
11.3
APPARATUS:
S. No.
Item
1
Ammeter
2
Ammeter
3
Voltmeter
4
Rheostats
Type
Range
Quantity
NAME PLATE DETAILS:
Motor
Voltage
Current
Output
Speed
11.4
CIRCUIT DIAGRAM:
Fig - 1
11.5
PROCEDURE:
1. Make the connections as shown in the circuit diagram.
2. Keeping the field rheostat (Rf) at the minimum position, switch on the supply and start the
motor.
35 | P a g e
3. Adjust the speed of the motor on no load to its rated value by means of the field rheostat.
do not disturb the position of the rheostat throughout the test.
4. Put on the load by tightening the screws of the spring balances. Note down the spring
tensions, the speed, the voltage and the currents at different loads until full load current
obtained.
11.6
CALCULATIONS:
1. Measure the circumference of the brake drum and calculate its radius (r), in meters.
2. Calculate the torque, T = Wrg (N.m). Where W = W1 – W2 = spring balance reading (the
difference between the spring tensions) and ‘g’ is acceleration due to gravity i.e.9.81.
Calculate the power output of the motor given by P0= 2NT/60
3. Calculate the input power, PI =VIL(IL is the line current = Ia+ If).
4. Calculate the percentage efficiency,  = P0/PIx 100
5. Draw the following graphs:
11.7
TABULAR COLUMN:
S.NO
IL
VL
W1
W2
W (kg) =
N
T = Wrg
P0=
P I=
=
(A)
(V)
kg
kg
W1 – W2
(RPM)
(N.m)
2NT/60
VL IL
P0/PIx 100
1
2
3
4
5
6
11.8
MODEL GRAPH:
Fig - 2
a) Output Vs , T, Ia and N in one graph.
b) Speed Vs Torque.
36 | P a g e
11.9
PRE LAB VIVA QUESTIONS:
1. Why did you use a 3-point starter for starting a D.C shunt motor?
2. What is the efficiency range of a D.C motor?
3. Where can you use the D.C shunt motor?
4. What is the starting torque?
11.10
POST LAB VIVA QUESTIONS:
1. If starter is not available, how can you start a D.C motor?
2. Why is it considered as a constant speed motor?
3. Why brake test is used to find the efficiency of DC motor?
4. Why the starting torque is low in dc shunt motor?
11.11
PRECAUTIONS:
1. The experiment should be done at constant speed.
2. The jockey should be moved only in one direction (i.e., from P to Q or Q to P). It should
not be moved back and forth for obtaining a particular field current.
3. At zero field there would be some emf due to residual magnetism
4. Avoid parallax errors and loose connections
11.12
RESULT:
37 | P a g e
EXPERIMENT – 12
OPEN CIRCUIT & SHORT CIRCUIT TEST ON A SINGLE PHASE TRANSFORMER
12.1
AIM:
To perform open circuit and short circuit test on a single phase transformer and to determine
the efficiency, regulation and equivalent circuit of the transformer.
12.2
APPARATUS:
S. No
12.3
Equipment
1
Voltmeter
2
Ammeter
3
Wattmeter
4
Wattmeter
5
Connecting Wires
Type
Range
Quantity
TRANSFORMER SPECIFICATIONS:
Transformer Rating :( in KVA) _________
Winding Details:
LV (in Volts): _______________________
LV side current:_____________________
HV (in Volts): ______________________
HV side Current:___________________
Type (Shell/Core):___________________
12.4
AUTO TRANSFORMER SPECIFICATIONS:
Input Voltage (in Volts):______________
Output Voltage (in Volts): ____________
Frequency (in Hz):____________________
Current rating (in Amp):_____________
38 | P a g e
12.5
CIRCUIT DIAGRAM:
12.5.1 OPEN CIRCUIT:
Fig - 1
12.5.2 SHORT CIRCUIT:
Fig - 2
12.6
PROCEDURE:
12.6.1
Open circuit test:
1. Connections are made as per the circuit diagram
2. Ensure that variac is set to zero output voltage position before starting the experiment
3. Switch ON the supply. Now apply the rated voltage to the Primary winding by using
Variac
4. The readings of the Voltmeter, ammeter and wattmeter are noted down in Tabular form
5. Then Variac is set to zero output position and switch OFF the supply
6. Calculate Ro and Xo from the readings
12.6.2 Short Circuit Test:
1. Connections are made as per the circuit diagram
2. Ensure that variac is set to zero output voltage position before starting the experiment
39 | P a g e
3. Switch ON the supply. Now apply the rated Current to the Primary winding by using
Variac
4. The readings of the Voltmeter, ammeter and wattmeter are noted down in Tabular form
5. Then Variac is set to zero output position and switch OFF the supply
6. Calculate Ro1 and Xo1 from the readings.
12.7
OBSERVATIONS:
12.7.1 For OC test:Voltmeter
reading( Vo)
S No.
Ammeter
reading (Io)
Wattmeter
reading Wo
Ro
Xo
Cos ɸo
Ammeter
reading (ISC)
Wattmeter
reading WSC
Ro1
Zo1
Xo1
12.7.2 For SC test
Voltmeter
reading ( VSC)
S. No
12.8
MODEL CALCULATIONS:
Find the equivalent circuit parameters R0, X0, R01, R02, X01 and X02 from the O. C. and
S. C. test results and draw the equivalent circuit referred to L. V. side as well as H. V. side.
Let the transformer be the step-down transformer
Primary is H. V. side.
Primary is H. V. side.
V
R0 
Secondary is L. V. side
1
Iw
X  V1 Where Im = I0 sin 0
I
0
X
0
where Iw = I0cos0
R 
01
m
 Z 01 2  R 2:X
01
02
K2 X
01
Where K =
1
V
2
W
I sc2
SC

, Z
V
I
01
SC
SC
 Transformation ratio.
V1
Calculations to find efficiency and
regulation For example at ½ full load
Cupper losses = Wsc x (1/2)2 watts, where WSC = full – load cupper losses
Constant losses = W0 watts
Output = ½ KVA x cosΦ [cosΦ may be assumed] Input
= output + Cu. Loss + constant loss
40 | P a g e
% 𝑒𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑐𝑦 =
𝑂𝑈𝑇𝑃𝑈𝑇
∗ 100
𝐼𝑁𝑃𝑈𝑇
Efficiency at different loads and P.f’s
Cos Φ = ______________
Regulation: From open circuit and Short circuit test
𝐼2𝑅02𝐶𝑜𝑠𝛷 ± 𝐼2𝑋02𝑆𝑖𝑛𝛷
𝑃𝑒𝑟𝑐𝑒𝑛𝑡𝑎𝑔𝑒 𝑅𝑒𝑔𝑢𝑙𝑎𝑡𝑖𝑜𝑛 =
𝑉2
‘+’ for lagging power factors
‘-‘ for leading power factor
S.No
p.f.
% reg
Lag
Lead
CosΦ = 0.8
S.No
12.9
Load
Wcu (W)
O/P (W)
I/P (W)
(%)
I/P (W)
Percent
GRAPHS: Plots drawn between
(i) % efficiency Vs output
(ii) % Regulation Vs Power factor
(iii)
CosΦ = 1.0
S.No
Load
Wcu (W)
O/P (W)
(%)
Fig - 3
41 | P a g e
12.10
PRECAUTIONS:
1. Connections must be made tight
2. Before making or breaking the circuit, supply must be switched off
12.11
PRE LAB VIVA QUESTIONS
1. What is the purpose of conducting open and short circuit test?
2. What is Auto transformer?
3. Why the copper losses negligible in OC test?
4. What do you mean by hysteresis loss, Eddy current loss and Copper Loss?
5. Which winding (LV or HV) should be kept open while conducting OC test?
12.12
POST LAB VIVA QUESTIONS
1. Why short circuit test is performed on transformer?
2. Can we reduce iron losses?
3. Why OC test is done on LV side and SC test is done on HV side?
4. Where the maximum efficiency occur in a transformer?
5. Why transformer efficiency is higher than rotating machines?
12.13
RESULT:
42 | P a g e
EXPERIMENT - 13
LOAD TEST ON A SINGLE PHASE TRANSFORMER
13.1
AIM:
To conduct load test on single phase transformer and to find efficiency and percentage regulation.
13.2
APPARATUS:
S.No.
13.3
AIM
1
Ammeter
2
Voltmeter
3
Wattmeter
4
Auto Transformer
5
Resistive Load
6
Connecting Wires
Range
Type
Quantity
CIRCUIT DIAGRAM:
Fig -1
13.4
PROCEDURE:
1. Connections are made as per the circuit diagram.
2. After checking the no load condition, minimum position of auto transformer and DPST
switch is closed.
3. Ammeter, Voltmeter and Wattmeter readings on both primary side and secondary side are
noted.
4. The load is increased and for each load, Voltmeter, Ammeter and Wattmeter readings on
both primary and secondary sides are noted.
5. Again no load condition is obtained and DPST switch is opened.
43 | P a g e
13.5
TABULAR COLUMN:
Primary
S.N
o
13.6
Loa
d
V1
(Volt
s)
I1
(Amp
s)
Secondary
W1
(Watt
s)
V2
(Volt
s)
I2
(Amp
s)
W2
(Watt
s)
Input
Power
W1 x
MF
Outpu
t
Power
W2 x
MF
Efficien
cy

%
%
Regulat
ion
FORMULAE:
Output Power = W2 x Multiplication factor
Input Power = W1 x Multiplication factor
Output Power
Efficiency  %
= -------------------- x 100%
Input Power
VNL - VFL (Secondary)
Regulation R % = ------------------------------ x 100%
VNL
MODEL GRAPHS:

Regulation R
%
Efficiency  %
13.7
R
Output Power
(Watts)
Fig - 2
44 | P a g e
13.8
PRECAUTIONS:
1. Auto Transformer should be in minimum position.
2. The AC supply is given and removed from the transformer under no load condition.
13.9
RESULT:
13.10
PRE LAB VIVA QUESTIONS
1. What type of loading is possible for 1-ph transformer?
2. What are the type of transformers?
3. Transformer is an --------------- device.
13.11
POST LAB VIVA QUESTIONS
1. What is the maximum efficiency possible for transformer?
2. Define turns ratio.
3. Name the other test to find efficiency of transformer.
45 | P a g e