LAB MANUAL
ELECTRICAL TECHNOLOGY LAB
Department of Electronics and Communication Engineering
Document No:
Date of Issue
Compiled by
MLRIT/EC/LAB
MANUAL/ET
01-July-2009
G. Karthik Reddy
Geethu Mohan
VERSION 2.1
Authorized by
HOD(ECE)
Date of Revision
Verified by
29-Dec-2014
M. Sreenivasa Reddy
Institute of technology
Electrical Technology Laboratory Manual
II B.Tech II-Sem (ECE)
2014-2015
PREFACE
The significance of the Electrical and Electronics Engineering Lab is renowned in the various
fields of engineering applications. For an Mechanical Engineer, it is obligatory to have the
practical ideas about the Electrical and Electronics Engineering. By this perspective we have
introduced a Laboratory manual cum Observation for Electrical and Electronics Engineering
Lab.
The manual uses the plan, cogent and simple language to explain the fundamental aspects of
Electrical and Electronics Engineering in practical. The manual prepared very carefully with our
level best. It gives all the steps in executing an experiment.
GUIDELINES TO WRITE YOUR OBSERVATION BOOK
1. Experiment Title, Aim, Apparatus, Procedure should be on right side.
2. Circuit diagrams, Model graphs, Observations table, Calculations table should be left
side.
3. Theoretical and model calculations can be any side as per your convenience.
4. Result should always be in the ending.
5. You all are advised to leave sufficient no of pages between experiments for theoretical or
model calculations purpose.
Institute of technology
Electrical Technology Laboratory Manual
II B.Tech II-Sem (ECE)
2014-2015
Instructions to the students to conduct an experiment:
1. Students are supposed to come to the lab with preparation, proper dress code and the set
of tools required (1. Cutter, 2. Tester (small size), 3. Plier (6-Inches))
2. Dress code: Boys: Shoe & Tuck. Girls: Apron & Cut shoe.
3. Don’t switch on the power supply without getting your circuit connections verified
4. Disciplinary action can be taken in the event of mishandling the equipment or switching
on the power supply without faculty presence
5. All the apparatus taken should be returned to the Lab Assistant concerned, before leaving
the lab.
6. You have to get both your Observation book and your Record for a particular experiment
corrected well before coming to the next experiment.
Guidelines to write your Observation book:
1.
2.
3.
4.
Experiment title, Aim, Apparatus, Procedure should be right side
Circuit diagrams, Model graphs, Observations table, Calculations table should be left side
Theoretical and model calculations can be any side as per convenience
Result should always be at the end (i.e. there should be nothing written related to an
experiment after its result)
5. You have to write the information for all the experiments in your observation book
6. You are advised to leave sufficient no of pages between successive experiments in your
observation book for the purpose of theoretical and model calculations.
Institute of technology
(A40288) ELECTRICAL TECHNOLOGY LAB
List of Experiments
PART-A:
1. Verification of KVL and KCL
2. Series and Parallel resonance
3. Time response of first order RC/RL network for periodic non sinusoidal input-Time
constant and steady state error determination
4. Two port network parameters-Z, Y, Parameters, Chain matrix and analytical Verification
5. Two port network parameters-ABCD and h Parameters
6. Verification of Superposition and Reciprocity theorems
7. Verification of maximum power transfer theorem
8. Verification of Thevenin’s and Norton’s theorems
PART-B:
1.
2.
3.
4.
5.
6.
Magnetization characteristics of D.C. Shunt Generator
Swinburne’s Test on a DC Shunt Motor
Brake test on 3-phase Induction Motor
OC & SC Tests on a Single phase Transformer
Load Test on a Single phase Transformer
Regulation of 3-phase alternator
Institute of technology
ELECTRICAL CIRCUITS LABORATORY
List of Experiments
PART-A:
1. Verification of KVL and KCL
2. Series and Parallel resonance
3. Time response of first order RC/RL network for periodic non sinusoidal input-Time
constant and steady state error determination
4. Two port network parameters-Z, Y, Parameters, Chain matrix and analytical Verification
5. Two port network parameters-ABCD and h Parameters
6. Verification of Superposition and Reciprocity theorems
7. Verification of maximum power transfer theorem
8. Verification of Thevenin’s and Norton’s theorems
Institute of technology
Expt. No: 1
Verification of KVL and KCL.
Aim:
a) To verify Kirchhoff’s Voltage Law and and Kirchhoff’s Current Law theoretically and
practically for R1=1K Ω, R2=10K Ω, R3=4.7K Ω,VS=10V
b) To verify Kirchhoff’s Voltage Law and and Kirchhoff’s Current Law theoretically and
practically for R1= 470 Ω, R2= 1K Ω, R3= 10K Ω, VS=10V
c) To verify Kirchhoff’s Voltage Law and and Kirchhoff’s Current Law theoretically and
practically for R1= 100 Ω, R2= 50 Ω, R3= 150K Ω, VS=10V
d) To verify Kirchhoff’s Voltage Law and and Kirchhoff’s Current Law theoretically and
practically for R1= 10 Ω, R2= 10K Ω, R3= 100 Ω, VS=10V
e) To verify Kirchhoff’s Voltage Law and and Kirchhoff’s Current Law theoretically and
practically for R1= 330 Ω, R2= 4.7K Ω, R3= 100 Ω, VS=10V
Apparatus:
S.No
1.
2.
3.
4.
5.
Name of the equipment
Range
Quantity
Voltmeter
Ammeter
Digital Multimeter
Bread Board
Connecting wires
(0-20V)
(0-200mA)
(0-200)
1
1
1
Procedure:
1. To verify KVL, Connections are made as shown in the Fig-1
2. Supply is given to the circuit and the readings of the voltmeters are noted down.
3. Kirchhoff’s Voltage law can be verified by Vs=V1+V2+V3.
4. To verify KCL, Connections are made as shown in the Fig-2.
5. Supply is given to the circuit and the readings of the Ammeters are noted down.
6. Kirchhoff’s Current law can be verified by I=I1+I2.
Precautions:
1. Making loose connections are to be avoided.
2. Readings should be taken carefully without parallax error.
Circuit Diagram of KVL
Circuit Diagram of KCL
RESULTS:
Viva questions:
1. State KVL and KCL?
2. What is limitation of Kirchhoff’s law?
3. List some of the examples of Voltage sources and Current sources?
4. Explain the Voltage division and Current division rule?
5. Differentiate between active and passive elements?
Institute of technology
Expt. No: 2
Series and Parallel Resonance
Aim:
a) To determine Bandwidth and Q-factor of RLC Series and Parallel Resonant circuits for
R=1K Ω, L=1mH, C=0.01µF
b) To determine Selectivity of RLC Series and Parallel Resonant circuits for R=10KΩ,
L=10mH, C=10nF
c) To determine half-power frequencies of RLC Series and Parallel Resonant circuits for
R=1K Ω, L=1mH, C=0.01µF
d) To determine resonant frequency and Q-factor of RLC Series and Parallel Resonant
circuits for R=10KΩ, L=10mH, C=10nF
e) To determine maximum current of RLC Series and Parallel Resonant circuits for R=1KΩ,
L=10H, C=100µF
Apparatus:
S.No
1.
2.
3.
4.
5.
Name of the equipment
Voltmeter
Ammeter
Digital Multimeter
Bread Board
Function Generator
THEORITICAL CALCULATIONS:
Series Resonance
1. Resonance frequency, f0 =
2. Quality factor,Q=
3. Bandwidth, BW=
4. Selectivity=Q0 =
=
Range
(0-20V)
(0-200mA)
(0-200)
Quantity
1
1
1
1
1
Parallel Resonance
1. Resonance frequency, f0 =
2. Quality factor,Q =
3. Bandwidth, BW=
4. Selectivity=Q0 =
=
Procedure:
Series Resonance:
1. Circuit is connected as shown.
2. A fixed voltage is applied to the circuit through function generator.
3. The frequency is varied in steps and the corresponding ammeter reading is noted down as Is.
4. A graph is drawn between frequency f and current Is. Resonant frequency (fo) and half power
frequencies (f1, f2) are marked on the graph.
5. Bandwidth = (f2-f1) & Quality factor Q=fo/BW are found from the graph.
6. Practical values of Resonant Frequency, Q-factor and Bandwidth are compared with
theoretical values.
Parallel Resonance:
1. Circuit is connected as shown
2. A fixed voltage is applied to the circuit through function generator.
3. The frequency is varied in steps and the corresponding ammeter reading is noted down as Ip.
4. A graph is drawn between frequency f and current Ip. Resonant Frequency (fo) and half power
frequencies (f1, f2) are marked on the graph.
5. Bandwidth = (f2-f1) & Quality factor Q=fo/BW are found from the graph.
6. Practical values of Resonant Frequency, Q-factor and Bandwidth are compared with
theoretical
Circuit Diagram of Series Resonance:
Model Graph:
Circuit Diagram of Parallel Resonance:
Model Graph:
Result table.
Precautions:
1. Making loose connections are to be avoided.
2. Readings should be taken carefully without parallax error.
Result:
Viva questions:
1. Define Resonance and 3dB points?
2. What is phase difference between voltage and current in inductor and capacitor? Which is
leading?
3. Define Selectivity, Bandwidth and Q-factor?
4. For RLC circuit what is the power factor at the lowest frequency?
5. What are the expressions for admittance, conductance and suceptance and also write its
units?
Institute of technology
Expt. No: 3
Time response of Series RL and RC circuits
Aim:
a.
b.
c.
d.
e.
Verify Series RC Circuit for
Verify Series RL Circuit for
Verify Series RC Circuit for
Verify Series RL Circuit for
Verify Series RC Circuit for
R=1K Ω, C=0.1uf, V=15Vp-p
R=1K Ω, L=50mH, V=15Vp-p
R=1K Ω, C=0.2 uf, V=15Vp-p
R=1K Ω, L=100mH, V=15Vp-p
R=1K Ω, C=0.01 uf, V=15Vp-p
Apparatus:
S. No
1.
2.
3.
4.
5.
Name of the equipment
Function generator
CRO
CRO probes
Connecting wires.
Bread Board
Theoretical Calculations:
Formulae required:
For RL Series circuit, Time constant, τ =L/R
For RC Series circuit, Time constant, τ = RC
Range
(0-10MHz)
(20 MHz)
Quantity
1
1
1
1
Circuit diagrams:
Series RL Circuit
Series RC Circuit
Model Graph:
Procedure:
Series RL Circuit:
1. Connections are made as shown
2. Input voltage (Square wave) is set to a particular value.
3. The waveform of voltage across inductor is observed on CRO and the waveform is drawn
on a graph sheet.
4. The time constant is found from the graph and verified with the theoretical value.
Series RC Circuit:
1. Connections are made as shown
2. Input voltage (Square wave) is set to a particular value.
3. The waveform of voltage across the capacitor is observed on CRO and the waveform is
drawn on a graph sheet.
4. The time constant is found from the graph and verified with the theoretical value.
RESULT TABLE:
RESULTS:
Viva questions:
1. Differentiate between transient state, transient time and transient response?
2. Define natural response and natural frequency?
3. Define time constants for RC and RL circuits?
4. What is meant by rise time, settling time and delay time?
5. What is meant by damping ratio?
Institute of technology
Expt. No: 4
Two port network parameters (Z-Y parameters)
Aim:
a)
b)
c)
d)
e)
Verify z-parameters of z11,z12 for R1=470 Ω,R2=1.8K Ω,R3=4.7K Ω.
Verify z-parameters of z21,z22 for R1=470 Ω,R2=4.7K Ω,R3=4.7K Ω
Verify y-parameters of z11,z12 for R1=1K Ω,R2=1.8K Ω,R3=4.7K Ω
Verify y-parameters of z21,z22 for R1=470 Ω,R2=1K Ω,R3=4.7K Ω
Verify y-parameters of z21,z22 for R1=470 Ω,R2=1K Ω,R3=1K Ω
Apparatus:
S. No
1.
2.
3.
4.
5.
Name of the equipment
Range
Ammeter
Voltmeter
Digital Multimeter
Connecting wires
Bread Board
(0-200A)
(0-20V)
Theoretical Calculations:
Formulae required:
Z-Parameters:
Quantity
1
1
1
1
Y-Parameters:
CIRCUIT DIAGRAMS:
When I2=O.
When V2 = 0:
When I1=
0:
When V1= 0:
Procedure:
1. Open Circuiting Output Terminals (I2 = 0):
a. Connections are made shown in fig (1).
b. Supply is given to input port.
c. The readings of ammeter as I1 and Voltmeter as V2 are noted down.
2. Short circuiting output terminals (V2 = 0):
a. Connections are made shown in fig (2).
b. Supply is given to input port.
c. The readings of ammeters as I1& I2 are noted down.
3. Open circuiting input terminals (I1 = 0):
a. Connections are made shown in fig (3).
b. Supply is given to output port.
c. The readings of ammeter as I1 and Voltmeter as V1 are noted down.
4. Short circuiting input terminals (V1=0):
a. Connections are made shown in fig (4).
b. Supply is given to output port.
c. The readings of ammeters as I1& I2 are noted down.
5. The Z, Y, ABCD, Hybrid parameters are calculated using formulae and verified with
theoretical values.
Observations:
Result Table:
Precautions:
1. Making loose connections are to be avoided.
2. Readings should be taken carefully without parallax error.
RESULTS:
Viva questions:
1. What is transfer impedance?
2. Why Z-parameters are used?
3. What are applications of Z and Y parameters?
4. What are relations used in Z parameters?
5. What is the relation between Z and Y parameters?
Institute of technology
EXP.NO: 5.
Two port network parameters (ABCD and Hybrid parameters)
Aim:
a.
b.
c.
d.
e.
Verify A,B,C,D-parameters for R1=470 Ω,R2=1.8K Ω,R3=4.7K Ω.
Verify h-parameters for R1=470 Ω,R2=4.7K Ω,R3=4.7K Ω
Verify A,B,C,D-parameters for R1=1K Ω,R2=1.8K Ω,R3=4.7K Ω
Verify h-parameters for R1=470 Ω,R2=1K Ω,R3=4.7K Ω
Verify A,B,C,D-parameters for R1=470 Ω,R2=1K Ω,R3=1K Ω
Apparatus:
S.No
1.
2.
3.
4.
5.
Name of the equipment
Voltmeter
Ammeter
Digital Multimeter
Bread Board
Function Generator
Theoretical Calculations:
Formulae required:
Z-Parameters:
Y-Parameters:
Range
(0-20V)
(0-200mA)
(0-200)
Quantity
1
1
1
1
ABCD Parameters:
Hybrid or h- Parameters:
CIRCUIT DIAGRAMS:
When I2=O.
When V2 = 0:
When I1= 0:
When V1= 0:
Procedure:
1. Open Circuiting Output Terminals (I2 = 0):
d. Connections are made shown in fig (1).
e. Supply is given to input port.
f. The readings of ammeter as I1 and Voltmeter as V2 are noted down.
2. Short circuiting output terminals (V2 = 0):
d. Connections are made shown in fig (2).
e. Supply is given to input port.
f. The readings of ammeters as I1& I2 are noted down.
3. Open circuiting input terminals (I1 = 0):
d. Connections are made shown in fig (3).
e. Supply is given to output port.
f. The readings of ammeter as I1 and Voltmeter as V1 are noted down.
4. Short circuiting input terminals (V1=0):
d. Connections are made shown in fig (4).
e. Supply is given to output port.
f. The readings of ammeters as I1& I2 are noted down.
5. The Z, Y, ABCD, Hybrid parameters are calculated using formulae and verified with
theoretical values.
Observations:
Result Table:
Precautions:
1. Making loose connections are to be avoided.
2. Readings should be taken carefully without parallax error.
RESULTS:
Viva questions:
1. What are applications of ABCD parameters?
2. Write the relations for ABCD parameters?
3. Write the relationship ABCD and Z-parameters?
4. What are applications of h-parameters?
5. Write the relationship ABCD and h-parameters?
Institute of technology
EXP.NO: 6
SUPERPOSITION THEOREM AND RECIPROCITY THEOREM
AIM:
a.
b.
c.
d.
e.
Verify superposition theorem for R1= 470 Ω, R2=1K Ω, R3=2.2K Ω, V1= 6V, V2=3V
Verify superposition theorem for V1= 5 V , V2= 10 V, R1= 470 Ω, R2= 1K Ω, R3= 470 Ω
Verify superposition theorem for R1= 470 Ω, R2= 1K Ω, R3= 470 Ω, V1= 10 V, V2= 10 V.
Verify reciprocity theorem for Vs=10V, R1= 4.7K Ω, R2= 1KΩ, R3= 1.5 KΩ.
Verify reciprocity theorem for R1= 470 Ω, R2= 1KΩ, R3= 1.5 KΩ, Vs=10V.
APPARATUS:
S.No
1.
2.
3.
4.
5.
Name of the equipment
Voltmeter
Ammeter
Digital Multimeter
Bread Board
Function Generator
Range
(0-20V)
(0-200mA)
(0-200)
Quantity
1
1
1
1
THEORY:
SUPERPOSITION THEOREM STATEMENT
In any linear bilateral network containing two or more energy sources the response at
any element is equal to the algebraic sum of the responses caused by the individual sources.
I.e. while considering the effect of individual sources, the other ideal voltage sources
and ideal current sources in the network are replaced by short circuit and open circuit across the
terminals. This theorem is valid only for linear systems.
RECIPROCITY THEOREM STATEMENT
In any linear bilateral network containing the response at any branch (or) transformation
ratio is same even after interchanging the sources is V/ I1 = V/ I2
THEORETICAL CALCULATIONS:
PROCEDURE:
SUPERPOSITION THEOREM:
1. Connect the circuit as shown in fig (1)
2. Current through load resistor is noted as Ix by applying both the voltages V1 and V2 through
RPS.
3. Make the supply voltage V2 short circuited and apply V1 as shown in fig (2) and note down the
current through load resistor as Iy.
4. Make the supply voltageV1 short circuited and apply V2 as shown in fig (3) and note down the
current through load resistor as Iz.
5. Now verify that Ix = IY + IZ theoretically and practically which proves Superposition theorem
RECIPROCITY THEOREM:
1. Connect the circuit as shown in fig (1).
2. Note down the ammeter reading as I1.
3. Now interchange the source and ammeter as in fig (2).
4. Note down the ammeter reading as I2.
5. Now verify that Vs/ I1 = Vs/ I2 theoretically and practically which proves reciprocity theorem.
Observations:
When both the sources are acting: fig (1)
Vs1
Vs2
Theoretical Practical
Ix
Ix
when v1 source alone is acting: fig (2)
Vs1
Vs2
Theoretical
Iy
Practical
Iy
When V2 source alone is acting: fig (3)
Vs1
Vs2
Theoretical
Practical
Iz
Iz
TABULAR COLUMN OF RECIPROCITY THEOREM:
Before interchanging the sources: fig (1)
Theoretical values
Vs
I1
Vs/I1
Practical values
I1
Vs/I1
After interchanging the sources: fig (2)
Theoretical values
Vs
I1
Vs/I1
Practical values
I1
PRECAUTIONS:
1. Avoid making loose connections.
2. Reading should be taken carefully without parallax error.
3. Avoid series connection of voltmeters and parallel connection of ammeters.
RESULT:
VIVA QUESTIONS:
1. What is superposition theorem?
2. What is reciprocity theorem?
3. What is done to voltage sources while applying superposition theorem?
4. What is done to current sources while applying superposition theorem?
5. What is bilateral circuit?
Vs/I1
Institute of technology
EXP.NO: 7
EXPERIMENTAL VERIFICATION OF THE VENIN’S THEOREM
AIM:
a. Verify thevenin’s theorem with Vs=5v, R1= 4.7K Ω, R2= 3.3K Ω, R3= 470 Ω
b. Verify thevenin’s theorem with Vs=5v, R1= 4.7K Ω, R2= 3.3K Ω, R3= 470 Ω
c. Find the thevenin’s current when with Vs=5V, R1= 4.7K Ω, R2= 1K Ω, R3= 470 Ω
d. Find the thevenin’s current when with Vs=10V, R1= 4.7K Ω, R2= 3.3K Ω, R3= 4.7 KΩ
e. Find the thevenin’s resistance when with Vs=5V, R1= 4.7K Ω, R2= 2.2K Ω, R3= 470 Ω
APPARATUS:
S.No
1.
2.
3.
4.
5.
Name of the equipment
Voltmeter
Ammeter
Digital Multimeter
Bread Board
Function Generator
Range
(0-20V)
(0-200mA)
(0-200)
Quantity
1
1
1
1
THEORY:
STATEMENT OF THE VENIN’S THEORUM:
Any two terminal linear bilateral networks containing of energy sources and
impedances can be replaced with an equivalent circuit consisting of voltage sources V th in series
with impedance, Zth, where Vth is open circuit voltage between the load terminals and Zth is the
impedance measured between the terminals with all the energy sources replaced by their internal
impedances.
PROCEDURE:
THE VENIN’S THEOREM:
a. Connections are made as per the circuit shown in fig (1).
b. Apply DC voltage to the circuit and note down the current IL flowing
through the load.
c. Connect the circuit as shown in fig (2) by open circuiting the load resistance.
Apply DC voltage and note down the reading of voltmeter as Vth.
d. Connect the circuit as shown in fig (3), measure the effective resistance Rth with
the help of a multimeter, by replacing the voltage source with short circuit.
e. Connect the venin’s equivalent circuit as shown fig (4) note down the load current
IL1.
f. The venin’s theorem can be verified by checking that the current IL and IL1 are
equal.
THEORETICAL CALCULATIONS:
OBSERVATIONS:
THEVENIN’S THEOREM:
Theoretical values
Vs
IL
Vth
Rth
Practical values
IL 1
IL
Vth
Rth
PRECAUTIONS:
1. Avoid making loose connections.
2. Readings should be taken carefully without parallax error.
3. Avoid series connection of voltmeters and parallel connection of ammeters.
Viva questions:
1.
2.
3.
4.
5.
State Thevenin’s theorem?
How to calculate Vth?
How to calculate Rth?
What is Norton’s theorem?
How to calculate Norton’s current?
IL 1
Institute of technology
EXP.NO: 7
MAXIMUM POWER TRANSFER THEOREM
AIM:
a.
b.
c.
d.
e.
Verify maximum power transfer theorem for Vs=10V, R1= 4.7K Ω, R2= 1K Ω, R3= 470 Ω.
Verify maximum power transfer theorem for Vs= 10 V, R1=1K Ω, R2= 470 Ω, R3= 4.7K Ω
Verify maximum power transfer theorem for Vs= 10 V, R1= 470 Ω, R2= 1KΩ, R3= 100 Ω.
Verify maximum power transfer theorem for Vs= 15V, R1= 470 Ω, R2= 100Ω, R3= 470 Ω.
Verify maximum power transfer theorem for Vs= 10 V ,R1= 470 Ω, R2= 270Ω , R3= 100Ω
APPARATUS:
S.No
1.
2.
3.
4.
5.
Name of the equipment
Voltmeter
Ammeter
Digital Multimeter
Bread Board
Function Generator
Range
(0-20V)
(0-200mA)
(0-200)
Quantity
1
1
1
1
THEORY:
THEOREM STATEMENT:
It states that the maximum power is transferred from the source to the load, when the
load resistance is equal to the source resistance.
THEORETICAL CALCULATIONS
PROCEDURE:
1. Make the connections as shown in fig (1).
2. By varying RL in steps, note down the reading of ammeter IL in each step.
3. Connect the circuit as shown in fig (2), measure the effective resistance R th with the help
of digital multimeter.
4. Calculate power delivered to load PL in each step.
5. Draw graph PL vs RL and find the RL corresponding to maximum power from it.
6. Verify that RL corresponding to maximum power from the graph is equal to the R th
(which is nothing but source resistance Rs).
OBSERVATIONS:
Tabular column:
Theoretical values
S.NO
RL
IL
PL=IL2RL
Practical values
IL
PL=IL2RL
MODEL CALCULATIONS:
PRECAUTIONS:
1. Avoid making loose connections.
2. Reading should be taken carefully without parallax error.
3. Avoid series connection of voltmeters and parallel connection of ammeters.
RESULT:
Viva questions:
1.State maximum power transfer theorem?
2.Give the expression for maximum power?
3. What is the condition for maximum power?
4.Give the 3 different equations of power?
5. What is the unit for power?
Institute of technology
ELECTRICAL MACHINES LABORATORY
List of Experiments
PART-B
1.
2.
3.
4.
5.
6.
Magnetization Characteristics of D.C. Shunt Generator
Swinburne’s Test on a DC Shunt Motor
Brake Test on 3-phase Induction Shunt Motor
O.C and S.C tests on a Single Phase transformer
Load Test on a Single Phase transformer
Regulation of 3-phase alternator
Institute of technology
Expt. No: 1
Magnetization characteristics of DC Shunt Generator
AIM:
a)
b)
c)
d)
To determine the critical field resistance (Rc) and critical speed (Nc) at 1400 r.p.m.
To determine the critical field resistance (Rc) and critical speed (Nc) at 1450 r.p.m.
To determine the critical field resistance (Rc) and critical speed (Nc) at 1500 r.p.m.
To determine the critical field resistance (Rc) and critical speed (Nc) at 1550 r.p.m
NAME PLATE DETAILS:
Specifications
DC Motor
DC Generator
Speed
1500 rpm
1500 rpm
power
5HP
3KVA
Current
20A
13.6A
Voltage
230V
230V
EQUIPMENTS REQUIRED:
S.No
Equipments
Type
Range
Quantity
1.
Voltmeter
M.C
0-300v
1 No
2.
Ammeter
M.C
0-1/2A
1 No
3.
Rheostats
Wire wound
300Ω/1.5A
1 No
4.
Tachometer
Digital
0-300)rpm
1 No
THEORY:
Open circuit characteristics or magnetization curve is the graph between the generated emf (E g)
and field current (If) of a dc shunt generator. For field current is equal to zero there will be
residual voltage of 10 to 12v because of the residual magnetism present in the machine. If this is
absent then the machine cannot build up voltage. To obtain residual magnetism the machine is
separately excited by a dc source. We can get critical field resistance (Rc) and critical speed (Nc)
from open circuit characteristics curve.
Critical field résistance: It is the maximum value of resistance of field winding of D.C. shunt
generator at critical speed..
Critical speed: It is the maximum speed of D.C. shunt generator at critical field resistance
beyond which generator fails to generate voltage.
CIRCUIT DIAGRAM:
PROCEDURE:
1.) Connections are made as per the circuit diagram and supply is given by closing the DPST
switch
2.) Motor is started with the help of three point starter and bring the motor to rated speed
by varying the motor field rheostat from minimum resistance position
3.) At rated speed by varying the generator field rheostat from maximum resistance position
note down the readings of open circuit voltage and field current up to the rated voltage of
D.C.shunt generator.
4.) Switch off the supply and draw the graph between Voc and If and hence it is the
magnetization characteristics curve.
PRECAUTIONS:
1.) Loose connections must be avoided
2.) Always check the connections before u switch on the supply
3.) Motor field rheostat is kept at minimum resistance position and generator field rheostat is
kept at maximum resistance position
4.) Experiment must be done in the presence of concern lab instructor.
TABULAR COLUMN:
S.No
1
2
3
4
5
VOC (Volts)
If (amps)
CALCULATIONS:
N1=minimum speed i.e.,1400 r.p.m
Rmin=Voc(max.)/If(max.)
Rmax= Voc(min.)/If(min.)
Where Rmax= critical field resistance
N1/Nc = Rmin/ Rmax
Hence critical speed and critical field resistance can be found from the above calculations.
RESULT:
VIVA QUESTIONS
1.)
2.)
3.)
4.)
5.)
What is the Basic Principle in dc generator?
In DC Machine which Induced emf is suitable?
The direction of induced emf and hence current in a conductor can be determined by?
Mechanical Energy Converted to Electrical energy is called as?
Write the EMF equation for D.C. Generator?
Institute of technology
Expt. No: 2
Swinburne’s Test on D.C shunt motor
AIM: To perform Swine burn’s test on the given DC machine and
a) Determine the efficiency of D.C. shunt machine at 1500 rpm.
b) Determine the efficiency of D.C. shunt machine at 1450 rpm.
c) Determine the efficiency of D.C. shunt machine at 1400 rpm.
d) Determine the efficiency of D.C. shunt machine at 1550 rpm.
NAME PLATE DETAILS
SWINBURNE’S TEST
Specifications
DC meter
Speed
1500 rpm
power
5HP
Current
20A
Voltage
230V
EQUIPMENT REQUIRED:
S.No
DESCRIPTION
RANGE
TYPE
QUANTITY
1
2
3
4
Voltmeter
Ammeter
Rheostats
Tachometer
(0-300)V
(0-10)A &(0-1/2 A)
300/1.5 A
Digital
M.C
M.C
Variable type
Rotatory
1 No
3 No
1 No
1 No
CIRCUIT DIAGRAM:
THEORY:
Swine burn’s Test is to determine the efficiency of a given DC shunt motor when working as
both motor as well as generator.
It is simple indirect method in which losses are measured separately and the efficiency at
any desired load can be predetermined. This test applicable to those machines in which flux is
practically constant i.e. shunt and compound wound machines. The no load power input to
armature consist iron losses in core, friction loss, windage loss and armature copper loss. It is
convenient and economical because power required to test a large machine is small i.e. only no
load power. But no account is taken the change in iron losses from no load to full load due to
armature reaction flux is distorted which increases the iron losses in some cases by as 50%
Principle of DC Motor: It starts that rotating conductor is placed in between the magnetic fields
the conductors experiences force and rotate the rotor, armature winding, yoke, eye bolt and
frame test.
PROCEDURE:
1. Make connections as per the circuit diagram.
2. Show the connections to the lab instructor.
3. Keeping the rheostat at minimum, Start the motor with the help of starter, and by
adjusting field rheostat bring the motor to rated speed.i.e.1500 rpm.
4. Note down all the meter readings at no load.
5. Do necessary calculations and find out the efficiency of the Machine as a motor and as a
generator.
OBSERVATIONS:
S.No
1
2
Ia
If
IL
CALCULATIONS:
1. Load input voltage = VL IL
2. Load armature copper losses Wi =Ia2Ra
3. Constant losses or no-load losses Wc = (VLO ILO) - Iao2Ra
where Wc= no load input – no load copper losses.
VL
Ra
Efficiency as a motor:
IL= Assumed load current at any load i.e., 5 amp or 10 amp or 15 amp.
VL= rated voltage= 230V.
Motor input power = VL IL
Motor armature copper losses (Wcu) = Ia2Ra = (IL –IF)2 Ra
Total losses= iron losses (Wi) + copper losses(Wcu)
Efficiency of motor= output power/input power.
Where, input power = VL IL
And output power = input power – power losses.
Or input power = output power + power losses.
Efficiency as generator:
IL= Assumed load current at any load i.e,5 amp or 10 amp or 15 amp.
VL= rated voltage= 230V.
Generator output power = VL IL
armature copper losses (Wcu) = Ia2Ra = (IL +IF)2 Ra
Total losses= iron losses(Wi) + copper losses(Wcu)
Efficiency of Generator = output power/input power.
Where, output power = VL IL
And output power = input power + power losses.
Or input power = output power - power losses.
RESULT:
VIVA QUESTIONS
1.
2.
3.
4.
5.
Which of the following is the unit of Torque ?
When the starting resistance of a D.C. motor is used generally?
Armature Reaction is related to?
Brushes are made up of?
The function of the commutator?
Institute of technology
Expt. No: 3
Brake Test on 3-Phase Induction Motor
AIM:
a) To conduct a brake test on the given 3-¢ Slip ring Induction motor and to draw its
performance Characteristics curves at load current of 1,2,3,4,5 amps.
b) To conduct a brake test on the given 3-Slip ring Induction motor and to draw its
performance Characteristics at load current of 1.2, 2.2, 3.2, 4.2, 5.2 amps.
c) To conduct a brake test on the given 3-Slip ring Induction motor and to draw its
performance Characteristics at load current of 2.8, 3.8, 4.8, 5.8, 6.8 amps.
d) To conduct a brake test on the given 3-Slip ring Induction motor and to draw its
performance Characteristics at load current of 1.5, 2, 25, 3, 3.5, 4, 4.5, 5 amps.
NAME PLATE DETAILS: (to be noted from the machine)
APPARATUS REQUIRED:
S.NO
DESCRIPTION
RANGE
TYPE
QTY
1
2
3
4
5
Ammeter
Voltmeter
Watt meters
Autotransformer
Tachometer
(0-10)A
(0-600)V
10A,600v,UPF
600v,3-¢
( 0-3000)
MI
MI
Unity
variable
digital
1
1
2
1
1
CIRCUIT DIAGRAM:
PRECAUTIONS:
1. There should not be any load on the motor initially.
2. The brake drum should be filled with water to cool it.
3. If the wattmeter shows negative deflection, reverse either pressure coil or current coil and
take that reading as negative.
4. The rotor external resistance should be kept at max resistance position initially.
THEORY:
As a general rule, conversion of electrical energy to mechanical energy takes place in to the
rotating part on electrical motor. In DC motors, electrical power is conduct directly to the
armature, i.e, rotating part through brushes and commutator. Hence, in this sense, a DC motor
can be called as ‘conduction motor’. However, in AC motors, rotor does not receive power by
conduction but by induction in exactly the same way as secondary of a two winding T/F receives
its power from the primary. So, these motors are known as Induction motors. In fact an induction
motor can be taken as rotating T/F, i.e, one in which primary winding is stationary and but the
secondary is free.
The starting torque of the Induction motor can be increase by improving its p.f by adding
external resistance in the rotor circuit from the stator connected rheostat, the rheostat resistance
being progressively cut out as the motor gathers speed. Addition of external resistance increases
the rotor impedance and so reduces the rotor current. At first, the effect of improved p.f
predominates the current-decreasing effect of impedance. So, starting torque is increased. At
time of starting, external resistance is kept at maximum resistance position and after a certain
time, the effect of increased impedance predominates the effect of improved p.f and so the torque
starts decreasing. By this during running period the rotor resistance being progressively cut-out
as the motor attains its speed. In this way, it is possible to get good starting torque as well as
good running torque.
PROCEDURE:
1) Give all the connections as per the circuit diagram.
2) Switch –ON the supply and slowly vary the auto transformer up to the rated voltage carefully.
3) At this voltage no load is applied.
4) Note the no-load readings of ammeter, voltmeter, wattmeters, speed & loads s1 and s2.
5) Gradually increase the load on the motor by tightening the belt or rotating the wheels of a
pulley and note the readings of voltmeter, wattmeters, spring balances and speeds at different
load currents .
6) Remove the load completely & Switch-Off the power.
GRAPH: Graphs are drawn between the following a) speed vs torque b) efficiency vs output
power c) load current vs output power d) slip vs torque.
OBSERVATIONS:
S.No
Voltmeter
reading
Ammeter
reading
Spring Balance
S1
S2
Torque
CALCULATIONS:
Input power= (W1+W2)*M.F
Where M.F= multiplying factor.
Torque = force * distance =F*r = mgr =((S1-S2)9.81*0.1)NM
Output power =(2ΠNT/60)watts
Efficiency=output power/input power.
Slip (S)=(NS-Nr)/Ns
Where, W1+W2 = wattmeter readings, T is the torque and N is the speed
And Ns= synchronous speed and Nr= rotor speed.
Also Ns=(120fs)/p where p= number of magnetic poles and fs=supply frequency
Speed
Model graphs:
Graph: Graphs are drawn between the following a) speed vs torque b) efficiency vs output
power c) load current vs output power d) slip vs torque.
RESULT
VIVA QUESTIONS
1. Which motor is suitable for Electric Traction?
2.
Which of the following are Iron Losses?
3.
DC Motors in Starters are used to?
4.
Swinburne’s test is conducted on DC Shunt Machine at?
5.
Armature windings are made up of?
Institute of technology
Expt. No: 4
OC & SC TESTS ON 1- PHASE TRANSFORMER
Aim:
a) To conduct OC & SC tests on 1-phase transformer and to calculate efficiency and
regulation at unity power factor.
b) To conduct OC & SC tests on 1-phase transformer and to calculate efficiency and
regulation at 0.7 power factor.
c) To conduct OC & SC tests on 1-phase transformer and to calculate efficiency and
regulation at 0.6 power factor.
d) To conduct OC & SC tests on 1-phase transformer and to calculate efficiency and
regulation at 0.8 power factor.
Name plate details:
1-PHASE TRANSFORMER
Power rating
2KVA
Input Voltage
110V
Output voltage
220V
Input current
18.2A
Output Current
9.1A
Apparatus required:
S.No
DESCRIPTION
RANGE
TYPE
QUANTITY
1
2
3
4
Voltmeter
Ammeter
Wattmeter
Auto Transformer
(0-150)V
(0-2)A &(0-10)A
L.P.F & U.P.F
230 V/0-270V,8A
M.I
M.I
Analog
Wire Wound
1 No
1 No
1 No
1 No
OPEN CIRCUIT TEST:-
SHORT CIRCUIT TEST:
Theory:
Transformer is a static device which transfers electrical power from one circuit to another circuit
either by step up or step down the voltage with corresponding decrease or increase in the current,
without changing the frequency.
OC Test
The main aim of this test is to determine the Iron losses & No- load current of the T/F which are
helpful in finding Ro & Xo.In this test generally supply will be given to primary and secondary
kept open. Since secondary is opened a small current (magnetizing current will flow and it will
be 5 to 10% of full load current. The wattmeter connected in primary will give directly the Iron
losses (core losses).
SC Test:
The main aim of this test is to determine the full load copper losses which is helpful in finding
the R01, X01, Z01, efficiency and regulation of the Transformer. Generally low voltage side will
be short circuited and supply will be given to high voltage side & it will be of 5-10% of the rated
voltage. The wattmeter connected in primary will give directly the full load copper losses of the
Transformer.
Procedure:
OC Test:
1) Give connections as per the circuit diagram.
2) Switch-ON the supply and apply rated voltage i.e., 110 volts to the primary winding by
using the 1- phase auto transformer.
3) At 110 volts of voltmeter reading wattmeter reading represents the iron losses or core losses
of a 1-phase transformer. Note the readings of Ammeter, Voltmeter & Wattmeter at 110
volts.
SC Test:
1) Give connections as per the circuit diagram.
2) Switch-ON the supply and vary the Dimmerstat till rated full load current flows through
transformer.
3) At rated current Note the readings of Ammeter, Voltmeter & Wattmeter .At rated current
wattmeter reading represents the copper losses or winding losses.
Observations from Open Circuit Test:
S.No.
1
2
Voltmeter
Ammeter
Wattmeter
Observations from Short Circuit Test:
S.No.
1
2
Voltmeter
Ammeter
Wattmeter
Calculations:
S.No.
1
2
3
4
load
Input
power
Output
power
Cu loss
Iron loss
Efficiency
full
1/4
1/2
3/4
1) Efficiency=output power/input power where input power = ViIicos ¢
2) output power = input power + iron loss + copper loss
3) Regulation=(Vr cos ¢+/-Vx sin¢)/V1
Where Vr=I1R01 and Vx=I1X01 i.e.,V1= primary voltage and
Vr=I1R01 = primary resistive drop. And Vx=I1X01 = primary reactive drop+ for power
factor lagging and – for power factor leading.
Where cos ¢=Woc/(Voc* Ioc) from open circuit test.
Z01=Vsc/Isc , R01=Wsc/Isc2 , and (Z01)2= (R01)2 + (X01)2
Precautions:
1)
2)
3)
4)
The Dimmer stat should be kept at minimum O/P position initially.
In OC test, rated voltage should be applied to the Primary of the Transformer.
In SC test, the Dimmer stat should be varied up to the rated load current only.
The Dimmer stat should be varied slowly & uniformly.
Result:
Viva Questions:
1. Induced emf in a coil is directly proportional to?
2. The transformer rating is?
3. The transformer transforms?
4. The main purpose of using Core in transformer is to?
5. The transformer cores are laminated in order to?
Institute of technology
Expt. No: 5
Load test on a 1-φ transformer
Aim:
a) To conduct Load test on the given 1-Φ Transformer at 20Watts
b) To conduct Load test on the given 1-Φ Transformer at 40Watts
c) To conduct Load test on the given 1-Φ Transformer at 60Watts
d) To conduct Load test on the given 1-Φ Transformer at 100Watts
Name plate details:
Apparatus required:
S. No
Apparatus
1
Voltmeters
2
3
Ammeters
Wattmeter
4
5
Auto T/F
Load
Range
0-150V, 0-75V
0-2A, 0-15A
2A, 150V, 600W
1.5A, 150V, 600W
230V/0-230V
(0-5/10)A
Type
M.I 1,
M.I
LPF
UPF
Qty
1 No
1 No
1 No
1 No
1 No
1 No
Procedure:
1. Connections are made as per the circuit diagram.
2.
By varying the Auto transformer, rated voltage is applied to the input side of the
transformer and should be maintained constant throughout the experiment.
3. By varying the load in steps, readings of ammeter, voltmeter, and wattmeter are noted
down in each step.
4. Efficiency and Regulations are calculated in each step and tabulated.
5. Graphs are drawn Output vs Efficiency
Calculations table:
Rated Secondary Voltage, V2 = 230V
Precautions:
1. The Dimmer stat should be kept at minimum O/P position initially
2. Rated voltage should be maintained on the Primary of the Transformer
3. The Dimmer stat should be varied slowly & uniformly
Results:
Institute of technology
Expt. No: 6
REGULATION OF 3-PHASE ALTERNATOR
Aim:
a) To conduct OC test & SC test on the given 3-Alternator and to determine its regulation
by synchronous impedance method at 0.7 power factor.
b) To conduct OC test & SC test on the given 3-Alternator and to determine its regulation
by synchronous impedance method at 0.6 power factor.
c) To conduct OC test & SC test on the given 3-Alternator and to determine its regulation
by synchronous impedance method at 0.8 power factor.
d) To conduct OC test & SC test on the given 3-Alternator and to determine its regulation
by synchronous impedance method at 0.9 power factor.
Nameplate details:
DESCRPTION
D.C MOTOR
3-ALTERNATOR
Capacity
Voltage
Current
Speed
Excitation
5 H.P
220V
19A
1500 Rpm
220V, 1.5A
3 KVA
415V
4.2A
1500 Rpm
220V, 1.4A
Apparatus required:
S.No.
1.
2.
3.
4.
Equipment
ammeter
voltmeter
ammeter
rheostats
type
mc
mi
mi
variable
Tabular column:
For O.C.Test:
Si.no. Voc
1.
2.
3.
4.
5.
If
range
quantity
(0-1/2)A
1
(0-300/600)V
1
(0-10)A
1
300 ohms/1.5A
2
For S.C.Test:
Si.no.
Isc
1.
2.
3.
4.
5.
If
CIRCUIT DIAGRAM: FOR O.C & S.C. TEST:
Precautions:
a.
b.
c.
d.
Operate the 3-point starter slowly & uniformely.
Keep the speed of the prime mover to its rated value throughout the experiment.
In OC test, there should not be any load on Alternator.
In SC test, the SC current should not exceed its rated value.
Theory:
Alternator is a machine, which converts mechanical energy to
electrical energy. Regulation of an Alternator can be calculated by synchronous impedance
method. In OC test the terminals of the alternator are kept opened and a voltmeter is connected.
Keeping speed constant, a relation b/w field current & open circuit voltage are obtained. In SC
test, the terminals are short circuited with a suitable ammeter & a relation b/w field current &
short circuit Current are obtained.
Voltage regulation:
It is defined as the rise in terminal voltage of an isolated
Machine when full load is thrown off w.r.t voltage on the full load,
when speed & excitation remaining constant.
Procedure:
OC test:
1) Give all connections as per the circuit diagram.
2) Switch-ON the supply & by varying the starter, prime mover speed is adjusted to
rated.
3) Now keeping the field current at zero, note the induced emf in armature duo to
residual Magnetism.
4) By slowly varying the potential divider, field current is increased& corresponding
emf Induced is noted up to above 20% of rated voltage.
SC test:
1) Give all connections as per the circuit diagram.
2) Switch-ON the supply & by varying the starter, prime mover speed is adjusted to rated.
3) By slowly varying the potential divider, field current is increased & corresponding short
Circuit current is noted up to rated value.
4) Measure Ra value using multimeter.
Graph:
1) A graph is drawn b/w If and V which is known as OC curve, by taking If on X-axis and V on
Y-axis.
2) A graph is drawn b/w If and ISC which is known as SC curve, by Taking If on X-axis and
ISCV on Y-axis.
Model graphs:
Model calculations:
Now, Syn.Impedance (ZS) = OC voltage / SC current
Xs =√Zs - √Ra
E0=√(Vcos+IRa)2 + √(Vsin+IXS)2 for power factor lagging.
% Regulation = [(E0-V) / V] 100
Where,
P=√3*V*I*cosθ
P=power rating
V=voltage rating
I=current rating
Ra=obtained from multimeter.
Model calculations:
RESULT