channabasaveshwara institute of technologyqmp 7.5 r/c-1 rev.1 channabasaveshwara institute of...
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QMP 7.5 R/C-1 Rev.1
Channabasaveshwara Institute of Technology (Affiliated to VTU, Belgaum & Approved by AICTE, New Delhi)
(NAAC Accredited & ISO 9001:2015 Certified Institution)
NH 206 (B.H. Road), Gubbi, Tumkur – 572 216. Karnataka.
BASIC ELECTRICAL
LAB MANUAL
18ELEL17/27 ( 2019 – ‘20)
Bachelor of Engineering I/II Semester
Name :
U S N :
Batch : Section :
QMP 7.5 R/C-1 Rev.1
Channabasaveshwara Institute of Technology (Affiliated to VTU, Belgaum & Approved by AICTE, New Delhi)
(NAAC Accredited & ISO 9001:2015 Certified Institution)
NH 206 (B.H. Road), Gubbi, Tumkur – 572 216. Karnataka.
Department of Electrical & Electronics Engineering
BASIC ELECTRICAL
LAB MANUAL
18ELEL17/27
( 2019 – ‘20)
Version 2.0 August 2019
Prepared by: Reviewed by:
Mrs. Radha B N Mr. Lokanathan M S
Mr. Lokanathan M S Assistant Professor
Assistant Professors Dept. of EEE
Dept. of EEE
Approved by: Prof. V C Kumar
Professor & Head,
Dept. of EEE
QMP 7.5 R/C-1 Rev.1
Channabasaveshwara Institute of Technology (Affiliated to VTU, Belgaum & Approved by AICTE, New Delhi)
(NAAC Accredited & ISO 9001:2015 Certified Institution)
NH 206 (B.H. Road), Gubbi, Tumkur – 572 216. Karnataka.
OUR VISION
To create centers of excellence in education and to serve the society by enhancing the
quality of life through value based professional leadership.
OUR MISSION
• To provide high quality technical and professionally relevant education in a diverse
learning environment.
• To provide the values that prepare students to lead their lives with personal integrity,
professional ethics and civic responsibility in a global society.
• To prepare the next generation of skilled professionals to successfully compete in the
diverse global market.
• To promote a campus environment that welcomes and honors women and men of all
races, creeds and cultures, values and intellectual curiosity, pursuit of knowledge and
academic integrity and freedom.
• To offer a wide variety of off-campus education and training programmes to individuals
and groups.
• To stimulate collaborative efforts with industry, universities, government and professional
societies.
• To facilitate public understanding of technical issues and achieve excellence in the
operations of the institute.
QUALITY POLICY
Our organization delights customers (students, parents and society) by providing value
added quality education to meet the national and international requirements. We also provide
necessary steps to train the students for placement and continue to improve our methods of
education to the students through effective quality management system, quality policy and
quality objectives.
QMP 7.5 R/C-1 Rev.1
Channabasaveshwara Institute of Technology (Affiliated to VTU, Belgaum & Approved by AICTE, New Delhi)
(NAAC Accredited & ISO 9001:2015 Certified Institution)
NH 206 (B.H. Road), Gubbi, Tumkur – 572 216. Karnataka.
DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING
VISION:
To be a department of excellence in electrical and electronics Engineering education and
Research, thereby to provide technically competent and ethical professionals to serve the
society.
MISSION:
• To provide high quality technical and professionally relevant education in the field of
electrical engineering.
• To prepare the next generation of electrically skilled professionals to successfully
compete in the diverse global market.
• To nurture their creative ideas through research activities.
• To promote research and development in electrical technology and management for the
benefit of the society.
To provide right ambience and opportunities for the students to develop into creative,
talented and globally competent professionals in electrical sector.
QMP 7.5 R/C-1 Rev.1
Channabasaveshwara Institute of Technology (Affiliated to VTU, Belgaum & Approved by AICTE, New Delhi)
(NAAC Accredited & ISO 9001:2015 Certified Institution)
NH 206 (B.H. Road), Gubbi, Tumkur – 572 216. Karnataka.
DEPARTMENT OF ELECTRICAL & ELECTRONICS ENGG.
‘Instructions to the Students’
1. Students should come with thorough preparation for the experiment to
be conducted.
2. Students will not be permitted to attend the laboratory unless they bring
the practical record fully completed in all respects pertaining to the
experiment conducted in the previous class.
3. Experiment should be started only after the staff-in-charge has checked
the circuit diagram.
4. All the calculations should be made in the observation book. Specimen
calculations for one set of readings have to be shown in the practical
record.
5. Wherever graphs are to be drawn, A-4 size graphs only should be used
and the same should be firmly attached to the practical record.
6. Practical record should be neatly maintained.
7. The students should obtain the signature of the staff-in-charge in the
observation/manual book after completing each experiment.
8. Theory regarding each experiment should be written in the practical
record before procedure in your own words.
9. Come prepared to the lab with relevant theory about the experiment you
are conducting.
10. Do not use the multimeter, if the low battery indication comes.
QMP 7.5 R/C-1 Rev.1
Channabasaveshwara Institute of Technology (Affiliated to VTU, Belgaum & Approved by AICTE, New Delhi)
(NAAC Accredited & ISO 9001:2015 Certified Institution)
NH 206 (B.H. Road), Gubbi, Tumkur – 572 216. Karnataka.
DEPARTMENT OF ELECTRICAL & ELECTRONICS ENGG.
1. Don’t play with electricity.
2. Carelessness not only destroys the
valuable equipment in the lab but also
costs your life.
3. Mere conduction of the experiments
without clear knowledge of the theory is
of no value.
4. Before you close the switch, think of the
consequences.
5. Don’t close the switch until the faculty
in-charge checks the circuit.
QMP 7.5 R/C-1 Rev.1
Channabasaveshwara Institute of Technology (Affiliated to VTU, Belgaum & Approved by AICTE, New Delhi)
(NAAC Accredited & ISO 9001:2015 Certified Institution)
NH 206 (B.H. Road), Gubbi, Tumkur – 572 216. Karnataka.
DEPARTMENT OF ELECTRICAL & ELECTRONICS ENGG.
Course objectives and Outcomes
Course Objectives:
• To provide exposure to common electrical components such as Resistors, capacitors
and inductors, types of wires and measuring instruments.
• To measure power and power factor measurement of different types of lamps and
three phase circuits.
• To explain measurement of impedance for R-Land R-C circuits.
• To determine power consumed in a 3 phase load.
• To determine earth resistance and explain methods of controlling a lamp from
different places.
Orientation class for an exposure to:
• Resistors, capacitors, inductors, rheostats, diodes, transistors, types of wires,
measuring instruments — voltmeter, ammeter, wattmeter, multi- meter, Regulated
power supply, Function generator, oscilloscope, transformer, dc motor, synchronous
generator, three phase induction motor etc.
• Basic safety precautions while dealing with electricity.
Course outcomes:
Course Outcomes: At the end of the course the student will be able to:
1. Identify the common electrical components and measuring instruments used for
conducting experiments in the electrical laboratory.
2. Compare power factor of lamps.
3. Determine impedance of an electrical circuit and power consumed in a 3 phase load.
4. Determine earth resistance and understand two way and three way control of lamps.
INDEX PAGE
18ELEL17/27: Basic Electrical lab
Sl.
No.
Name of the Experiment
Date
Ob
serv
atio
n M
arks
(Max
. 2
0)
Re
cord
Mar
ks
(Max
. 0
5)
Sign
atu
re (
Stu
de
nt)
Sign
atu
re (
Facu
lty)
Conduction
Repetition
Submission of
Record
01
02
03
04
05
06
07
08
09
10
11
12
Average
Note: If the student fails to attend the regular lab, the experiment has to be completed in the same week. Then the
manual/observation and record will be evaluated for 50% of maximum marks.
Syllabus
BASIC ELECTRICAL ENGINEERING LABORATORY
Semester : I/II CIE Marks : 40
Course Code : I8ELEL17/27 SEE Marks : 60
Teaching Hours/week (L:T:P) : 0:0:2 Exam Hours : 03
Credits : 01
LIST OFEXPERIMENTS
1. Verification of KCL and KVL for DC circuits.
2. Measurement of current, power and power factor of incandescent lamp, fluorescent
lamp, and LED lamp.
3. Measurement of resistance and inductance of a choke coil using 3 voltmeter method.
4. Determination of phase and line quantities in three phase star and delta connected
loads.
5. Measurement of three phase power using two wattmeter method.
6. Two way and three way control of lamp and formation of truth table. Measurement of
earth resistance.
7. Study of effect of open and short circuit in simple circuits.
Demonstration Experiments (for CIE only):
1. Demonstration of fuse and MCB separately by creating a fault.
2. Demonstration of cut-out sections of electrical machines (DC machines, Induction
machines and synchronous machines).
3. Understanding ac and dc supply. Use of tester and test lamp to ascertain the healthy
status of mains.
4. Understanding of UPS.
QMP 7.5 R/C-1 Rev.1
Channabasaveshwara Institute of Technology (Affiliated to VTU, Belgaum & Approved by AICTE, New Delhi)
(NAAC Accredited & ISO 9001:2015 Certified Institution)
NH 206 (B.H. Road), Gubbi, Tumkur – 572 216. Karnataka.
DEPARTMENT OF ELECTRICAL & ELECTRONICS ENGG.
Contents
Exp
No. Title of the Experiment Page
No.
1 Verification of KCL and KVL for DC circuits 2
2 Measurement of current, power and power factor of incandescent lamp,
fluorescent lamp and LED lamp 4
3 Measurement of resistance and inductance of a choke coil using 3
voltmeters method. 6
4 Determination of phase and line quantities in three phase star and delta
connected loads. 8
5 Measurement of three phase’s power using two wattmeter methods. 12
6 Two way and three control of lamp and formation of truth table. 14
7 Study the effect of open and short circuit in simple DC circuit. 18
8 Measurement of earth resistance. 20
Demonstration experiments ( For CIE only)
9 Demonstration of fuse and MCB separately by creating faults. 21
10 Demonstration of cut-out sections of electrical machines ( DC machines,
Induction machines and synchronous machines) 25
11 Understanding ac and dc supply. Use of tester and test lamp to ascertain
the healthy status of mains. 27
12 Understanding of UPS 28
Question Bank 29
18ELEL17/27: BASIC ELECTRICAL ENGINEERING LAB 2019-20
Dept of EEE, CIT-Gubbi 1
Circuit diagram : For KCL
Tabular column: For KCL
Sl. No. I1
(mA)
I2
(mA)
I3
(mA)
I1= I2+ I3
(mA) 1
2
3
Note: If I1 is equal to (I2+ I3), then KCL is verified
Circuit diagram : For KVL
Tabular column: For KCL
Sl.
No.
V1
(Volts)
V2
(Volts)
V3
(Volts)
V4
(Volts)
V1= V2+ V3+ V4
(Volts)
1
2
3
Note: If V1 is equal to (V2+ V3+ V4) then KVL is verified
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Dept of EEE, CIT-Gubbi 2
EXPERIMENT NO.1
VERIFICATION OF KIRCHHOFF’S LAWS
AIM: To verify Kirchhoff’s current law and Kirchhoff’s voltage law for the given circuit.
APPARATUS REQUIRED:
Sl.No. Apparatus Range Quantity
1 Rheostats 30 Ω, 11Ω, & 6 Ω 1 each
2 Ammeter 0-500mA( MC) 3
3 Voltmeter / Multimeter 0-30V(MC) 4/1
STATEMENT:
KCL: The algebraic sum of the currents meeting at a node is equal to zero.
KVL: In any closed path / mesh, the algebraic sum of all the voltages and resistive drops
equal is zero.
PROCEDURE FOR KCL:
1. Make the connections as per the circuit diagram.
2. Keeping RPS In zero voltage position, supply switch is closed.
3. Set particular voltage value in RPS, such that all meters are should show readable
values.
4. Repeat the step no 3 for different voltages and tabulate the readings.
5. Reduce the RPS to zero voltage position and supply switch is opened
PROCEDURE FOR KVL:
1. Make the connections as per the circuit diagram.
2. Keeping RPS In zero voltage position, supply switch is closed.
3. Set particular voltage value in RPS, such that all meters are should show readable
values.
4. Repeat the step no 3 for different voltages and tabulate the readings.
5. Reduce the RPS to zero voltage position and supply switch is opened
RESULT:
VIVA QUESTIONS :
1. State Kirchhoff’s voltage law? 2. State Kirchhoff’s current law? 3. State ohm’s law? 4. Which
law is required for applying Kirchhoff’s voltage law to a closed path if we know only resistances
and current flowing in that path? 5. Is Kirchhoff voltage law applicable to loop containing open
in it? 6. Is Kirchhoff’s laws applicable to A.C circuits? 7. Limitations of Kirchhoff’s laws?
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CIRCUIT DIAGRAM:
TABULAR COLUMN:
Sl.No. V1
(Volts)
A1
(Amps)
Power=
Wattmeter Reading X K
(watts)
Power factor
COS = POWER
VL I L
CALCULATIONS:
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EXPERIMENT NO.2
MEASUREMENT OF CURRENT, POWER AND POWER FACTOR OF
INCANDESCENT LAMP, FLUORESCENT LAMP & LED LAMP.
AIM: To measure the Power, Current and Power Factor in
i) Incandescent lamp ii) Fluorescent Lamp iii) LED Lamp.
APPARATUS REQUIRED:
Sl. No. Apparatus Range Quantity
1 Ammeter (MI) 0-1A 01
2 Voltmeter (MI) 0-300V 01
3 Wattmeter (LPF ) 0-300V 01
PROCEDURE:
1. Make the connections as per circuit diagram
2. Supply switch is closed.
3. Note down all the meter readings.
4. Open the supply switch.
5. Repeat the same above procedure for another two lamps.
RESULT:
VIVA QUESTIONS
1. What will be the power factor for a purely resistive load? And what is the formula for pf?
2. How can the power factor of an inductive circuit be improved?
3. What are the disadvantages of a low power factor?
4. How does a wattmeter work? And What is the meaning of MLCV in wattmeter?
5. What happens to the current when you reduce the voltage?
6. When voltage is increased what happens to the current?
7. What is current load? Is a light bulb an inductive load?
8. What is an example of a load in an electrical circuit?
9. What is source and load? Which are the three types of electrical loads and What is the use of
lamp load?
11. What is Electrodynamometer type wattmeter?
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CIRCUIT DIAGRAM:
TABULAR COLUMN:
Sl. No.
I
(Amps)
Vs
(volts)
VR
(volts)
VL
(volts)
in Ω
COS =
(V 2 − V 2 − V 2 )
S R L R= (Zcoil)x(Cos )
in Ω
XL=
(Zcoil)x (sin ) in Ω 2VRVL
VS= VR+VL
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Dept of EEE, CIT-Gubbi 6
EXPERIMENT NO. 3
MEASUREMENT OF RESISTANCE & INDUCTANCE OF A
CHOKE COIL USING THREE VOLTMETER METHOD.
AIM : To measure the resistance and inductance of a choke coil using three voltmeter method.
APPARATUS REQUIRED:
SL.No. Apparatus Range Quantity
1 Voltmeter (0-300)V 3
2 Ammeter (0-1)A 1
3 Rheostat 0-750 Ω/ 1
4 Choke Coil 0.4A, 40W, 230V 1
PROCEDURE:
1. Make the connections as per circuit diagram.
2. Keeping the rheostat in cut in position, Supply switch is closed.
3. Adjust the rheostat for suitable current value.
4. Note down all meter readings.
5. Repeat same for another current value
6. Bring rheostat to cut in position , then Supply switch is opened.
VIVA QUESTIONS
1. What are RC and RL circuits used for?
2. Is resistance and impedance the same?
3. What is the impedance of an RLC circuit?
4. What is the formula for the impedance of a capacitor?
5. What is the capacitor?
6. What is the resistor?
7. What is the inductor?
8. What are the three types of electrical loads?
9. What is the power factor?
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CIRCUIT DIAGRAM: STAR CONNECTED LOAD
Hint : Star connection :
OBSERVATIONS:
V L
( Line Voltage)
volts
V Ph
(Phase Voltage)
volts
I L
( Line current)
Amps
I Ph
(Phase current)
Amps
CALCULATION:
IL= IPh = …………. Amps
VL = ………. volts , VPh= VL /√3 = ……………….. = ……… . volts
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Dept of EEE, CIT-Gubbi 8
EXPERIMENT NO. 4
DETERMINATION OF PHASE AND LINE QUANTITIES IN
THREE PHASE STAR AND DELTA CONNECTED LOADS.
AIM: To determine the phase and line quantities in three phase star and delta
connected loads.
APPARATUS REQUIRED:
Sl. No. Apparatus Range Quantity
1 Voltmeter 0-600V(MI) 2
2 Ammeter 0-2A(MI) 2
PROCEDURE:
For Star connected load:
1. Make the connections as per circuit diagram.
2. Close the supply TPST switch.
3. Note down the ammeters and voltmeter readings.
4. Open the supply switch.
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CIRCUIT DIAGRAM : DELTA CONNECTED LOAD
Hint : Delta connection:
OBSERVATIONS:
V L
( Line Voltage)
volts
V Ph
(Phase Voltage)
volts
I L
( Line current)
Amps
I Ph
(Phase current)
Amps
CALCULATION:
VL = VPh = ………………..volts
IL = √3IPh = ……………………….. = ……………… Amp
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Dept of EEE, CIT-Gubbi 10
PROCEDURE:
For Delta connected Load:
1. Make the connections as per circuit diagram.
2. Close the supply TPST switch
3. Note down the ammeters and voltmeter readings.
4. Open the supply switch.
RESULT:
VIVA QUESTIONS
1. What is the difference between star and delta?
2. What is the star and delta connection?
3. What is the magnitude of 3 phase voltage?
4. What are the advantages of 3 phase system?
5. Define phase, line & neutral?
6. Define line voltage and line current?
7. Define balanced load?
8. Define unbalanced load?
9. What is a three-phase circuit (source, line, and load)?
10. What are the terminals of wattmeter?
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CIRCUIT DIAGRAM:
Note : Cos Φ =1 for resistive load.
TABULAR COLUMN:
Sl. No. VL
(volts) IL
(Amps) W1xK (watts)
W2xK (watts)
W= W1+ W2
(watts) P
(watts)
CALCULATION:
Note: P = √3 x VL x IL x Cos Φ
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Dept of EEE, CIT-Gubbi 12
EXPERIMENT NO.5
MEASUREMENT OF THREE PHASE POWER USING TWO
WATTMETER METHOD
AIM: To measure the three phase power using two wattmeter method for balanced load.
APPARATUS REQUIRED:
SL.NO Apparatus Range Quantity
1 Ammeter 0-10 A (MI) 2
2 Voltmeter 0-600 V(MI) 1
3 Wattmeter 0-600V, 0-10A,
UPF 2
PROCEDURE:
1. Make connections as per circuit diagram.
2. Keeping all loads in off position, the supply TPST switch is closed.
3. Switch on one load, Note down all the meter readings.
4. Repeat the same another two more loads.
5. All loads are switched off and supply switch is opened.
RESULT:
VIVA QUESTIONS
1. How do you measure power?
2. State the difference between wattmeter and an energy meter?
3. Types of wattmeter’s?
4. Which types of wattmeter is widely used?
5. How is the controlling torque obtained?
6. What are the errors in dynamometer type watt meters? State a few.
7. How many watt meters do we require to measure 3-phasepower?
8. What is reactive power? State the formula.
9. How many watt meters are required to measure 3-phase reactive power? 10. How do we
minimize the errors due to eddy currents in wattmeter’s?
10. . What is the difference between 1 phase and 3 phase power?
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CIRCUIT DIAGRAM : TWO WAY CONTROL OF LAMP
Truth table for two way control of lamp :
Sl. No. Position of switch S1
Position of switch S2
Condition of lamp
1 ab de
2 ab df
3 ac df
4 ac de
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EXPERIMENT NO.6
TWO WAY & THREE WAY CONTROL OF LAMP AND
FORMATION OF TRUTH TABLE
AIM : a) To control one lamp from two places.
b) To control one lamp from three places.
APPARATUS REQUIRED:
SL.No. Apparatus Range Quantity
1 Two way switches 5A 2
2 Intermediate switch 5A 1
3 Lamp 40W 1
PROCEDURE: (Two way control of lamp)
1. Make the connections as circuit diagram of two way lamp control.
2. Supply switch is closed.
3. By operating the two way switches1 and 2, observe the condition of lamp in the truth
table.
4. Supply switch is opened.
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CIRCUIT DIAGRAM : THREE WAY CONTROL OF LAMP
Truth table for three way control of lamp :
Sl. No. Position of switch
S1
Position of switch S2
Intermediate switch S3
Condition of
lamp
1 a1b1 a2b2 1,2 & 3,4
2 a1b1 a2c2 1,2 & 3,4
3 a1c1 a2c2 1,2 & 3,4
4 a1c1 a2b2 1,2 & 3,4
5 a1b1 a2b2 1,4 & 2,3
6 a1b1 a2c2 1,4 & 2,3
7 a1c1 a2c2 1,4 & 2,3
8 a1c1 a2b2 1,4 & 2,3
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PROCEDURE: (Three way control of lamp)
1. Make the connections as circuit diagram of two way lamp control.
2. Supply switch is closed.
3. By operating the two way switches1 and 2, observe the condition of lamp in the truth
table.
4. Supply switch is opened.
RESULT:
VIVA QUESTIONS
1. What is the difference between a two and three-way switch?
2. What is the purpose of a two-way switch?
3. What is the purpose of a three-way switch?
4. What is an SPST switch?
5. How many terminals are needed in a two-way switch?
6. Staircase wiring is an example of which type of control of lamp?
7. What is an intermediate switch?
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BATTERY
A
AMMETER
VOLTMETER
V
I
EARTH E D A C B
EARTH
ELECTRODE AUXILLARY
ELECTRODE
VBC
V
VED
AUXILLARY
ELECTRODE
CIRCUIT DIAGRAM:
E D C B
TABULAR COLUMN:
Sl. No. Distance between electrode A&B Resistance in MΩ
1 10m
2 15m
3 20m
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Dept of EEE, CIT-Gubbi 18
EXPERIMENT NO.7
MEASUREMENT OF EARTH RESISTANCE
AIM: To measure the earth resistance.
APPARATUS REQUIRED:: Earth insulation tester
THEORY: Ground resistance testing covers the testing of earth electrode and the measurement
of soil resistivity. Megger offers top end systems for design and soil surveys as well as tough
easy to use testers for field engineers. We have tried to make the testers self-checking as much as
we can, to allow you to concentrate on collating and understanding the results. The instrument
requirements depend on the range of applications.
PROCEDURE:
1. Make the connection as shown in figure.
2. Short E1 and P1 with a wire.
3. Connect E1 to Earth point.
4. Connect E2 to last electrode
5. Connect P2 to any one the electrode 1, and move the selector switch to 10Ώ position.
6. Press the TEST button and Note down the reading displayed in the DISPLAY board.
7. Now connect P2 to 2, 3 and repeat the step 6.
.
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CIRCUIT DIAGRAM: Short and open circuit
TABULAR COLUMN:
Sl. No.
Open circuit Short circuit
I (Amps)
V (volts)
I (Amps)
V (volts)
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Dept of EEE, CIT-Gubbi 20
EXPERIMENT NO.8
STUDY THE EFFECT OF OPEN AND SHORT CIRCUIT IN
SIMPLE DC CIRCUIT
AIM : To study the effect of Open and Short Circuit condition in a simple DC circuit.
APPARATUS REQUIRED:
Sl.No. Apparatus Range Quantity
1 Regulated power supply (0-30)V 1
2 Resistors 30Ω 11Ω
1 1
3 Voltmeter 0-30V 1
4 Ammeter (0-5)A 1
5 SPST - 1
PROCEDURE:
1. Make the connection as per circuit diagram.
2. Keeping the RPS voltage knob in minimum position, supply switch is closed.
3. Keeping the SPST switch in open position, apply around 20V.
4. Note down the voltmeter and ammeter readings ( This gives open circuit condition)
5. Close the SPST switch and readings of voltmeter and ammeter readings( This gives Short
circuit condition)
6. Reduce the RPS to zero position and supply switch is opened.
RESULT:
VIVA QUESTIONS:
1. What is open circuit and short circuit?
2. What are the effects of open circuit?
3. What are the effects of short circuit?
4. What is the effect on total resistance in a circuit if an open occurs in (a) a parallel branch
(b) series portion of circuit?
5. What is the effect on total current in a circuit if an open occurs in (a) a parallel branch (b)
series portion of circuit?
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DEMONSTRATION EXPERIMENTS
1 Demonstration of fuse and MCB separately by creating fault
2 Demonstration of cut out sections of electrical machines
3 Understanding of ac and dc supply .Use of tester and test lamp to ascertain
the healthy status of mains
4 Understanding of UPS.
EXPERIMENT NO. 9
DEMONSTRATION OF FUSE AND MCB SEPARATELY BY
CREATING FAULT
Fuse:
Fuse Operation and Principle
Fuse is a fundamental component used to protect electronic and electrical circuits from excessive
current or short circuit condition. Fuse must protect the circuit under abnormal condition by
quickly opening the circuit. A fuse is connected in series to the circuit that is required to be
protected or can be inserted to any branch to protect the devices on the specific branches.
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In the event of short circuit or abnormal increase in circuit current, the fuse will quickly open and
the large current cannot flow anymore to the circuit.
Important parameters for selection of a fuse.
(i) Current Rating: The current rating is the amount of current that a fuse will safely pass
before blowing. When the current flow through a fuse exceeds its rating, it opens up and breaks
the circuit. This rating must not be fully utilized in the circuit. A good rule of thumb is to set the
circuit typical current to 75% of this rating only. Mathematically,
The current rating above is only valid for steady state condition.
(i) Ampere Square Seconds: It is a unit measure based on the energy or heat allowed to pass through the fuse during a short-circuit condition. The product of the square of the circuit current
and the time should be less than the I2t of the device to avoid damage. Mathematically,
(iii)Breaking Capacity: Breaking capacity or interrupting rating is the current that a fuse, circuit
breaker, or other electrical apparatus is able to interrupt without being destroyed or causing an
electric arc with unacceptable duration.
(iii) Voltage Rating: The fuse voltage rating is the maximum voltage the fuse can withstand
before it is physically damaged; the maximum operating voltage.
(iv) Temperature Variation:The current carrying capacity of a fuse will be greatly affected by
the operating temperature. Once the operating temperature is high, the current capability will
decrease and the fuse will melt designed at typical or nominal conditions. Fuse manufacturers
provided a graph in their datasheets which containing the current versus operating temperature.
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MCB:
Working Principle Miniature Circuit Breaker:
There are two arrangement of operation of miniature circuit breaker. One due to thermal
effect of over current and other due to electromagnetic effect of over current. The thermal
operation of miniature circuit breaker is achieved with a bimetallic strip whenever continuous
over current flows through MCB, the bimetallic strip is heated and deflects by bending. This
deflection of bimetallic strip releases mechanical latch. As this mechanical latch is attached with
operating mechanism, it causes to open the miniature circuit breaker contacts.
But during short circuit condition, sudden rising of current, causes electromechanical
displacement of plunger associated with tripping coil or solenoid of MCB. The plunger strikes
the trip lever causing immediate release of latch mechanism consequently open the circuit
breaker contacts. This was a simple explanation of miniature circuit breaker working principle.
MCB has some advantages compared to fuse:
1. It automatically switches off the electrical circuit during abnormal condition of the network
means in over load condition as well as faulty condition. The fuse does not sense but
miniature circuit breaker does it in more reliable way. MCB is much more sensitive to over
current than fuse.
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2. Another advantage is, as the switch operating knob comes at its off position during tripping,
the faulty zone of the electrical circuit can easily be identified. But in case of fuse, fuse wire
should be checked by opening fuse grip or cutout from fuse base, for confirming the blow of
fuse wire.
3. Quick restoration of supply cannot be possible in case of fuse as because fuses have to be re-
wired or replaced for restoring the supply. But in the case of MCB, quick restoration is
possible by just switching on operation.
4. Handling MCB is more electrically safer than fuse.
Only one disadvantage of MCB over fuse is that this system is more costlier than fuse unit
system.
Operation of Miniature Circuit Breaker
There are three mechanisms provided in a single miniature circuit breaker to make it switched
off. If we carefully observe the picture beside, we will find there are mainly one bi - metallic
strip, one trip coil and one hand operated on-off lever. Electric current carrying path of a
miniature circuit breaker shown in the picture is like follows. First left hand side power terminal
- then bimetallic strip - then current coil or trip coil - then moving contact - then fixed contact
and - lastly right had side power terminal. All are arranged in series.
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EXPERIMENT NO. 10
DEMONSTRATION OF CUT OUT SECTIONS OF ELECTRICAL
MACHINES
A DC Machine is an electro-mechanical energy conversion device. There are two types
of DC machines; one is DC generator, and another one is known as DC motor. A DC
generator converts mechanical power (ωT) into DC electrical power (EI), whereas, a DC
motor converts DC electrical power into mechanical power.
CUT OUT OF DC MACHINE
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AC machines : The two major classes of ac machines are synchronous and induction
machines. AC voltage generators convert mechanical power to AC electric power. AC motors
convert AC electric power to mechanical energy (power) .
The field current of synchronous machines (motors and generators) is supplied by a separate dc
power source, while the field current of induction machines is supplied by magnetic induction
(transformer action) into the field windings.
CUT OUT OF AC MACHINE
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EXPERIMENT NO. 11
UNDERSTANDING OF AC AND DC SUPPLY. USE OF TESTER
AND TEST LAMP TO ASCERTAIN THE HEALTHY STATUS OF
MAINS
TESTER
TEST LAMP
Using Tester we can test or ascertain the healthy condition of AC & DC Mains.
Tester:When we hold the tester and make the contact of pointed edge of the tester to line
terminal (Positive terminal of DC Supply) and our fore finger or thumb touches the metal portion
on the tester, then if the neon indictor located inside the tester glows then it is understood that
voltage (Power) is available at that mains. If the same procedure is done with neutral (Negative
terminal of DC supply) the indicator should not glow. This indicates the healthy condition of
electric supply.
The above procedure makes us to find whether power is available at the mains. Some
times if neutral line is having any discontinuity it difficult to identify with this tester. But by
using the test lamp we can assure the power is not only available but there is no discontinuity in
neutral wire. Connect the test lamp between line and neutral and switch on the supply, if bulb
glows then it is understood that neutral is not having any discontinuity. If bulb is not glowing
means there is a discontinuity in neutral connections.
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EXPERIMENT NO. 12
UNDERSTANDING OF UPS
The full form of UPS is uninterrupted power supply. The block diagram of the UPS is as
shown below. The designing of UPS is similar to the Standby UPS, excluding that the primary
power source is the inverter instead of the AC main. During failure of an input AC power, this
UPS operation results in no transfer time.
Block Diagram of online UPS
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Question Bank
1. Conduct an experiment to verify Kirchoff’s Current Law for a given circuit
2. Conduct an experiment to verify Kirchoff’s voltage law for given circuit.
3. Conduct suitable experiment to compare the power and power factor of Incandescent
lamp, Florescent lamp and LED lamp.
4. Conduct an experiment to determine the value of Inductance and Resistance of given
Choke Coil using Three Voltmeter method.
5. Conduct an experiment to measure the Power consumed by a three phase load using Two
Wattmeters method and compare it with theoretical value by calculating it using suitable
equation.
6. Conduct suitable experiment and demonstrate the concept of Open Circuit and Short
Circuit.
7. Conduct a suitable experiment on Two Way and Three Way control of lamp and verify
the Truth Table.
8. Conduct an experiment to verify the relationship between line and phase quantities in a
three phase Star connected system.
9. Conduct an experiment to verify the relationship between line and phase quantities in a
three phase Delta connected system.
10. Conduct an experiment to measure the Earth Resistance at different distances from a
Earthing/Grounding point and plot the graph of resistance versus distance.