channabasaveshwara institute of technologyqmp 7.5 r/c-1 rev.1 channabasaveshwara institute of...

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




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




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




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




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





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





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, multimeter, 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





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



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?



CIRCUIT DIAGRAM:

TABULAR COLUMN:

Sl.No. V1

(Volts)

A1

(Amps)

Power=

Wattmeter Reading X K

(watts)

Power factor

COS = POWER

VL I L

CALCULATIONS:



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?



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



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?



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



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:


2. Close the supply TPST switch.

3. Note down the ammeters and voltmeter readings.




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



PROCEDURE:

For Delta connected Load:


2. Close the supply TPST switch

3. Note down the ammeters and voltmeter readings.


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?



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



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?



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



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.


3. By operating the two way switches1 and 2, observe the condition of lamp in the truth

table.

4. Supply switch is opened.



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



PROCEDURE: (Three way control of lamp)

1. Make the connections as circuit diagram of two way lamp control.


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?



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



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.

.



CIRCUIT DIAGRAM: Short and open circuit

TABULAR COLUMN:

Sl. No.

Open circuit Short circuit

I (Amps)

V (volts)

I (Amps)

V (volts)



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?



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.



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.



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.

https://www.electrical4u.com/electric-current-and-theory-of-electricity/



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.



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



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



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.



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



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.

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