Electrical basic engineering by Ramesh meti karanataka

HISTORY AND BASICS OF
ELECTRICITY
Introduction
 Although man has been aware of electricity for several centuries, a
proper scientific understanding of it began only in the 18 th century. In
this session, we will learn about the history of electricity and its basics.
History of Electricity
 Around 600 BC,Thales, a Greek philosopher, discovered frictional
electricity. In 1600 AD, William Gilbert, an English physicist, coined the
word „electrical‟(Latin word derived from the Greek word electron. In 1646,
Sir Thomas Brown, an English writer, modified the term to „electricity‟. In
1800, Alessandro Volta, an Italian scientist, discovered a chemical form
of producing electricity. In 1831, Dr Michel Faraday, an English scientist
(also known as the „father of electricity‟), discovered dynamic electricity
with electromagnetic Induction. He is also called as the ' father of the
electricity.'

when was electricity first used in
homes
 In 1882 Edison helped form
the Edison Electric
Illuminating Company of
New York, which brought
electric light to parts of
Manhattan. But progress was
slow. Most Americans still lit
their homes with gas light
and candles for another fifty
years. Only in 1925 did half
of all homes in the U.S. have
electric power.

when was incandescent lamp
used
 1879 After many
experiments, Thomas Edison
invented an incandescent
light bulb that could be used
for about 40 hours without
burning out. By 1880 his
bulbs could be used for 1200
hours. 1879 Electric lights
(Brush arc lamps) were first
used for public street
lighting, in Cleveland, Ohio.

Thomas Edison Born Thomas Alva Edison
February 11, 1847
Milan, Ohio, U.S.
 DiedOctober 18, 1931 (aged 84)
West Orange, New Jersey, U.S.
 Burial placeThomas Edison National
Historical Park
 Nationality American
 Education Self-educated Occupation
Inventor, businessman Years active
1877–1930
 Spouse(s)Mary Stilwell
(m. 1871; d. 1884)
 Mina Miller
(m. 1886)
 Children6, including Madeleine Edison,
Charles Edison and Theodore Miller
Edison
Relatives Lewis Miller (father-in-
law)Signature

When was electricity used in india
 Established Asia’s first – Hydro
Electric Power Station in
Shivanasamudram, on the banks of
river Cauvery during 1902.
Karnataka the first to embark on
Alternating current, when
Bangalore Citys lighting scheme
was completed. Karnataka had the
longest transmission line in the
world in 1902, from
Shivanasamudram to KGF,
covering a distance of 147 km and
it was the first state in the country
to conceive

Who is the father of Electricty
Michael Faraday
 A self-taught scientist, Michael
Faraday (1791-1867) excelled in
chemistry and physics to
become one of the most
influential thinkers in history.
He's been called the "father of
electricity," (Nikola Tesla and
Thomas Edison also wear that
crown) and his appetite for
experimenting knew no bounds.

What is the speed of electricity per
second?
 Therefore, the speed of
electricity in a 12-gauge
copper wire is
299,792,458 meters per
second x 0.951 or
second. This is about
second.
 2,80000km/sec

The Law of Conservation of Energy
The Law of Conservation of Energy states
that energy cannot be created or
destroyed; it can only be changed from
one form to another.
Sources of Electrical Energy
Water, Sun, Coal, Fuels, Nuclear, Wind

PRINCIPLES OF ELECTRICITY
Introduction
 Electricity has become an integral part of
our lives. It is essential for lighting, power,
air conditioning, refrigeration and a host of
other applications. Life without electricity is
almost unimaginable. We must therefore have a
fair knowledge of the principles of electricity.

What is electricity?
 What is electricity?
 Electricity is an invisible and untouchable form of energy. But it can felt through its effects.
The components of electricity are current, voltage and resistance.
 Current
 Current is defined as the free flow of electrons through a conductor, which is measured by an
Ammeter, measuring unit is Amps and letter represented by I.
 Voltage
 Voltage is an electrical pressure required to drive free flow of electrons through a conductor.
It is measured by a voltmeter; measuring unit is volts and letter represented by V or E.
 Resistance
 Resistance is the property of a material which opposes free flow of electrons through it. It is
measured by an ohmmeter; measuring unit is ohms and letter represented by R.

How electricity gets to your home
 Electricity starts its life in a power station.
Power stations are huge plants – often
located near energy sources like natural gas
plants, hydroelectricity dams, and solar or
wind farms – that produce electricity.
Depending on the type of fuel or source of
energy input - whether it’s coal, solar, wind,
or even nuclear - power plants may have
components such as a furnace, boiler,
turbine, cooling towers, and generators.
These types of components are essential for
the generation process.Once the electricity is
generated, it leaves the power station
through overhead lines to large substations.
At this stage, the electricity can be at as high
as 25,000 volts or ever higher.
POWER STATION

220kv
110kv
33kv/11k
v
440v/23
0v11kv
33kv
66kv
110kv
220kv
S
T
E
P
-
U
P
S
T
E
P
-
D
O
W
N
Voltage Generating process

First substation transformer
 Substations are usually located near
power stations. Substations play an
important role in the electricity
transmission process: they further
increase the voltage of the current,
allowing it to be sent over long
distances without losing too much
power. Substations do this by using
transformers, and these can be used to
either increase or decrease the voltage
of electric currents. Decreasing the
voltage of electricity can be important
at distribution substations as it needs
to be made less powerful and safe
before it enters your house.
 Once it passes through the first
substation transformer, your electricity
makes its way to the transmission
networks.

Transmission networks
 The transmission networks help
shift electricity from power
stations on to distribution networks
to facilitate delivery to households,
businesses, and other end users. At
this stage, the electricity remains at
a high voltage since it still needs to
move across vast distances.
 The transmission networks are
made up of overhead lines on
metal pylons or lines buried under
the ground. These lines are
designed to carry ultra-high
voltages and they’re insulated to
prevent the electric current from
accidentally moving to the ground,
where it can be dangerous for
people.

220kv substation transformer
 At the second substation transformer point,
your electricity is reduced in voltage, again
through the use of transformers, to make it
safe for use by households and end users. At
this point the electricity is considered to
have reached the distribution network and
left the transmission network.
 The type of substation and voltage can vary
depending on the use and location. For
example, in rural areas, smaller substations
might be used to reduce the voltage to
around 33,000 volts, which makes it suitable
for powering trains and factories. In urban
areas with factories, the voltage could range
between 11,000 and 33,000 volts to serve
smaller factories. Contrast with delivery to
homes, offices, and business, where the
neighbourhood transformer might lower the
voltage to as little as 230 volts.

Distribution powerlines
 Once your electricity leaves the
substation transformer, it enters
distribution power lines on its way
to the final destination. Power
lines can be overhead or
underground, and they’re a
familiar sight in most areas around
Australia. Once it reaches your
neighbourhood, the electricity
passes through a small pole-top
transformer for another voltage
reduction. This ensures it’s safe to
use inside the home, office, or
business.

Your home
 Your electricity passes through the service
drop and gets recorded at your metre. The
metre tracks how much electricity you
use. At your switchboard, your electricity
gets divided up into circuits for each area
of your house. Finally, the electricity
moves through wires behind your walls to
power outlets and switches, where you
operate your lights and appliances.
 It’s easy to take the electricity used to
light your house for granted, but this
precious energy source has travelled a
long way, through complex generation
and transmission infrastructure, to get to
your house. Knowing this, you’re
probably less likely to take electricity for
granted when you next switch on your
light or power up the TV.

EFFECTS OF ELECTRIC
CURRENT
Introduction
 As we discussed earlier, electricity is an invisible form
of energy that can be perceived only
 through its effects. Whenever current flows
through a conductor, it is actually electrons
 flowing from one place to another. It is not possible to
see the electrons or current flow. So it
 is essential to know about the effects of electric
current.

Effects of Electricity
 Physical effect: The human body is a good conductor of
electricity. So when we touch an object through which
current is flowing, we get a shock. Severe shock may even
lead to death (examples through case studies, activity,
etc.)
 Heating effect: Whenever current passes through any
conductor, heat is produced in
that conductor. Such effect is used in a heater, press, lamps,
soldering iron, etc.
(activity based experiment)

Effects of Electricity
 Magnetic effect: This effect is seen in fans, meters, calling
bells, etc. (demonstrate a calling bell)
 Chemical effect: When current passes through an
electrolyte, a chemical reaction takes place. Battery charging
and electroplating are good examples.
 X-ray effect: When high frequency is passed through a
vacuum tube, a special type of high-penetration rays come out,
which cannot be seen. They are called x rays; they are used to
take images of the insides of our body to diagnose diseases and
determine treatment.

POWER AND ENERGY
Power
 Power is the rate of doing work.
Power (P) = Work done (W) / Time taken (T)
The unit of power is joules / second or watts /
second. I kilowatt (kW) = 1000 w
Another unit of power is hp; 1 hp = 746 w, or 1.34 hp in MKS system; 1 kW = 1.36 hp
Energy
 Energy is the capacity for doing work. Energy exists in several forms, which
may be
interchanged.
1 joule = 1 Newton / meter A small unit of power is watt / second
A bigger unit of power is kwh (also called (botu); 1 botu = 1000 w or 1 kwh
= 36,00,000 joules

Energy Calculation
S.
No
Name of point No. of points Load
1 Lamps 10 100w
2 Ceiling fans 8 75w
3 Electric heater 1 1500w
4 Motor 1.5 hp 1 2000w
Total load

SAFETY PRECAUTION
Introduction
 Electricity helps us in many ways. But it can take a
lot more than it gives us, and can be dangerous if it is
not treated properly. So we need to be very careful while
working with the live supply.
Safety Precautions
 Careful handling of electrical appliances, using
insulated hand tools, using correct rating fuses,
effective earthing.
 Metallic parts, using of hand gloves, using rubber
mat, never tamper unnecessarily with live lines and
never use damaged appliances.

Causes of Electric Shock
 Carelessness
 Accidental
 Over confidence
 Lack of awareness / ignorance
 Natural causes (lightning etc.)
Effects of Shock on the Human Body
 On the brain, body, kidney, etc. (refer to text books)
The Severity of a Shock Depends on:
 Duration of current flow
 Amount of current
 Path of flow of current -location
 Type of energy and line voltage, etc.
An electric shock occurs by touching:
 Phase and natural simultaneously
 Phase conductor and standing on ground
 A metallic part, when current is leaking.

CAUSES OF ELECTRIC FIRE, AND EQUIPMENT USED
TO CEASE FIRE
 Introduction
 When a conductor carrying electric current gets
overloaded, it heats up and softens the insulating
cable. This may lead to a short circuit and fire. It is
therefore important that we understand various types
of fire and how to put them out with fire
extinguishers.

 Causes of electric fire
 Fire is a chain of chemical reaction, caused by combustion of
inflammable material producing heat, light and smoke. The
reasons for a fire could be:
 Improper / substandard cables for wiring
 Short circuits
 Overloading the equipment
 Maintenance negligence
 Inadequate / poor insulation
 Lightning

S.
No
Type of
fire
Name of
fire
Source Fire
extinguishers
used
1 Class A Solid fires Wood, cloth paper A class fire
extinguishers
2 Class B Liquid fire Petrol, fuel Dry Chemical
Powder (DCP)
3 Class C Gas fire LPG gas Dry Chemical
Powder (DCP)
4 Class – D Metal Fire Sodium,
Magnesium
ABC Fire
extinguishers
5 Electrically Started
Fires (ESF)
Electrical
Fire
Electrically Starts ABC Fire
extinguishers,
CO2 Gas

Types of Fire Extinguishers
 Soda acid, Water-CO2, Form-type, Dry Chemical Powder (DCP), CO2 gas,
ABC Powder Extinguisher
Pressurizing mechanism in a Fire Extinguisher
 Gas cartridge (CO2, water)
 Spot pressure (soda, acid, and gas)
 Stored pressure (readily available)
Advantages of ABC Fire Extinguishers
 Very easy to handle
 Anybody can operate
 Can be located at the level of pressure
 Very economical and effective
 Can be used for any type of fire (Class A / B / C)
 Readily available with stored pressure

Current level
(Milli-
amperes)
Probable Effect on Human Body
1 mA
Perception level. Slight tingling sensation. Still dangerous
under certain conditions.
5mA
Slight shock felt; not painful but disturbing. Average individual
can let go. However, strong involuntary reactions to shocks in
this range may lead to injuries.
6mA - 16mA
Painful shock, begin to lose muscular control. Commonly
referred to as the freezing current or "let-go" range.
17mA - 99mA
Extreme pain, respiratory arrest, severe muscular contractions.
Individual cannot let go. Death is possible.
100mA -
2000mA
Ventricular fibrillation (uneven, uncoordinated pumping of the
heart.) Muscular contraction and nerve damage begins to
occur. Death is likely.
> 2,000mA
Cardiac arrest, internal organ damage, and severe burns. Death is
probable

Minimizing Electrical Hazards
• Grounding/Earthing
• Guarding
• Locking and Tagging Equipment
• Mechanical Protection Devices
• Protective gears and clothing
• Plugs and receptacles
• Inspect Electrical Equipment before use
• Cable Routing

CONDUCTORS AND
INSULATORS
 Introduction
 Conductors and insulators play a vital role
in domestic / industrial wiring, including
networking systems. While conductors carry
the current, insulators provide safety for it. It is
important to understand them well.

Introduction to conductor and Insulator
 Conductor: A material which contains many free electrons and is
capable of carrying electric current is known as a conductor.
Properties of a conductor:
 Have a law specific resistance
 Are mechanically rigid
 Should be easily available
 Should not be very expensive
 Should be non corrosive
 Should be ductile
 Should be durable, malleable
 Should have high stencil power
 Should be highly conductive

DIFFERENT CONDUCTORS
USED FOR HOUSE WIRING
SYSTEM
 Introduction
 The conductor of a cable is like the heart of the human
body. The function of the conductor is to carry
current, like the heart circulates blood in the body. If
the blood circulation is irregular and improper, it may
cause various diseases in the body. Similarly if the
conductor (copper) is not good, due to reasons like
impurity of copper or improper bunching, the current
carrying capacity of the conductor will reduce. So we
need to use good conductors.


Types of wires used in domestic and industrial
 According to the core
Single core wire
Two core wire
Three core wire
Four core wire
According to insulation (Stand wires)
VIR wire
CTS or TRS wires
PVC wires
FRLC
HFFR
Weather proof wires
Enameled wire
Fire resisting etc.
According to the metal
 Bare Copper
 ACSR Conductor
 Fuse wire
 Nichrome wires

 The main criteria for selection of Cables
 Voltage grade for house wiring 1100 V, 1.1 KV grade
Current rating of cables Voltage drop in cables on
current flow Short circuit withstanding capacity
Derating or safety load etc.
 Avoid using obsolete British standard cables such as
1 / 18, 3 / 20 etc.
 ISI recommends the use of metric system such as, 1.5
sq mm, 2.5 sq mm, 4 sq mm, 6 sq mm, 10 sq mm

 Flow color codes for wiring (as shown in the picture)
o Green – Earthing
o Black – Neutral
o Red, Yellow, Blue – Phases
Abbreviations
 CTS : Cab Tire Sheathed
 VIR : Vulcanized Indian Rubber
 PVC : Poly Vinyl Chloride
 ETP : Electrolytic Tough Pitch
 FRLS : Fire Retardant Low Smoke
 HFFR : Halogen Free Flame Retardant
 Conclusion
There is a need to give examples of many case studies, conventional cables and fire
retardant cables to the aspirants. Technicians should recognize the quality of a
conductor by seeing it.

 The following points must be considered before selecting a particular wiring.
 1. Durability: The wiring must be able to withstand wear & tear under any
circumstances.
 2. Safety: The wiring must be able to provide safety by safely concealing
the wiring systems.
 3. Mechanical Protection: Conduit wiring must be protected from damage through
physical or natural changes during its use.
 4. Appearance: Appearance is the most important aspect to consider from the
architectural point of view.
 5. Permanency: The wiring must not be affected by weather, smoke, dampness etc.
 6. Accessibility: In the wiring system facility for the extension or renewal or
attraction should provided. he wiring must be done in a way that makes distribution
of power easy, without any hassles.
 7. Cost: The wiring system adopted must be economically suitable to the client.

ISI recommends conductor
 ISI recommends the use of metric system of wires as
given below:
 a. 1.0 Sq mm b. 1.5 Sq mm c. 2.5 Sq mm
 d. 4 Sq mm e. 6 Sq mm f. 10 Sq mm
 Note: Obsolete British standard cables are 1/18, 3/20,
7/20 etc.

ELECTRICAL ACCESSORIES
Switches, Sockets
House wiring accessories can be classified into the following categories:
 a. Control and distribution system
 b. Cable carrier and support system
 c. Current carrying conductors (wires)
 d. Switching and termination products
 e. Sensor Switches
 Control (Protection) and distribution system
 This system is used to control the main supply and distribute it to the circuits. The main
protective devices used in house wiring circuits are:
i. Fuses (Fuse that can be re-wired, HRC Fuses available at diff ranges [6Amp to 200Amp])
ii. ICDP, ICTP (available at 32A to 200A)
iii. Miniature Circuit Breakers (available at 1A to 40A)
iv. Isolator (available at 32A to 63A)
v. ELCB / RCCB – (available at 32A, 40A & 63A) and MCCB above 63A
All the above mentioned items are installed in control and distribution boards. The Boards are
available in 1 phase, 3 phase, single door and double door as shown in the picture.

Cable carrier and support
 The house wiring cable can‟t be run or laid on walls without support. Hence the
wires need to be supported from the main distribution till the terminating product.
The systems used to carry, support and run these wires are called cable carriers and
support systems. The different systems which we adopt for the same are as follows:
 i. Wooden capping & casing wiring
 ii. Cleat wiring
 iii. Conduit wiring (open/ surface)
 iv. Conduit wiring (concealed)
 Different accessories available to carry wires
 i. PVC conduits available in 19 mm, 25 mm
 ii. Junction Box – 1 way, 2 way, 3 way and fan hooks
 iii. MS / GI conduits and its accessories such as MS inspection bend, Inspection „T‟ and
 „J‟ boxes etc.
 iv. The conduits are available in sizes of 16mm, 19mm, 25mm and 30mm and are
normally of 16 SWG thickness
 v. Casing and capping batten patties are also available in different sizes for temporary
wiring

Switching and terminating products
 All these products have certain common features like insulation bases and covers.
All the house wiring cables normally terminate in:
 i. Switches (All types)
 ii. Sockets
 iii. Ceiling roses
 iv. Holders and adaptors etc.
 i. Switches:
Switches are classified as under:
1. According to the rating – 6 A, 10 A, 16A
2. According to the connection – 1 way, 2 way and intermediate
ii. Sockets:
 1. According to the rating: 6A, 10A, 16A, 25A etc.
 2. According to the connection: 2 pin, 3 pin, 5 pin, multi pin etc.

iii. Ceiling Roses:
 The wiring from switch terminals is taken to ceiling roses, lamp holders and
connectors.
 The ceiling roses are available in two types. These are 2 pin and 3 pin.
iv. Holders and Adaptors:
 There are some other terminating products named as holder and adaptors.
Different holders are available in the market:
a. Angle Holder b. Batten Holder c. Pendent Holder
d. Screw type / Pin type Holder etc.
Sensor Switches:
 Sensor switch is also similar to the switch but it works on sensor signals. It is a
small
electronic circuit. The sensor switches are as under:
a. Temperature sensor b. Light sensor
c. Dark sensor d. Sound sensor
e. Acoustic sensor f. Vibration sensor
g. Altitude sensor h. PIR (Passive Infrared) etc.

Stand by power sources: Power outages are very
common in all parts of the country which is why
standby power sources are very essential to fulfill the
power shortage. Standby power sources may be:
a. Alternators / Generators
b. UPS (Uninterrupted Power Supply) system
c. Inverter
d. Emergency lights etc.

The common conductors used for electrical purpose are:
Silver Copper Bronze
Brass Aluminum Lead
Tin Micromere Tungsten
Eureka Carbon etc.
 Insulators: A substance which cannot pass current through it under normal conditions
is
termed as an insulator.
 Properties of insulators:
 Insulators:
 Should have low conductivity
 Should have a high specific resistance
 Should have a resistance and ability to bear high temperatures
 Should have a good mechanical strength
 Should be moisture resistant and water proof
 Should have a high dielectric strength (voltage bearing capacity)
 Should be permanent in nature (remain in the same state and condition regardless of
the environmental conditions)

The common insulation used for
electrical uses:
• Bakelite, Porcelain, Mica , Rubber, Fiber, Vanish
Glass, Wood , Cotton tape ,PVC Oil
• Classifications of cables according to the insulator
used:
• VIR wires
• PVC wires
• Flexible wires
• Enameled wires
• Cotton covered wires

UNDER GROUND CABLES
Introduction
 Electric power can be transmitted or distributed either by OHL or by underground
cables. The underground cables have several advantages, the only disadvantage
being the initial cost. Underground cables An underground cable essentially
consists of one or more conductors covered with suitable insulation and
surrounded by a protecting cover.
 Construction of cables
The various parts of underground cables are as under
as shown in the picture.
a. Cores or conductors
b. Insulation
c. Metallic sheath
d. Bedding
e. Armoring
f. Serving

Insulating material for cables
 The satisfactory operation of a cable depends to a
great extent upon the characteristics of insulation
used.
 The principal insulating materials used in cables
are:
a. Rubber
b. Vulcanized Indian Rubber (VIR)
c. Impregnated paper
d. Varnished cambric

Classification of cables
Cables for underground service may be classified in two ways according to:
1. The type of insulating material used
2. The voltage for which they are manufactured According to the voltage
1. Low tension (LT) cable – up to 1000V
2. High tension (HT) cable – up to 11,000V
3. Super tension (ST) cable – up to 33 KV
4. Extra high tension (EHT) cable – 3 KV to 66 KV
5. Extra super voltage cable – beyond 132 KV
 Cables for 3 phase service
1. Better cable – up to 11 KV
2. Screened cables – 22 KV to 66 KV
3. Pressure cable – Beyond 66 KV

Electricity today is playing an ever increasing role in the lives of
every human being. Increased use of electricity has resulted in
increased danger to human beings. When lightening occurs, it
not only damages consumer‟s premises but it also destroys
property and lives. So today Earthing is considered the
most
essential provision of any electric supply system. But
unfortunately it is the most neglected aspect in house
wiring and implement it on grounds. Hence today we discuss
about Earthing.
and in many cases even in industrial and commercial wiring. So
earthing is thus laid down as a statutory requirement in Indian
electricity rules so as a trainer / trainee we need to understand
and implement it on grounds. Hence today we discuss about
Earthing.

What is Earthing?
A wire coming from the ground 2.5m to 3m deep from an
electrode (Plate) is called Earthing.
A wire 2.5m to 3m long connected from an electrode
(plate) to the main switch board to
avoid shock is called Earthing.
Note: The metal plate, copper plate, rod or
conductor is called as earth electrode.

Purpose / Objects of Earthing
• To save human life from
Danger / shock
• To protect large buildings and
towers from lightening
• To protect all machines fed
from OH lines from lightening
arresters
• To maintain the line voltage
• To provide easy return path for
leakage current
• Good Earthing is that which
gives low resistance and enables
smooth flow of heavy
•current

Methods of Earthing
•There are mainly two methods of Earthing. They are:
•a. Plate Earthing (most common and effective method)
•b. Pipe Earthing
•ISI Rules
• The standard Earthing code is IS 3043
• The Earth pit must be 1 ½ m distance from the building wall
• The earth wire must be of the same material as that of the electrode used
• The cross sectional area of the earth wire should not be less than 8 SWG
• The size of the earth conductor should not be less than half the size of
the line
•conductor
• All the joints must be properly joint, bolted, soldered or brazed
• All the metal parts, motors, generators and other appliances must be
properly
•connected by the earth conductor
• All the third pin of sockets must be connected to earth conductor
• Every stay wire must be Earthed

Earthing
•Earthing.
•Necessary of earthing.
•Safety of earthing.
•Method of earthing.
•Plate earthing.``
•Pipe earthing.```
•Chemical earthing.
•Application of earthing.
•Recommended of earthing resistance value

•Bare copper condEarthing means copper
plate/cast iron plate with G.I plate to be
inserted in the ground. About 2.5 to 3
meters depth in the ground, &Earthing is
flow of leakage & excessive current.
•uctor is to be connected to plate & taken
out as earthing wire called earthing.

Safety of earthing
•danger of electric
shock.
• To protect building ,
machinery &
appliances & under
fault condition.
• To provide safe path
to neutraTo save the
human life from the
lize the access
voltage.

What is earthing and why it is
done?
 Earthing is used to
protect you from an
electric shock. It does this
by providing a path (a
protective conductor) for a
fault current to flow to
earth. It also causes the
protective device (either a
circuit-breaker or fuse) to
switch off the electric
current to the circuit that
has the fault.

Which type of earthing is used in homes?
 Electric earthing may be
either pipe or plate earthing.
Normally GI pipe (2.5 inch
diameter) or plate (500 mm
X 500 mm X 10 mm) is
used but if the soil is
corrosive then copper pipe or
plate should be used. Use
Double GI Strip size 30 mm
X 10 mm to connect GI Plate
to System Earthing.

Plate type earthing
 Plate Earthing: A copper
plate or galvanized plate
is buried in an earth pit
below ground level. The
plate electrode connects
the electrical conductors to
the earth

•chemical earthing is consider more
effective solution for consistent &
permanent earthing.
•They are maintenance free & have
minimum fluctuations & are eco
friendly.
•In chemical earthing we use
bentonite powder
•They are highly reliable for safety
of human life.
Chemical earthing

Application of earthing
•Telecommunication.
•Tramission.
•Sub station & power
generation.
•Transformer neutral earthing
& body earthing.
•Lightning arrester earthing.

Recommended of earthing resistance
value
• Earth resistance less
then 2 ohm’s
residential/commercial/i
ndustrial.
• For electronic
components
(computer/T.V/UPS) it
should be within 1ohm.
• if the results are out of
range needs to check &
rectify until it reaches
within the limits.

`What is fuse explain?
 In electronics and electrical
engineering, a fuse is an
electrical safety device that
operates to provide
overcurrent protection of an
electrical circuit. Its essential
component is a metal wire or
strip that melts when too
much current flows through
it, thereby stopping or
interrupting the current.

Current rating of fuse in Amps
 6A
 10A
 16A
 20A
 25A
 32A
 35A
 40A
 50A
 63A
 80A
 100A
 125A
 160A
 200A
 250A
 315A
 400A
 500A
 630A

What is MCB and its function?
 A miniature circuit breaker
(MCB) automatically
switches off electrical circuit
during an abnormal
condition of the network
means in overload condition
as well as faulty condition.
Nowadays we use an MCB
in low voltage electrical
network instead of a fuse. ...
Handling an MCB is
electrically safer than a fuse

Types of MCB
 There are four types of
MCB
 1 Pole MCB
 2 Pole MCB
 3 Pole MCB and
 4 Pole MCB

Current Ratings of MCB
 0.5 A
 1 A
 2 A
 3 A
 4 A
 5 A
 6 A
 10 A
 16 A
 20A
 25 A
 32 A
 40 A
 50 A
 63 A

Parts of MCB
 A breaker is a device
designed to isolate a circuit
during an overcurrent event
without the use of a fusible
element. A breaker is a
resettable protective device
that protects against two
types of
overcurrent situations:
 Overload and
 Short Circuit.

Small circuit breakers are
either installed directly in
equipment, or are arranged in a
breaker panel. The design of
MCB includes the following
components:
1.Actuatorlever
2.Tripmechanism
3.Contacts
4.Terminals
5.Bimetallicstrip
6.Calibrationscrew
7.Solenoid
8.Arcdivider/Extinguisher

Thermal / Magnetic trip units
 Current Limiting Breakers
use an electromechanical
(Thermal /Magnetic) trip
unit to open the breaker
contacts during a
overcurrent event. The
thermal trip unit is
temperature sensitive and the
magnetic trip unit is current
sensitive.
 Both units act independently
and mechanically with the
breaker’s trip mechanism to
open the breaker’s contacts.

What is MCCB
 Molded Case Circuit Breaker
(MCCB) is a circuit breaker
and trip device assembled in
a mould case. Also it can
automatically cut off electric
power in case of overload
and short circuit. It is meant
for higher rated current and
is commonly used in
Industrial applications. Its
usual range is 250A-800A.

Current rating of MCCB
 15 A
 20 A
 30 A
 40 A
 50 A
 60 A
 75 A
 100 A
 125 A
 150 A
 175 A
 200 A
 225 A
 250 A
 300 A
 350 A
 400 A
 500 A
 630 A
 700 A
 800 A
 1000 A
 1200 A

MCB MCCB
Miniature Circuit Breaker Moulded Case Circuit Breaker
Rated current not more than 63
A.
Rated current up to 1000 A.
Trip current
normally not adjustable.
Trip current may be adjustable.
normally not adjustable.
Thermal or thermal-magnetic
operation.
Thermal or thermal-magnetic
operation.
which is used to break small
currents. Like in domestic LT
circuitz
which has a rugged
construction as it can break
larger currents usually from
(100-1000A).
For domestic purpose. For commercial and industrial
use.
Type of switch which protects
the system from overloaded
current.
Protects the equipment from
over temperature and fault
current.

RCB (Residual Current Circuit
Breaker)
 While RCCB is a current
sensing electro-mechanical
device that breaks an electric
circuit and trip in case of the
earth fault.
 Line (Phase or Live) and
Neutral (N) both wires are
connected to the load points
through RCCB (RCD)
 It is only connected to Phase
and Neutral Wire.

Residual Current Circuit Breaker
 If there is no connection
between the ground and the
enclosure of the device, and
a person touches the metallic
body of that device. In this
case, incoming and outgoing
current will be different and
RCB will Trip in contrast
with ELCB.
 Functionality of RCB
(Residual Current Breaker)
does not effect by lightning
strikes.
 It does not trip falsely.

ACB ( Air Circuit Breaker )
 Air Circuit Breaker
(ACB) is an electrical
device used to provide
Over current and short-
circuit protection for
electric circuits over 800
Amps to 10K Amps. These
are usually used in low
voltage applications below
450V.

vacuum circuit breaker
 A vacuum circuit breaker is a
kind of circuit breaker where the
arc quenching takes place in
vacuum medium. The operation of
switching on and closing of
current carrying contacts and
interrelated arc interruption takes
place in a vacuum chamber in the
breaker which is called vacuum
interrupter
 3000 Amperes
 The VCB (Vacuum circuit
breaker) current rating is up to
3000 Amperes. The main
characteristics of vacuum circuit
breaker are, it interrupts the arc in
a vacuum bottle. These can be
applied at up to 35 thousand volts

Sulfur hexafluoride circuit
breakers
 Sulfur hexafluoride circuit breakers
protect electrical power stations and
distribution systems by interrupting
electric currents, when tripped by a
protective relay. Instead of oil, air, or a
vacuum, a sulfur hexafluoride circuit
breaker uses sulfur hexafluoride (SF6)
gas to cool and quench the arc on
opening a circuit. Advantages over
other media include lower operating
noise and no emission of hot gases,
and relatively low maintenance.
Developed in the 1950s and onward,
SF6 circuit breakers are widely used in
electrical grids at transmission
voltages up to 800 kV, as generator
circuit breakers, and in distribution
systems at voltages up to 35 kV.

Georg Simon Ohm
 Born16 March 1789
Erlangen, Brandenburg-Bayreuth in
the Holy Roman Empire
(present-day Germany)
 Died6 July 1854 (aged 65)
Munich, Kingdom of Bavaria in the
German Confederation
(present-day Germany)
 Nationality German Alma mater
 University of Erlangen Known for
Ohm's law
Ohm's phase law
Ohm's acoustic law
 Awards Copley Medal
(1841)Scientific career Fields
Physics (studies of
electricity)Institutions University of
Munich Doctoral advisor Karl
Christian von Langsdorf

A multimeter or a multitester, also known as a VOM (volt-ohm-milliammeter), is an
electronic measuring instrument that combines several measurement functions in one
unit. A typical multimeter can measure voltage, current, and resistance. Analog
multimeters use a microammeter with a moving pointer to display readings.
Study of Multimeter
 Measure AC/DC voltage
 Measure current
 Continuity test
 Measure resistance

MATERIAL REQUIRED
 Multimeter (1000V for AC and 650V for DC) - 1 each
 Torque tester (600A) - 1 no.
TOOLS REQUIRED
 Cutting pliers - 1 no.
 Neon tester - 1 no.
 Screwdriver set - 1 no.
PROCEDURE AND OBSERVATION
Task 1: Measuring AC voltage
 1. Take multimeter /clip-on-meter and set the switch to AC position
 2. Plug the two leads of the meter
 3. Measure the voltage between phase & neutral, phase & earth and neutral & earth.
(if any leakage)

Task 2: Continuity Test
1. Set the multimeter switch to position
2. Plug the leads if the meter to
3. Check for continuity of a wire, bulb, choke etc. It gives beep sound in case of
continuity.
4. Set the meter switch to position
5. Follow step 2
6. Meter shows the resistance of the particular things
Task 3: Measuring current
1. Unplug the leads of the meter
2. Set the switch to position
3. Hook the clips/ jaws of the meter to any live wire
4. Meter shows the flow of current
SAFETY PRECAUTION
1. Set the meter position and range properly.
2. Do not measure beyond the rated voltage, current etc.
3. Hold / touch the leads properly.

 An Analog Multimeter
is a device used to
measure limited
electrical quantities such
as Current, Voltage and
Resistance etc.
 They have meter
movement mechanism, a
calibrated scale and a
pointer. Reading is
obtained by looking at
the position of the
pointer on the scale.

 Digital Multimeter is a
device used to measure
multiple electrical quantities
such as Current, Voltage,
Resistance, Capacitance,
Diode values, Transistors
etc.
 In a digital multimeter, the
meter movement is replaced
by a digital read out. This
read out is similar to that
used in electronic
calculators.

Using a Multimeter safely is an important technical skill.
The following safety precautions should always be followed:
Never use the ohmmeter section on a live circuit.
Never connect the ammeter section in a parallel with voltage source.
Never overload the ammeter or voltmeter sections by attempting to measure
currents or voltages far in excess of the range switch setting.
Check the meter test leads for broken insulation before working with them.
Avoid touching the bare metal clips or tips of the test probes.
To avoid the danger of accidental shock, disconnect the meter test leads
immediately after the test is completed.
Multimeter – Safety precautions

What is Resistor
 Resistor is an electrical component
that reduces the electric current. The
resistor's ability to reduce the
current is called resistance and is
measured in units of ohms (symbol:
Ω). If we make an analogy to water
flow through pipes, the resistor is a
thin pipe that reduces the water flow.
 A resistor is a passive two-terminal
electrical component that
implements electrical resistance as a
circuit element. In electronic
circuits, resistors are used to reduce
current flow, adjust signal levels, to
divide voltages, bias active elements,
and terminate transmission lines,
among other uses

What is Resistance
 Resistance is a measure of
the opposition to current
flow in an electrical circuit.
Resistance is measured in
ohms, symbolized by the
Greek letter omega (Ω).
Ohms are named after Georg
Simon Ohm (1784-1854), a
German physicist who
studied the relationship
between voltage, current and
resistance.
 Tungsten resistance used in
Incandescent lamp
 Nichrome resitance used in
Electrical heater

RESISTANCE RESISTOR
Its heat up It doesn’t heat up
In physically it inform of coil In physically it is inform of
solid cylinder
It has no any colour code on it Basically it has no’s of colour
code printed on it
It can’t used in PCB board due
to it heat up
Relevantly its used in all PCB
borad to reduce current
Resistance is the property of a
conductor, which determines
the quantity of current that
passes through it when a
potential difference is applied
across it.
A resistor is an electric
component with a
predetermined electrical
resistance, like 1 ohm, 10
ohms 100 ohms 10000 ohms
etc
Its used for electrical heating
appliances like lamp, heater
,projector etc
Its used in all electronic circuit
i.e computer, mobile , fan
regulator ,speaker woofer to
increase volume etc

Resistor Colour code Formula
 BB ROY has a Great Britan Very Good Wife
 B -Black -head hair
 B -Brown
 R -Red
 O -Orange
 Y -Yellow
 Great -Green -Indian Flag
 Britan -Blue
 Very -Voilet
 Good -Gray
 Wife -White -feet

Series Circuits
Two elements in a series
Connected at a single point
No other current-carrying
connections at this point
A series circuit is constructed by
connecting various elements in
series

R2
R1
v2
v1
+ +
+
_
_
_
v i1
1 2eqR R R 

Resistors in series
 Analogous formula is true for any number of resistors,
 It follows that the equivalent resistance of a series
combination of resistors is greater than any of the
individual resistors

Resistors in parallel
Since both R1 and R2 are connected to the same battery, potential
differences across R1 and R2 are the same,
I
I2 I1
R2 R1
V
+
_
I
Req
V
+
_
1 2
1 2
eq
R R
R
R R

1 2
1 1 1
eqR R R
  or

Resistors in parallel: notes
 Analogous formula is true for any number of resistors,
 It follows that the equivalent resistance of a parallel
combination of resistors is always less than any of the
individual resistors

Comparison between series and parallel:
Series connection Parallel connection
1. Current flows in single path 1.Current flows in several paths
2. Voltage is divided across each
resistance
v = v1 + v2 + v3
2. Voltage is constant
3. Current is constant 3. Current is divided i =i1+i2+i3
4. Total resistance is equal to the sum
of
individual resistance r = r1+ r2+ r3
4. The reciprocal of the total resistance
is
equal to the reciprocal the sum of
individual
resistance i.e. 1/r = 1/r1 + 1/r2+ 1/ r3
5. Fault finding is difficult 5.Fault finding is easy
6.Used for decoration purpose 6. Used for domestic purpose

Define Ohm’s law
 The current flowing in a conductor is directly
proportional to the applied voltage V and inversely
proportional to its resistance R at temperature being
constant.
• I = V/R
• V = IR
• R = V/I

OHM’S LAW
The Ohm‟s Law was propounded by George Simon Ohm,
which defines the relationship between current (i), power (p),
voltage (v) and resistance (r)
I = v / r - 1 r = v / i - 2 v = i x r - 3
Ohm‟s Law states that, in any closed electrical circuit the current
is directly proportional to
voltage applied and universally proportional to the resistance of the
circuit, temperature and
other physical conditions being constant.

Solving Problems Using Ohm’s Law Triangle
 Example 1: If the resistance of an electric iron is 50Ω and 3.2A
Current flows through the resistance. Find the voltage between
two points.
 Ans. If the value of Resistance is asked and the values of the
current and voltage are given, then to calculate resistance
simply cover the R. Now, we are left with the V at the top and
I to the bottom left or V ÷ I.
Given, Resistance (R) = 50Ω
Current (I) = 3.2A
Therefore,
Voltage (V) = I X R = 3.2A x 50 Ω =160V

 Example 2: An EMF source of 8.0 V is connected to a
purely resistive electrical appliance (a light bulb). An
electric current of 2.0 A flows through it. Consider the
conducting wires to be resistance-free. Calculate the
resistance offered by the electrical appliance.
 Ans. If the value of current is asked and the values of the
resistance and voltage are given, then to calculate current
simply cover the I. We are left with Voltage over Resistance or
V ÷ R. So the equation for Current is Voltage divided by
Resistance.
Given,
Voltage (V) = 8.0 V
Current (I) = 2.0 A
Therefore, Resistance (R) = V ÷ I = V/I
= 8/2=4Ω

History about Gustav Robert
Kirchhoff
 Gustav Robert Kirchhoff, a German physicist, was
born on March 12, 1824, in Konigsberg, Prussia.
His first research topic was on the conduction of
electricity. This research led to Kirchhoff
formulating the Laws of Closed Electric Circuits in
1845. These laws were eventually named after
Kirchhoff and are now known as Kirchhoff’s
Voltage and Current Laws. Since these laws apply
to all electric circuits, understanding their
fundamentals is paramount in the understanding of
how an electronic circuit functions. Although these
laws have immortalised Kirchhoff in the field of
Electrical Engineering, he has additional
discoveries. He was the first person to verify hat an
electrical impulse travelled at the speed of light.
Furthermore, Kirchhoff made a major contribution
to the study of spectroscopy and he advanced the
research into blackbody radiation.
Gustav Robert Kirchhoff

There are two types of Kirchhoff's laws , they are:
 1.Kirchhoff’s first law or Current Law
 2.Kirchhoff’s second law or voltage Law

Kirchhoff’s Current Law
 In any electrical network the algebraic sum of currents
meeting at a junction is always zero. I = 0
The currents directed towards the junction are taken as positive
while those directed towards away from the junction are taken
as negative
I1 + I2 – I3 – I4 – I5 = 0
I1 + I2 = I3 + I4 + I5
From above expression we can say that the sum of current
flowing towards the junction is equal to the sum of currents leaving
the junction.

Kirchhoff’s voltage Law
The algebraic sum of all the potential drops around a closed loop is
equal to the sum of the voltage sources of that loop.
Equation can be given by
V source = V1 + V2 + V3 = I1R1 + I2 R2 + I3 R3
V = IR
i.e. Kirchhoff’s voltage law can be applied only to closed loop. A
closed loop must meet two conditions.
1. It must have one or more voltage sources.
2. It must have a complete path for current flow from any point, around the
loop and back to that point.

Magnetic Induction
• Electromagnetic induction is the production of
an electromotive force across a conductor when it is exposed to
a varying magnetic field.
• It is described mathematically by Faraday's law of induction,
named after Michael Faraday who is generally credited with
the discovery of induction in 1831.
• Electromagnetic induction was discovered independently
by Michael Faraday in 1831 and Joseph Henry in 1832.

FIRST LAW : Whenever there is a change in the magnetic flux linked
with a circuit an e.m.f and consequently a current is induced in the
circuit. However, it lasts only so long as the magnetic flux is changing.
(or)
Whenever a conductor cuts magnetic flux, an e.m.f is induced in that
conductor.
SECOND LAW: It states that the magnitude of the induced e.m.f is
equal to the rate of change of flux linkage.
FARADAY’S LAWS OF ELECTRO-
MAGNETIC INDUCTION

State Lenz’s Law
 Lenz’s law states that the direction
of the current induced in a
conductor by a changing magnetic
field is such that the magnetic field
created by the induced current
opposes the initial changing
magnetic field which produced it.
 Lenz’s Law is named after the
German scientist H. F. E. Lenz in
1834. Lenz’s law obeys Newton’s
third law of motion (i.e to every
action there is always an equal and
opposite reaction) and the
conservation of energy (i.e energy
may neither be created nor
destroyed and therefore the sum of
all the energies in the system is a
constant).

Lenz’s law
The direction of the current is found by using this law which
was formulated by Lenz in 1835.
This law states that electro-magnetically induced
current always flows in such direction that the action of the
magnetic field set up by it tends to oppose the very cause
which produces it.

 A relay is an electrical switch that opens and closes
under control of another electrical circuit.
 So relay is a switch which controls (open and close)
circuits electromechanically. The main operation of this
device is to make or break contact with the help of a signal
without any human involvement in order to switch it ON
or OFF. It is mainly used to control a high powered circuit
using a low power signal.
Relay

•Generally relay is having following terminals and contacts.
• Input Coil: Operating voltage for relay is feeded to it.
• Normally closed (NC) Contact: It disconnect the circuit
when the relay is activated.
• Normally Open Contact (NO): It connects the circuit
when the relay is activated.
• Pole: It is the common terminal between NC and NO.

Types of Relay
 EFR Relay [ Earth fault relay ]
 OCR Relay [ Over current Relay ]
 OLR Relay [ Over load Relay ]

TRANSFORMER
Principle, Types, Parts, Cooling
Methods, Maintenance

Introduction
 Now a days AC system, Specially 3 phase (poly phase)
system is most commonly adopted for generation,
transmission and distribution, because it is economical
and efficient. In India all generating stations and
alternators are practically producing 11 KV/ 21 KV.
Using the AC system, such power can be stepped up,
transmitted and distributed to reach the consumers‟ point,
keeping low cost and reduced size of conductor in
mind. A transformer is a device which conveys power
from the generating station to the consumers‟ point.

Define Transformer
 The transformer may be defined as a static piece of
electrical apparatus which converts electrical power
from one circuit to another at the same frequency
while changing the corresponding values of current and
voltage.
OR
 Transformer is a static device which transfer the voltage
from one circuit to another circuit but without changing
the frequency is called Transformer

Working Principle
 The transformer works on the principle of Mutual
Induction.
OR
 Transformer works on the principal of Farday’s law of
electromagnetic induction

Classification of Transformers
1. According to the magnetic core
 a. Core type
 b. Shell type
 c. Berry type
2. According to the voltage
 a. Step up transformers
 b. Step down transformers
3. According to the phases / winding
 a. Single phase transformer
 b. Three phase transformer
4. According to the power / usage
 a. Lighting / distribution transformer
 b. Power transformer

 5. According to cooling
a. Self cooled
b. Air force cooled
c. Oil self cooled
d. Forcibly oil cooled
 6. According to the location
a. Indoor transformer
b. Outdoor transformer
7. According to the output:
a. Auto transformer
b. Instrument transformer

Protection devices
a. Conservator
b. Breather
c. Temp Gauge
d. Explosion vent
e. Pipes etc.

For an Ideal transformer the voltage ratio is equal to the turns ratio
and power in equals to the power out. It means
V2/ V1=N2/ N1=I1/I2
Where,
V2 = Secondary voltage
V1 = Primary voltage
N2 = No. of turns in secondary coil
N1 = No. of turns in primary coil
I2 = Secondary Current
I1 = Primary Current

Basic Parts of a Transformer
 These are the basic components of a transformer.
 Laminated core
 Windings
 Insulating materials
 Transformer oil
 Tap changer
 Oil Conservator
 Breather
 Cooling tubes
 Buchholz Relay
 Explosion vent

Function of Silica Gel Breather
Most of the power generation companies use silica gel breathers
fitted to the conservator of oil filled transformers. The purpose of
these silica gel breathers is to absorb the moisture in the air
sucked in by the transformer during the breathing process.
What is Transformer Breathing?
When load on transformer increases or when the transformer
under full load, the insulating oil of the transformer gets heated
up, expands and gets expel out in to the conservator tank present
at the top of the power transformer and subsequently pushes the
dry air out of the conservator tank through the silica gel breather.
This process is called breathing out of the transformer.
When the oil cools down, air from the atmosphere is drawn in to
the transformer. This is called breathing in of the transformer.

Use of Silica gel breather

During the breathing process, the incoming
air may consist of moisture and dirt which
should be removed in order to prevent any
damage. Hence the air is made to pass
through the silica gel breather, which will
absorb the moisture in the air and ensures
that only dry air enters in to the
transformer. Silica gel in the breather will
be blue when installed and they turn to pink
colour when they absorb moisture which
indicates the crystals should be replaced.
These breathers also have an oil cup fitted
with, so that the dust particles get settled in
the cup.
Thus Silica gel breathers provide an
economic and efficient means of
controlling the level of moisture entering
the conservator tank during the breathing
process.

OLTC
 OLTC stands for On Load Tap Changer, which
is a device used for selecting different taps to
make fine adjustments in the output voltage,
without disconnecting the load. It is oil trip
circuit breaker. which will cut-off the
Transformer when the oil in the transformer
is degenerated due to continuous heating.

RTCC
 REMOTE TAP CHANGER CONTROL PANEL RTCC is
“Remote Tap Changer Control “which is a Programmable
device to control the output of the transformer through
OLTC unit fitted in the transformer through control cables

Electrical basic engineering by Ramesh meti karanataka

Electrical basic engineering by Ramesh meti karanataka

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Similar to Electrical basic engineering by Ramesh meti karanataka

Similar to Electrical basic engineering by Ramesh meti karanataka (20)

More from Ramesh Meti

More from Ramesh Meti (20)

Recently uploaded

Recently uploaded (20)

Electrical basic engineering by Ramesh meti karanataka