Wires and Cables, Series and Parallel circuits,ohm's law,circuits

1. Basics of Electrical Engineering
By
Ms. Nishkam Dhiman
Assistant Professor -EEE Deptt.
Chitkara Institute of Engg. & Technology

2. Wires and Cables
Wires & Cables are purpose built conductors.
The size & type of wire/cable must suit the power rating required
for their use. The higher the power the thicker the wire/cable.
Uses of Wires
Domestic & small industry
Wiring in appliances
Uses of Cable
Small & big industries
Distribution Lines
Transmission lines

3. Wires
Various types of wires.
1.VIR wire:
 It is called vulcanized insulation rubber wire. Copper &
aluminum conductor and rubber coating are used in it.
Now single & double braided wires are mostly in a use.
But it has lower tensile strength, chemical reaction & bad
insulation so it is not used.
 suitable for: low & medium voltage supply only
 old type: not readily available to purchase

4. 2. CTS & TRS wire:
It is called crab tyre sheath wire & tuff rubber sheath wire.
Hard & good rubber coating on copper wire is used in this
wire. Its used in house wiring & industrial wiring.
Available in 250/440V only

5. 3. Weather proof wire:
No weather reaction , in this types of wire. Because it
has cotton breeding with water proof. But it is flammable so
no in use now.
4. LC wire:
It is called lead covered wire. Lead pipe on rubber
insulation & its coating on conductor. It is very good in
moisture condition but less tensile strength so low uses now.
5. MICC wire :
It is called mineral insulated copper covered wire. In this
type wire copper conductor coated is with magnesium oxide.
And After copper coating is coated on it. In case of
moisture weather PVC coating (serving) is coated on its. It
is uses in mines, factory, furnace, boiler, rolling mills etc.
magnesium oxide is used for avoiding moisture problems.

6. 6. PVC wire:
It is called poly vinyl chloride wire. PVC coating on copper
conductor so its so many advantages as follows.
(a) High dielectric strength
(b) High tensile strength
(c) More defense against moisture
(d) High life
(e) No disturb in vibration
Available in 600, 660, 1100 Voltage, Widely used Long life
Durable against water, heat, oil, UV light

7. Three Core Wire
This is three core wire. It is pvc insulated wire.
Its used for 1-phase.
1.Blue wire for Neutral
(Returns current to power source)
2. Brown for live wire
(Provides current to appliance)
3. Yellow wire for earth
(Takes current to ground if appliance has fault)
There is color code used for wiring
&supply.

8. CABLE STRUCTURE
There is cable wire. Its
Use for power transmit ion.
1- core
2- pvc insulation
3- oil duct
4- metallic screen
5- rubber insulation

9. General construction & main parts of
cable
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Core
Insulation
Metallic sheath
Bedding
Armouring
Metallic Sheath: A power cable is an assembly of two or
more electrical conductors, usually held together with an overall sheath.
The assembly is used for transmission of electrical power.
Armouring: Armoured cable is the name given to any electrical cable
constructed with a layer of aluminium wire armour or steel wire armour.
The armour sits below the sheath of the cable to provide protection for the
conductor and insulating layers.
Bedding: Cable bedding compounds are mainly used in multiconductor cables, filling the spaces between conductors and
making the cable round.

10. Classification of Cables
Type of insulation
1. Cotton covered
2. Silk coated
3. Asbestos covered
4. Rubber coated
5. PVC coated
Type of conducting material
1. Copper
2. Aluminum

11. Shape
1. Flat
2. Round
Mechanical Protection
1. Unarmored
2. Armored
Voltage Rating
1. Low voltage cable.(1000V)
2. High voltage cable.(11KV)
3. Super tension cable.(upto 132kV)
4. Extra high tension.(132kV and more)
5. Ultra high voltage cables(400kV and more)

12. Grading of cables
The voltage gradient is maximum at the surface of the
conductor and minimum at the inner surface of the sheath
(i.e., the stress decreases from conductor surface to sheath).
This causes breakdown in the insulation. For avoiding this
breakdown, it is advisable to have more uniform stress
distribution throughout the dielectric. The process of
achieving uniform distribution in dielectric stress is called
the grading of cables.

13. S.W.G. (standard wire gauge)
Introduction
A Instrument which is use for measure Cross Area (gauge)
of wire
Various uses of wire gauge
• To measure Cross
area of wire
• To measure gauge

15. Cable Termination
 When a cable enters into an accessory its called a termination
or Cable termination is the process of connecting power cables
up to the final equipment or the upstream circuit breaker.
 Thimble or terminals must be used at termination points, where
thimble is the termination point which can be connected to the
source or load.
 These must be as mechanically & electrically strong as the
conductor or device which it is used.

16. Cable Safety
 Weather Proof
 Rust proof
 Free from wear and tear
 Armoured
 Good insulation

17. DIFFERENT TYPES OF JOINTS


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Britannia Joint
Straight Joint
Tee Joint
Western Union Joint
1. Britannia Joint : The Britannia joint is a form of
electrical joint used for bare overhead wires where great
tensile strength is required. The two wires are each
tinned, and then each have a short shoulder bent in
them, and are then bound together with tinned wire before
the whole is soldered.

18. 2. Straight Joint
 The braiding is cut back to a distance of about 6
inches, and a shoulder is neatly formed with a sharp knife.
The rubber insulation is also cut back and neatly tapered
to a conical form about 1 1/2 inch in length. The copper
wires are separated for a length of about 2 inches from the
end, and carefully cleaned with emery cloth. The
remainder of the exposed copper wires are twisted tightly
together, and the central strand is cut out as close as
possible to the point where the strands commence to
separate.

19. 3. T Joint
 When a tee joint is to be made in single wires, about 2
inches of the main cable and 2 inches of the branch
cable are bared, the insulating material being treated
as before described. The wires are cleaned, and about
1 inch of the branch is wound round the main
cable, and soldered to it at the extreme end.

20. 4. Western Union Joints
The wires are crossed positioned to make a long twist or
bend in each wire. One end of the wire is wrapped and then
the other end four or five times around the straight portion
of each wire The ends of the wires are pressed down as close
as possible to the straight portion of the wire.

21. 5. Married Joint
 The married joint is an electrical joint used for
joining multi-strand cables. The wires are
unstranded, then interlaced with the wires of the
other cable, and then married (twisted) together
before finally being soldered.

22. Signs and Symbols
Introduction:
In electrical, so many signs & symbols are used for drawing
electrical circuits also use for short identification.
Different types of sign & symbols used in Electrical Engineering.
1) A.C. = ~
2) D.C. =
3) Power = w
4) Voltage = v
5) Current = I
6) Resistance = R
7) Inductor = L

27. Ohm’s Law
For a fixed metal conductor, the temperature & other conditions
remaining constant the current (I) through it is proportional to the
potential difference (V) between its ends
Equation ,
I=V/R
I=current , V=voltage and R=resistance
Applications of Ohm’s Law
By using Ohm's law, you are able to find the resistance of a
circuit, knowing only the voltage and the current in the circuit.
In any equation, if all the variables (parameters) are known
except one, that unknown can be found.

28. Concept of Electric Circuit
 An electric circuit is formed by interconnecting
components having different electric properties.
 A collection of devices such as resistors and sources in
which terminals are connected together by connecting wires
is called an electric circuit. These wires converge
in nodes, and the devices are called branches of the circuit.
 Components of electric circuit
1. Resistance
2. Voltage or Current Sources
3. Wires

29. Series and Parallel Circuits
 Series circuits
 A series circuit is a circuit in which resistors are arranged in a
chain, so the current has only one path to take. The current is
the same through each resistor. The total resistance of the
circuit is found by simply adding up the resistance values of the
individual resistors:
 equivalent resistance of resistors in series : R = R1 + R2 + R3 +
...

30.  Parallel circuits
 A parallel circuit is a circuit in which the resistors are arranged
with their heads connected together, and their tails connected
together. The current in a parallel circuit breaks up, with some
flowing along each parallel branch and re-combining when the
branches meet again. The voltage across each resistor in
parallel is the same.
 The total resistance of a set of resistors in parallel is found by
adding up the reciprocals of the resistance values, and then
taking the reciprocal of the total:
 equivalent resistance of resistors in parallel: 1 / R = 1 / R1 + 1 /
R2 + 1 / R3 +...

31. Mixed Circuits
 Resistor circuits that combine series and parallel resistors
networks together are generally known as Resistor
Combination or mixed resistor circuits. The method of
calculating the circuits equivalent resistance is the same as that
for any individual series or parallel circuit and hopefully we
now know that resistors in series carry exactly the same current
and that resistors in parallel have exactly the same voltage
across them.