Reg no: 3878
Muhammad Akbar
Abasyn University
Passion to Design Futures
LAB 08
SUBJECT:
PGTD
SUBMITTED BY:
NAME: Muhammad Akbar
ROLLNO: 3878
DEP: BEEE
SEMESTER: 07
LAB INSTRUCTOR:
Syed Mujtaba Ali Naqvi
SUBMISSION DATE:
07/11/2022
PGTD
Lab: 08
Muhammad Akbar
Reg no: 3878
To study different types of Overhead Line Conductors & one line
diagram
Objective:
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

To study materials of overhead line conductors.
To study comparison of different materials.
To analyze conductor properties.
Theory:
A conductor is one of the most important components of overhead lines. Selecting a
proper type of conductor for overhead lines is as important as selecting economic
conductor size and economic transmission voltage. A good conductor should have the
following
properties:




high electrical conductivity
high tensile strength in order to withstand mechanical stresses
relatively lower cost without compromising much of other properties
lower weight per unit volume
Conductor Materials
Copper was the preferred material for overhead conductors in earlier days, but,
aluminum has replaced copper because of the much lower cost and lighter weight of
the aluminum conductor compared with a copper conductor of the same resistance.
Following are some materials that are considered to be good conductors.
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Copper: Copper has a high conductivity and greater tensile strength. So, copper in
hard drawn stranded form is a great option for overhead lines. Copper has a high
current density which means more current carrying capacity per unit crosssectional area. Therefore, copper conductors have relatively smaller crosssectional area. Also, copper is durable and has high scrap value. However, due to
its higher cost and non-availability, copper is rarely used for overhead power lines.
Aluminum: Aluminum has about 60% of the conductivity of copper; that means, for
the same resistance, the diameter of an aluminum conductor is about 1.26 times
than that of a copper conductor. However, an aluminum conductor has almost half
the weight of an equivalent copper conductor. Also, tensile strength of aluminum is
less than that of copper. Considering combined factors of cost, conductivity, tensile
strength, weight etc., aluminum has an edge over copper. Therefore, aluminum is
being widely used for overhead conductors.
Cadmium-copper: Cadmium-copper alloys contain approximately 98 to 99% of
copper and up to 1.5% of cadmium. Addition of about 1% of cadmium to copper
Lab: 08
Muhammad Akbar

Reg no: 3878
Increases the tensile strength by up to 50% and the conductivity is reduced only by
about 15%. Therefore, cadmium-copper conductors can be useful for exceptionally
long spans. However, due to high cost of cadmium, such conductors may be
uneconomical in many cases.
Other materials: There are many other metals and alloys that conduct electricity.
Silver is more conductive than copper, but due to its high cost, it is not practical in
most of the cases. Galvanized steel may also be used as a conductor. Although
steel has very high tensile strength, steel conductors are not suitable for
transmitting power efficiently due to the poor conductivity and high resistance of
steel. High strength alloys such as phosphor-bronze may also be used sometimes
at extreme conditions.
Types Of Conductors
As it is already mentioned above, aluminum conductors have an edge over copper
conductors considering combined factors of cost, conductivity, tensile strength, weight
etc. Aluminum conductors have completely replaced copper conductors in overhead
power lines because of their lower cost and lower weight. Though an aluminum
conductor has larger diameter than that of a copper conductor of same resistance, this
is actually an advantage when 'Corona' is taken into consideration. Corona reduces
considerably with increase in the conductor diameter. Following are four common types
of overhead conductors used for overhead transmission and distribution to carry
generated
power
from generating
stations to
the
end
users.
Generally, all types of conductors are in stranded form in order to increase the flexibility.
Solid wires, except for very small cross sectional area, are very difficult to handle and,
also, they tend to crystallize at the point of support because of swinging in winds.
1.
2.
3.
4.
AAC : All Aluminum Conductor
AAAC : All Aluminum Alloy Conductor
ACSR : Aluminum Conductor, Steel Reinforced
ACAR : Aluminum Conductor, Alloy Reinforced
AAC : All Aluminium Conductor
This type is sometimes also referred as ASC (Aluminum Stranded Conductor). It is
made up of strands of EC grade or Electrical Conductor grade aluminum. AAC
conductor has conductivity about 61% IACS (International Annealed Copper Standard).
Despite having a good conductivity, because of its relatively poor strength, AAC has
limited use in transmission and rural distribution lines. However, AAC can be seen in
urban areas for distribution where spans are usually short but higher conductivity is
required.
AAAC : All Aluminium Alloy Conductor
These conductors are made from aluminum alloy 6201 which is a high strength
Aluminum-Magnesium-Silicon alloy. This alloy conductor offers good electrical
conductivity (about 52.5% IACS) with better mechanical strength. Because of AAAC's
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Lab: 08
Muhammad Akbar
Reg no: 3878
lighter weight as compared to ACSR of equal strength and current capacity, AAAC may
be used for distribution purposes. However, it is not usually preferred for transmission.
Also, AAAC conductors can be employed in coastal areas because of their excellent
corrosion
resistance.
ACSR : Aluminium Conductor, Steel Reinforced
ACSR consists of a solid or stranded steel core with one or more layers of high purity
aluminum (aluminum 1350) wires wrapped in spiral. The core wires may be zinc coated
(galvanized) steel or aluminum coated (aluminized) steel. Galvanization or aluminization
coatings are thin and are applied to protect the steel from corrosion. The central steel
core provides additional mechanical strength and, hence, sag is significantly less than
all other aluminum conductors. ACSR conductors are available in a wide range of steel
content - from 6% to 40%. ACSR with higher steel content is selected where higher
mechanical strength is required, such as river crossing. ASCR conductors are very
widely used for all transmission and distribution purposes.
Aluminium Conductor, Alloy Reinforced
ACAR conductor is formed by wrapping strands of high purity aluminum (aluminum
1350) on high strength Aluminum-Magnesium-Silicon alloy (6201 aluminum alloy) core.
ACAR has better electrical as well as mechanical properties than equivalent ACSR
conductors. ACAR conductors may be used in overhead transmission as well as
distribution lines.
Bundled Conductors
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Lab: 08
Muhammad Akbar
Reg no: 3878
Transmission at extra high voltages (say above 220 kV) poses some problems such
as significant corona loss and excessive interference with nearby communication
lines when only one conductor per phase is used. This is because, at EHV level, the
electric field gradient at the surface of a single conductor is high enough to ionize the
surrounding air which causes corona loss and interference problems. The electric
field gradient can be reduced significantly by employing two or more conductors per
phase in close proximity. Two or more conductors per phase are connected at
intervals by spacers and are called as bundled conductors. The image at right shows
two conductors in bundled form per phase. Number of conductors in a bundled
conductor is greater for higher voltages.
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Lab: 08
Muhammad Akbar
Reg no: 3878
Questions
Q#_01:
What do you understand about cross sectional area of transmission line?
Ans: If you cut directly and squarely across the width of a wire then you will look at the
end and it looks like a circle. The area of that end is the cross section area, which is Pi x
r^2. A larger cross section area results in lower resistance per foot when the type of wire
is the same.
Q#_02: What are the applications of a Hollow wire?
Ans: The conductor that permits the flow of charges through a
Central channel is referred to as a hollow conductor. In comparison to solid conductors,
hollow conductors have a larger diameter.
Our hollow conductors provide new possibilities to cool down electric motors. The
internal cooling hole on the stator windings enables efficient thermal transfer out from
the core - exactly from the source where the heat is generated.
Q#_03: What is meant by stranded conductor?
Stranded conductors are made of multiple small strands, which group together to make
up a single conductor. It is more flexible than a solid conductor, but less durable.
Q#_04: What are the examples of American homogenous and non homogenous
standard?
In North America bird names are used for the code words while animal names are used
elsewhere. For instance in North America, Grosbeak is a 322.3 mm2 (636 kcmil) ACSR
conductor with 26/7 Aluminum/Steel stranding whereas Egret is the same total
aluminum size (322.3 mm2, 636 kcmil conductor) but with 30/19 Aluminum/Steel
stranding. Although the number of aluminum strands is different between Grosbeak and
Egret, differing sizes of the aluminum strands are used to offset the change in the
number of strands such that the total amount of aluminum remains the same.
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Lab: 08
Muhammad Akbar
Reg no: 3878
Conclusion
In this lab we have studied about the different types of conductors. We have learnt the
study of material of overhead line conductor, comparison of different materials and the
different standards respectively.
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Lab: 08