MAHARASHTRA STATE
BOARD OF TECHNICAL EDUCATION
Government Polytechnic, Vikramgad
MICRO-PROJECT
Academic Year: 2022-23
“Transmission Line General Requirements Including Typical
Overhead Line Structures”
Program: Second Year
Diploma Program Code: SY
Course Title: Electrical
Engineering Course Code: EE4
MAHARASHTRA STATE
BOARD OF TECHNICAL EDUCATION
Certificate
This is to certify that Mr……………….Roll No………... of Third Semester of Diploma in
Electrical Engineering of Institute, Government Polytechnic, Vikramgad-(Code:1547) has
completed the micro-project satisfactorily in subject EPT-22419 for the academic year 2022
– 2023 as prescribed in the curriculum.
Place: Vikramgad Enrollment No:……………………
Date: 30/4/2023 Exam. Seat No:…………………..
Subject Teacher Head of the Department Principal
Group Details
Name of the Seat
Sr. No Enrollment No. Roll No.
group No.
members.
Chirag Vijay 2202 146751
1 Gotarne. 2115470080
Prince Arun
2 Patil 2115470088 2205 14655
Tanmay Suresh
3 2115470099 2210 146761
Samber
Manas Ramakant
4 2115470111 2211 146763
Patil
Surendra Gorakh
5 2215470203 2228 146779
Chand
Vinayak Sitaram
6 2215470204 2229 146778
Chavan
7 Krishna Pandit Patil 2215470205 2230 146777
Ganesh Digamer
8 221570208 2233 146782
Funde
Name of the Guide: Mr. Sandesh Kadu
WEEKLY PROGRESS REPORT MICRO PROJECT
Sign of the faculty. Sign of the student.
SR. NO. WEEK ACTIVITY PERFORMED SIGN OF GUIDE DATE
Discussion and finalization of
1 topic
1 st
2 Preparation and submission of
2nd
Abstract
3 Literature Review
3rd
Collection of Data
4 4th
Collection of Data
5 5th
Discussion and outline of Content
6 6th
Formulation of Content
7 7th
8 Editing and proof Reading of
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Compilation of Report And
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10 Seminar
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11 Viva voce
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Final submission of Micro
12th Project
12
TRANSMISSION LINE
A transmission Line is used by electrical power systems to transfer electricity between any two
distant points. In terms of electrical engineering, the Transmission Line is a set of conductors that is
designed to transfer the power from the generating station to a far-end substation that is located near
the load centers, in the most efficient and secure way.
The transmission line is generally made up of ACSR (aluminum conductor steel reinforced) type
conductors, the steel is used to improve the mechanical strength of the conductor. The majority of
strands in the ACSR conductor are made up of aluminum as it is a good conductor of electricity and
its weight per unit length is less compared to copper.
What is a Transmission Line?
Transmission line are conductors that serve as a path for electrical waves to be transmitted through
them. This essentially establishes a link between the transmitter and the receiver, allowing for signal
transfer. A transmission line allows electrical impulses to be transferred between two conducting
wires separated by a dielectric medium, which is often air.
Classification of Transmission Line
In general, the transmission line will be classified on the basis of the length they have covered, but
in practice, frequency is also a decisive parameter in the classification of the transmission line.
Hence, the product of the length and frequency of a transmission line (lf) as the basis of the
transmission line are classified into 3 types. They are namely:
Short transmission line
Medium transmission line
Long transmission line
Short Transmission Line;
If the product of length (l)and its operating frequency(f)of the transmission line is less than 4000,
then the transmission line is known as a short transmission line. For the operating frequency of 50
Hz, the length of such a line will be less than 80 km.
Medium Transmission Line;
If the product of length (l)and its operating frequency(f)of the transmission line is between 4000 to
10000, then the transmission line is known as a medium transmission line. For the operating
frequency of 50 Hz, the length of the line lies between 80 km to 200 km. 4000≤lf≤10000
Long Transmission Line:
If the product of length (l)and its operating frequency(f)of the transmission line is greater than
10000, then the transmission line is known as a long transmission line. For the operating frequency
of 50 Hz, the length of the line will be greater than 200 km.
Transmission Line General Requirements Including Typical
Overhead Line Structures
Definitions
In this document the following words and expressions will have the followingmeanings:
Item Meaning
AAAC All Aluminum Alloy Conductor
AAC All Aluminum Conductor
AC Aluminum Cladding
ACSR Aluminum Conductor Steel Reinforced
Grazer Visual information system used by Electra Net
GZ Galvanized
kV Kilo-Volt
NER National Electricity Rules
OPGW Optical Ground Wire (earth cable that contains
optical fibers usedfor telecommunications)
PG Parallel Groove
PVC Polyvinyl Chloride
SC Steel Conductor
Purpose
The purpose of this document is to provide a high-level summary of the various components
which make up ElectraNet's Transmission Lines. Primary and secondary functions of transmission
line components are provided for context.
Introduction
The term Transmission Lines broadly refers to overhead transmission lines and underground
cables. The key function of a transmission line is to transfer bulk power between generation sources
and load centers. ElectraNet owns, manages and operates transmission lines at 275kV, 132kV
and 66kV.
Transmission Lines are made up of various components, namely poles. lattice structures, conductors,
cables, insulators, foundations and earthing systems. These components are described in more detail
in this document.
Transmission Lines Components
Transmission Line Structures.
The primary functions of transmission line structures are to provide mechanical support to
conductors. This is achieved by maintaining mechanical integrity without permanent structural
deformation under ultimate load conditions whilst preserving structure geometry to retain operational
electrical clearances under prescribed serviceability and ultimate load conditions.
Secondary functions of transmission line structures are to:
a) Ensure safety of people and the environment.
b) Maintain structure geometry to preserve maintenance-safe approach distances for
serviceability and ultimate load conditions.
c) Provide an electrical path to earth for fault currents.
d) Provide a whole-of-life cost-effective service.
Structure types include free-standing and guyed.
a) Lattice towers / masts.
b) Steel tubular poles.
c) Stobie poles.
d) Concrete poles.
Refer to Appendix C for a diagram of typical overhead transmission line structures.
Typical foundations of transmission line structures are;
a) Bored piers
b) Mass concrete,
e) Driven cast in-situ piles,
d) Soil/rock anchors;
e) Special Foundations (e.g. raft foundations).
Transmission Line Conductors
The primary function of transmission line conductor systems is to transfer electrical power between
designated locations, within prescribed performance, operating and environmental conditions.
Secondary functions of transmission line conductors are to:
a) Maintain electrical safety and minimize adverse effects on the environment; and
b) Provide a whole of life cost-effective service.
Transmission Line Insulators
Transmission line insulation has two primary functions:
a) To insulate energized components from earthed structures at rated operating
voltages and specified switching and lightning impulses, and
b) To support the conductor system up to ultimate mechanical load limits and
transfer the mechanical loads to structure.
Transmission line hardware has four primary functions:
a) To support the Insulator system up to electrical load limits; b) To support the Insulator system up to
ultimate mechanical load limits;
c) To provide effective attachment interface between Conductor and Insulators
to securely transfer loads to the structure; and
d) To provide a whole-of-life cost effective service
Transmission Line Earthing
The primary functional requirement of a transmission line earthing system is to:
a) Provide an electrical path for lightning and fault currents to earth, to ensure safety of
people, assets and the environment;
b) Ensure that faults are cleared within the NER time limits, transmission line components are not
damaged, and the network performance (due to lightning) is within agreed NFR limits; and Provide
an earth (i.e. zero) potential reference to ground under normal circuit conditions for the dissipation of
leakage currents.
Secondary functional requirements of a transmission earthing system for its design
life are to:
a) Maintain electrical safety and minimize adverse effects on the environment;
b) Provide an effective technical solution; and
c) Provide a whole-of-life cost-effective service.
Transmission Line Earthing relates to:
a) Aerial earthing this sub-system includes shield-wire and OPGW and its various supporting
hardware and fittings (strain assembly, suspension assembly, spark-gap insulators, vibration
dampers, joints and marker balls);
b) Ground level earthing this sub-system includes buried earth stakes, earth bounds PVC cable,
copper strap), cable lugs, fasteners and clamps. This earthing sub-system forms a dedicated electrical
connection between the structure and the soil surrounding it. This is in addition to the electrical
connection provided by the embedded structure/ foundation and soil; and
c) Communication hardware-this sub-system includes the interface fiber hardware for OPGW assets.
This includes fiber splice boxes, fiber termination boxes, etc.
Transmission High Voltage Cables
The primary functions of transmission high voltage cables is to transfer electrical power between
designated locations, within prescribed performance, operating and environmental conditions and to
insulate energized components from earthed structures at rated operating voltages and specified
switching and lightning impulses.
Secondary functions of transmission high voltage cables are to:
a) Maintain electrical safety and minimize adverse effects on the environment;
b) Provide electrical insulation; and
e) Provide a whole-of-life cost-effective service.
d) The high voltage cable components are:
e) Cable and accessories including joints, scaling ends, link boxes, partial discharge detection
equipment:
f) Condition Monitoring System/Distributed Temperature Sensor, and
g) Cable trench, joint bays, link box equipment pits, support structures, expansion chambers.
Figure-1 GeneralSystemBoundary
The system boundary is depicted in Figure-1.
Figure-1: Transmission Lines Functional Systems
Figure-2 StructureInsulatorandEarthingSystemBoundary
The structure and insulator systems boundary are defined as the attachment bracket / plate
intrinsically connected to the structure (i.e. welded or bolted connection). See Figure-2.
Figure-2: Structure system boundaries with Insulator Systems
Figure-3: Structure system boundaries with Aerial Earthing Systems
The structure and aerial earthing systems boundary is defined as the attachment bracket
/plate intrinsically connected to the structure. The structure / earthing system boundary
at ground level is the connecting bolt fastening the earth bond lead to the structure.
Figure-3 Structure/FoundationSystemBoundary
The structure and foundation system boundaries are:
a) Free-standing lattice tower: stub connection;
b) Guyed Mast: base-plate and guy assembly attachment to connecting eye
of the buried anchor tie rod;
c) Pole with base-plate and anchor-bolt connection: base-plate; and
d) Embedded pole: pole member contained within footing.
Transmission line support structure sub-elements comprise of:
a) Structural members – includes primary members such as lattice
tower/mast leg andbracing sections, steel tube pole section, Stobie
pole composite material sections (steel / concrete) or reinforced
concrete pole sections;
b) Fasteners – includes plates, bolts, nuts and washers;
c) Stay arrangements – includes stay wires and associated fittings; and
d) Auxiliary members – includes anti climbing device, fall arrest system,
climbing aids and structure ID and danger warning plate signage.
The foundation system is comprised of two sub-elements:
a) Structural footing sub-element that transfer load actions to the
geotechnical foundation sub-element. Components comprise reinforced
concrete footings, steel / concrete or other pile types, rock / soil anchors,
and include structure / footing interface components (lattice tower stubs,
anchor bolts and related plates, nuts and washers); and
b) Geotechnical foundation sub-element consists of the soil/rock medium
(including engineered backfill) that interact with the “structure footing” to
resist load actions.
Transmission lines are used for varied applications:
Power transmission line.
Telephone lines.
Traces on Printed Circuit Boards.
Traces on Multi-Chip Modules.
Traces on Integrated Circuit Packages.
TypicalOverheadStructures
Figure-3: illustrates the typical structures used in overhead line design.
Figure-3: Typical Overhead Line Structures
Conclusion:
Transmission Lines are made up of various components, namely poles, lattice structures,
conductors, cables, insulators, foundations and earthing systems. These components are described in
more detail in this document. The primary functions of transmission line structures are to provide
mechanical support to conductors.
Reference:
https://www.electranet.com.au/wp-content/uploads/2018/06/1-03-FR- 09-Transmission-Line-General-
Requirements-Including-Typical- Overhead-Line-Structures.pdf
https://solarcis.anl.gov/guide/transmission/index.cfm
https://en.wikipedia.org/wiki/Electric_power_transmission
