The major challenge in Indian power sector is operating upgrading of the transmission & distribution lines with efficient meteringApplication of smart grid devices for consistently condition monitoring of overhead lines &substation can decides the action of maintenance required and thus condition-based maintenance (CBM) technique can be implemented. To meet ever increase in demand, reduction of value of losses, utilization of huge renewable energy and absence of automation in power Transmission & Distribution, there is need of Preventive Maintenance (PM) & logy(RCM). The financial growth of India also depends on availability of electricity. Indian power sector having characteristics as shortage of generation and high T & D losses up to 30% of total electricity generation with some parts of states of country up to 40%. When losses due to theft are added in the total then average losses increases up to 30%. The economical loss reaches at 1.5% of the national GDP which is increasing. To maintain stability of power system up gradation is essential. Transmission system is operated & regulated as per the Regulations & standards given by Central Electricity Regulatory Commission (CERC), Central Electricity Authority (CEA), State Electricity Regulatory Commissions (SERC). At present Maintenance technology is one of the topics of R & D for various countries.

1. i
A
SEMINAR REPORT
ON
EHVAC TRANSMISSION LINE MAINTENANCE TECHNIQUES IN
INDIAN PERSPECTIVE-A REVIEW
SEMINAR
PRESENTED
BY
Mr. YASHWANT H. CHAUDHARI
(Registration No – 20140203)
B.TechIn Electrical Engineering
ACADEMIC YEAR 2017-2018
Under the Guidance of
Prof. ANISH SALVI
DEPARTMENT OF ELECTRICAL ENGINEERING,
DR. BABASAHEBAMBEDKAR TECHNLOGICAL UNIVERSITY
LONERE, RAIGAD,MAHARASHTRA–402103 (2017-2018)

2. ii
LONERE, RAIGAD, MAHARASHTRA-402103
DEPARTMENT OF ELECTRICAL ENGINEERING
CERTIFICATE
This is to certify that the seminar entitled “EHVAC
TRANSMISSION LINE MAINTENANCE TECHNIQUES IN INDIAN
PERSPECTIVE-A REVIEW” for B.Tech Final Year seminar report being
submitted by Mr.Yashwant H. Chaudhari, Registration No. 20140203in
partial requirement for the awardof degree of Bachelor of Technology in
Electrical Engineering is a record of his own work carried by him under
supervision and guidance of Prof. Anish Salvi as prescribed in the
curriculum of Dr. Babasaheb AmbedkarTechnological University, Lonere
during the academic year 2017-2018.
Dr.K.Vadirajacharya
(Head Dept. of Electrical Engineering)
Examiners:
1]
2]
Date:
Place: University Campus, Vidyavihar, Lonere, Raigad-402103

3. iii
ACKNOWLEDGEMENT
As we began to reflect on magnitude of this seminar, we are overwhelmed by the guidance
and support extended by my teacher, friends and others. There is difficulty in assigning the
hierarchy since it has been true effort from the beginning.
We would like to express my sincere gratitude and like to mention that this
work would not have been possible without time to time guidance provided by my facilitator
Prof. ANISH SALVI. We have been greatly benefited by his valuable suggestions, constant
encouragement, moral boosting support & patience throughout his work.
We are thankful to all teaching & non-Teaching staff of department of
electrical engineering of Dr. Babasaheb Ambedkar Technological University, Lonere.
YASHWANT H. CHAUDHARI
(20140203)

4. iv
LIST OF FIGURES
Figures
Fig.1 Cold Line Maintenance
Page No
6
Fig.2 Hot Stick Method 9
Fig.3 Bare Hand Method
Fig.4 Line Maintenance Activity
9
13

5. v
LIST OF ABBREVATIONS
CBM Condition Based Maintenance
PM Preventive Maintenance
RCM Reliability Centred Maintenance Technology
CERCCentral Electricity Regulatory Commission
SERC State Electricity Regulatory Commissions
CEACentral Electricity Authority
RAPDRPRestructured Accelerated Power Development & Reform Program
FACTS Flexible AC Transmission System
WAM Wide Area Monitoring
OCM Online Condition Monitoring
SG Smart Grid
HSM Hot Stick Method
BHM Bare Hand Method
RCM Reliability Centered Method

6. vi
CONTENTS
SR.NO. TOPICS PG. NO.
Acknowledgement iii
List of Figures iv
List of Abbreviation v
1 Introduction 1
2 Overview of the Indian power scenario
2.1 Issues and challenges in Indian power S.
2.2 Reasons of grid collapse in India
2.3 Future outlook for charging Indian P.S.
2
2
3
4
3 Overview of EHVAC transmission lines
maintenance in India.
3.1 Methods of transmission line maintenance
3.1.1 Predictive maintenance
3.1.2 Preventive maintenance
3.1.2.1 Cold line maintenance
3.1.2.2 Live line maintenance
5
5
5
5
5
6
4 Methods of live line maintenance
4.1 Hot stick method
4.2 Bare hand method
4.3 Combination of HSM and BHM
8
8
9
10
5 Overview of The Maintenance Technology 11
6 Advantages of Maintenance Technology 15
7 Conclusion 16
8 References 17

7. 1
1. INTRODUCTION
The major challenge in Indian power sector is operating upgrading of the transmission &
distribution lines with efficient meteringApplication of smart grid devices for consistently
condition monitoring of overhead lines &substation can decides the action of maintenance
required and thus condition-based maintenance (CBM) technique can be implemented. To
meet ever increase in demand, reduction of value of losses, utilization of huge renewable
energy and absence of automation in power Transmission & Distribution, there is need of
Preventive Maintenance (PM) & logy(RCM).
The financial growth of India also depends on availability of electricity. Indian power sector
having characteristics as shortage of generation and high T & D losses up to 30% of total
electricity generation with some parts of states of country up to 40%. When losses due to
theft are added in the total then average losses increases up to 30%. The economical loss
reaches at 1.5% of the national GDP which is increasing. To maintain stability of power
system up gradation is essential. Transmission system is operated & regulated as per the
Regulations & standards given by Central Electricity Regulatory Commission (CERC),
Central Electricity Authority (CEA), State Electricity Regulatory Commissions (SERC). At
present Maintenance technology is one of the topics of R & D for various countries.

8. 2
2.OVERVIEW OF THE INDIAN POWER SCENARIO
Vision statement of the Ministry of Power as per the RFD document follows: “Whenever
required, sufficientand quality standard power for everyone at cheapest cost”. Power System
Operation Corporation Limited(POSOCO) operating the National and Regional grid from
National Load Dispatch Centre (NLDC) with its Regional State Load Dispatch Centre
(RLDC) via state situated load dispatch & communication facilities to improve the
applicability of Green Energy in India, combination of conventional energy sources with
Renewable Energy is in priority. National Load Dispatch Centre (NDLC) of POSOCO is the
Central agency for Green Certificates (Renewable Energy Certificates or RECs) and
regulation for trading is provided by CERC. Present Power Scenario in India having all India
Installed Capacity 304760.75 MW. All the State-of-the-Art Load Dispatch Centre in the
country having SCADA/ EMS have been established by POWERGRID with 1,28200kms of
circuit of transmission lines of 765kV with 25,647Ckms. 400kV lines of 1,50,021Ckms,
220kV lines of 1,58,688 & EHVAC of 132kV & HVDC of + 500kV with 206 sub-stations.
As on 29th
February 2016, the transformation capacity is about 2,49,578 MVA. RAPDRP
(Restructured Accelerated Power Development & Reform Program) programs conducted for
power distribution companies in the country for organizing baseline data for various projects
covering Metering of all DT (Distribution Transformer) and substation Feeders, GIS
Mapping, Consumer Indexing. It covers automated data logging for all DTs and Feeders. It
also consists of SCADA (Supervisory Control and data Acquisition), DMS (Distribution
Management System) for energy management by auditing and accounting with software
dependent service center of consumer.
2.1 Issues & Challenges in Indian Power System
a) Limitation of HVAC transmission systems are:
1) Power Loss – Reactive 2) Stability limit 3) capacity of carrying current 4) Ferranti
effect 5) Difficult to control power flow.

9. 3
b) Methods to Minimize Issues & Challenges:
To maintaining the grid stable, secure and reliable under different operating condition
by on line monitoring, establishment of supervisory control & data acquisition system
(SCADA). To obtain ROW, largest transmission circuit network (MW per meter ROW)
by increasing of voltage magnitude, current magnitude or both i.e. increase in voltage
and current magnitudes are required to be developed.
2.2Reasons of Grid Collapse in India
On July 30, 2012, at 2:35 AM Indian Standard Time (IST)&31st July 2012 at 1:00 PM,
the Grid collapsed various factors.
• System weak due to multiple outages.
• Over drawl of Northern Grids.
• Unavailability of Power islands to isolate essential services and regions from the effect.
• Unavailability inter regional – connecting links and Backfiring of protection system.
• During the planned outage of part of the line; the other half part tripped, at the same
time demand from northern states increases due to the failure of southwest and surplus
in the western region from the NEW grid.
• Thus, Outage of this line caused cascade tripping of other links, interrupting the
complete AC link and separating the entire Northern region from the North-East-West
grid.
• Inadequate coordination in planning, operation & maintenance.
As per recommendations of committees Smart Grids with Line Maintenance makes the
grid operation smarter and intelligent. In India as per maintenance strategy modification in
line equipment’s started. Maintenance Methods & tools meeting general safety regulations.
Design of tools are started as per IS, factor of safety requirement with specific quality.

10. 4
2.3Future Outlook for Changing Indian Power Sector
As per energy experts future work would be on line monitoring data, intelligent
maintenance using expert systems, reliability analysis and accurate evaluation system. There
is need in development of high voltage intelligent equipment’s and their residual life
estimation and life cycle management system.
a) Renovation and Modernization of Generation Sector.
• Development of National Grid.
• Strengthened role of Renewable in the sector.
• Implementation of modern techniques for electric power conservation (DSM).
• Introducing Cogeneration Systems.

11. 5
3. OVERVIEW OF EHVAC TRANSMISSION
LINESMAINTENANCE IN INDIA
To maintain continuity of electricity and stable supply for consumer’s higher availability
of transmission system is required. Main reasons for failure of 30% overhead distribution
lines are due to failing of electrical equipment, e.g. cutouts, insulators, conductors, lightning
arresters, earthing etc. Before taking outages, equipment failure can be identified & plan for
replacement of same. Changing of failure equipment reduces reliability index. Preventive
maintenance provides Cold Line Maintenance and live line Maintenance techniques gives
best results.
3.1Methods of Transmission Line Maintenance
3.1.1 Predictive Maintenance
• Thermo graphic test is important maintenance programs in condition monitoring of
hardware elements in substations and transmission lines.
• PID Testing for insulators in substations and overhead lines.
3.1.2 Preventive Maintenance
3.1.2.1 Cold Line maintenance:
Cold Line Maintenance Method is the method of maintenance in which supply is completely
switched off (de energized the line during the maintenance work) on which maintenance has
to carried out. Planned outage is carried out by disconnection of supply to avoid any accident
or risk involved due work under high voltages. Cold Line Maintenance can perform
following Operations of EHV lines.
• Line Survey, Thermography, Attending hotspot.
• Punctured Insulator Detection (PID).
• Insulator Replacement & Insulator Washing.
• Testing – Contact Resistance Measurement.
• Re conducting, Mid span joint replacement.

12. 6
• Replacement of Insulator, hardware’s and conductor accessories.
• Jumper strengthening & replacement.
• Tower Extension, Raising height of tower.
• Earth wire replacement.
• Erection of ERS (Emergency Restoration System).

Fig. 1. Joining of clamp to insulator string of 220 KV Suspension.
3.1.2.2 Live line Maintenance
Live line is the technique of maintenance of transmission lines, conductors, line insulators,
substation equipment’s, structural, parts etc. operating at high voltages while the Line or
equipment’s are energized.
Supply utilities trying to maintain continuity of supply otherwise they face customer’s
complaints and penalized. To maintain the continuity of supply there is need to inspect,
rectify & replacement of defective parts to avoid costly forced outages. Advanced tools and
technologies developed are taken into consideration. Most of maintenance works can be
made with energizing the line. Advanced techniques developed like anchor replacement,
monitoring systems mounting, line arresters mounting, ground wire replacement etc. This
shows most of the maintenance work can be done on OHL's maintenance projects. Quality of
supply indicated by duration of continuity of supply and frequency. Switching cycles of
switchgears can be reduced by live working and it helps to reduce the incident risks
considering the age of equipment.

13. 7
Proper development of Hot Line maintenance techniques offers following benefits:
• The stability of the grid is increases, Reduces Probability of permanent circuit
interruptions
• Avoid accidents, increasing safety at work.
• Live line Saves Line breakdown, eliminating interruptions to the supply, compensate
the initial investment.
• Avoid revenue loss, breakdown cost & maintenance cost. This is cheaper from social &
economical point.
• Requires less manpower compared to manpower for breakdown maintenance.
Works done by live line LW technique:

• Repair of conductor of overhead line or bus bars.
• Repair of overhead earthling wire, while circuit is live.
• Inspection, repairs & replacements of Insulators with circuit live.
• Hot line washing of insulators.
• Aerial numbering plates installation or replacement
• Vibration dampers replacement on live conductor and on ground wire.
• Suspension clamps replacement or installation with or without armor-rod.
• Changing of broken Pin-cap insulators.
• Changing of composite insulators with.PS 11 insulator chains.
• Changing of insulator string straps on the cross arm and arching devices.
• Work on the tower foundation.

14. 8
4. METHODS OF LIVE LINE MAINTENANCE
4.1 Hot Stick Method (HSM)
In this method the lineman will be at ground potential, working with Hot Sticks (tools)
keeping safe clearance from the line.
TABLE 1. OSHA STANDARDS FOR SAFE WORKING
Voltage range phase to
Safe working distance for hot line
operations as per OSHA standards
phase in kv
Meters Feet
46.1 to 72.5 0.91 3’
72.6 to 121 1.02 3’4”
138 to 145 1.07 3’6”
161 to 169 1.12 3’8”
230 to 242 1.52 5’
345 to 362 2.13 7’
500 to 552 3.35 11’
700 to 765 4.57 15’

15. 9
Fig. 2. Changing of insulators on 220 KV Suspension String
4.2 Bare Hand Method (BHM):
Here the lineman will be working at line potential keeping safe clearance from ground. For
this conductive suits made of 25% microscopic stainless steel and 75% nomex will be
provided. In 1937, Michel Faraday proved that electricity between two points at the same
potential is same. If a Lineman can be shielded in a Faraday Cage, and the cage is bonded to
an energized conductor, he may work on the conductor and associated hardware without
shock or discomfort.
Fig. 3. Bare Hand Method

16. 10
4.3 Combination of Hot Stick & Bare Hand Method:
Generally a combination of above two methods is used in practice as HSM & BHM are
complimentary and supplementary to each other. To reach on tower structures and live
conductors, insulated ladders and insulated aerial platforms are used along with helicopters.
As per maintenance requirements, available local conditions, tools resources advance
techniques have been design and developed.

17. 11
5. OVERVIEW OF THE MAINTENANCE STRATEGY IN THE
WORLD
Live Line maintenance practice started in Hungarian transmission network since '60s and it
becomes regular practice in practical application. An advantage of this technique is
continuity of supply to consumers during maintenance. After economic analysis of live
work technique it shows that live work method helps to improves weak points of systems.
Live Maintenance technique gives the better result analysis, overall financial benefits after
comparing with cold line maintenance technique thus this Maintenance technique provides
cost benefits and gives scope to develop in the live technology for improvement.
In Parana state, Curitiba city of Brazil, during 1982 to 1997, 1152 CKT km of TL were
changed to upper grade (17.8% of increased transmission system). Out of this 8353 km of
TL were changed to higher grade from 69 kV to 138 kV and 3167 km from 88 kV to 138
kV. In the period from 1982 to 1997, Services performed using Stick Techniques up to new
voltage level of 138 kV & Bare Hand Techniques. In live technique risk in working is
insulation failure causes electrical flashover. Failure of equipment and tools due to
mechanical failure is at higher risk by experience & risk assessment. Mechanical failure of
equipment’s & tools causes damage to equipment & dangerous to working staff this leads to
electrical short circuit. International norms for live Maintenance practices and standard
procedure followed as per IEC, IEEE and work by EPRI and CIGRE.
Utility company of State CEEE-GT of Southern Brazil written manual and detailed analysis
of the fault occurrences in past, to improve the maintenance strategy for the company and
which may be useful to similar other companies. Two methods are given in maintenance,
predictive maintenance first method shows various types of defects as per risk involved to
functionality of system to provide standard guideline for maintenance procedure. Second
method gives the report of detail monitoring and inspection done as per past fault
occurrences in transmission system. Condition of porcelain type insulators can view by its
stress & age. To find the applicability of insulators for replacement or to be continuing in
work depends upon aged line conditions, various tests on insulators and procedures.
Procedure of distribution maintenance on the basis of asset management strategy can be
used.

18. 12
To analyze the given maintenance planning in compare with given utility planning can be
made by procedure analysis by collecting five years past data of nine feeders.
For case study of failure rate modeling main parameters is time since preventive
maintenance done, length of feeder, age, load and wind speed. Analysis of various
parameters made like type of insulator, total failure units, failure unit location of broken
units & tools present. Expert from various areas like maintenance, structure design,
laboratory, conductor designing, safety. To view the result of test from planning stage,
various team experts of conductor design, structural design, laboratories, safety and
maintenance involved in this project.
Reliability of system is calculated by data monitoring; benefit of each line due to
maintenance is evaluated & ranking order is established by benefit/cost ratio index. Given
methodology gives the best improvement in reliability at minimum cost of maintenance and
in budget. In southwest China, studies were made on a transmission system of 182-bus,
5474-MW. RTE started Live Maintenance Work (LW) in Power link substations in year
2001.For every Task and environment specific analysis is used with regard to risk analysis.
Live Work maintenance with safety depends upon suitable equipment’s, tools and using
both, meeting safety regulations with conditions for Live Working (LW). Overall
development of Live Wire maintenance started in Thailand at EGAT lineman school various
training program and developed like live working activity, different types of Live Wire
technique. Summary of actual Live Wire maintenance activity and future plan of new LW
maintenance for EGAT shall be available. Live working (LW) Policy aims various activities
to reduce outages of strategic circuits for improve network performance. It has various
objectives like to develop and maintain professionalism of employees, promote innovative
techniques. Managers are pretended to improve operating services and math technique
known as balanced benchmarking with sophisticated mechanism by which Live Line work
done with different team with various resources and practices (insulated equipment, live line
tools, man-hour, total time) with aims to complete job which shows large difference
between team's performance leverage and the bad performers for making decision simply
and more quantitative.

19. 13
Fig. 4. Line Maintenance Activity
Technical Report (TR) gives procedures and solutions adopted for live line work with
a transmission line (TL) with Hot Stick and Bare Hand method to increase voltage level 138
kV. In upgrade process important problem solved are increasing of minimum distances
between conductors and ground also at theStructure minimum distances between ground and
conductors
Balancing of technical and economic factor is the advantage of Live Line Maintenance.
Other advantages of this method are no disturbance to consumer, no outage to any service
required, hence fewer losses in the system. Hence live-
Line Maintenance at HV, EHV &UHV lines becoming more popular. Various maintenance
techniques can be applied to low voltage, middle voltage and high voltage lines. For Extra
High Voltage levels "Bare Hand Technique" is used everywhere.
Main working principle of BHT is metal surface enclosed around the worker acts as faraday
cage. 80% activity of Live Substation team depends on Live Work. Routine activity of Live
Substation work includes cleaning of clamps, disconnect or tightening of clamps, various
maintenance using bridging; finding out of Hot spots and removal of Hot spot; remedies of
power outages; Live Work maintenance reduces accidents. For improving safety of
personnel’s, work organization should adapt training of personnel and proper tools with
several factors efficiently. Operations of Live Substation Team as per Technical Sheets
involved operation of connection and disconnection to various plant: connector and
disconnections, voltage transformers, Circuit breakers, bus-bar sections (bolted or
crimped);surge diverters, improve operation of equipment, e.g. disconnect or finger contacts
or pivot points; Change or disconnect connections, posts and arms bus insulators. Live Work

20. 14
rules are adapted for complete maintenance of 275 kV switch yard operations, to maintain
continuity of supply to 275 kV buses and feeders. From feedback it has concluded that Live
Work improves the service quality. In summer 2013, Distribution teams of EDP completed
the maintenance work by changing of two poles of a High Voltage isolator facing problem of
overheating on zones of different metal contacts. Thermography inspection of overhead lines
and substations network elements was carried out. During inspection various hot spots were
observed on a High Voltage isolator. Live Line maintenance gives tools that give value to
safety of persons and goods. This method also gives importance to maintenance procedures
and limiting interruptions in power supply. During Live maintenance or electrical
installations or modification this technique maintains continuity of supply while working on
lines, changing or repairing them without disconnection. Thus it reduces down times of line
which increases availability rates thus gives quality standard of service with continuous
improvement.
It is mandatory to identify main aim of maintenance and replacement policies of live line
equipment against potential losses due to failure. To expand recommendations and specific
standards to expand and improve the safety offered in hot line work several points needs to
share with the stakeholders working in transmission and distribution utilities, contractors,
tools manufacturers, normalizing entities, etc.

21. 15
6. ADVANTAGES OF MAINTENANCE TECHNOLOGY
• Maintenance Technology with Smart Grid (SG) technology gives features such as
maintaining stability of the system, increase in transmission capacity, improving
supply quality, improvement in overall performance etc.

• Remodeling the energy scenario of the global market.

• It also improves other performances such as advanced communication, protocol,
advanced management and architecture with fast data exchange.

This technology has a quality to improve performance of other technologies such as Flexible
AC Transmission System (FACTS) and Wide Area Monitoring (WAM) in urban & rural
area.

22. 16
CONCLUSION
This study on review of various methods on Transmission line Maintenance and Line
monitoring deployed in India by the government utilities and many private parties. The
seminar report presents overall maintenance initiatives and implications of maintenance in
various countries in the world.
Efforts made to highlight the present maintenance techniques and advanced development of
maintenance technology based on predictive maintenance & monitoring of line for future
perspective. Paper also shows factors affecting on maintenance techniques with the advanced
development technology, research and development since its inception.

23. 17
REFERENCES
[1]2016 International Conference on Global Trends in Signal Processing, Information
Computing and Communication”EHVAC Transmission Lines Maintenance Techniques in
Indian Perspective - A Review”.978-1-5090-0467-6/16/$31.00 ©2016 IEEE.
[2] M. Fairer, M. Khalil, C. Lauran, G. Leone, S. Toscana, “Outage Data Analysis and
RAMS Evaluation of the Italian Overhead Transmission Lines”, IEEE, June 2016.
[3] Gokturk Poyrazoglu, “Scheduling Maintenance for Reliable Transmission Systems”,
IEEE, pp. 1-5, April 2016.