Hot Line Cleaning Robot Inspection

A
FINAL YEAR SEMINAR REPORT
ON
“HOT LINE CLEANING ROBOT USED IN
TRANSMISSION LINE AND SUBSTATION”
In the partial fulfilment of B. Tech. in Electrical Engineering course
Submitted in fulfilment of B. Tech
BY
MISS SRUSHTEE PRDEEP PATIL
ROLL NO-20140240
ACADEMIC YEAR : 2017-2018
Under The Guidance of
Prof. ANISH SALVI
DEPARTMENT OF ELECTRICAL ENGINEERING DR.
BABASAHEB AMBEDKAR TECHNOLOGICAL UNIVERSITY,
LONERE- 402103, DIST- RAIGAD, MAHARASHTRA. 2016 - 2017

Dr. Babasaheb Ambedkar Technological University, lonere,
Raigad-Maharastra-402103
Department of Electrical Engineering
CERTIFICATE
This is to certify that the seminar report on HOT LINE CLEANING ROBOT
USED IN TRANSMISSION LINE AND SUBSTATION. for B.Tech. Seminar report being
submitted by Miss Srushtee P. Patil Registration No. 20140240 in the partial requireme nt
for the award of the degree of Bachelor of Technology in Electrical Engineering is a record of
the student work carried out by him under supervision and guidance of Prof Anish Salvi, as
prescribed in the syllabus of Dr. Babasaheb Ambedkar Technological University, Lonere
during the academic year 2017-2018.
Dr. K. Vadirajacharya
(Head, Dept. of Electrical Engineering)
(Seminar Guide)
Examiners –
1)
2)
Date: / /2017.
Place: Vidyavihar, Lonere-402103.

Acknowledgement
I am pleased to present this seminar report entitles hot line cleaning robot used in
transmission line and substation.. We would like to express our sincere gratitude and like to
mention that this work would not have been possible without time to time guidance provided
by our facilitator prof. Anish salvi . We have been greatly benefited by his valuable
suggestions, constant encouragement, moral boasting support & patience throughout his
work. He has given his full effort in guiding the team in achieving the goal as well as his
encouragement to maintain our progress in track. From the very onset he has taken a keen
interest in the development of our project and we are very grateful for his time, efforts and
timely suggestions.
We are thankful to all teaching & non-teaching staff of department of electrical engineering
of Dr. Babasaheb Ambedkar Technological University, Lonere for providing us with all the
necessary documents required for reference from time to time.
Date: / /2017. Miss Srushtee P. Patil
Place: Vidyavihar,Lonere-402103 (20140240)

I
Abstract
This report deliberates Maintenance of transmission line by using robot
by application of monitoring transmission line and also for the transmission line
damages detection. Managing maintenance of overhead transmission line is
difficult, hence in order to maintain the same, robotic will play very important
role in electrical system. Which will improves time of maintenance and
predictive maintenance for transmission line. Considering workers safety while
working on overhead line it will have good potential. Now-a-days inspectorsare
carrying inspection of transmission line by survey through aviation method
which is cost to electricity board. On the basis of survey of workers, the robot
will segregates the data and will directly transfers to control room. The robot
continuous run to transmission line in 500kv power line. In this techniques
equipped with voltage sensor used for measuring voltage on transmission line,
current sensor used for measuring current on transmission line. RF module for
communication purpose. Visual Camera are installed in robot to capture the
images and sent to the control area. Simulation is done by Proteus software.

II
List Of Figures
Sr No Title Page No
1 Insulator In Need Of Replacement 3
2 Replacement Of Failed Splice 4
3 Corona On Failing 50kv Porcelain 5
4 Service Personnel Working On Energized Lines 6
5 Helicopter Inspection Of Transmission Line 7
6 Integral Structure Of Hot Line Cleaning Robot 10
7 Overall View Of Expliner And Its Components (Left)
And Robot Overcoming Suspension Clamps
13
8 Sequence Of Motion For ‘Acrobatic Modes.’ 14
9 Portable Control Unit (Right) And Wireless
Communication Diagram Of Expliner Robot (Left)
16
10 Insulators (110kv Duplex) 19
11 Bundle Conductors With Spacer 19
12 Stockbridge Type Vibration Damper 20
13 Transposition 20
14 Difficult Obstacles: A Substation (Left) And Two
Tension Clamps With Creative Cable Loops
21

III
List Of Abbrevations
TSO Transmission System Operator
UAV Unmanned Aerial Vehicle
RF Radio Frequency
LED Light Emmiting Diode
LCD Liquidcrystal Display
PC Printed Circuits
DOF Degree Of Freedom
TXD Data To Be Transmitted Over Coms Line
RXD Data To Be Recovered Over Coms Line
OPGW Optical Ground Wire

Index
Sr no Title Page no
Acknowledge
Abstract I
List Of Figures II
List Of Abbrevations III
1. Introduction 1
2. The Transmission Line Inspection 2
2.1 What Is Transmission Line. 2
2.2 Types Of Transmission Line 2
2.3 Maintenance Of Transmission Line 2
2.4 Inspection 3
3. Existing Transmission Line Inspection Methods 6
3.1 Ground Inspection 6
3.2 Aerial Inspection 7
3.3 Automatic Inspection 8
4. Method Proposed Inspection 9
4.1 The Line Inspection Robot 9
5. Overall Structure Of Inspection Robot. 10
5.1 Under The Ground Inspection: The Master Slave Hot Line Robot. 10
5.2 Under The Automatic Inspection: The Expliner Robot 12
5.3 Mechanical Design 14
5.4 Control System 15
5.5 Inspection Cycle 16
5.6 Application. 21
Conclusion. 22
References. 23

1
1. Introduction
High voltage transmission lines and insulators are expose to outdoor so long that a
impurity layer is formatted at the surface of insulators by the industrial filth and the natural
filth diffusing in the air. However, the impurity layer usually contains the components of salt,
acid, alkaline and so on, so under the condition of humid climates like rains and fogs,the
insulator conductance increases, the insulation performance drops down, the leakage current
increases sharply and the flashover voltage reduces greatly. As aresult, it will easily lead to
the pollution flashover accidents. Therefore, it is necessary to clean the insulator regularly.
The insulators and power transmission line has been usually inspected manually by workers
riding in gondolas that travel suspended from the transmission lines or watching with
telescope in the ground.[1]
In our country, there are some kinds of dry hot-linecleaningequipment’s, such as high
voltage hot-line cleaning rod with portable soft shaft connection and high voltage hotline
automatic cleaning machine with forklift supporting.The former needs someone to hold the
cleaning rod while operating, so the labour intensity is increased and falling accidents easily
happen. In addition, it has the disadvantagesof the low level of applied voltage and low
cleaning height. While, the latter depends on the movement of forklift truck to adjust the
cleaning direction and distance, so theoperation is not convenient and the automation degree
is relatively low. [2]
In order to solve the problems in the latter, the development of Expliner was
presented, a robot running on high voltage live lines arranged in bundles of 1, 2, or 4 wires in
Japan. The robot uses a crank arm hydraulic elevating car as the mobile carrier. This cleaning
robot can not only solve the formers’ problems—the low efficiency of labour operation and
the poor security, but also have the advantages of mobility and easy operation. The inspection
tasks are performed by the robot carrying detection instruments androlling/crawling along the
overhead ground wires. Thus,the coupling dynamic performance between the robotand its
moving path directly impact its motion precision.A mobile robot that can crawl along the
overhead groundwires to perform part of Transmission line inspection tasks.

2
2. The Trasmission Line Inspection
2.1 What Is Transmission Line
Transmission line is the long conductor with special design (bundled) to carry bulk amount of
generated power at very high voltage from one station to another as per variation of
the voltage level.
2.2 Types Of Transmission Lines
In transmission line determination of voltage drop, transmission efficiency, line loss
etc. are important things to design. These values are affected by line parameter R, L and C of
the transmission line. Length wise transmission lines are three types.
1. Short transmission line
• Length is about 50 km
• Voltage level is up to 20 kv
• Capacitance effect is negligible
2. mediun transmission line
• length is about 50 to 150km
• operational voltage level is between 20kv to 100 kv
• capacitance effect is present
3. long transmission line
• length is more than 150km
• voltage is more than 100kv .
2.3 MaintainanceOf Transmission Lines
Transmission lines are everywhere. Over the past hundred years, electricity has become a part
of our daily life and something most of us take for granted. To supply us with electricity,
there is a need for a well-developed power infrastructure. Electric power needs to be
generated, transmitted and distributed. Much of the power infrastructure is now nearing its
end of life. In places, structures originally built in the 1920’s and 1930’s are still in operation.
Power transmission equipment and apparatus is generally counted as having an active service
life of 50 years. The main investments in the current power transmission infrastructure were
made in the 40’s and 60’s, and are thus bound for replacement.

3
The ageing power infrastructure needs both continual maintenance and renewal.
Transmission system operators (TSO) typically spend more time on renewing the
transmission grid than they spend on the maintenance of it . Renewal means that a whole line,
or sections of it, is taken down for raw material reuse and new equipment is installed in its
place. Maintenance is all activities which aim at prolonging the active life and good condition
of equipment.[4]
2.4 Inspection
To perform effective maintenance and renewal of any equipment, there is a need to
know the current status of that equipment. Transmission line infrastructure is no different.
Fig1. Insulators in need of replacement
Transmission line inspection is a multi-faceted problem. What is needed is
information about the status of the Transmission line, so a well-founded decision can be
made to perform maintenance, renewal or to do nothing. Obtaining this information is not a
trivial task. Transmission lines are built in many different ways. There are different voltages
which must comply with different standards. Even a TSO operating in a single country might
have lots of different equipment in use. Between countries and continents, differences are
even greater. To inspect such equipment, the inspector needs to know exactly what the
equipment looks like (or sounds like, or what readings a heat sensor should give, etc.) when it
is in proper condition and when it is running a risk of failure (Figure1).

4
2.4.1 Failing compression splices
Some equipment is notoriously difficult to inspect. An example is a compression
splice running risk of failure. When two lengths of conductor are connected, a compression
splice is used to hold them together. Compression splices sometimes fail,and when they do
they need to be quickly repaired (Figure 2) or the whole line might fail. The resistance over a
compression splice in good condition is lower than that over regular conductor of equal
length. When the compression splice is failing this resistance is increased. The increased
resistance result in heat in the splice, and the status of the splice deteriorates even further in a
downward spiral. The current way to detect this is to either measure the resistance over the
splice or to measure the temperature of the splice. Both are tricky things to do, considering
the splice is on extreme voltage potential, high over ground and more often than not subject
to winds that cool any temperature differences down to the immeasurable.
Figure 2 Replacement of failed splice (full-tension splicing of energized
conductor).
2.4.2 Corona discharges
A corona discharge is “an electrical discharge brought on by the ionization of a fluid
surrounding a conductor, which occurs when the potential gradient exceeds a certain value, in
situations where sparking (also known as arcing) is not favoured”
In the context of Transmission lines, corona formation is considered a very bad
thing as it results in radio interference, ozone formation and equipment fatigue. Corona
discharges are further associated with strange sounds and can even be visible at night time,
resulting in public concern over Transmission line safety. Coronas form especially easy on
protrusions from a conductor, where the electric field (potential gradient) is focused.
Equipment designed for operation on live Transmission lines needs to take this into account.
Two, otherwise functionally identical, parts might cause or not cause corona discharges

5
depending on the shape of extending edges. Smooth and round edges generally cause less
corona issues. Another cause of corona discharge formation is faulty equipment, see Figure 3.
Figure 3. Corona on failing 150 kV porcelain insulator.
Corona inspection has been the target of recent product development. Combining
images fromseveral camera types using advanced algorithms, it is possible to spot corona
discharges in daylight. Cameras capable of this are available for purchase [6]. These cameras
are used by a spotter on a helicopter or airplane.[4]

6
3.Existing Transmission Line Inspection Methods
Existing transmission line inspection can be divided into three separate categories;
ground inspection, air inspection and automatic inspection. Out of these, ground and air
inspection are by far the most common, but automatic inspection is regarded as the method
with the best potential for the future.
3.1 Ground inspection
Ground inspection is the oldest and most intuitive transmission line inspection
method. A crew of service personnel is sent out on the mission to inspect a transmission line.
The personnel carry equipment to aid them in their task, but ultimately rely on their senses to
perform the inspection. If the transmission line is close to roads or passable waterways, these
are used. If no similarly convenient option is available, the service personnel have to traverse
the length of the transmission line on foot.
Primary method of doing this is to visually asses the structures, using binoculars,
cameras, or plain eyesight. Visual assessment is sufficient for most inspection of vegetation,
insulators, towers and cables .Certain transmission line faults, such as corona discharges,
result in characteristic sounds. In these cases the ground crew can listen for the presence or
absence of a fault. An antenna can be used to detect corona discharges, as they cause radio
interference.Infra-red cameras or other sensors capable of remotely sensing temperature are
used to find other faults, such as failing compression splices.
At times, the service personnel performing the ground inspection need to climb
towers or even 10 mount the actual line. Examples of this can be seen in Fig 4.
Figure 4.Service personnel working on energized lines

7
3.2 Aerial inspection
Airborne surveillance is the next logical step after ground inspection. If visual
surveillancesuffices for the inspection needs, then a fly-over will be much more efficient than
traversing the transmission line on foot. Airborne inspection is performed from helicopter or
aircraft.
3.2.1 Airplane inspection
Airplanes have been used to inspect transmission lines for a long time. Pilots fly close
over the line while an inspector, called spotter, sit next to them looking down at the line.
Sometimes more than one spotter is used to look at different features of the equipment.
3.2.2 Helicopter inspection
Helicopter inspection is performed much the same way as airplane inspection, with
one pilot and one or possibly more spotters; see Figure 5. The use of helicopters and airplanes
for inspection differs somewhat, as helicopters are much less fuel efficient and come with a
higher maintenance tag.
Figure 5.Helicopter inspection of transmission line
Helicopters are used when their ability to hover is needed. Typically, this is when
inspecting smaller lines or transmission lines in populated areas. When inspecting long
stretches of high voltage transmission lines, airplanes are preferred [5].
One exception where helicopters are used on high voltage lines is in fault location.
When a fault has brought a transmission line out of service, helicopters are used to locate the
fault. The cause of a fault is often a tree or forestry equipment in contact with the conductor.

8
3.3 Automatic inspection
Automatic inspection of transmission lines is a collection of promising new methods
for inspection. There are many possibilities to automate the inspection process. Current
products focus on one inspection task and solve it by developing a specific product. One can,
for example, order inspection of compression splices by a robotic inspection unit mounted
under a helicopter.
As automatic transmission line inspection is a new and developing business it is hard
to get a good overview of available technology and the quality of offered services. Here a
distinction will be made between fixed and mobile sensor systems.
3.3.1 Fixed sensor systems
A fixed sensor is mounted on the transmission line equipment and remains there
throughout its service life. Data from such a sensor is transmitted by cable or by RF-
communication. The need for power in modern sensor systems can be made so tiny that a
battery is sufficient for years of operation. Other power supply options in use today are solar
cells, and equipment mounted on the conductor itself can through induction gather power
from the varying magnetic field of thelive line [4].A fixed sensor system can answer many
important questions for a TSO, such as how much current flow through a specific point of the
line or the current conductor temperature at the same point.Information provided by fixed
sensor systems can have an impact on the operation of a power line. As an example, a sensor
measuring the sag of a span of a power line gives indirect information about the distance to
ground of that power line. Without measurements, this distance will be assumed to be worst-
case. If a sensor provides actual numbers, a TSO can allow more current through the line.
3.3.2 Mobile sensor systems
In this text a mobile sensor system is broadly defined as any sensor which is not fixed
to a transmission line structure. Examples of mobile sensor systems are UAV carrying
sensors for transmission lineinspection, or line-crawling robots for transmission line use.
The sensors in this category are more experimental in nature than the fixed sensor systems.
Research in this field is ongoing, much of it funded by the power industry. With many
published papers each year by several research groups, the future for transmission line
inspection using mobile sensor systems looks bright and promising.[6]
.

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4.Method Proposed Inspection
This text proposes the line inspection robot as a solution to the transmission line
inspection problem. The line inspection robot is a line-crawling autonomous robot,
constituting a mobile sensor system. The robot will be able to clear transmission towers and
other reasonable obstacles. While traveling along the line it will carry sensors enabling it to
perform most inspection activities performed today, and more. A key concept of the approach
is the gathering of power from the live line, enabling the robot to inspect for long periods of
time without being bothered with energy-supply issues.This section will begin with demands
on the robot, followed by a look at a use scenario of the system.
4.1 The line inspection robot
The robot forming the core of the line inspection robot mobile sensor system must
comply withseveral demands for the system to be useful.
The robot must:
• Travel along the conductor of a high voltage transmission line
• Pass pre-defined obstacles on the transmission line (i.e. all common obstacles)
• Capture enough power for robot’s use, from the magnetic field generated by the
conductor (possibly storing power for intermittent operation)
• Inspect pre-defined features on the transmission line
• Communicate with a base station (or other unit of similar function)
The line inspection robot will be part of a system offering the inspection capability. The
system must, at least, have the ability to:Conveniently raise the robot to, and lower it from,
the line to be inspected Report, and provide some initial analysis of, the results of an
inspection Offer some way of communicating with the operating robot, perhaps offering
some remote-control abilities. The operating conditions close to a live conductor of a high
voltage transmission line are extreme. The line inspection robot may not cause harm to
people or equipment, specifically:
• It must not damage the conductor on which it travels..
• It must not cause damage to insulators.
• It must not cause flashovers between tower and conductor.
• It must not cause flashovers between different phases.
• It must not cause corona discharge.

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5.Overall Structure Of Inspection Robot
5.1 Under the ground techniques- The Master Slave Hot Line Robot-
This presents a master-slave hot-line robot working in high voltage for cleaning
insulators. Compared with existing cleaning robots, this robot mechanism is superior in
insulation as it uses a series of insulation methods, such as the crank arm insulative elevating
mechanism, insulative hydraulic system, master-slave control, optical fibre and ZigBee
communication, to ensure the safety of robot and the operator, and is more useful in
mountainous or salt damage areas by adopting a crawler chassis.
The master-slave hot-line cleaning robot adopts a scheme that uses insulated
elevating mechanism to clean insulators and regards crawler vehicle chassis as mobile carrier
Which is shown in fig 6.
Fig. 6. Integral structure of hot-line cleaning robot
[①operator②masterhand③elevating mechanism
④slave hand⑤rotatingplatform⑥crawlermechanism]
The whole robot contains a mechanical system, a hydraulic system, a control system
and a communication system. The mechanical system consists of a crawler chassis, an
insulated elevating mechanism with rotating platform, a master hand, a slave hand and an
operating tool—rotating brush. The hydraulic system is the power source of the whole system
and mainly comprises an insulated cylinder, an insulated turbine, a hydraulic motor, electro-
hydraulic servo valves and so on. This system not only provides the power for all kinds
of operations, but also has the insulative performance required under the high voltage. The
control system can be divided into three parts— a data acquisition system, a vehicle control
system and an executive mechanism system. These three parts work together to complete the
task of cleaning insulators. The wireless communication module interacts the information

11
between the master control system and the slave control system. In particular, this module
solves many problems, such as electromagnetic compatibility, anti-electromagnetic
interference, high voltage insulation, real time and so on.
The hot-line cleaning robot’s mechanical systems is made up of a crawler chassis, an
insulated elevating mechanism, a master hand, a slave hand and a cleaning tools. The
hydraulic system of hot-line cleaning robot mainly comprises hydraulic actuators—hydraulic
cylinders and hydraulic motors, electro-hydraulic servo valves, hydraulic pipelines, etc.
When the hydraulic system works, it can convert external power into hydraulic energy by the
hydraulic pump. At the same time, the electro-hydraulic servo valves convert weak electrical
signals into hydraulic energy to drive the hydraulic actuators and hydraulic actuators convert
hydraulic energy into mechanical energy to drive slave hand [1].The whole hydraulic system
is made up of two parts—the insulated elevating mechanism and the slave hand Electro-
hydraulic servo valve is a device that converts electrical signal into hydraulic signal.
Hot-line cleaning robot’s control system mainly uses a mode that combines the man-
machine integrated with local intelligence control. In process of the man-machine integrated
operation, operator achieves identification, analysis and decision, while the robot completes
the task of organization, coordination and executive functions. In addition, local intelligence
refers to complete the task independently under the local structure of the unstructured
environment. The task includes the automatic adjust insulator, automatic levelling insulative
elevating platform, safeguard in unexpected condition and so on, which is low efficiency and
difficult for the man machine integrated. The overall control diagram of control system
divided into three parts, data acquisition system, vehicle control system and executive
agencies
A. Data acquisition system
The main function of data acquisition system is collecting data of motion states, including
insulated elevating mechanism, slave hand and master hand.
B. Vehicle control system
The main work of vehicle control system is generating and controlling the trajectory used to
clean insulators. This system is made of master controller and slave controller, and the two
departments transmit information via wireless module.
Vehicle control system has two controllers—master controller and slave controller. They
communicate information with each other by wireless communication module—Zigbee.

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5.2 Under automatic inspection techniques- Expliner Robot-
This describes the development of a mobile robot that can navigate power
transmission lines completely unattended by a human operator. Its ultimate purpose is to
automate the inspection of power transmission line equipment.
5.2.1.Attempts to automate the inspection task-
The automation of inspection of transmission lines has often been hampered by the presence
of spacers and suspension clamps. In order to overcome such obstacles tens of meters above
the ground, any machine would need a high degree of mobility and reliability. However, high
mobility usually implies heavy and complex mechanisms, whereas a machine for inspection
of transmission lines should be easy to transport (compact and light weight), easy to assemble
and reliable. For maintenance of transmission lines up to 33kV,ground-based, insulated and
tele-operated booms are employed, as shown in fig6.. However, for high-voltage lines, the
ground is not always available (in mountains or forests, for example), the lines are too high to
be reached by booms, and insulation may not be feasible for extremely-high voltage lines[9].
5.2.2.Requirments of Automation-
This work is being carried out in conjunction with KansaiElectric Power Corp.
(KEPCO, Japan) and Japan PowerSystems Corp. (JPS). Therefore, many of the requirements
forthe robot presented next apply to the Japanese high-voltagetransmission lines.
Requirements (motion on transmission lines):
• distance between cables: between 400mm and 500mm
• diameter of cables: from φ24mm to φ48mm
• voltage levels: up to 500kV
• portability (high-voltage towers may be located in remote areas, in mountains or inside
forests. All the parts of the robot must be portable and easy to carry)
• mass: within 60kg
• time of operation: at least 8h, continuous
• speed: 20m/min
• maximum inclination of cable: 30 degrees

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5.2 3.Proposal of automation-
1 Basic concept
Transmission lines are unstructured environments, where robots would be exposed to
changes in weather and obstacles in several different configurations. A more robust approach
had to be sought. For this purpose, mobility by controlling the center of mass of the robot was
proposed. This concept had already been employed in different robots based on crawlers for
moving loads on slopes. However, for inspection of transmission lines, the robot would need
at least two supporting points and one counter-weight (Figure7 ). By moving the counter-
weight, it is possible to change the position of the center of mass, and thus lift one of the
supporting points. To keep the stability of the robot when moving on the lines, the center of
mass must be positioned as low as possible ideally under the lower transmission lines of the
bundle of conductor cables. Therefore, the supporting points must be united to the base by
vertical poles. The counter-weight is also connected to the base by a mechanism that changes
its position, as shown in Figure 7.
Fig7.- Overall view of Expliner and is components on left and Robot Overcoming suspension
clamps on right
1. Acrobatic modes-
The process of overcoming suspension clamps was briefly mentioned before. This
sequence of motions, in which the robot is at times supported by only one motion unit, is
called “Acrobatic Mode 1”, and is shown in Figure 8.In order to prevent interruptions in the
transmission of electricity, it may be necessary to assemble the robot on the tower and drive it
to the transmission lines by an access cable. In this case, the robot will have to move on a
single cable by controlling the position of its center of mass (Fig. 8-1). When reaching the
lines, the front motion unit will be lifted (Fig 8-2) and rotated to be aligned to the lines (Fig.

14
8-3). The robot moves forward, and brings the front motion unit down in contact with the
lines by changing its center of mass (Fig. 8-4).Then, the rear motion unit is lifted, rotated, and
the robot moves forward on the transmission lines (Fig. 8-5), supported only by the front
motion unit. Finally, the rear motion unit is aligned to the cables, and it can be brought back
down in contact with the lines (Fig.8-6). The robot is then ready to conduct the inspection of
the transmission lines, having its two motion units mounted on them. The entire sequence is
called “Acrobatic Mode 2”.
Fig.8.- Sequence of motion for “Acrobatic Modes”.
5.3 Mechanical design-
1. Motion units-
The motion unit consists of two shafts, each with two pulleys. A DC motor is
embedded in one of the pulley shafts. The torque is then transmitted to the other pulley shaft
by a timing belt. The inner structure of the motion unit is composed of aluminum plates that
form a cell. The structure is lightweight, has enough structural strength, and is relatively
simple to build. The pulleys are made of aluminum plates bent to the desired shape by
pressing, and coated with conductive rubber. If normal rubber were used, it would function as
a layer of insulation, resulting in the formation or electric arcs between the lines and the
metallic body of the robot. To avoid this problem, the entire robot is kept at the same voltage
of the transmission lines. Each vertical pole is made of an aluminum pipe, connected to the

15
motion unit by a passive revolution joints (P1 or P2 in Fig. 7), and to the base of the robot by
an active revolution joint (M3 or M5 in Fig. 7). The vertical pole can be easily connected or
disconnected to the motion unit by a pin, and to the base by a locking mechanism.
2. Manipulator and counter weight-
The counter-weight must be placed as far as possible from the base of the
manipulator in order to maximize its influence over the position of the center of mass of the
robot. However, this requires the actuators of the manipulator to be powerful and relatively
heavy if compared to the other components of the robot. The manipulator is composed of two
links, with actuators located at its base (“shoulder joint”) and between the two links (“elbow
joint”). The links can be quickly connected or disconnected by means of shafts with
transversal safety pins, employed to lock the links of the manipulator in place. When the
manipulator is fully extended, it has a reach of 2m. In order to move the counter-weight,
located at the tip of the manipulator, the actuator of the “elbow joint” can provide a
maximum continuous torque of 216Nm.The counter-weight is composed of three sealed
boxes, containing respectively the batteries, the electronics associated with sensing and data
acquisition, and the CPU and motor drives. The latter box contains also the antennas and
circuitry for wireless communication with the control unit. The total mass of the counter-
weight is 25kg. The total mass of the robot (counter-weight included) is 84kg.
5.4 Control system
Expliner can be controlled in semi-automatic mode, which means the user is always in
charge of the operation, but does not need to control every single detail. In other words, when
Expliner is performing the Acrobatic modes, the user simply authorizes the execution of the
steps, but does not need to drive the manipulator and vertical poles to the correct,pre-defined
positions. Those positions are stored in the memory of the controller. The following
subsections describe the portable control unit for Expliner and the wireless communication
system.
1. Portable control unit-
The portable control unit was implemented with a tablet notebook, a panel with
switches and joysticks, antennas for wireless communication, batteries and the associated
circuitry, assembled inside a robust and compact case. The entire assembly is dust-proof and
splash-proof, and has been extensively tested in outdoor environments.

16
2. Wireless communication-
The communication system is based on wireless LANTCP/IP protocol. The Wi-Fi
bridge is made between the control box and the robot CPU Box. The access point of the
robot is made by installing a wireless LAN JRL-710AP2station in the CPU Box. The 10/100
Base T port is connected to a normal network hub. From the hub, a LAN line goes to a
Lantronix X Port LAN to serial converter. On the control unit side, another wireless LAN
JRL-710AP2 is utilized for the wireless connection to the robot. The X Port device receives
in input the command from the Joystick of the control box by Serial (TTL level)
communication and copies in output the same input command in LAN TCP/IP
communication. Implementing a reliable, long-distance wireless communication system can
be very tricky due to the restrictions in power usage and the limited angular range of the
antennas. With the system described above, it was possible to establish stable wireless
communication over200m away from the robot, provided the robot is in clear view from the
control unit.
Fig: 9 Portable control unit (right), wireless communication diagram of Expliner
5.5 Inspection cycle
This section describes the intended function of the line inspection robot, step by step,
in a use scenario. This analysis of the intended use of the robot system will hopefully be
useful in specifying exactly what problem the system intends to solve, and to identify the
difficulties which must be overcome in order to realize it.
The vision of the complete line inspection robot system is a system which is available for
TSO use with little or no preparation. When an inspection need arises, the system is quickly
programmed and the robot is transported out to the inspection site and raised to the line where
it right away starts the inspection.[4] This scenario step-by-step:

17
• Robot is in storage
• Mission definition; set parameters for robots operation
• Transportation of robot to inspection site
• Robot is raised to transmission line
• Robot travels on transmission line
o Obstacle detection and clearing
o Inspection
o Status control and possibly some remote control of robot
• Robot is lowered from transmission line
• Robot is transported to storage
• Gathered data is analyzed and reported
• Maintenance of robot
This algorithm places demands on the robot, covered in turn in the following sections.
A] Storage
The robot must be stored in a convenient way. This is also important to facilitate
maintenance, as maintenance is easier if the robot parts are easily accessible during storage.
The way the robot is stored should also make it possible to transport the robot as standard air
cargo. These two demands are contradicting; a compact case is not easily accessible. Two
separate storage solutions might be developed to facilitate each need.
Long term storage and transportation of the robot to inspection sites might cause
harm to then robot. A case for protection, fitting the standard air-cargo dimensions should be
used. Placing and removing the robot from this case should be a rapid process. For
maintenance purposes a cradle is more purposeful. The cradle could support the robot in a
position where all parts are accessible and maintained.
B] Transportation
The transportation of the robot should not put restraints on the construction of the
robot in itself. But easy transportation is essential for the system as a whole to function well
and it must be accommodated for. The long-term storage solution described under storage
above should suffice for foreseeable transportation needs.

18
C] Mission preparations
When the robot system is to be used, the robot needs to be programmed with
information about the current mission. The information is what the robot relies on to perform
an inspection, together with generic routines. Mission parameters will include initial and
target coordinates, how many towers will be passed, what kind of towers will be passed, other
known obstacles on the line, what data to gather, etc.
D] Attaching and retrieving the robot to/from the conductor
The high voltage of the transmission line makes it a difficult task to raise the robot to
the conductor. A number of approaches might be considered:
• Using some mechanical arm (well insulated) to raise the robot.
• Bringing the robot up a tower and lower it to the conductor from the tower.
• Lowering the robot to the conductor from a helicopter
• Throwing a rope over the conductor and pulling the robot up
The mechanical arm approach would require a substantial development effort in itself.
Climbing a tower with a possibly very large and heavy robot is a dangerous task, even if there
was no high voltage transmission line close by. Lowering the robot from a helicopter is
straightforward and proven, but bringing in a helicopter defies one of the purposes of the line
inspection robot – to get rid of the flying machines. So from this short list of methods only
the rope remains.[4]
E] Obstacles
The line inspection robot will climb on the live transmission line wire, and it must be
able to pass expected obstacles in its way. Transmission lines come in a multitude of forms
and so does the obstacles the robot must face. But just as there are many differences between
Different transmission lines, there are also similarities. Some common obstacles are listed
below [4].
• Insulator
• Bundle conductors with spacers
• Vibration damper(s)
• Tension clamp
• Transposition
• Aircraft warning spheres

19
• Unknown obstacle
A]Insulators
An insulator attaches the conductor to a tower or other structure, see Figure10. The
exact configuration of insulator relative to tower is very varied. When climbing around this
type of obstacle it is vital not to protrude too much from the live line. Unless the extending
part is entirely shielded and does not conduct electricity, it might cause flashover between
live line and grounded structure. In the majority of transmission towers it is safe to extend
below the line while climbing, but there are unfortunately many cases where this is not true
and where it is better to extend to the sides.
Figure.10. Insulator (110 kV duplex).
B] Bundle conductors with spacers
Using multiple bundled conductors separated by spacers as in fig11.is one common
way of alleviating corona issues. Bundled conductors dilute the electric field to the point
where no coronas form. In the Swedish transmission grid maintained by SvK, some 15000
km of 220 kV and 400 kV transmission lines, twin or triple bundled conductors is used
without exception.

20
Figure 11. Bundle conductor with spacer
C] Vibration Dampers
Vibration dampers are placed on conductors to minimize the effects of wind-induced
vibrations . The Stockbridge type dampers vary between 0.5 and 0.8 m in length (Figure 12).
Vibration dampers occur sometimes in pairs and relatively close to towers. Thus they add to
the difficulty of passing obstacles on the conductor. If obstacles occurred one on one
separated by a length of empty wire, a method to climb around obstacles could be used that
relied on this empty space.[4]
Figure.12. Stockbridge-type vibration damper.
D] Transposition
The three phases on a high voltage transmission line are electrically different. The
phases on the side of suffer higher resistances than the phase in the middle. To counter this
phenomenon, the lines are rotated in regular intervals (10-30 km) so the phases change place.
This occurs regularly on all larger transmission lines and is called a transposition of the
transmission line. As can hopefully be seen and understood by looking at the illustrating
picture below(Figure 13), a transposition is quite complicated. It is hard to tell where you will
be at any moment if following a conductor through a transposition. Transpositions are
generally constructed with a safety distance between different phases but it is impossible to
tell how large this safety distance is.

21
Figure.13 Transposition
E] Unknown Obstacles
Besides these obstacles there are numerous obstacles on transmission lines that just
don’t fit any of the above categories but still block the path of a robot. Some examples of the
strange creatures transmission lines can be are shown below (Figure 14). A robot needs not
be able to clear every conceivable obstacle, the categories above should suffice. A robot
needs, however, the ability to distinguish obstacles it does not know from the categories
above. If faced with an unknown obstacle, the preferable choice is to document the obstacle
and contact some sort of operator station where human operators can decide on what action to
take. Perhaps a brief remote operation of the robot is enough to get the robot through the
difficulty, or perhaps the robot needs ground assistance to clear the obstacle.
Figure 14 Difficult obstacles; a substation (left) and two tension clamps with
Creative cable loops
5.6 Application
1. Application to double OPGWs inspection:
With only minor modification the robot can be applied to not only single but
double OPGWs as well. Only the dimensions of the guide rail need to be altered..
2. Application to inspection of single runs of OPGW:
The robot can easily be converted for use on single runs of OPGW by
removing the guide rail and associated mechanisms.
3. Application to inspection of transmission lines
The robot could be applied to inspection of transmission lines with some
modifications. The robot’s dimensions would be adjusted to the transmission lines’ diameter
and subsidiary equipment. The robot could transfer itself from transmission line to
transmission line via lifters and or other devices installed on the towers.

22
Conclusion
This report has described the transmission line inspection problem. The report has
alsopresented and analyzed a novel solution to it: the line inspection robot.
If the line inspection robot is to work, it needs to master five key technologies:
• Climb on Energized Line
• Pass Obstacles
• Inspect Equipment
• Autonomous operation
• Gather power from line
These five technologies are all vital to the completed line inspection robot. Details were
given on individual design choices and their motivation. Also Considering above details
conclude that by using robot for maintenance of transmission line we can reduce the time
which will affect the other system at the time of Maintenance. Hot-line cleaning robot
belongs to specialized robot who works in dangerous environments. It assembles many-sided
technologies, such as high voltage insulation, hydraulic, communication, automatic control
and so on. However, performance tests show that hot-line cleaning robots satisfy the
performance index and it is very effective to solve the problem of hot-line cleaning insulator
in substation. Also important is the life of human being, avoids Hap hazardous considering to
safety point & reliability of system. To carry servicing of transmission line it will be helpful
in future use of robot. This system works on automatic system by remote control system
using RF transmitter & receiver by sending images & videos.

23
References
JOURNALS
1. Joon-Young Park, Byung-Hak Cho, Seung-Hyun Byun, et al. “Development of
Cleaning Robot System for Live-line Suspension Insulator String”. International
Journal of Control, Automation, and Systems, vol 2, July 2009, pp.211-220.
2. Yu Hua-yu, Xu Wen-deng, “Hot-line automatic sweeper with CZQ-50 forklift
assembly in EHV,”Northwest China Electric Power,vol 29, May 2001, pp.7-10.
3. Miss. PradnyaB.Wale, Mr.Kamal Sandeep k.-“ Maintenance of Transmission Line by
Using Robot”. 2016 International Conference on Automatic Control and Dynamic
Optimization Techniques (ICACDOT) International Institute of Information
Technology (I²IT), Pune
4. TorkelDanielsson-“ Line inspection robot”. Uppsala, 12 February 2006.
5. C.C. Whitworth, A.W.G. Duller, D.I. Jones, G.K. Earp, “Aerial video inspection of
overhead transmission lines,” Power Engineering Journal, vol. 15, no. 1, pp. 25-32,
February 2001.
6. S. Peungsungwal, B. Pungsiri, K. Chamnongthai, M. Okuda, “Autonomous robot for
a power transmission line inspection,” The 2001 IEEE International Symposium on
Circuits and Systems, ISCAS, vol. 3, pp. 121-124, 6-9 May 2001.
7. Lu Shou-yin, Ma Pei-sun, Qi Hui, et al, “Research on High Voltage Electric Power
Live Line Working Robot,”Automation of Electric Power System, vol 27, July 2003,
pp.56-58.
8. Che Li-xin,Yang Ru-qing,Gu Yi, “Design of High-voltage Hot-line Sweeping Robot
Used in 220/330kv Substation,”Robot, vol27, Feb 2005.
9. M. F. M. Campos et al., “A mobile manipulator for installation andremoval of aircraft
warning spheres on aerial power transmission lines”,Proc. IEEE Int'l Conf. on
Robotics & Automation, Washington D. C.,USA, 2002, pp. 3559-3564.
WEBSITE
1. www.electrical4u.com/transmission-line-in-power-system/

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