MEKELLE UNIVERSITY

EIT-M
SCHOOL OF ELECTRICAL AND COMPUTER ENGINEERING
STREAM OF INDUSTRIAL CONTROL ENGINEERING
Hosting Company: Mesfin Industrial Engineering

Title: PLC Based Overhead Crane Control System

Group Members ID.No.

1, Suzan werkkeluel………………………………….129354/10
2, Kisanet lemlem …………….………………………129408/10
3, Hwa hagos………….…………………….……….134465/10
4, Zeyneb mohamed…………………………….…….129584/10

Advisor by: Mahder

May 17 2024
Mekelle, Tigray
INTERNSHIP REPORT AND PROJECT ON MIE

DECLARATION
We declare that, this final internship document is an independent work of students’ Suzan
werkeluel, Kisanet lemlem, Hwa hagos, Zeyneb mohammedbrhan take internship program in the
hosting company of MESFIN INDUSTRIAL ENGINEERING, PLC. All writings in this
document contain things that are done by our effort under the guidance of our adrviser Mr.
Mahder.

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ACKNOWLEDGEMENT
First of all, we have the pleasure to express our gratitude to almighty God for giving us the
opportunity to complete our internship program and finally to prepare this internship project.
And we would like to express our great gratitude to Mesfin Industrial Engineering PLC (MIE)
who allowed us to get a chance of three month intern period and for gaining much more practical
knowledge related to our education. It is also our pleasure to give our special thanks to our
supervisors Mr. Kiflom and other employers for their help and guidance and also for supporting
us throughout the preparation of this project. And we would like to give my special thanks to our
advisor Mr. Mahder for advising and guiding us through our internship. This internship paper
might have never been complete without the necessary practical knowledge, assistance of many
books, articles and websites. We would like to thank all engineers, employees and operators of
each section who played a great role and supported us from the first arrival date until the end of
our internship program. We would also like to thank the authority of IMC for providing internet
facilities and other all necessary things for us.

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ABSTRACT
This project describes the automatic control of electrical overhead travelling crane. An
overhead travelling crane, also known as a bridge crane, is a type of crane where the
hook-and-line mechanism runs along a horizontal beam that it runs along two widely separated
rails. Also included would be a hoist to lift the items, the bridge, which spans the area covered
by the crane, and a trolley to move along the bridge. The operation of overhead travelling crane
is completely controlled by using Programmable Logic Controller (PLC) which is used for
automation of real-world processes, such as control of machinery on factory assembly
lines. The system sequence of operation is designed by ladder diagram and PLC
programming software. In this paper, we are using sensors that are used to sense the
overhead travelling crane motion supplied by 220 AC or DC 24 V and an inverter used to turn
up or down the motor speed to meet the speed requirement. By implementing this paper, man
power can be decreased and the production of the industry can be increased. Finally for
efficient operation, an induction motor with DC in industrial applications. The relay logic in
overhead crane machine control is simulated using PLC. The model sequence of operation is
designed by ladder diagram and PLC programming software for Mesfin industrial engineering
Company.

Table of Contents
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DECLARATION............................................................................................................................................i
ACKNOWLEDGEMENT.............................................................................................................................ii
ABSTRACT.................................................................................................................................................iii
TABLE OF FIGURE....................................................................................................................................vi
ABBREVIATIONS.....................................................................................................................................vii
CHAPTER ONE............................................................................................................................................1
BACKGROUND OF MESFIN INDUSTRIAL ENGINEERING PLC (MIE).............................................1
1.1 Brief History........................................................................................................................................1
1.2 Vision of the Company........................................................................................................................2
1.3 Mission of the Company......................................................................................................................2
1.4 Values of the Company........................................................................................................................3
1.5 Competitive Advantages of the Company...........................................................................................3
1.5.1 Professional, highly skilled, and committed workforce................................................................3
1.6 Objectives of the Company..................................................................................................................3
1.7 Main Products and Sectors...................................................................................................................3
1.7.1 Major Production of the Company...............................................................................................4
1.7.2 Sectors...........................................................................................................................................4
1.8 Main Suppliers of the Company..........................................................................................................5
1.9 Main Customers and End Users...........................................................................................................5
1.11 Over All Organization of the Company.............................................................................................6
1.12 Company Business Units...................................................................................................................7
1.13 Work Flow in MIE.............................................................................................................................7
1.14 Specific Processes of the Company...................................................................................................9
1.14.1 Workshop 1.................................................................................................................................9
1.14.2 Workshop 2...............................................................................................................................11
1.14.3 Workshop 3 And 4....................................................................................................................12
1.14.4 Air Compressor.........................................................................................................................15
1.14.5 Fabrication Shop.......................................................................................................................18
1.14.6 Automotive Assembling Plant..................................................................................................18
1.14.7 Mega Rolling Plant...................................................................................................................18
CHAPTER TWO.........................................................................................................................................19
OVERALL INTERNSHIP EXPERIENCES...............................................................................................19
2.1 Work Section We Have Been Executing...........................................................................................19
2.2 The Work Tasks We Have Been Executing......................................................................................23
2.3 Challenges We Have Been Facing.....................................................................................................24
2.4 Goals We Planned To Achieve In Our Internship.............................................................................24

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CHAPTER THREE.....................................................................................................................................25
PLC BASED OVERHEAD CRANE MACHINE CONTROL SYSTEM..................................................25
3.1 Introduction........................................................................................................................................25
3.2 Literature Review...............................................................................................................................26
3.3 Problem Statement...........................................................................................................................26
3.4 Objectives..........................................................................................................................................27
3.4.1 Main objective............................................................................................................................27
3.4.2 Specific objectives......................................................................................................................27
3.5 Scope..................................................................................................................................................27
3.6 Significance........................................................................................................................................27
3.7 Methodology......................................................................................................................................28
3.8 System Design...................................................................................................................................28
3.8.1 System Analysis and Controller Design.....................................................................................33
3.8.2 Design of Hoist Control System.................................................................................................34
3.8.3 Design of Trolley Control System..............................................................................................38
3.8.4 Design of the Crane Bridge Control System...............................................................................40
3.9 Result and Discussion......................................................................................................................43
3.9.1 Start Stop Control Ladder...........................................................................................................43
3.9.2 Hoist Control Ladder...............................................................................................................43
3.9.3 Trolley Control Ladder............................................................................................................44
3.9.4 Bridge Control Ladder............................................................................................................45
CHAPTER FOUR........................................................................................................................................47
BENEFIT GAINED FROM THE INTERNSHIP.......................................................................................47
4.1Theoretical Knowledge and Practical Skill.........................................................................................47
4.2 Team Playing Skills...........................................................................................................................47
4.3 Inter Personal Skills...........................................................................................................................47
4.4 Leadership Skills................................................................................................................................47
4.5 Entrepreneurship Skill and Kaizen Process Of Management............................................................47
4.5.1 Work Ethics................................................................................................................................48
CHAPTER FIVE.........................................................................................................................................49
CONCLUSION AND RECOMMENDATION...........................................................................................49
5.1 Conclusion.........................................................................................................................................49
5.2 Recommendation...............................................................................................................................50
REFERRENCES..........................................................................................................................................51

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TABLE OF FIGURE
Figure1. 1 Partial view of MIE in Mekelle.....................................................................................2
Figure1. 2 Overall organization of MIE..........................................................................................7
Figure1. 3 Work flow of MIE..........................................................................................................8
Figure1. 4 General work flow..........................................................................................................9
Figure1. 5 Lathe machine.............................................................................................................10
Figure1. 6 Drill machine................................................................................................................10
Figure1. 7 Drill machine................................................................................................................11
Figure1. 8 Rolling machine...........................................................................................................13
Figure1. 9 Bending machine..........................................................................................................15
Figure1. 10 Gasparini shearing machine.......................................................................................15
Figure1. 11 Flow of air in air compressor.....................................................................................16
Figure1. 12 Oxy-acetylene plant...................................................................................................17
Figure1. 13 Mega rolling plant......................................................................................................18
Figure2. 1 Industrial operation and asset management.................................................................19
Figure2. 2 Sample of maintenance order request voucher............................................................21
Figure2. 3 Flow chart for planned and unplanned break down maintenance................................22
Figure2. 4 Maintenance data handling...........................................................................................22
Figure 3. 1 Kuli overhead crane....................................................................................................29
Figure 3. 2 induction motor..........................................................................................................29
Figure 3. 3 Limit switches............................................................................................................30
Figure 3. 4 PLC input and output terminals..................................................................................33
Figure 3. 5 Block diagram of control system................................................................................34
Figure 3. 6 Block diagram of hoist control system........................................................................34
Figure 3. 7 Flowchart for hoist upward.........................................................................................35
Figure 3. 8 Flowchart for hoist downward...................................................................................36
Figure 3. 9 Ladder diagram for hoist motor.................................................................................37
Figure 3. 10 Block diagram of trolley control system...................................................................38
Figure 3. 12 Ladder diagram for trolley........................................................................................39
Figure 3. 13 Block diagram of travel bridge control system.........................................................40
Figure 3. 14 Flowchart for bridge..................................................................................................41
Figure 3. 15 Ladder diagram for bridge motor..............................................................................42
Figure 3. 16 Start stop ladder diagram...........................................................................................43
Figure 3. 17 Hoist control ladder diagram....................................................................................44
Figure 3. 18 Trolley control ladder diagram................................................................................45
Figure 3. 19 Ladder diagram for bridge.........................................................................................46

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ABBREVIATIONS
MIE Mesfin Industrial Engineering

PLC Programmable Logic Controller

DC Direct Current

AC Alternative Current

EFFORT Endowment Fund For the Rehabilitation of at Tigray

TDA Tigray Disabled veterans Association

ODA Oromia Disabled veterans Association

ADA Amhara Disabled veterans Association

GERD Grand Ethiopian Renaissance Dam

BSI British Standards Institution

HVAC Heat and Ventilated Air Conditioner

AAM Automotive and Agricultural Machinery

MIO Manufacturing and Industrial Operation

DPM Design and Project Management

MD Managing Director

IGBT Insulated Gate Bipolar Transistor

PCB Print Circuit Board

IR Infra-red

VVCF Variable Frequency Drive

I/O Input Output

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CHAPTER ONE
BACKGROUND OF MESFIN INDUSTRIAL ENGINEERING
PLC (MIE)
1.1 Brief History
Mesfin Industrial Engineering PLC (MIE) was established in 1993 as the engineering wing of
EFFORT (Endowment Fund for the Rehabilitation of at Tigray) With Its Head quarter in the city
of Mekelle, Northern part of Ethiopia, MIE has branches for assembly of automobiles in Wukro
town, 45 kilometers from the head office and manufacturing plant in Gelan, 25kilometers from
Addis Ababa. During its establishment MIE’s capital was about USD 358 thousand. Currently
the company’s capital is more than USD 25 million. Similarly, the number of employees during
its establishment was about 30 people. MIE currently employs more than 1600 permanent and
temporary workers. MIE started its activities by manufacturing of metal windows, doors
maintenance of vehicles and the like. Currently MIE’s products include liquid and dry cargo
bodies and trailers, semi-trailers, low beds, fuel storage tanks, equipment for sugar, cement,
hydropower industries, assembly of automobiles and tractors. MIE is also active in
electromechanical erection and installation works which include construction of pre-engineered
buildings, erection of machinery and equipment for various industrial projects, fuel storage
facilities, and civic buildings.
As a company which believes in a corporate social responsibility, MIE is also active in various
social endeavors such as working with small and micro enterprises, sponsoring various social
events, supporting of orphans, supporting of the Tigray Disabled Veterans Association, Regional
Development Associations such as TDA, ODA, and ADA. MIE has also established a team of
athletes that are participating in National and International matches with some of them gold
medalists MIE also has women bicycle club to contribute its part in this sport type. Support of
football clubs, Marshal Arts and contributions to the Grand Ethiopian Renaissance Dam (GERD)
are also mentioned as the company’s social activities.

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Figure1. 1 Partial view of MIE in Mekelle

MIE is an ISO 9001:2008 certified company from the British Standards Institution (BSI) and a
proud member of Addis Ababa and Mekelle Chambers of Commerce and Sectorial Associations,
Ethiopian Society of Mechanical Engineers, Basic Metals and Engineering Association and
Electro-mechanical Contractors Association. This company is certified on the following scopes:
 Design, manufacture, supply and service of Low Bed/High Bed Dry/liquid Trailers,
 Design, manufacture, supply and erection of petroleum liquid reservoirs (including
electrical / instrumentation system)
 Supply and erection of HVAC (heat and ventilated air conditioner) systems,
 Manufacture and supply of steel fabricated products for industrial application,
 Vehicle equipment maintenance and renting.
1.2 Vision of the Company
Become a leading engineering company in automotive industry, power, heavy duty vehicles,
Electro-mechanism and manufacturing sectors in East Africa.
1.3 Mission of the Company
To provide competitive engineering products, Electro-mechanism and industrial construction
services to customers, create maximum wealth to EFFORT, provide development opportunity to
employs, bring a positive impact on society and play a leading role in the industrialization of the
country.

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1.4 Values of the Company

 Integrity, accountability and transparency
 Full Customer satisfaction and strive to exceed their expectations
 Always add value, handle properties with care and ensure efficient utilization of
resources.
 Work hard to be best in class and lead the way for quality.
 Technical excellence with professional ethics
 Organizational and individual development
 Ensure safe working conditions to all employees
 Build sustainable, closer and long-lasting relationship with customers and partners.
 Provide necessary support to our employees as much as possible.  Social responsibility
1.5 Competitive Advantages of the Company
1.5.1 Professional, highly skilled, and committed workforce
 Excellent reputation
 Being partner of first choice
 Investment in employees
 up-to-date equipment and technology
1.6 Objectives of the Company
 To increase the profitability
 To satisfy customers
 To be competitive in the market
 To minimize cost of product
 To minimize foreign currency
 To create employ
 To transfer technology etc.
1.7 Main Products and Sectors
Mesfin industrial engineering produces different products such as:
 Sugar plate components
 Liquid trailers
 Solid trailers
 Semitrailers

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 Cement plant components

 Hydraulic components and others.
 Track mounted dry cargo body
 Mechanical hand break
 And so on
1.7.1 Major Production of the Company
 Erection of 5.6 million liters capacity storage tanker
 Antenna towers up to 60 meters high
 Various dry products storage tank, portable water storage tank.
 Fabrication cement factory equipment
 Agricultural trailer and Sugar component
 penstock element and intake liners for hydro power project
 Low bed trailers for equipment transport
 Civil buildings and Renting and maintenance of heavy duty light vehicles
1.7.2 Sectors
Below the sectors are listed individually;
Transport sector: MIE is the biggest single trailer manufacturing factory in Ethiopia. It designs
and manufactures vehicle bodies, trailers, high and low bed semi-trailer as well. MIE has a
capacity of manufacturing over 1500 trailers and semi-trailers per annual. It produces truck
bodies, 2 axle, 3 axle trailers & semi-trailers for dry and fuel cargo transport low beds for
transporting heavy duty equipment, bus body, and tipper bodies.
Some of the products under the transport sector are;
 Bus body
 Tipper bodies
 3-axle draw bar fuel trailer
 cargo body mounted on truck
 low bed semi-trailer
Energy sector: With the help of a radiographic, ultrasonic and other testing services provided
in its testing laboratory, MIE has a full capacity of manufacturing and erecting hydroelectric
components such as penstocks, steel liners, gates and reservoirs. Furthermore, it has a unique

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rolling machine in east Africa that produces very large fuel storage tanks. The Mega Rolling
Plant has a total annual design capacity of producing storage tank of one billion liters.
Industrial sector: With the support of CAD and CAM software MIE designs, manufactures and
erects industrial components for cement, textile, brewery, and food and sugar industry.
Moreover, MIE manufactures multi-purpose industrial cranes and boilers. In addition to the
aforementioned tasks MIE renders renting services of light and heavy-duty vehicles, 50 tone
mobile cranes, 3-5 tone forklifts and 15 meter cube dump trucks. It also gives maintenance
service to light & heavy duty vehicles in its well organized Garages in Mekelle and Addis
Ababa.
1.8 Main Suppliers of the Company
Mesfin industrial engineering PLC uses different source material inputs from different countries
of manufacturing company. Those main suppliers of the company are listed below.
 Turkey metal market PLC.------Different pipes steel
 Turkey tufan trading PLC
 Turkey metal trading center PLC.
 Ukraine
 Germen --Axle
 China habit uxuage PLC
 Italy normal trading PLC Grind machine& electrical system
 U.S.A --Bronze
 China chufa steel manufacturing PLC
 china sty steel manufacturing PLC raw material
 France --breaking system
1.9 Main Customers and End Users
The production capacity of this company and its customers are increasing from time to time. The
main customers or end users of its products are;
 Trance Ethiopia
 Tikurabay
 United alpha
 Shebelle
 Ministry of national defense

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 Messobo building material

 Ethio-Djibouti Railway corporation
 Ethiopia Airports Enterprise and others
 Other governance and non-governance PLC.
1.11 Over All Organization of the Company

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Figure1. 2 Overall organization of MIE

1.12 Company Business Units

MIE has re-organized itself into eight business units based on market assessments. These are:
 AAM: chief automotive and agricultural machinery
 CORPORATE: chief corporate services
 HRN: chief human resource
 SUPPLY: chief supply chain
 MIO: chief manufacturing and industrial operation
 DPM: chief design and project management
 MARKETING: chief strategy and marketing
 MD: managing director
1.13 Work Flow in MIE
The overall work flow chart of Mesfin industrial engineering (MIE) is shown below

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Figure1. 3 Work flow of MIE

Generally, the workflow can be summarized as below:

 The supply system includes components and accessories store, raw material store,
consumable and gas store, spare parts stores and oxyacetylene preparation section.
 The manufacturing system consists of three major processes. These are material
preparation process, fabrication process, finishing and painting processes.
 The distribution system comprises different distribution channels. These are central full
stores, branch warehouses, dealers and end users.

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Supply system

Material preparation

Manufacturing system

Finishing and painting

Figure1. 4 General work flow

1.14 Specific Processes of the Company

1.14.1 Workshop 1
In this shop low bed, high bed semitrailers and axle assembling are performed. There is also a
large rolling machine in this shop.
 One automatic band saw
The main machines used for these operations and are available in this workshop are listed below.
Lathe machine
As we know machining is a manufacturing process in which a sharp cutting tool is used to cut
away material to leave the desired part shape. Hence lathe machine as one of machining tool it
uses sharp cutting tools to produce a desired shape and dimension. The main operations
performed in this machine are turning (reducing diameter), facing, threading, groove cutting and
boring (increasing internal diameter).
In this shop most of lathe machines work by gear system, belt system and hydraulic system.

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Figure1. 5 Lathe machine

Radial drill machine

A drill machine is a machine used to create a round hole in a work part. Drilling is usually
performed with a rotating cylindrical tool that has two cutting edges on its working end. The tool
is called a drill or drill bit, the most common drill bit is the twist drill.
The operation in the drill machine is feeding the rotating drill in to the stationary work part to
form a hole whose diameter is equal to the drill bit diameter. For different diameter a different
drill bit is used.
There are two drill machines in this shop each have three degree of freedom. I.e.
 They can move radially
 They can move axially (horizontal direction)
 They can revolve about the vertical

Figure1. 6 Drill machine

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1.14.2 Workshop 2
 This workshop is the only workshop equipped with a two bridge (overhead) crane of
lifting capacity of 5 ton.
 Everything in this shop is welding,
 The main welding method held in this shop is arc welding. Sometimes mig welding is
used.
 High human power is used in this shop.
Crane
A crane is a type of machine, generally equipped with a hoist, wire ropes or chains, and sheaves,
that can be used both to lift and lower materials and to move them horizontally. It is mainly used
for lifting heavy things and transporting them to other places. It uses one or more simple
machines to create mechanical advantage and thus move loads beyond the normal capability of a
man. Cranes are commonly employed in the transport industry for the loading and unloading of
freight, in the construction industry for the movement of materials and in the manufacturing
industry for the assembling of heavy equipment.
An overhead crane, also known as a bridge crane, is a type of crane where the hook-and-line
mechanism runs along a horizontal beam i.e. it runs along two widely separated rails. Often it is
in a long factory building and runs along rails along the building's two long walls. It is similar to
a gantry crane.

Figure1. 7 Drill machine

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Welding machine
Welding can be defined as the process of joining two metal parts by applying heat. In industry,
welding process is primarily used for fabricating works. Welding is useful in making permanent
joints. It can be performed by applying or not applying pressure. The contours of the metal parts
are molten to make the joint in some methods. In some types of welding processes, filler metal is
used. In some other methods, filler metal is not used. The process of welding finds application in
manufacturing automobiles, aero planes, rail coaches, machine components, metal structures,
boilers and ships. Generally, welding process is applied wherever metal works are performed.
Arc welding
In arc welding, the edges of two metal parts are melted by an electric arc and the joint is made.
An electrode made of a suitable metal is utilized for this purpose. The electrode is taken closer to
the parts to be joined and electric current is supplied to both the parts and the electrode. An
electric arc is made between the electrode and the metal parts. This arc generates high
temperature and melts the metal parts. The parts are joined at this molten state.
The filler metal in the form of electrode is deposited along the joint. The metal parts are joined
without the application of any pressure. Electrical energy is converted into heat energy in arc
welding. Water tanks, truck trailers and sugar factory components are welded in this work shop.
1.14.3 Workshop 3 And 4
This shop is equipped with welding equipment’s such as MAG, TIG arc and overhead crane for
transportation system. In this shop all the welding processes are completed. The welding
machine uses CO2 gas and copper wire to have good Welding result.
Some of machines available on those shops are:
Submerged arc welding
This welding machine is very important considering its economic advantage and health of
workers. Because it does not let smoke to the atmosphere as the welding is covered with a
substance called flux.
Rolling machine
This machine works hydraulically and it is used to roll plate to the form of cylinder (pressure
vessel) which are used for sugar components and manufacturing of liquid trailers.

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Figure1. 8 Rolling machine

Material Preparation Plant

This is the plant where all the raw materials for the fabrication process are prepared in the
material preparation shop and equipped with state-of-the-art cutting Shearing, bending and
rolling machines. In the material preparation shop all the pre Welding and assembly activities are
carried out. The quality of products in the material preparation plant determines the precision and
functionality of the final product.
The main machines available in this shop are;
CNC Flame and plasma cutting machine
As we discussed in the lathe machine a CNC machine is a machine which is controlled by
computer & data (geometry) is entered by a program. Hence receives any profile we want to cut
With CD or USB (removable disk).
Advantage of this machine
 High rate of production
 Able to cut complex shapes(profile)
 Accurate cutting
 Reduce labor cost
As its name indicates it is flame and plasma cutting machine, hence its cutting capacity is also
classified in to two. Such that when it uses flame and when it use plasma is as the following.
Flame cutting capacity (thickness) 6-80mm
Plasma cutting capacity (thickness) 1-30mm

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This machine has three tips in which one tip is plasma and the other two tips are flame. The fluid
entered to each (flame or plasma tip) is also different. i.e.
1. Fluid input for flame cutting
2. Fluid in put for plasma cutting
3. Oxygen and acetylene air
Pantograph cutting machine
 It is also a cutting machine which we cannot get any specification and code. The use of
this machine is the same to the flame and plasma cutting
 It receives drawing with CD or USB, but it should be in the language in which the
machine can read.
 Arc length is adjusted by the operator which makes the surface finish of the cutting is
not accurate.
Band saw
It is cutting method which uses a very flexible cutter. Depending the type teeth and variable pitch
it requires variable loads to cut different thickness of material.
Cutting speed varies from material to material, such that the speed is minimum for hard
materials. Based on this the cutting speed varies from 30-120meter per minute.
The thickness of material to be cut ranges from 2mm and above, but while we increase the
thickness we should have to decrease the speed of cutting for safety and life of the cutter. The
relation between the parameters while changing one of them is tabulated on the machine. The
parameters include
 Type of coolant to be used
 Cutting speed
Bending machine
There are two bending machines available in this shop, both differs in their place of origin,
bending capacity and the material they can bend. Those bending machines have the ability to
bend any material including mild steel. These are Baykal and Gasparini bending machine.

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Figure1. 9 Bending machine

Shearing machine
There are two shearing machines used to cut metals, where the old one is made of Italy and is
able to cut mild steel where the new one from turkey can cut mild steel and stainless steel. Both
Baykal and Gasparini shearing machines work hydraulically.

Figure1. 10 Gasparini shearing machine

1.14.4 Air Compressor

Air compressor is a machine that extracts air from the atmosphere and compresses it in to a
holding chamber. This machine uses atmospheric air as an input and process it to give us
pressured air which is necessary in industries for Varity purposes. The most use of compressed
air is for the operation pneumatic tools such as painting. And here in MIE it is widely used for
painting with air guns, plasma machine.

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Types of air compressor

There are two types of air compressor
 Piston air compressor
 Screw air compressor
Here in MIE a screw air compressor is used atmospheric air is main input or resource Oil used
as coolant agent, high pressure and lubrication purpose Screw compresses air and oil to create
pressure.
How air compressor works
The overall flow of air compressor from atmospheric air to consumer goes as:

Atmospheric
separator condenser tanker
screw
Oil +air

consumer filter dryer filter

Figure1. 11 Flow of air in air compressor

As we have stated on chapter one there are two types of air compressor, called piston and screw
compressor. In MIE screw compressor is used.
Atmospheric air: is main input or resource
Oil: used as coolant agent, high pressure and lubrication purpose.
Screw: compresses air and oil to create pressure.
Separator: separates the compressed air and oil due to their density. Oil is the denser one that’s
why it dumps down and air with smaller density floats. Both air and oil here are very hot so they
need to cool down in condenser.

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Condenser: uses to condense or cool down air.

Tanker: reserved air and uses to-to have constant flow and uses for
 To separate air from its own moisture
 Uses to cool down air which doesn’t cool down will in the radiator
Filter: use to filter out the moisture and dust particles from air.
Dryer: it dries out the filtered air by sucking moisture from it. Finally, we get the desire
pressured air. The maximum capacity of this air compressor is 10 bars and minimum 8bar.the off
time between max and min (10&8) is called ideal bar time.
Power House

Power house is a station in which an electric power is distributed through cable and wires. Power
house consists of generator, solar PV, nuclear power sources, Biomass e.tc here in MIE, the
power house consists of two sources i.e. an EEPCO and generator since there is large electrical
machining in the workshops. A step-down transformer is used in the power house.
Oxy-Acetylene Production Plant

The oxy-Acetylene production plant produces oxygen and acetylene both for internal
consumption and for external customers like hospitals, vehicle maintenance shops, construction
projects and other fabrication shops.

Figure1. 12 Oxy-acetylene plant

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1.14.5 Fabrication Shop

MIE fabrication shops are equipped with welding equipment like Column Welding Machine
MAG, TIG Arc and Submerged Arc Welding Machines, different types of hand tools for
assembly and overhead cranes for the transportation of products within the shop floor.
1.14.6 Automotive Assembling Plant
This shop is related with track mounting, stand preparation, board preparation, frame welding
and plate formation is produced here and sometimes also tractor assembling is performed.
1.14.7 Mega Rolling Plant
This shop consists of heavy-duty Mega Rolling plant, which is used to manufacture reservoir
tanks with a capacity of holding 6 to 10 million liters each. These reservoir tanks can be used for
the storage of petroleum, chemicals, water, grain etc. this work shop has a capacity of producing
various size storage tanks with a total capacity of one billion liters per annum.
 The main customer for those huge reservoirs is the national fuel agency.
 The mega rolling is a capable for producing of 6-10 million liters capacity storage tanks.

Figure1. 13 Mega rolling plant

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CHAPTER TWO
OVERALL INTERNSHIP EXPERIENCES
2.1 Work Section We Have Been Executing
Industrial operational and asset management
According to the company’s human resource management idea we worked in the electrical and
electronics maintenance department and in workshops, power house and machine shops in order
to understand the work flow in the company and in order to achieve better knowledge and skill
about electrical engineering.
Most of our time we have been working in the electrical and electronics maintenance department
of asset management and equipment learning because the department contains basic electrical
component ,motors and machine cards PCB (Print Circuit Board) that can improves knowledge
about electrical engineering as well as our stream industrial control.

Figure2. 1 Industrial operation and asset management

Hence maintenance is an urgent. Need to keep the machines functioning.

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Industrial operation and asset management department is carried out in two ways. Those are:
Maintaining inside the center: machines and equipment that can move from place to place such
as electrical cards, motors and other small electrical equipment are maintained within the center
itself.
Maintaining outside the center: machines and equipment that can’t move from place to place
such as overhead cranes, lathe, CNC cutters rolling etc. are maintained outside the center.
Objectives of industrial operation and asset management
 To increase functional reliability of production facilities.
 To enable desired quality through correctly adjusted, serviced and operate equipment’s.
 To maximize the useful life of equipment’s.
 To minimize cost of production.
 To minimize frequency of interruptions.
 To enhance safety of man power
Maintenance types
We have seen three maintenance types carried out in the company. These are;
1. Predictive /condition based maintenance
2. Preventive maintenance
3. Corrective/break down maintenance
1. Preventive maintenance
Maintenance performed while a machine is still working order to keep it from breaking down. It
includes lubricating, tightening and replacing worn parts.
2. Corrective/breakdown maintenance
This can be defined as the maintenance which is required when an item has failed or worn out, to
bring it back to working order. It is carried out on all items where the consequences of failure or
wearing out are not significant and the cost of this maintenance is much greater than the
preventive maintenance.
3. Condition-based maintenance
This maintenance is performed after one or more indicators show that the equipment is going to
fail or that equipment performance is deteriorating.
Maintenance procedures
 Receiving work order

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 Troubleshooting
 Identify the problem
 Repair
Maintenance costs
 Because of the breakdowns, both of the machinery and as well as the man power are left
idle, per force.
 This results in production, delay in schedules and emergency repairs
 The downtime cost generally exceeds the preventive maintenance costs of inspection,
service and schedule repairs.
The maintenance order requests format to maintain a certain defected machine in the company
i.e. in the industrial operation and asset planning work shop used by the technicians and
engineers looks like as follows in the table.

Figure2. 2 Sample of maintenance order request voucher

In the maintenance procedure flow chart style chart for troubleshooting of planned and
unplanned break down maintenance looks like as below in the table.

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Figure2. 3 Flow chart for planned and unplanned break down maintenance

Figure2. 4 Maintenance data handling

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Safety rules
Mesfin Industrial Engineering (MIE) is committed to conduct its business and projects in a
manner that the safety and health of its employees and avoids damage to company assets. The
company will strive as far as possible to prevent all accidents, and occupational illness through
the active participation of each employee. The company will put continuous effort to identity,
and eliminate or manage, different safety risks with its activities. The effective safety procedures
and implementation of safety code at compound a project is an essential key for successful and
timely completion of the projects. These procedures when properly exercised would result in
minimizing accidents, damages and loss of man-hours and properties of the client to the
maximum progress potentials achieved in particular span of time.
In order to implement this safety manual MIE will:
 Ensure that all its manufacturing and project services are executed in such a manner that
safe guard for life and property against accidental occurrences and occupational hazards
 Ensure that accident, damage and loss prevention remain a direct responsibility of line
managements.
 Respond effectively, promptly and carefully, to accidents and emergencies resulting
from its operation in cooperation with other business organization and government
agencies.
 Cooperate with relevant government and other authorities, as appropriate; to develop
and implement applicable safety and health working conditions regulations and
standards.
2.2 The Work Tasks We Have Been Executing
Generally, through our stay in MIE we have gained knowledge of maintenance, problem
identifications and the methods performed to avail the detected component, testing and checking
electrical components, motor rewinding and a lot more.
Besides of this knowledge of maintenance we have been trying to know the short coming of the
machines in MIE. To bring better quality of working operation by adding some modifications we
have been searching for good solutions from our deepest understandings of the working
environment.
Procedures that should be used while performing a work task
The procedures of our task were going as follows:

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 Before starting any practical work we have to get full information about the device by
asking the personnel/operator or reading manual and searching from books. Then we can
continue doing our task surely.
2.3 Challenges We Have Been Facing
When we have been in MIE during the internship period we have faced with different challenges
such as
 We had the problem how to read or understand the manual
 It was difficult to know the work flow of the shops
 There is no library to read manuals
The measures we had been taken in order overcome the challenges to
 Asking to the personnel to tell us the about the working processes
 Searching and reading written documents related to the problem we have been facing
 Working close together with the technicians of the maintenance group
 Asking students of other campus who were our colleagues/co-workers
2.4 Goals We Planned To Achieve In Our Internship
 Be familiarize with the company
 Understand the work flow of the company
 Use theoretical knowledge in practice
 Know the overall process such as time taken, cost required and method of manufacturing
of a product
 Identify problems available in the company

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CHAPTER THREE
PLC BASED OVERHEAD CRANE MACHINE CONTROL
SYSTEM
3.1 Introduction
Electrical technology for crane control has undergone a significant change during the last few
decades. The shift from Ward Leonard system to DC drive technology and the advent of
powerful Insulated Gate Bipolar Transistors (IGBTs) during the 1990s enabled the introduction
of the AC drive [1]. The standard crane comprises a welded steel frame, liberally rated crane-
type motors, high carbon steel gears, precision ball bearings, oil-sealed gearboxes, robust
Electro-mechanism brake, automatic over winding prevention and centralized lubrication.
Nowadays, cranes are very popular equipment in factories. They are part of everyday work to
move heavy objects between production lines. Cranes can be found in metal factories, car
industries loading and unloading ships, machinery factories. In many cases, the efficiency of
production is decided by how fast load-moving operation is. Therefore, many factory owners
have been investing money and effort in order to improve the safety, consistency and velocity of
their cranes. [2]
The project gives an introduction of the control system of overhead cranes and realizes semi-
automatic operation through Logo v8 PLC programing and variable frequency drive. This paper
mainly presents the programming and operation of an Overhead Travelling Crane in Automobile
Production Factory. It can pick up the container which included an automobile to a desired place.
PLC can control operation sequence of a large system. [3]
Crane is a device used to lift or lower materials in the vertical direction and to move them
horizontally while being hanged, generally equipped with a hoist, wire or chains, and sheaves. Or
a crane is the type of machine mainly used for handling heavy loads in different industry
branches: metallurgy, paper and cement industry. [1] By the construction, cranes are divided into
overhead cranes and gantry cranes. An overhead cranes and gantry cranes are typically used
moving containers, loading trucks and material storage. An overhead crane consists of three
separate motions for transporting materials. The first motion is hoist motion, which raises and
lowers the material. The second is trolley (cross travel) which allows the hoist to be directly
above the material for placement. The third is the gantry or bridge motion (long travel), which
allows the entire crane to be moved along the working area. [4]

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Three-motor namely Main hoist, long travel and Cross travel are used for accomplishing
movements of an electric overhead travelling cranes in a desired direction. PLCs are used for
controlling the three motors using programs. Drives are used to control the speed of motors
proportional to the weights. Electrical technology for overhead crane control has undergone a
significant change during the last few decades. [5] The shift from the standard crane comprises a
welded steel frame, liberally rated crane-type motors, high-carbon steel gears, precision ball
bearings, oil-sealed gear-boxes, robust Electro-mechanism brake, automatic over winding
prevention and centralized lubrication. [6]
3.2 Literature Review
Even this modernized and advanced technique is not yet more applied (introduced) in our
country Ethiopia there are another nation which acts this technology. As a result, a number of
projects have been done. Under this chapter it covers the ideas done before related to our project
such as:
The authors JOSHUA VAUGHAN, AJEYA KARAJGIKAR, AND WILLIAM SINGHOSE
(1999) had done the paper open loop based an overhead crane machine control system to reduce
oscillation. An open loop controller is often used in simple processes because of its simplicity
and low cost. But this paper focuses on the control of two dimensional overhead crane motions
that allow the travelling bridge and hoisting motions. [7]
MOUSTAFA and ABOU-EI-YAZID (1996) discussed the stability of the crane motion system
for hoisting motions of the load based on feedback controller. One challenge of implementing
feedback control systems on cranes is the difficulty in accurately and robustly sensing the crane
payload. [8]
Unlike the above ideas, we improve the system by using the PLC based overhead traveling crane
control system. The proposed system will solve most of those problems. Programmable Logic
Controller (PLC) issued to control operation of the three dimensional motions of the overhead
crane machine. Because in different industry branches: metallurgy, paper and cement industry
three dimensional overhead crane are used.
3.3 Problem Statement
Due to wiring complexity system of the traditional relay logic it is difficult to control the
movements of an overhead crane using the current system. Fault detection is also difficult due to
complicated wires. In hard- wired control system power consumption is also high because of the

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lots of wires present. By connecting the PLC controller with inputs and outputs and an inverter
which is used to change frequency instead of two winding motor, we design the project to solve
the above mentioned problem.
3.4 Objectives
3.4.1 Main objective
The main objective of the project is to design PLC based overhead crane machine control
system.
3.4.2 Specific objectives
The specific objective of our project is:
 To design a control system that makes the hoist to lift and drop materials.
 To design a control system to move the trolley into right and left side of the bridge.
 To design a control system to move the travelling bridge into forward and reverse
direction.
 To develop simulation for the proposed system.
3.5 Scope
The scope of this project is to develop a crane machine control system around MIE. All the
systems are controlled using Programmable Logic Controller (PLC) as it is the controller in this
system. Programming for PLC is done in software named LOGO V8 Programmer by using
ladder logic method. Besides programming, simulation can also be done in LOGO V8
Programmer to detect errors in the program created. It has three sub control systems which are
designing a control system for the hoist, trolley and bridge.

3.6 Significance
This project will enable the company to get a better control system of overhead crane machine
which is good for the motor working life because inrush current problem and insulation
breakdown are abolished or minimized due to the use of inverter. The machine will have easy
control system and can be modified in very short time if new modification is needed. There is
also a better speed control system of the motion of the crane.
PLC control in control system for overhead cranes is becoming more and more common. The
application of PLC could simplify circuit and make the design easier, safer and more reliable.in
traditional designs, relays and contactors are adopted. Starting of the crane and speed control of
the crane is realized through AC winding and resistance series. This kind of design has low
reliability, complex operation, high failure rate, power waste and low efficiency. Based on the

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above issues, this topic put PLC and inverter o overhead control system and carried out thorough
research, which indicates that after this improvement, energy consumption becomes smaller,
mechanical wear out becomes less and starting performance is better.
3.7 Methodology
 Design a control system that makes the hoist to lift and drop materials using PLC.
 Design a control system to move the trolley into right and left side of the bridge using
PLC.
 Design a control system to move the travelling bridge into forward and reverse direction
using PLC.

 Simulating the designed program on PLC software.

3.8 System Design

This is the type of machine mainly used for handling heavy loads in different industry branches:
metallurgy, paper and cement industry. Components of bridge crane:
Trolley: Carries the hoist across the bay along the bridge girder traversing the span.
Hoist: Mounted in the trolley and performs the lifting and lowering action via a hook or lifting
attachment.
End trucks: Located on either side of the span. The end trucks house the wheels on which the
entire crane travels. These wheels ride on the runway beam allowing access to the entire length
of the bay. And to complete our project we use the following equipment’s.

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Figure 3. 1 Kuli overhead crane

Induction motor: An induction motor is an electrical machine which converts electrical energy
to mechanical energy. three-motors namely main hoist, long travel and cross travel are used
for accomplishing movements of electric overhead travelling cranes in desired directions.
PLC is used for controlling the three motors using programs. [9]

Figure 3. 2 induction motor

Limit switch
Overhead cranes are used for lifting and moving around heavy materials or objects in a factory.
To make this operation run without problems the overhead crane needs information about the

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environment. Limit switch is contact sensing devices widely used for detecting the presence or
position of objects in industrial applications. [10] As an object (or target) makes contact with the
operator of the switch, it eventually moves the actuator to the "limit" where the electrical
contacts change their state. [11]
The load limiting devices are safety components for the hoisting units (hoist cranes, in particular
in our project for upward hoist) and they are meant for interrupting automatically the driving of
the hoisting gears when the prescribed values are exceeded. [12] And also, in lifting mechanism
load limiting devices are devices used to detect a load and then perform some action if the
detected load is beyond the capacity of the machine. [11]

Figure 3. 3 Limit switches

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IR sensor
Infrared sensor is an electronic device, which emits light in order to sense some aspects of the
surroundings. An IR sensor can measure the heat of an object emitted by an object and detects
the motion. IR sensors work by using a specific light sensor to detect a select light wavelength
in the infra-red (IR) spectrum. With low amount of installation work required IR sensor enables
reliable and non-contact distance measurement between rail-mounted crane to crane machines.
[13] If the adjustable distance limits are reached or if the cranes are travelling too fast, the data
will be transmitted via a switching signal to the PLC controller. [15]
Electric Buzzer
An electric buzzer or beeper is an audio signaling device that provides audio signaling function.
The device may be mechanical or electronic or combination of the two. It uses a similar
Mechanism to electric bell. But it is quieter than bells. [16] It is adequate for warning tone over a
small distance. It takes some sort of input and emits a sound in response to it. It may use various
means to produce the sound; everything from metal clappers to electromechanical devices. A
buzzer needs to have some way of taking in energy and converting it to acoustic energy. Typical
uses of buzzer include alarm devices, timers, confirmation of user input such as mouse click or
keystroke, and many others. It is commonly used as emergency warning device, such as klaxons,
sirens and so forth. It is available in designs that are suited for use in specifically dangerous
environments.
Buzzer is also available at various price levels, from devices that cost very little to very
expensive [10].
Inverter or variable frequency drive (VFD)
A variable- frequency drive (VVVF) or inverter also called adjustable - frequency drive is a type
of adjustable- speed drive used in Electro- mechanical drive system to control AC and DC motor
speed and torque by varying motor input frequency and voltage because frequency is
proportional to motor speed. It is an electronic device that can transform a direct current (DC)
into alternating current (AC) at a given voltage and frequency. The higher the frequency the
higher will be the speed of motor. If an application does not require an electric motor to run at its
full speed, inverter can be used to ramp down the frequency and voltage to meet the
requirements of the electric motors load. As the applications motor speed change, the inverter
can simply turn up or down the motor speed to meet the speed requirement. [3]

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Programmable Logic Controller (PLC)

A programmable Logic Controller (PLC) is a specialized computer used for the control and
Operation of manufacturing process and machinery. It uses a programmable memory to store
instructions and execute functions including on/off control, timing, counting, sequencing,
arithmetic, and data handling. Programmable Logic Controllers (PLC) is used in almost every
aspect of industry to expand and enhance production. The major components of PLC are:
Power Supply: Provides the voltage needed to run the primary PLC components
I/O Modules: Provides signal conversion and isolation between the internal logic- level signals
inside the PLC and the field’s high level signal.
Processor: Provides intelligence to command and govern the activities of the entire PLC
systems.
Programming Device: Used to enter the desired program that will determine the
sequence of operation and control of process equipment or driven machine
Communication Channel – Each sensor in the system must be able to communicate fluidly
with the proper computer, which must then be able to communicate with the crane it is
controlling.

Logo PLC

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Figure 3. 4 PLC input and output terminals

3.8.1 System Analysis and Controller Design

Our system is done to activate the crane motors using inverter which is controlled using PLC.
When the operator presses the button on the pendant, it sends out signal to PLC. The relay which
is the output of the PLC will activate the inverter so as to power the motor connected to the
inverter. Speed of the motor is variable i.e. It can be varied by the frequency selector of the
inverter. That means we can vary the speed of the motor as we need.
Overhead crane working speed includes lifting speed, trolley traveling speed, bridge crane
travelling speed. Working speed is influenced by many factors. First, it is related to the weight.
The overhead crane with small and medium load and long travelling distance and high lifting
height can adopt high speed to improve efficiency, the overhead crane with heavy load and short
travelling distance is suitable to choose low speed to reduce driving power and improve
travelling stability and safety.
According to practical needs it can also adopt double speed (high and low speed) dead speed or
adjustable speed. With development of industry, the overhead crane with much transporting
work mostly adopts high speed. The overhead crane used for installation and maintenance adopts
adjustable speed.
The girder of a crane moves in the travelling axis, the trolley moves in the traversing axis and
the object transferred by the crane goes up and down. Their movements are described with

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positions and velocities in the X-Y-Z coordinates. For overhead cranes, cross travel, long travel and
main lifting all need to be working independently.

Figure 3. 5 Block diagram of control system

3.8.2 Design of Hoist Control System

The hoist that is lifting mechanism composed of driving devices (electric motor), breaking
device (brake) and fetching rotating device (hook, grab, magnetic disc, and wire rope, chain,
trolley and drum). When the inputs are pressed, signal is sent to the PLC and the hoist ordered
either to be lifted or lowered. If operator presses the move to down ward button on the pendant,
hoist will move downward and if he presses the move to upward button, it will move upward. If
the load to be lifted is beyond the hoist capacity, the buzzer will be activated to inform the
operator.
Moves the hoist
Up pb upward
Moves the hoist
Down pb PLC Inverter1
downward

Load limiting Buzzer on

device
Figure 3. 6 Block diagram of hoist control system

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The following Flow chart shows over all process of the hoist control system. It is used to simply
to analyze and understand the processes and procedures that the user follows:

Start

no Load limit
Load <10ton
sensor detect

yes
no

Limit Move hoist Move hoist

yes no
switch motor fast motor slow
no

yes
Limit switch

Stop mov’t
Yes

Stop mov’t
end

end

Figure 3. 7 Flowchart for hoist upward

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start

no
load?

no yes

Limit
Move hoist
switc yes motor fast no Move hoist motor slow
h
no
yes
Limit
switch
Stop mov’t

yes

end Stop mov’t

end

Figure 3. 8 Flowchart for hoist downward

And the following ladder diagram shows the control of hoist motor of overhead travelling crane
using PLC by Logo v8 software.

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Figure 3. 9 Ladder diagram for hoist motor

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3.8.3 Design of Trolley Control System

Travelling trolley is composed of electric motor, brake transmission device and trolley wheel
device. The trolley control system is designed to move the trolley machine in two directions.
When the operator presses the move to right push button on the screen, the trolley frame that
contains the trolley and hoist moves to right direction and when he presses then move to left the
direction button, it moves to left direction.

Left pb Moves the

PLC Inverter2
Moves the
Right pb
Figure 3. 10 Block diagram of trolley control system

The following Flow chart shows over all process of the trolley control system.

Figure 3. 11 Flowchart for the trolley

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And the following ladder diagram shows the control of trolley motor of overhead travelling crane
using PLC by Siemens s-7 v-200 software.

Figure 3. 12 Ladder diagram for trolley

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3.8.4 Design of the Crane Bridge Control System

The control system for Crane Bridge or bridge beam is designed to move the trolley frame in to
two directions. When operator presses the move to forward direction button on the pendant, the
bridge will run in to forward direction on the bridge runway rail. When the operator presses the
move to reverse direction button on the pendant, the bridge will move in to reverse direction.

Figure 3. 13 Block diagram of travel bridge control system

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Figure 3. 14 Flowchart for bridge

The following ladder diagram shows the control of bridge motor of overhead travelling crane
using PLC by Siemens s-7 v-200 software.

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Figure 3. 15 Ladder diagram for bridge motor

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3.9 Result and Discussion

3.9.1 Start Stop Control Ladder
This ladder is used to control the whole system. When the start push button (I0.0), is pressed the
ladder power coil Q0.1 is energized. After Q0.1 is energized it is used to supply the power to the
whole ladder. If we want to stop the system, we will press the stop button (I0.1), so Q0.1 will be
de- energized to cut the power supplying the whole ladder program.

Figure 3. 16 Start stop ladder diagram

3.9.2 Hoist Control Ladder

When the operator presses the move hoist down push button (I0.2), Q0.2 will be energized and
hoist will move to downward direction with slow speed. If (I0.3) is pressed, Q0.5 will be
energized and hoist will move downward with fast speed. If (I0.4) is pressed Q0.3 will be
energized and hoist moves upward slowly. To move hoist upward with fast speed we should
press (I0.5) to energize Q0.6. If the load is beyond the capacity of the hoist (above 10 ton), the
normally closed contact (I1.6) (load limiting device) will be opened then motor will stop to run.
Note that Q0.5 is a coil connected to the inverter terminal whose function is to run the system
with fast speed.

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Figure 3. 17 Hoist control ladder diagram

3.9.3 Trolley Control Ladder

When (I0.6) is pressed Q0.7 is energized to move the trolley to left side slowly. And when (I0.7)
is pressed Q1.2 and Q1.1 are energized and trolley moves to left side with fast speed after the
timer reaches 10ms. If (I1.0) is pressed the coil Q1.0 will be energized to move the trolley with

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slow speed to right side and if (I1.1) is pressed, Q1.1 And Q1.2 will energize move with fast
speed into right side.

Figure 3. 18 Trolley control ladder diagram

3.9.4 Bridge Control Ladder

The bridge moves to forward and reverse directions slowly if (I1.2) and (I1.4) are pressed
respectively. And if (I1.3) and (I1.5) are pressed the bridge will move to forward and reverse
direction with fast speed respectively.
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Figure 3. 19 Ladder diagram for bridge

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CHAPTER FOUR
BENEFIT GAINED FROM THE INTERNSHIP
During our internship period we have gained a variety of skills; of which the following can be
mentioned.
4.1Theoretical Knowledge and Practical Skill
We have strengthened the theoretical concepts we have learned so far and a new one about
PLCs. We have adopted practical skills like motor winding, electrical fault inspection and
installation of equipment’s like circuit breakers and motors.
4.2 Team Playing Skills
In our internship period we were working with all technicians, operators, foremen and other
members of the staff. We were asking them whatever question we had. So therefore, we believe
that our team playing skill has developed.
4.3 Inter Personal Skills
Interpersonal skills are set of abilities enabling a person to interact positively and work
effectively with others. These skills include the areas of communication, listening, delegation of
tasks and leadership. Here we can say that we were communicating with all staffs effectively
and we were listening to them their response wisely.
4.4 Leadership Skills
Even though we didn’t participate in leadership arena directly, we were observing how the
foreman, supervisors and department heads manage and convey their order to the workers. This
was a bench mark for us.
4.5 Entrepreneurship Skill and Kaizen Process Of Management
As we presented the background of the company in beginning, it was a small garage but now a
leading company; from here we understand how a business is started. To start a business, it only
needs an idea not much about the initial capital. In addition to this the company is introducing a
management system called Kaizen which is the practice of continuous improvement that is based
on certain guiding principles including;
 Good processes bring good results
 Go see for yourself to grasp the current situation
 Speak with data, manage by facts
 Take action to contain and correct root causes of problems

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 Work as a team
 Kaizen is everybody’s business
 And much more.
4.5.1 Work Ethics
Work ethics is the ability to maintain proper moral values with in the workplace. In this
internship program we had upgraded work ethics including punctuality, being responsible on
work, coordination to work and respecting with each other, being honest to work communication

skills, organization skills, cooperation and respect, etc.

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CHAPTER FIVE
CONCLUSION AND RECOMMENDATION
5.1 Conclusion
To conclude the three month lessons of the internship, it was successful and we have developed
the fundamental abilities in practical works. It was full of practical work tasks with experienced
Engineers and Technicians of Mesfin Industrial engineering (MIE) employers.
In MIE the crane control system of all control devices are wired directly to each other according
to how the system is supposed to operate. Here human is the main to control the crane & that
passes through large drawbacks such as more wiring work, appears large mechanical faults &
difficulties in troubleshooting & repair work. Due to these drawbacks industrial production
decreases largely. In order to remove irregularity of relays and wiring issue we design PLC to
control and monitor the operation of crane in the industry.
The speed control is achieved using VFD drives. In this project, Programmable Logic
Controller (PLC) , pushbutton, limit switch, buzzer, DC and AC supply (220/24) V, cable
software, resistance of control speed by armature method, and hoist-load sensor to designed
and implemented overhead travelling crane testing this model, the operation of motor in the
travelling axis, the trolley moves in the traversing axis and the object transferred by the crane
goes up and down. Their movements are described with positions and velocities in the X-Y-Z
coordinates, when the motor crane ON, see the all motors off (trolley and hoist), when the hoist
motor on, and we see the crane motor and trolley motor off, when the trolley motor on, we
see the hoist and bridge motor off.
Generally the System works during normal operation and greatly improved the automation
processes with the use of the PLC ladder diagram. The ladder logic for contactor logic and
variable frequency simulation has been designed and comparison shows that variable frequency
drives based simulation shows better performance in starting as well running current for
motions in desired directions at different values of speed and troubleshooting and monitoring
is easy. The robust crane control system is designed by using PLC and operated using radio
remote control. The speed control is achieved variable frequency drives or inverter. This control
system will be of immense use in fabrication industries. With PLC, troubleshooting is made easy
and the process becomes simple. Thus this method is user -friendly and can be implemented in
process industries.
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5.2 Recommendation
We would like to recommend the company and anybody who use an overhead travelling carne
machine or who wants to do the project the basic things that it should give cares are listed as
follows.
 The company should have to replace the conventional overhead crane control system by
PLC control system.
 Include the function of the inverter on the PLC controlling unit in order to minimize the
cost of two winding motor and wired system. But buying the three inverters may be
costly. So it is better to use another options.
 The machine manuals should be kept properly at appropriate place to be used easily by
the trainer
 Manuals in the company are written in Spanish or French languages, so it is better if they
are written in English language
 Furthermore, it is better to use modern control system like as fuzzy logic control and
artificial neural control system for more efficiency and accuracy and to eliminate the load
swing.

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