SIX MONTH INDUSTRIAL TRAINING REPORT ON INSTRUMENTATION AND CONTROL COMPLETED AT OCM INDIA LTD SUBMITTED IN PARTIAL FULFILLMENT FOR AWARD OF DEGREE OF BACHELOR OF TECHNOLOGY IN ELECTRONICS & COMMUNICATION ENGINEERING Submitted by Navjot Kaur (100030412289) Preeti Mittal (100030412303) Satnam Kaur (100030412315) Shaina Chhabra (100030412317) Simerjeet Kaur (10030412319) AMRITSAR COLLEGE OF ENGINEERING & TECHNOLOGY, AMRITSAR DEPARTMENT OF ELECTRONICS & COMMUNICATION ENGINEERING 1
Transcript
SIX MONTH INDUSTRIAL TRAINING REPORTON
INSTRUMENTATION AND CONTROLCOMPLETED AT
OCM INDIA LTD
SUBMITTED IN PARTIAL FULFILLMENT FOR AWARD OF DEGREE OF
AMRITSAR COLLEGE OF ENGINEERING & TECHNOLOGY, AMRITSAR
DEPARTMENT OF ELECTRONICS & COMMUNICATION ENGINEERING
DECEMBER, 2013
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DECLARATION CERTIFICATE
We hereby certify that the work which is being presented in the report entitled
“INSTRUMENTATION AND CONTROL” by “SHAINA CHHABRA, NAVJOT KAUR,
SATNAM KAUR, PREETI MITTAL, SIMERJEET KAUR” in partial fulfillment of
requirements for the award of degree of B.Tech. (ECE) submitted to Department of
Electronics and Communication Engineering at Amritsar College Of Engineering And
Technology, Amritsar under PUNJAB TECHNICAL UNIVERSITY, JALANDHAR is an
authentic record of my own work carried out during a period from _________ to _________.
Signature of the Students
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ABSTRACT
The Textile Sector in India ranks next to Agriculture. Textile is one of India’s oldest
industries and has a formidable presence in the national economy in as much as it contributes
to about 14 per cent of manufacturing value-addition, accounts for around one-third of our
gross export earnings and provides gainful employment to millions of people. OCM is one of
the leading textile industry in india. Our work was associated with The Instrumentation and
Control Department of the Industry. This department deals with all the instrumentation and
machinery installed in the mill and various control systems designed to have an effective
control over the whole system.
We studied the use and working of various machinery used in the process of fabric making.
We also studied the control systems installed to make sure the smooth working of different
departments and work areas in the mill.
The experience of six months in the instrumentation department was helpful to make us
familiar with the working of an industry with the latest technology in the control systems.
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ACKNOWLEDGEMENT
I wish to express my profound gratitude to the ALMIGHTY with whose grace and blessings,
I have been able to complete another chapter of my life. I would like to extend my
appreciation to my industrial supervisor, Mr Harjeet Kumar for his advices and patiently
guiding me through while I working here as a trainee. Not forgotten for all the staffs working
at OCM INDIA LTD. I very much appreciate for their entire kindness helping and teaching
me when I'm working there. I am very lucky to have such a helpful colleagues and I never
felt left out in any situation.
I am entrusted to undergo my industrial training at OCM Amritsar for six months before I
can complete my subject course in order to graduate. The motive of this action is to expose
students and let them experience the environment of the real world of working before
graduating. It is also to prepare us to face the real challenge and learn how to find solution
when problem encountered besides completing the course. This exposure not only
prepare us but it is also a great opportunity to gain knowledge at industry. Besides that, it can
prepare us on how to polish more their soft skill especially on how to communicate with
others and learn to do work in a group. I have learnt a lot of valuable things while working
here. I realize that learning theoretical is never the same when it comes to practice. There are
a lot more to master than just learning from book. .
I am thankful to Professor Dr. Vijay Kumar Banga (Principal and Head (ECE), ACET
Amritsar) for making arrangements for the training and supporting with all means during my
training period.
I am thankful to Mr. Gaurav Soni, (Associate Professor, ECE), for the positive and co-
operative response with time, energy and valuable suggestions . He gave me to fulfill the
task. His knowledge and know-how were of extreme importance throughout the work, as well
as his advice, help and guidance. His dedication and opinion were useful not only for the
completion of the training, but also for the professional life ahead of me.
I find no words to acknowledge the sacrifice, love, help and inspiration rendered by my
parents to take up this study.
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TABLE OF CONTENTS
CHAPTER 1
1.1 Introduction
1.1.1 Company profile 8
1.1.2 History(brief) 9
1.1.3 Year Of events 21
1.2 Necessity 25
CHAPTER 2
2.1 Electrical Department
2.1.1 Detail about Motors Used 26
2.2 Machines used at OCM 34
2.3 Electronic Department 41
CHAPTER 3
3.1 Electrical Substation at OCM 62
3.2 Manufacturing Process and Machines 80
3.3 Evaluation of Industrial Control System 87
3.3.1 SCADA systems 92
3.3.2 PLC 98
CHAPTER 4
4.1 Conclusion 99
4.2 References 100
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LIST OF TABLES
Table 1.1.3 Years of Events……………………………………………..21
Table 2.2.1 Machines and their functions………………………………..35
Table 2.3.1 Specifications of Automatic voltage stabalizers…………….53
Table 2.3.2 Features of ACS 150………………………………………...58
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LIST OF FIGURES
Figure 2.1.1.1 Induction Motor………………………………..26
Figure 2.1.1.2 Stepper Motor…………………………………..29
Figure 2.2.1 Donier Machine at OCM……………………….35
Figure 2.2.2 Working of Dornier…………………………….37
Figure 2.2.3 Sulzer Machine at OCM………………………..38
Figure 2.3.1 Transistor……………………………………….43
Figure 2.3.2 Circuit Diagram of FET………………………...44
Figure 2.3.3 Inductive Sensor ……………………………….47
Figure 2.3.4 PLC…………………………………………......49
Figure 2.35 EPROM………………………………………....51
Figure 2.3.6 SMPS…………………………………………...54
Figure 2.3.7 Inverter Driver………………………………….56
Figure 2.3.8 Motor Inverter Driver…………………………..57
Figure 2.3.9 Circuit Diagram of Radix Sensor………………60
Figure 3.1.1 Electrical Substation at OCM…………………..62
Figure 3.3.1 ICS operation…………………………………...89
Figure 3.3.1.1 SCADA systems………………………………..94
Figure 3.3.1.2 Basic SCADA communication topologies……..95
Figure 3.3.1.3 SCADA system implementation………………..97
Figure 3.3.2.1 PLC ……………………………………………..98
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Chapter 1
1.1 INTRODUCTION
1.1.1 COMPANY PROFILE
(An ISO 9001:2000 Certified Company)
“LOVE LIFE & VICE VERSA…..”
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About Us
Since its inception in 1924 as a manufacturer of hand-knotted carpets, OCM has come a long
way to become one of the largest worsted suiting producers, the first one to implement a
customized textile ERP solution.
A completely vertically integrated plant, OCM has in-house production facilities to convert
tops to finished fabrics through dyeing, spinning, weaving and finishing using state-of-the-art
machinery. All the materials and processes pass through stringent checks at every stage and
help in delivering outstanding quality.
At present the company’s capacity includes 34064 Spindles and 182 high speed shuttle less
Looms thereby giving spinning capacity of 12000 kgs yarn and weaving capacity of 25000
Mtrs of fabric per day. The spinning preparatory is from NSC, France, Spindles from Zinser,
Germany, Autoconers from Schlhafhorst, Germany, TFO’s from Leewha, Korea and looms
from Lindaeur Dornier, Germany, Sulzer, Switzerland and Picanol, Belgium. Apart from this,
colour continuity is tested on colour matching system from Gretag Macbreath, UK and fabric
gets final finish on KD from Biella Shrunk, Rotary Press of Mario Crosta, Italy, Continuous
Diarising from Speretto Rimar, Italy, Super finish from M-Tec, Germany and Shearing
machine from Xetma Vollenweider, Switzerland.
1.1.2 HISTORY OF OCM
The images on the following pages illustrate OCM's evolution from a large company in a
small Turkish town to an Oriental carpet giant in the City of London, controlling a huge
network stretching over Asia.
The images on the following pages illustrate OCM's evolution from a large company in a
small Turkish town to an Oriental carpet giant in the City of London, controlling a huge
network stretching over Asia.
OCM - in the minds of many people among the most British of companies - began life based
in the market town of Smyrna, a famous centre for the making of Turkish carpets, but
otherwise a million miles from anywhere. This was the OCM headquarters in Smyrna's main
square:
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The famous photo (in the Oriental carpet world at least) on the right shows locally made
Turkish carpets being brought in by local village weavers to the giant new company that had
suddenly sprung up in their midst. Most of the carpets comprised the ubiquitous red and blue
'Turkey' carpets still in use in many English town and country homes. With its standardised
design, two basic colours and quickly-made but highly durable quality, OCM created in the
Turkey Carpet the first-ever widely affordable handmade Oriental carpet. When it almost
immediately became one of Europe's biggest selling types of carpet, handmade or machine
made, OCM reached a level of success that went far beyond anyone's wildest expectations.
OCM (London) Limited
With its massive early success, OCM quickly moved its core operation from Smyrna to
London - at that time the center of the world Oriental carpet trade.
The London headquarters were established in a showroom/warehouse in Newgate Street, in
the heart of the City of London, adjoining the Old Bailey law court.
What began as a quaint single showroom based upon an English country house interior
rapidly developed into the largest Oriental carpet building in London, comprising five floors
of showroom space accessed from the Warwick Square side of the OCM building and the
only privately owned Bonded Warehouse for Oriental carpets in London that was reached via
the original Newgate Street entrance.
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The original OCM showrooms in Newgate Street, City of London - circa 1908
OCM bonded warehouse in Newgate Street, City of London - circa 1950
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The layout of OCM's London showrooms symbolised the company's increasing domination
of carpet production in the East - an entire floor was devoted to each of major producing
countries
The Chinese Carpets on the 3rd Floor of the OCM London Showrooms
The Persian Carpets on the First Floor of the OCM London Showroom
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Huge Bales of Carpets arriving from India at OCM London's Newgate Street
warehouse. Keeping the global importation and distribution hub that OCM London
had rapidly become supplied was the vast infrastructure of OCM's presence in the
producing countries. Nowhere was this presence more extensive than in India.
The Persian Carpets on the First Floor of the OCM London Showroom
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India - the Jewel in the OCM Crown
While starting out as the dominant manufacturers in Persia and Turkey, it was OCM's revival
of India as a major Oriental carpet origin that first provided the company with the volume of
merchandise and control over designs and colors upon which its success in the Western
markets depended.
Girl weavers at OCM's Amritsar workshop making the finest quality of Indian carpets.
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The huge wool spinning machines installed by OCM at their Amritsar manufactory in India
The huge wool spinning machines installed by OCM at their Amritsar manufactory in India
OCM carpets on the first leg of their journey back to London and from there to America
While it was OCM's Persian and Turkish carpets that enjoyed the greatest popularity in the
Old World of Britain and Europe, it was the far larger output of these exclusively designed
Indian items, and subsequently the company's huge Chinese production, which served to gain
them market leadership in Canada and the USA.
During the 1920s and 1930s, OCM reached the zenith of its fame, prestige and world-wide
influence. In this period the USA and Canada became the company's biggest customers.
OCM's unique ability to meet the rapid growth in demand and highly specific decorative
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requirements of the North American market were the key elements of its success in this
golden era of its long history.
The American Dream The decision to target and develop the huge American market was
made by OCM's managing director during these years, A. Cecil Edwards, later to author the
most famous of all Oriental carpet books - The Persian Carpet - published in 1953.
Fritz and La Rue Under his guidance, the company went into partnership with Fritz and La
Rue, which had been one of the 'Big Three' Oriental carpet importers and wholesalers in the
USA since the beginning of the century. Benefiting from the huge OCM supply, Fritz and La
Rue supplied virtually every major department store chain in the United States in the years
leading up to World War II. Most especially, they completely dominated in the supply of the
new styles of handmade carpets coming from OCM's initiative in India. These brought a new
level of affordability to the Oriental carpet, and soon outsold all other origins, including
Persia....and then Canada OCM also set up OCM (Canada) Ltd during this era, which was
immediately established as the foremost importers of Oriental carpets for the Canadian
market. Biggest in America By 1939, North America had become OCM's largest market:
OCM rugs could be found in every top store in the United States including Macys, Marshall
Fields and B. Altman’s, and their ability to quickly respond to changing tastes in colour and
design was helping to increase their market share daily. Then came the outbreak of the
Second World War. Impact of World War 2 As a company so closely associated with the
British Empire, and one so dependent upon Britain's colonial power, OCM suffered more
than most from the ending of the Empire that World War II made inevitable.
While on the surface OCM remained the dominant force in the British Oriental carpet trade
throughout the frugal post-war years, they were increasingly unable to sustain the global
presence they had been building so effectively in the pre-war era.
Despite this, they remained the most famous Oriental carpet company in the world, and
continued to attract both management and customers of the highest calibre.
Then, in 1985, OCM was acquired by the huge investments company Scottish Heritable Trust
plc and was merged with its oldest UK competitors Eastern Kayam (formerly Eastern Carpets
Ltd) to became Eastern Kayam OCM - the largest Oriental carpet company in history...
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The most authoritative book on Persian carpets of the past hundred and fifty years, The
Persian Carpet was written by A. Cecil Edwards, Managing Director of OCM London, based
upon his experiences while OCM's senior representative In Persia during the 1930s. It is
undoubtedly among the most famous of all Oriental carpet publications.
Succeeding A.Cecil Edwards as OCM's senior buyer in the producing countries, P.R.J. Ford
further emulated his achievements by writing Oriental Carpet Design, among the most
comprehensive of all Oriental carpet books and a world best seller since its publication in the
1980s.
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Eastern Kayam OCM Limited
A Giant is Born
The 1985 acquisition of OCM by Scottish Heritable Trust plc and its subsequent merger with
erstwhile competitors Eastern Kayam (formerly Eastern Carpets, founded 1912) resulted in
the creation ofby far the largest Oriental carpet company in history
This giant company was named Eastern Kayam OCM
Also known as EKOCM
The New Giant Eastern Kayam OCM Ltd - EKOCM - not only encompassed the two huge
British companies after which it was named, but also the largest Oriental carpet company in
the USA, Amiran Inc., the largest Oriental carpet company in France, CNA Tapis, the most
successful Oriental carpet washing company in the world, Oundjian Ltd. and the Indian
carpet manufacturing subsidiary of OCM, E. Hill & Co. No business remotely so large or so
powerful had ever been created in the world of the handmade Eastern carpet.
Its magnificent new headquarters at the Palace of Industry in London's Wembley Stadium
complex was filled with millions of dollars’ worth of the finest goods...
The Impact of EKOCM No other company had ever succeeded so fast, so decisively:
The first and only Oriental carpet company ever quoted on the London Stock
Exchange
Appointed as Preferred Suppliers to Harrods, Libertys, The House of Fraser,
Debenhams, The John Lewis Partnership, Selfrides and even Marks & Spencers
Creators of many high profile branded and trademarked decorator designs and styles which
enjoyed widespread sales success and recognition - e.g. Kangri (Nepalese rugs), Kaimuri
(high calibre Indo-Persian carpets) Indo-Gabbeh (Low priced Indian rugs in modern Abstract
designs)
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A Multi-Million Dollar Inventory
A vast stock of hand-knotted, hand-woven and hand-tufted merchandise from all the major
producing countries, in every conceivable size, style and color, filled the enormous EKOCM
headquarters at the Palace of Industry in Wembley. Huge areas within this massive building -
comprising an entire wing of Wembley Stadium - were given over to the choicest goods from
each of the major knotting origins...
The Kangri Area inside EKOCM's Palace of Industry - these exclusive Nepalese designs
were among EKOCM's most successful lines.
OCM INDIA LTD.
Industry is the soul of a country, which reflects in itself as to where on a country with
regard to its development, technology and economy is standing. It contributes a vital role in
the economy of a country, because its product, if exported, ears foreign currency for the
country where in it is located, which make the country capable to have a hold upon the world
market. Hence, it would not be out of place to mention over here in that industry is backbone
of the country.
OCM is one of the industrial establishments of India, which has provided a remarkable
identification of India, with international market.OCM, the inceptive name of which was
ORIENTAL CARPET MANUFACTURER, was established in 1924 by a British Citizen in
the holly city AMRITSAR. Formerly, it was manufacturing superior quality of carpets and
with passing of time it started manufacturing superior quality of woollen cloth which has an
effective grip not only over the Indian Market but also over the global market.
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In 1971, the OCM is taken over by BIRLA GROUP OF INDUSTRIES and its name was
changed as BIRLA VXL (P) LTD. (OCM WOOLEN MILLS) and from 2007 The Company
has been taken over by WL ROSE and till date it is run and controlled by him with the help
of CEO GK.SHINGHAL. Its products are largely exported which earn foreign currency for
India. The International Trade mark allotted is ISO9001.The full form of ISO is international
Organization for Standardization and at ISO level, the establishment has touched such an
apex of quality, which has done the establishment as first rank in the global market.
OCM India limited manufacturer wool blended, poly wool, polister, woollen and linen
textiles and fabrics. It also provides suits, safaris, uniforms, tweets and jacket, troserand
specialities, as well as shawls, blankets and lohis. The company exports its products in
Europe, United States and Asia. OCM India ltd. was formerly known as the east India carpet
co.ltd.and changed its name in January 1989. The company was incorporated in 1922 and its
headquarters are in New Delhi, India. OCM India ltd. Operate as a former subsidiary of dig
jam ltd. Since 1946 OCM recanzone S.R.L., located in Biella, produce and export high
quality industrial doors
OCM always propose all their customers the best quality-price ratio available on market.
Customer can choose between several different types of products, all extremely durable, such
as high speed pack-away or rollup-doors, partition walls, strip curtains, polyethylene doors
and much more.
While using OCM product you can save both money and energy. This is one of our main
aims such as the constant research of safe guarding our planets and surroundings.
Moreover, OCM technical team help customer to consider which would be the best door to
install in there plant that gives them all the information and details they need in order to make
up their mind.
OUR VISION:
While using OCM product you can save both money and energy. This is one of our main
aims such as the constant research of safe guarding our planets and surroundings.
OUR MISSION:
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Moreover, OCM technical team help customer to consider which would be the best door to
install in there plant that gives them all the information and details they need in order to make
up their mind.
1.1.3 Years of Events
YEARS EVENTS
1948 The Company was incorporated on 15 March, at Mumbai. The company
manufacturer all kinds of woollen and worsted yarns and piece goods.
1980 A letter of intent was received for 1,200 NMM worsted spindles which
were installed and commissioned
1981 8, 38,796 Bonus shares issued in prop.1:1.
1982 The Company received Govt. approval to further expand the spinning
capacity. One more diesel generating set of 750KVA was added.
During November the Company issued 1,60,000-13.5% secured
convertible debentures of Rs 125 each of foe a total amount of Rs 2 crore
out of which 95,000 debenture were offered to the public.
Out of each debenture Rs 45 was convertible into 3 equal shares of Rs 10
each of at of premium of Rs 5 per share on 1st July 1983. The balance Rs
80 per debenture was to be redeemed at par in three annual instalments of
Rs 25, Rs 25and Rs 30 commencing from the end of the 8 th year from the
date of allotment.
1983 The company undertook to set up a modern vegetable oil extraction plant
at Harda in the District Hoshangabad in Madhya Pradesh
The Oriental Carpet Manufacturer Ltd. (OCM) and Universal Electric
Ltd. were amalgamated with Shree Digvijya Woollen Mills ltd. with
effect from 1st July. Consequent upon this amalgamation shareholder of
OCM were to be allotted 8, 33,468 No. of equal share of Rs 10 each in the
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PROP. Of 1 equal share of Rs 1575 No. of equal share of held in OCM
and 15000-11% preference share of Rs 100 each in the Prop. Of 1
preference share of SDM for every 10 preference share held in OCM.
The shareholder of UEL were to be allotted 7, 90,778 No. of equal share
of Rs10 each in the prop. Of 1equal share of SDM for every 2025 equal
share held in UEL and 8,100-6.5% preference share of Rs 100 each in the
Prop. Of 1 preference share of SDM for every preference share held in
UEL.
Out of these, 15000-11% preference share holder of OCM and UEL were
allotted during 1985-86. Allotment of 8,100-6.5% preference share for the
preference share holder of UEL and 1, 23,661 No. of equal shares to the
equal share holder of OCM and UEL was pending.
4, 79, 925 shares allotted in conversation of deb. Prem. Rs 5 per share.
1984 The company proposal to take up a modernization programme at the
Jamnagar and Amritsar Units
Land, building, plant and machinery and vehicles of Mujesan
(Ahmedabad) unit were revaluing and net surplus of Rs 263.15 lakhs
arising out of this was credited to capital reserve.
1985 Some shuttle less looms were installed at the Dig jam and the OCM
woollen Mills division
The name of the company was changed from Shree Digvijay Mills ltd. to
the one which is at present. During 1994-95 the company name was again
changed from VXL India Ltd. to the present one.
Authorised capital reclassified, 15000-11% Pref. and 15, 00,585 No. of
equal shares issued without payment in cash as per the scheme of merger.
The company considered a proposal to manufacturer ready to wear men’s
suits.
The company proposed to expand its business in high-tech electronic
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equipment in Universal Engineering, high protein soya-based meals and
fields in Sidharth Oils
An agreement was entered into with the Mitsubishi Electric Corporation
in connection with export of components and protection panels
manufactured by the company.
Authorised capital increased 37, 81,763 bonus shares issued in prop.1:1.
1989 The company installed 15 high speed sulzer looms.
A letter of content was received for the manufacture of the microwave
components and connectors.
Also an agreement was entered into with Landis and Gyr a Swiss
company for jointly setting up facilities in India to manufacture a superior
range of electricity meters and test benches with a substantial export
commitment.
Landis and Gyr also agreed to subscribe to the quality capital of VXL to
the extent of S.Fr. 2 million
During February-March ,the company offered 15,50,000-12.5% secured
redeemable partly convertible of Rs 100 each on Right basis in the
proportion 1 debenture 5 equal share held(all were taken up). Additional
2,32,500 debentures were allotted to retain over-subscription.
During the same period, the Company issued through a prospectus
14,50,000-12.5% partly convertible debentures of Rs 100 each out of
which the following debentures were reserved for preferential allotment:
(i)1,50,000-12.5% to employees (including Indian working
directors)workers on equitable basis (only 11,790 debentures taken up)
and (ii)3,00,000 debenture to NRIs on repatriation basis(all were taken
up).
The balance 10,00,000 debentures along with 1,38,210 debentures not
taken up by the employee were offered to the public. Additional 2,17,500
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debentures were allotted to retain over subscription(45,000 debentures to
NRI and 1,72,500 debentures to the public.)
Rs 50 of the face value of each debenture was to be converted to equal
share of Rs 10 each at a premium of Rs 15 per share on the expiry of 6
months from the date of allotment of debentures.
The remaining of the Rs 50 of the face value of the each debenture was to
be redeemed in the pair at 3 annual instalments of Ra 17,Rs 17 and Rs 16
Table 1.1.3 Years of events
1.2 NECESSITY
Instrumentation Department:
Instruments play a big role in industry. Now almost in every industry automation system is
introduced. So during running time of plant we have to set some control in input and output
and also during processing. These all are done in auto now a days. So we have to measure
some parameters like level, pressure, flow and temperature. While automation system is
running we look all these parameters carefully so that production are not hampered, otherwise
we may face to a big problem or loss.
Control Systems:
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Industrial control system (ICS) is a general term that encompasses several types of control
systems, including supervisory control and data acquisition (SCADA) systems, distributed
control systems (DCS), and other control system configurations such as skid-mounted
Programmable Logic Controllers (PLC) often found in the industrial sectors and critical
infrastructures. ICS are typically used in industries such as electrical, water and wastewater,
oil and natural gas, chemical, transportation, pharmaceutical, pulp and paper, food and
beverage, and discrete manufacturing (e.g., automotive, aerospace, and durable goods.)
Moreover Control system ensures the proper working of the various workshops in the
industry .
Chapter 2
2.1 ELECTRICAL DEPARTMENT
2.1.1 Details about Motors used:
AC MOTORS
INDUCTION MOTORS
An induction or asynchronous motor is a type of AC motor where power is supplied to the
rotor by means of electromagnetic induction. These motors are widely used in industrial
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drives, particularly polyphase induction motors, because they are robust and have no brushes.
Their speed can be controlled with a variable frequency drive.
Figure 2.1.1.1 Induction motor
Operation and comparison to synchronous motors
In a synchronous AC motor, the rotating magnetic field of the stator imposes a torque on the
magnetic field of the rotor, causing it to rotate steadily. It is called synchronous because at
steady state, the speed of the rotor matches the speed of the rotating magnetic field in the
stator. By contrast, an induction motor has a current induced in the rotor; to do this, stator
windings are arranged so that when energized with a polyphase supply they create a rotating
magnetic field that induces current in the rotor conductors. These currents interact with the
rotating magnetic field, causing rotational motion of the rotor.
For these currents to be induced, the speed of the physical rotor must be lower than that of the
stator's rotating magnetic field (ns), or the magnetic field would not be moving relative to the
rotor conductors and no currents would be induced. If this happens while the motor is
operating, the rotor slightly slows down, and consequently a current is induced again. The
ratio between the speed of the magnetic field as seen by the rotor (slip speed) and the speed
of the stator's rotating field is unitless and it is called slip. For this reason, induction motors
are sometimes referred to as asynchronous motors. An induction motor can be used as
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induction generator, or it can be unrolled to form the linear induction motor which can
directly generate linear motion.
Induction motors are also called as asynchronous motors. Induction motors may be single
phase or three phases. The single phase Induction motors are built in small sizes and these
motors are also called fractional horse power motors. The three phases Induction motors are
the most commonly used in the O.C.M. industry, because they have simple and rugged
construction, low cost, high efficiency, reasonably good power factor, self-starting torque.
These motors are require little maintenance almost more than 90% of the mechanical power
used in the industry is provided by three phase Induction motors.
CONSTRUCTION FEATUERS OF THREE PHASE
INDUCTION MOTORS:-
There are two main parts of motors:-
1. STATOR-
It is stationary part of motors. It has three parts:
1. Outer frame
2. Stator core
3. Stator
(A). OUTER FRAME:-
It is Outer body of the motors. Its function of two supports the stator core winding and to protect the inner parts of the machine.
(B). STATOR CORE:-
The Stator core is to carry the alternating magnetic field which produces hysteresis and eddy current losses, therefore core is built up of high grade silicon steel stampings. These are stampings are insulated from each other.
(C). STATOR WINDING:-
Stator core carries a three phase winding which is usually supplied from a three phase supply system. The six terminal of the winding are connected in the terminal box of the machine.
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The stator of the motor is wound for definite no. of poles the exact number being find by the requirement of speed. The three phase winding may be connected in star or delta externally. The winding is designed to be delta connected for normal running.
2. ROTORS:-
It is rotating parts of the motor. There are two types of rotors. Which are employed in three phase Induction Motors
(A). SQUIRREL CAGE ROTOR:-
The motor employing these types of rotor is known as squirrel cage induction motor. Most of the induction motor is of these types because simple of rugged construction of the rotor. A squirrel cage rotor consists of laminated cylindrical core having semi closed circular slots at outer periphery. Copper and aluminium bars are inserted in these slots are joined at each end by copper and aluminium rings called short circuiting rings. Thus winding is permanently short circuited and it is not possible to add any external resistance in the rotors circuit. The slots are usually not parallel to the shaft but are skewed because of humming magnetic locking, resulting smoother torque, and increases rotor resistance.
(B).PHASE WOUND ROTORS:-
These types of rotor is called slip ring rotor and the motor employing this types of rotor is known as phase wound and slip ring rotor. Slip ring rotor consist of laminated cylindrical core having semi closed circular slots at outer periphery and carries a three phase insulated winding the rotor is wound for same no poles as that of stator. The finishing terminals are connected together and the three start terminals are connected to the three copper slip ring fixed on the shaft. In the case depending upon requirement any external resistance can be added in the rotors circuit.
PRINCIPLE OF OPERTION:-
When three phase supply is given to the stator of three phase wound induction, rotating field is set up in the stator. The stationary rotor conductors cut the revolving and by induction e.m.f. is induced in the conductors. As the rotors conductors are short circuited, current flow through them in the direction of revolving flux rotors current carrying conductors set up a resultant field. By the alignment of the field an electromagnetic torque is developed in the anti-clockwise direction. Thus the rotors start rotating in the same direction in the same in which stator field is revolving.
STEPPER MOTOR
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A stepper motor (or step motor) is a brushless, electric motor that can divide a full rotation
into a large number of steps. The motor's position can be controlled precisely without any
feedback mechanism (see Open-loop controller), as long as the motor is carefully sized to the
application. Stepper motors are similar to switched reluctance motors (which are very large
stepping motors with a reduced pole count, and generally are closed-loop commutated).
Figure 2.1.1.2 Stepper Motor
Stepper motors operate differently from DC brush motors, which rotate when voltage is
applied to their terminals. Stepper motors, on the other hand, effectively have multiple
"toothed" electromagnets arranged around a central gear-shaped piece of iron. The
electromagnets are energized by an external control circuit, such as a microcontroller. To
make the motor shaft turn, first, one electromagnet is given power, which makes the gear's
teeth magnetically attracted to the electromagnet's teeth. When the gear's teeth are aligned to
the first electromagnet, they are slightly offset from the next electromagnet. So when the next
electromagnet is turned on and the first is turned off, the gear rotates slightly to align with the
next one, and from there the process is repeated. Each of those slight rotations is called a
"step", with an integer number of steps making a full rotation. In that way, the motor can be
turned by a precise angle.
TYPES:
There are four main types of stepper motors:
Permanent Magnet Stepper (can be subdivided in to 'tin-can' and 'hybrid', tin-can being a
cheaper product, and hybrid with higher quality bearings, smaller step angle, higher power
density)
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Hybrid Synchronous Stepper
Variable Reluctance Stepper
Lavet type stepping motor
Permanent magnet motors use a permanent magnet (PM) in the rotor and operate on the
attraction or repulsion between the rotor PM and the stator electromagnets. Variable
reluctance (VR) motors have a plain iron rotor and operate based on the principle that
minimum reluctance occurs with minimum gap, hence the rotor points are attracted toward
the stator magnet poles. Hybrid stepper motors are named because they use a combination of
PM and VR techniques to achieve maximum power in a small package size.
DC MOTOR
A DC motor is an electric motor that runs on direct current (DC) electricity. The dc motors is an electro chemical energy device which convert electrical power into mechanical power. Battery is prime source of D.c motors. The main constructional features of D.c motors are given below:
• Magnetic frame or yoke
• Pole core and pole shoes
• Fields coil or exciting coil
• Armature core
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• Armature winding
• Commutator
• Brushes
• End housing or covers
• Bearing
• Shaft etc.
MAGNETIC FRAME:
The outer cylindrical frame to which main poles and inter poles are fixed and by mean of which the machine is bolted to the foundation plate is called the yoke or magnetic frame.
POLE CORES AND POLES SHOE:
The Pole core and pole shoes are fixed to magnetic frame or yoke by bolts.
FIELDS COILS OR EXICTING COILS:
The field’s coils consist of copper wire or strip. The fields is wound on the former and placed around the pole core.
ARMATURE CORE:
It is a cylindrical in shape. It is rotating parts of motors keyed to the shaft at the outer periphery there are slots which accommodate the conductors.
ARMATURE WINDING:
The armature winding is a heart of D.C motors. The insulated conductors housed in the armature slots are suitably connected.
COMMUTATORS:
It is connected the rotating armature conductor to the stationary external circuit through brushes. It converts alternative torque to the unidirectional torque produced in the motor action.
BRUSHES:
These are rubbing upon the commutator and from the connecting link between the armature winding and the external circuit. They are usually made up of high grade carbon because
31
carbon is conducting material and at same time in powdered from provide lubricating effect on the commutator surface.
END HOUSING:
These are attached to the ends on the main frame and supports bearings.
BEARINGS:
The function of bearings is to reduce between rotating and stationary parts of rotor.
SHAFT:
The mechanical energy comes on the shaft of the motor.
TYPES:
DC motors are of two types:
1. Brushed DC electric Motor:
The brushed DC electric motor generates torque directly from DC power supplied to the
motor by using internal commutation, stationary magnets (permanent or electromagnets), and
rotating electrical magnets.
Like all electric motors or generators, torque is produced by the principle of Lorentz force,
which states that any current-carrying conductor placed within an external magnetic field
experiences a torque or force known as Lorentz force. Advantages of a brushed DC motor
include low initial cost, high reliability, and simple control of motor speed. Disadvantages are
high maintenance and low life-span for high intensity uses. Maintenance involves regularly
replacing the brushes and springs which carry the electric current, as well as cleaning or
replacing the commutator. These components are necessary for transferring electrical power
from outside the motor to the spinning wire windings of the rotor inside the motor.
2. Brushless:
Brushless DC motors use a rotating permanent magnet or soft magnetic core in the rotor, and
stationary electrical magnets on the motor housing. A motor controller converts DC to AC.
This design is simpler than that of brushed motors because it eliminates the complication of
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transferring power from outside the motor to the spinning rotor. Advantages of brushless
motors include long life span, little or no maintenance, and high efficiency. Disadvantages
include high initial cost, and more complicated motor speed controllers. Some such brushless
motors are sometimes referred to as "synchronous motors" although they have no external
power supply to be synchronized with, as would be the case with normal AC synchronous
motors
2.2 MACHINES USED AT OCM
WARPING MACHINES:
Name of machines Makers
BANNIZER WARPING SWITZERLAND
S.F WARPING GERMAN
B.M WARPING INDIAN
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RABATEX INDIAN
KNOTTING MACHINE:
Name of machines Makers
STABULI KNOTTING MACHINE SWITZERLAND
WEAVING MACHINE:
Name of machines Makers
CIMMCO DORNIER INDIAN
H.T.V.S DORNIER GERMAN
PICANOL G.T.X BELGIUM
SULZER P.U SWITZERLAND
GC-14 GILL BOXES (4 SET M/Cs) NSC, FRANCE
PB-31 COMBIER NSC, FRANCE
GC-14, GC-14 A/BOLLING NSC, FRANCE
FM-7 FLYING ROVER NSC, FRANCE
BM-14 ROVER NSC, FRANCE
ZINSER RING FRAME 421(44 NOSAL MACHINE) ZINSER, GERMANY
34
NAME OF MACHINES FUNCTION MAKER• NEW K.D DECATIZING BIELLA SHRUNK
Filling insertion with positively controlled center transfer is the heart of the P1 rapier
weaving machine .The filling is picked up and transferred precisely and reliably through the
open shed and held securely until bound in. The human hand as the model With positive
center transfer, the rapier motion is precisely controlled via complementary cam gear
boxes. The open left-hand clamp of the left hand rapier grips the yarn presented by the filling
selector needle before entering the shed. After controlled closure of this clamp, scissors cut
off the filling at the fabric side. Filling transfer from left-hand to right-hand rapier is effected
positively in the center under full control. Following the pick transfer, the taker rapier brings
35
the filling to the right-hand fabric edge. The shed remains open throughout the entire
insertion phase. The filling is released by the controlled rapier clamp only when it is firmly
secured by the catch selvedge. Rapier motion and function during filling insertion are similar
to baton changing between two athletes during a relay race.
The DORNIER-specific filling insertion system
1. Yarn pick-up by the left-hand rapier before entry into the shed.
2. Filling yarn transfer in the fabric center.
3. Release of the inserted filling by the righth and rapier only after being secured by the
catch selvedge.
Filling insertion with positively controlled center transfer is the heart of the P1 rapier
weaving machine.
The filling is picked up and transferred precisely and reliably through the open shed and held
securely until bound in.
36
Figure 2.2.2 Working Of Dornier
37
SULZER MACHINE
Sulzer machine is also called a shutless loom. In this projectile are used for weft pattern two
boxes are used.
• Picking box
• Receiving box
In the weft thread comes from picking side and receives from receiving box. In this
accommodators are used to give continues supply of weft according to requirement of weft.
SETTING IN THE SULZER
• Picking is done at 150 degree.
• Revision is done at 80 degree.
• Monthly is done at 80 degree.
• Saviour is cutting thread done at 10 degree.
• Needles setting at 190,240,270 degree for selvedge.
• Gap between pripper and projectile 4mm and setting at 325 degree.
Figure 2.2.3 Sulzer machine at OCM
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BREAK
Break is used to stop the automatic machine. Automatic break is used in sulzer machine when any wrap thread or weft thread break machine is automatically stopped.
Setting of the break is done are -:.1mm, .2mm, .3mm, .4mm. It can be easily checked with the help of the gauge. It can be easily move in the break. We can easily open the parts of the machine at 80 degree monthly also done at the setting of 80 degree.
PARTS OF THE BREAK
1. DRUM
2. TWO PULLEYS
3. FOUR BELTS
4. SETTING OF BREAK .1MM, .2MM, .3MM, .4MM
PARTS OF PICKING SIDE
• FEEDER OPENER
• FEEDER PROJECTILE OPENER
• SLIDE PIECE
• UPPER GUIDE RAIL
• LOWER GUIDE RAIL
• SLIDE PIECE LINK
• PICKING SHOE
• LIFTER
RECEIVING BOX
• FRONT BREAK
• RARE BREAK
• LOWER BREAK
• RETURNER
• RETURNER LINK
TYPES OF LET OFF USED IN O.C.M.39
• SIMCO LET OFF
• HI-TECH LET OFF
• SUPER HUNT LET OFF
PARTS OF BREAK
• DRUM
• SPRINGS 16-18 SPRINGS IS USED
• BRASS SIM
• PLATE
• ROTOR
• 9 PLATES, 4 FIBRE DISC, 5 STEEL PLATES
• SLIVES
• CLUTCH PLATE
• PULLEY
• HAND BREAK
FUNCTIONS
• HAND WHEEL- We can easily move the machine with the help of the hand wheel.
• PULLEY - Pulleys is used to attach with motor with the help of belts.
• CLUTCH PLATE-It is used for setting of fibre plates. It is as locking device.
• SLIVES- Slives is used to press the rings or it is also used to move the fibre plates.
• ROTOR- Rotor is used for setting of plates it is also used move the fibre plates .
FOUR TYEPS OF LOOMS USED IN O.C.M.
• POWER LOOM
• DORNIER (SHUTTLE LESS)
• SULZER
• PICANOL
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2.3 ELECTRONIC DEPARTMENT
Electronics is the backbone of any firm. Every department is dependent on it right from
spinning to finishing. HOD is responsible to all activities of impletion and adherence to all
the procedures concerned of the respective department. The whole organization has been
divided into various departments. Each department has a huge difference in the working.
Each department has different machines of working. The machines were used to create a
design for summer and winter season every year. After the creation of design yarn
identification is done. After that the whole information regarding the design is noted on a
master card and then the cloth is to be made with the help of automatic machines just by
feeding suitable programs.
Electronics is the branch of science, engineering and technology that deals with electrical
circuits involving active electrical components such as vacuum tubes, transistors, diodes and
integrated circuits, and associated passive interconnection technologies. The nonlinear
behaviour of active components and their ability to control electron flows makes
amplification of weak signals possible and is usually applied to information and signal
processing. Similarly, the ability of electronic devices to act as switches makes digital
information processing possible. Interconnection technologies such as circuit boards,
electronics packaging technology, and other varied forms of communication infrastructure
complete circuit functionality and transform the mixed components into a working system.
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There are various types of electronic components on which the working of the machines is
dependent. These components are:
Transistor
Transformer
EPROM
PLC
Processor
Controller
Diodes
TRANSISTORS:
A transistor is a semiconductor device used to amplify and switch electronic signals and
power. It is composed of a semiconductor material with at least three terminals for
connection to an external circuit. A voltage or current applied to one pair of the transistor's
terminals changes the current flowing through another pair of terminals. Because the
controlled (output) power can be much more than the controlling (input) power, a transistor
can amplify a signal. Today, some transistors are packaged individually, but many more are
found embedded in integrated circuits.
The transistor is the fundamental building block of modern electronic devices, and is
ubiquitous in modern electronic systems. Following its release in the early 1950s the
transistor revolutionized the field of electronics, and paved the way for smaller and cheaper
radios, calculators, and computers, among other things.
42
Figure 2.3.1 Transistor
TYPES OF TRANSISTORS:
NPN and PNP are the two types of standard transistors, each having different circuit symbols.
The letters used in these descriptions are references to what material is used to create these
devices. NPN is the most commonly used because they are easily made silicon.
A Darlington pair describes a connection of two transistors paired for the purpose of emitting
a very high current gain.
The PNP Transistor could be considered the reverse opposite of the NPN Transistor. This
Transistor employs the two diodes are reversed with respect to the NPN. This type gives a
Positive-Negative-Positive configuration, which also defines the Emitter terminal.
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An additional type of transistor is the field-effect transistor, usually referred to as FETs
Figure 2.3.2 Transister
The essential usefulness of a transistor comes from its ability to use a small signal applied
between one pair of its terminals to control a much larger signal at another pair of terminals.
This property is called gain. A transistor can control its output in proportion to the input
signal; that is, it can act as an amplifier. Alternatively, the transistor can be used to turn
current on or off in a circuit as an electrically controlled switch, where the amount of current
is determined by other circuit elements.
There are two types of transistors, which have slight differences in how they are used in a
circuit. A bipolar transistor has terminals labeled base, collector, and emitter. A small
current at the base terminal (that is, flowing from the base to the emitter) can control or
44
switch a much larger current between the collector and emitter terminals. For a field-effect
transistor, the terminals are labeled gate, source, and drain, and a voltage at the gate can
control a current between source and drain.
The image to the right represents a typical bipolar transistor in a circuit. Charge will flow
between emitter and collector terminals depending on the current in the base. Since internally
the base and emitter connections behave like a semiconductor diode, a voltage drop develops
between base and emitter while the base current exists. The amount of this voltage depends
on the material the transistor is made from, and is referred to as VBE.
RELAY
A relay is an electrically operated switch. Many relays use an electromagnet to operate a
switching mechanism mechanically, but other operating principles are also used. Relays are
used where it is necessary to control a circuit by a low-power signal (with complete electrical
isolation between control and controlled circuits), or where several circuits must be
controlled by one signal. The first relays were used in long distance telegraph circuits,
repeating the signal coming in from one circuit and re-transmitting it to another. Relays were
used extensively in telephone exchanges and early computers to perform logical operations.
A type of relay that can handle the high power required to directly control an electric motor is
called a contactor. Solid-state relays control power circuits with no moving parts, instead
using a semiconductor device to perform switching. Relays with calibrated operating
characteristics and sometimes multiple operating coils are used to protect electrical circuits
from overload or faults; in modern electric power systems these functions are performed by
digital instruments still called "protective relays".
45
Figure 2.3.3 a Transistor
A simple electromagnetic relay consists of a coil of wire surrounding a soft iron core, an iron
yoke which provides a low reluctance path for magnetic flux, a movable iron armature, and
one or more sets of contacts (there are two in the relay pictured). The armature is hinged to
the yoke and mechanically linked to one or more sets of moving contacts. It is held in place
by a spring so that when the relay is de-energized there is an air gap in the magnetic circuit.
In this condition, one of the two sets of contacts in the relay pictured is closed, and the other
set is open. Other relays may have more or fewer sets of contacts depending on their function.
The relay in the picture also has a wire connecting the armature to the yoke. This ensures
continuity of the circuit between the moving contacts on the armature, and the circuit track on
the printed circuit board (PCB) via the yoke, which is soldered to the PCB.
TYPES OF RELAYS:
Latching relay
Reed relay
Mercury-wetted relay
Polarized relay
Machine tool relay
Ratchet relay
Contactor relay
Solid-state relay46
Solid state contactor relay
Buchholz relay
Forced-guided contacts relay
Overload protection relay
INDUCTIVE SENSOR
An inductive sensor is an electronic proximity sensor, which detects metallic objects without
touching them.
The sensor consists of an induction loop. Electric current generates a magnetic field, which
collapses generating a current that falls asymptotically toward zero from its initial level when
the input electricity ceases. The inductance of the loop changes according to the material
inside it and since metals are much more effective inductors than other materials the presence
of metal increases the current flowing through the loop. This change can be detected by
sensing circuitry, which can signal to some other device whenever metal is detected.
Common applications of inductive sensors include metal detectors, traffic lights, car washes,
and a host of automated industrial processes. Because the sensor does not require physical
contact it is particularly useful for applications where access presents challenges or where dirt
is prevalent. The sensing range is rarely greater than 6 cm, however, and it has no
directionality.
Figure 2.3.3 Inductive sensor
PHOTO SENSORS47
Photo sensors are sensors of light or other electromagnetic energy. There are several
varieties:
Active pixel sensors are image sensors consisting of an integrated circuit that contains
an array of pixel sensors, each pixel containing a both a light sensor and an active
amplifier. There are many types of active pixel sensors including the CMOS APS
commonly used in cell phone cameras, web cameras, and some DSLRs. An image
sensor produced by a CMOS process is also known as a CMOS sensor, and has
emerged as an alternative to Charge-coupled device (CCD) sensors.
Charge-coupled devices (CCD), which are used to record images in astronomy, digital
photography, and digital cinematography. Although before the 1990s photographic
plates were the most common in astronomy. Glass-backed plates were used rather
than film, because they do not shrink or deform in going between wet and dry
condition, or under other disturbances. Unfortunately, Kodak discontinued producing
several kinds of plates between 1980 and 2000, terminating the production of
important sky surveys. The next generation of astronomical instruments, such as the
Astro-E2, include cryogenic detectors. In experimental particle physics, a particle
detector is a device used to track and identify elementary particles.
Chemical detectors, such as photographic plates, in which a silver halide molecule is
split into an atom of metallic silver and a halogen atom. The photographic developer
causes adjacent molecules to split similarly.
Cryogenic detectors are sufficiently sensitive to measure the energy of single x-ray,
visible and infrared photons.
LEDs reverse-biased to act as photodiodes. See LEDs as Photodiode Light Sensors.
Optical detectors, which are mostly quantum devices in which an individual photon
produces a discrete effect.
Optical detectors that are effectively thermometers, responding purely to the heating
effect of the incoming radiation, such as pyro electric detectors, Golay cells,
thermocouples and thermistors, but the latter two are much less sensitive.
Photo resistors or Light Dependent Resistors (LDR) which change resistance
according to light intensity
Photovoltaic cells or solar cells which produce a voltage and supply an electric
current when illuminated
48
Photodiodes which can operate in photovoltaic mode or photoconductive mode
Photomultiplier tubes containing a photocathode which emits electrons when
illuminated, the electrons are then amplified by a chain of dynodes.
Phototubes containing a photocathode which emits electrons when illuminated, such
that the tube conducts a current proportional to the light intensity.
Phototransistors, which act like amplifying photodiodes.
Quantum dot photoconductors or photodiodes, which can handle wavelengths in the
visible and infrared spectral regions.
PROGRAMMABLE LOGIC CONTROLLER
A programmable logic controller (PLC) or programmable controller is a digital
computer used for automation of electromechanical processes, such as control of machinery
on factory assembly lines, amusement rides, or light fixtures. PLCs are used in many
industries and machines. Unlike general-purpose computers, the PLC is designed for multiple
inputs and output arrangements, extended temperature ranges, immunity to electrical noise,
and resistance to vibration and impact. Programs to control machine operation are typically
stored in battery-backed-up or non-volatile memory. A PLC is an example of a hard real time
system since output results must be produced in response to input conditions within a
bounded time, otherwise unintended operation will result.
Figure 2.3.4 PLC
49
PROGRAMMING:
Early PLCs, up to the mid-1980s, were programmed using proprietary programming panels
or special-purpose programming terminals, which often had dedicated function keys
representing the various logical elements of PLC programs. Programs were stored on cassette
tape cartridges. Facilities for printing and documentation were very minimal due to lack of
memory capacity. The very oldest PLCs used non-volatile magnetic core memory.
More recently, PLCs are programmed using application software on personal computers. The
computer is connected to the PLC through Ethernet, RS-232, RS-485 or RS-422 cabling. The
programming software allows entry and editing of the ladder-style logic. Generally the
software provides functions for debugging and troubleshooting the PLC software, for
example, by highlighting portions of the logic to show current status during operation or via
simulation. The software will upload and download the PLC program, for backup and
restoration purposes. In some models of programmable controller, the program is transferred
from a personal computer to the PLC though a programming board which writes the program
into a removable chip such as an EEPROM or EPROM.
EPROM:
An EPROM (rarely EROM), or erasable programmable read only memory, is a type of
memory chip that retains its data when its power supply is switched off. In other words, it is
non-volatile. It is an array of floating-gate transistors individually programmed by an
electronic device that supplies higher voltages than those normally used in digital circuits.
Once programmed, an EPROM can be erased by exposing it to strong ultraviolet light from a
mercury-vapour light source. EPROMs are easily recognizable by the transparent fused
quartz window in the top of the package, through which the silicon chip is visible, and which
permits exposure to UV light during erasing.
50
Figure 2.3.5 EPROM
As the quartz window is expensive to make, OTP (one-time programmable) chips were
introduced; here, the die is mounted in an opaque package so it cannot be erased after
programming - this also eliminates the need to test the erase function, further reducing cost.
OTP versions of both EPROMs and EPROM-based microcontrollers are manufactured.
However, OTP EPROM (whether separate or part of a larger chip) is being increasingly
replaced by EEPROM for small amounts where the cell cost isn't too important and flash for
larger amounts.
A programmed EPROM retains its data for a minimum of ten to twenty years, with many still
retaining data after 35 or more years, and can be read an unlimited number of times. The
erasing window must be kept covered with an opaque label to prevent accidental erasure by
the UV found in sunlight or camera flashes. Old PC BIOS chips were often EPROMs, and the
erasing window was often covered with an adhesive label containing the BIOS publisher's
name, the BIOS revision, and a copyright notice. Often this label was foil-backed to ensure
its opacity to UV.
Erasure of the EPROM begins to occur with wavelengths shorter than 400 nm. Exposure time
for sunlight of 1 week or 3 years for room fluorescent lighting may cause erasure. The
recommended erasure procedure is exposure to UV light at 253.7 nm of at least 15
W-sec/cm2 for 20 to 30 minutes, with the lamp at a distance of about 1 inch.
Erasure can also be accomplished with X-rays:
"Erasure, however, has to be accomplished by non-electrical methods, since the gate
electrode is not accessible electrically. Shining ultraviolet light on any part of an unpackaged
device causes a photocurrent to flow from the floating gate back to the silicon substrate,
51
thereby discharging the gate to its initial, uncharged condition. This method of erasure allows
complete testing and correction of a complex memory array before the package is finally
sealed. Once the package is sealed, information can still be erased by exposing it to X
radiation in excess of 5*104 rads, a dose which is easily attained with commercial X-ray
generators." (5*104 rad = 500 J/kg)
"In other words, to erase your EPROM, you would first have to X-ray it and then put it in an
oven at about 600 degrees Celsius (to anneal semiconductor alterations caused by the x-rays).
The effects of this process on the reliability of the part would have required extensive testing
so they decided on the window instead." (Any temperature between 450 - 1410 °C should
work).
EPROMs had a limited but large number of erase cycles; the silicon dioxide around the gates
would accumulate damage from each cycle, making the chip unreliable after several thousand
cycles. EPROM programming is slow compared to other forms of memory. Because higher-
density parts have little exposed oxide between the layers of interconnects and gate,
ultraviolet erasing becomes less practical for very large memories. Even dust inside the
package can prevent some cells from being erased.
AUTOMATIC VOLTAGE STABILIZERS
Our automatic voltage controller are precisely designed & engineered to deliver higher output
to our clients. Used for different electrical applications, our automatic voltage stabilizers
ensure longer performance and they are built to provide effective solution to problems like
voltage fluctuations. The ruggedness in construct & heavy duty function meets the Indian
working environment.
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Table 2.3.1 Specifications of Automatic Voltage Stabalizer
Input Voltage 380-440 Volts, 3-Phase 50Hz. AC supply
Output Voltage Fixed Rated maximum DC voltage or variable from zero to
maximum rated voltage.
Output Current Rated maximum DC current
Temperature Rise Less than 35 C above ambient at the top of the oil.
Efficiency 12V Rect-82%
24V Rect-90%
100V Rect-94%
200V Rect- 96%
More than 250V
Rect-More than 97%
Maximum load current 108.69 amp
Capacity 75Kva
SMPS
53
A switched-mode power supply (switching-mode power supply, SMPS, or simply
switcher) is an electronic power supply that incorporates a switching regulator in order to be
highly efficient in the conversion of electrical power. Like other types of power supplies, an
SMPS transfer’s power from a source like the electrical power grid to a load (e.g., a personal
computer) while converting voltage and current characteristics. An SMPS is usually
employed to efficiently provide a regulated output voltage, typically at a level different from
the input voltage. Unlike a linear power supply, the pass transistor of a switching mode
supply switches very quickly (typically between 50 kHz and 1 MHz) between full-on and
full-off states, which minimizes wasted energy. Voltage regulation is provided by varying the
ratio of on to off time. In contrast, a linear power supply must dissipate the excess voltage to
regulate the output. This higher efficiency is the chief advantage of a switched-mode power
supply.
Switching regulators are used as replacements for the linear regulators when higher
efficiency, smaller size or lighter weights are required. They are, however, more complicated,
their switching currents can cause electrical noise problems if not carefully suppressed, and
simple designs may have a poor power factor.
Figure 2.3.6 SMPS
A linear regulator provides the desired output voltage by dissipating excess power in ohmic
losses (e.g., in a resistor or in the collector–emitter region of a pass transistor in its active
mode). A linear regulator regulates either output voltage or current by dissipating the excess
54
electric power in the form of heat, and hence its maximum power efficiency is
voltage-out/voltage-in since the volt difference is wasted. In contrast, a switched-mode power
supply regulates either output voltage or current by switching ideal storage elements, like
inductors and capacitors, into and out of different electrical configurations. Ideal switching
elements (e.g., transistors operated outside of their active mode) have no resistance when
"closed" and carry no current when "open", and so the converters can theoretically operate
with 100% efficiency (i.e., all input power is delivered to the load; no power is wasted as
dissipated heat).
In an SMPS, the output current flow depends on the input power signal, the storage elements
and circuit topologies used, and also on the pattern used (e.g., pulse-width modulation with
an adjustable duty cycle) to drive the switching elements. Typically, the spectral density of
these switching waveforms has energy concentrated at relatively high frequencies. As such,
switching transients, like ripple, introduced onto the output waveforms can be filtered with
small LC filters.
INVERTER DRIVER
An inverter is an electrical device that converts direct current (DC) to alternating current
(AC); the converted AC can be at any required voltage and frequency with the use of
appropriate transformers, switching, and control circuits.
Solid-state inverters have no moving parts and are used in a wide range of applications, from
small switching power supplies in computers, to large electric utility high-voltage direct
current applications that transport bulk power. Inverters are commonly used to supply AC
power from DC sources such as solar panels or batteries.
The inverter performs the opposite function of a rectifier.
55
`
Figure2.3.7 inverter driver
TYPES
MODIFIED SINE WAVE
The output of a modified sine wave inverter is similar to a square wave output except that
the output goes to zero volts for a time before switching positive or negative. It is simple and
low cost (~$0.10USD/Watt) and is compatible with most electronic devices, except for
sensitive or specialized equipment, for example certain laser printers, fluorescent lighting,
and audio equipment.
Most AC motors will run off this power source albeit at a reduction in efficiency of
approximately 20%.
PURE SINE WAVE
A pure sine wave inverter produces a nearly perfect sine wave output (<3% total harmonic
distortion) that is essentially the same as utility-supplied grid power. Thus it is compatible
with all AC electronic devices. This is the type used in grid-tie inverters. Its design is more
complex, and costs more per unit power. The electrical inverter is a high-power electronic
oscillator. It is so named because early mechanical AC to DC converters were made to work
in reverse, and thus were "inverted", to convert DC to AC.
GRID TIE INVERTER
A grid tie inverter is a sine wave inverter designed to inject electricity into the electric
power distribution system. Such inverters must synchronize with the frequency of the grid.
56
They usually contain one or more Maximum power point tracking features to extract the
maximum amount of power, and also include safety features.
MOTOR Inverter Driver
The ACS150 is an ABB component drive which is designs for machine building. Typical
applications include fans, pumps, gate control, materials handling and conveyor belts.
Figure 2.3.8 Motor Inverter Driver
Table 2.3.2 Features of the ACS150 drive range includes:
A capacitor (formerly known as condenser) is a passive two-terminal electrical component
used to store energy in an electric field. The forms of practical capacitors vary widely, but all
contain at least two electrical conductors separated by a dielectric (insulator). Capacitors are
58
used as parts of electrical systems, for example, and consist of metal foils separated by a layer
of insulating film.
When there is a potential difference (voltage) across the conductors, a static electric field
develops across the dielectric, causing positive charge to collect on one plate and negative
charge on the other plate. Energy is stored in the electrostatic field. An ideal capacitor is
characterized by a single constant value, capacitance, measured in farads. This is the ratio of
the electric charge on each conductor to the potential difference between them.
The capacitance is greatest when there is a narrow separation between large areas of
conductor; hence capacitor conductors are often called "plates," referring to an early means of
construction. In practice, the dielectric between the plates passes a small amount of leakage
current and also has an electric field strength limit, resulting in a breakdown voltage, while
the conductors and leads introduce an undesired inductance and resistance.
Capacitors are widely used in electronic circuits for blocking direct current while allowing
alternating current to pass, in filter networks, for smoothing the output of power supplies, in
the resonant circuits that tune radios to particular frequencies and for many other purposes.
FELSIC- 039
Manufactured by SIC SAFCO CAPACITIOR 450VDC 2000UF Weight: 1.81 lbs.’
RADIX SENSOR
Radix is a leading Indian company manufacturing instruments as well as sensors. It was
established in 1980.Our thermocouples are exported to leading OEMs in USA and Germany.
Our instruments are private labelled in USA and widely used in India. Radix manufacturer
the most complex thermocouples, RTDs and accessories to customer's specifications. Try us. 59
Radix has an in-house R & D centre with expertise in product & pcb design, microcontroller
software, specialised sensors design, smps design etc. Our World beaters-head-mounted
temperature transmitter TX1 HM, digital DIN Rail Timer T25, programmable loop powered
led indicator PLD40- speak for our technology.
Figure 2.3.9 CIRCUIT DIAGRAM OF RADIX SENSOR
THREE PHASE RECTIFIER
A rectifier is an electrical device that converts alternating current (AC), which periodically
reverses direction, to direct current (DC), which flows in only one direction. The process is
known as rectification. Physically, rectifiers take a number of forms, including vacuum tube
diodes, mercury arc valves, solid-state diodes, silicon-controlled rectifiers and other silicon-
based semiconductor switches. Historically, even synchronous electromechanical switches
and motors have been used. Early radio receivers, called crystal radios, used a "cat's whisker"
of fine wire pressing on a crystal of galena (lead sulfide) to serve as a point-contact rectifier
or "crystal detector".
Rectifiers have many uses, but are often found serving as components of DC power supplies
and high-voltage direct current power transmission systems. Rectification may serve in roles
other than to generate direct current for use as a source of power. As noted, detectors of radio signals serve as
rectifiers. In gas heating systems flame rectification is used to detect presence of flame.
The simple process of rectification produces a type of DC characterized by pulsating voltages
and currents (although still unidirectional). Depending upon the type of end-use, this type of
60
DC current may then be further modified into the type of relatively constant voltage DC
characteristically produced by such sources as batteries and solar cells. A device which
performs the opposite function (converting DC to AC) is known as an inverter.
Three Phase Bridge Rectifier (DF200A1600)
Model NO.: DF200A1600
Standard: ISO9001 CE
Productivity: 10000PCS/Month Shipment
Terms: by Air or Sea
Trademark: WORWO/Saishemok
Origin: China Mainland Export
Markets: North America, South America, Eastern Europe,
Southeast Asia, Oceania, Eastern Asia, Western Europe
Chapter 3
3.1 ELECTRICAL SUB STATION AT OCM
An electrical substation is a subsidiary station of electricity generation transmission and distribution system where voltage is transformed from high to low or low to high using transformer
61
Extreme care while designing and building a substation. Power transformer.
Local network for Connection point.
Switchyard – Bus bars, circuit breakers, disconnections.
Measuring point for control centre – Potential and current transformers.
Fuses and other protection device.
Figure 3.1.1 Electrical substation at OCM
Classification of substations:There are the two most important ways of classifying a substation.
1. Production requirement
2. Constructional features
According to Production requirement:
A substation may be called upon to change voltage level or improve power
factor or convert ac power into dc power etc. According to service
requirement 11kV substation is transformer substation. In this substations
using power transformer changes voltage level of electric supply.
According to constructional features:
A substation has many components (e.g. Circuit breaker, switches, fuses,
instrument etc.) Which must be housed properly to ensure continuous and 62
reliable service. According to constructional features the substation is outdoor type
Substation.11/ 440 kV Substation Arrangement
The arrangement of substations can be done in many ways.
However the main sectors of arranging the substations are -
At load center: Where voltage is getting down 11kV to 400 volts using
transformer and this is near to be load center.
Substation Layout
a) Principle of Substation Layouts
Substation layout consists essentially in arranging a number of switch gear
components in an ordered pattern governed by their function and rules of spatial
separation.
b) Spatial Separation
i. Earth Clearance: This is the clearance between live parts and earthed
structures, walls, screens and ground.
ii. Phase Clearance: This is the clearance between live parts of different phases.
iii. Isolating Distance: This is the clearance between the terminals of an isolator and the
connections.
iv. Section Clearance: This is the clearance between live parts and the terminals of a work
section. The limits of this work section, or maintenance zone, may be the ground or a
platform from which the man works
c) Separation of maintenance zones:
Two methods are available for separating equipment in a maintenance zone
that has been isolated and made dead.
i. The provision of a section clearance
ii. Use of an intervening earthed barrier
The choice between the two methods depends on the voltage and whether
horizontal or vertical clearances are involved.
Functions of a Substation
1 – Supply of required electrical power.
2 – Maximum possible coverage o f the supply network.
A lightning arrester is a device used on electrical power systems to protect the
insulation on the system from the damaging effect of lightning. Metal oxide
varistors (MOVs) have been used for power system protection since the mid 1970s. The
typical lightning arrester also known as surge arrester has a high voltage terminal
and a ground terminal. When a lightning surge or switching surge travels down the
power system to the arrester, the current from the surge is diverted around
the protected insulation in most cases to earth.
Isolators and earth switches :
Isolator is a no-load switch designed as a knife switch to operate under
no-load conditions therefore the isolator o pens only after the opening after
the circuit breaker. While closing, isolator closes first and then circuit
breaker. Isolator is also called as disconnecting switch or simply
disconnected. It is interlock with circuit breaker such that wrong operation is avoided.
Its main purpose is to isolate one portion o f the circuit from the other
and is not intended to be opened while current is flowing in the line.
Such switches are generally used on both sides of circuit breakers in order that
repairs and replacement of circuit breakers can be made without any danger. During the
opening operation the conducting rods swing apart and isolation is obtained.
The simultaneous operation of three poles is obtained by mechanical
interlocking of the three poles. Further, for all the three poles, there is a
common operating mechanism.
The operating mechanism is manual plus one of the following:
° Electrical motor mechanism
° Pneumatic Mechanism.
They should never be opened until the circuit breaker in the same circuit
has been opened and should always be closed before the circuit breaker is
closed. . MPS has 3 pole isolators have three identical poles. Each pole consists
of three insulator posts mounted on a fabricated support.
The conducting parts are supported on the insulator posts. The conducting
parts consist of conducting copper or aluminum rod, fixed and moving contacts.
Isolators installed in the outdoor yard can be operated controlled manually or
electrically on electrical mode both local / remote operations is possible. All
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circuit breakers can be operated / controlled in electrical mode either local /
remote position. The remote control / monitoring of all isolators and circuit
breakers is done with the help of a set of control and metering panels Earth Switch is
connected between the line conductor and earth. Normally it is open and
it is closed to discharge the voltage trapped on the isolated or disconnected
line. When the line is disconnected from the supply end, there is some
voltage on the line to which the capacitance between the line and earth is
charged. This voltage is significant in HV systems . Before commen
cement o f maintenance work it is necessary that these voltages are discharged to
earth by closing the earth switch. Normally the earth switches are mounted
on the frame of the isolator
Classification of Circuit Breaker
According to the voltage level circuit breaker are classified into three categories, such as
1. Low Voltage Circuit Breaker( Up to 619 volt)
2. Medium Voltage Circuit Breaker(Up to 11kV)
3. High Voltage Circuit Breaker(Up to 145kV )
Low Voltage Circuit Breaker
1. Molded Case Circuit Breaker (MCCB): Molded case circuit breaker
operation as like as thermal or thermal-magnetic operation and rated current
start from100A. Trip current may be adjustable in larger ratings. The
molded case circuit breaker (MCCB) co mprises the following features:
• A contact system with arc-quenching and current-limiting means
• A mechanism to open and close the contacts
• Auxiliaries which provide additional means of protection and indication of
the switch positions
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Molded Case Circuit Breaker
The MCCB may be used as an incoming device, but it is more generally
used as an outgoing device on the load side of a switchboard. It is normally
mounted into a low-voltage switchboard
or a purpose-design ed panel board. In addition to the three features listed
at the start of this section, it also includes:
• An electronic or thermal/electromagnetic trip sensing system to operate
through the tripping mechanism and open the circuit breaker under overload or fault
conditions
• All parts housed within a plastic molded housing made in two halves
• Current ratings usually from 10A to 1600A.
Miniature Circuit Breaker (MCB): Miniature circuit breakers rated current not
more than 100A. Trip characteristics normally not adjustable. The miniature
circuit breaker (MCB) has a contact system and means of arc quenching, a
mechanism and tripping and protection system to open the
circuit breaker under fault conditions.. Early devices were generally of the
‘zero-cutting’ type, and during a short circuit the current had to pass through a zero
before the arc was extinguished;
this provided a short-circuit breaking capacity of about 3kA. Most of these
early MCBs were
housed in Bakelite moldings. The modern MC B is a much smaller and
more sophisticated device. All the recent developments associated with molded
case circuit breakers have been incorporated into MCBs to improve their
performance, and with breaking capacities of 10 kA to
16 kA now available, MCBs are used in all areas of commerce and industry
as a reliable means of protection. Most MCBs are of single-pole construction for use in
single-phase circuits.
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Miniature circuit Breaker
Medium Voltage Circuit Breakers
Medium-voltage circuit breakers rated between 619 Voltage and 11 kV
assemble into metal- enclosed switchgear line ups for indoor use in MPS
substation. Medium voltage circuit breakers
are also operated by current sensing protective relays operated through
current transformers. Medium-voltage circuit breakers nearly always use
separate current sensors and protective relays, instead of relying on built-in thermal
or magnetic over current sensors.
Vacuum circuit breaker: Vacuum circuit breaker with rated current up to
3000 A, these breakers interrupts the current by creating and extinguishing
the arc in a vacuum container. These are generally applied for voltages up to
about 35,000 V but PS use vacuum circuit breaker
for 11KV which corresponds roughly to the medium-voltage range of power
systems. Vacuum circuit breakers tend to have longer life expectancies
between overhaul than do air circuit breakers. Vacuum circuit breakers tend
to have longer life expectancies between overhaul th an do air circuit breakers.
In a vacuum circuit breaker, two electrical contacts are enclosed in a
vacuum. One of the contacts is fixed, and one of the contacts is movable.
When the circuit breaker detects a dangerous situation, the movable contact
pulls away from the fixed contact, interrupting the current. Because the
contacts are in a vacuum, arcing between the contacts is suppressed,
75
ensuring that the circuit remains open. As long as the circuit is open, it
will not be energized.
Vacuum recluses will automatically reset when conditions are safe again, closing
the circuit and
allowing electricity to flow through it. Re-closers can usually go through
several cycles before they will need to be manually reset
Vacuum interrupters, mounted vertically within the circuit breaker frame,
perform the circuit breaker interruption. Consisting of a pair of butt contacts,
one movable and one fixed, interrupters require only a short contact gap for
circuit interruption. The resulting high-speed operation allows the entire operating
sequence, from fault to clear, to be consistently performed in three cycles or less.
The primary connection to the associated switchgear is through the six
primary disconnects
mounted horizontally at the rear of the circuit breaker. Do not subject the primary
disconnects to rough treatment. The operating mechanism is of the stored
energy type. It uses charged springs to perform breaker opening and closing
functions. The operating mechanism contains all necessary controls and interlocks.
It is mounted at the front of the circuit breaker for easy access
during inspection and maintenance.
Specification of Vacuum circuit breaker:
• Rated frequency-50 -60Hz
• Rated making Current-10 Peak kA
• Rated Voltage-11kV
• Supply Voltage Closing-220 V/DC
• Rated Current-1250 A
• Supply Voltage Tripping-220 V/DC
• Insulation Lev el-IMP 75 kVP
• Rated Short Time Current-40 kA (3 SEC)
High-voltage circuit breakers
Electrical power transmission networks are protected and controlled b y high-
voltage breakers.
The definition of high voltage varies but in power transmission work is
usually thought to be
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72.5 kV or higher. In MPS used SF6 circuit breaker for high voltage in sub station .High-
voltage
breakers are always solenoid-operated, with current sensing protective relays
operated through current transformers. In substations the protective relay
scheme can be complex, protecting equipment and busses from various types of
overload or ground/earth fault.
FUSES:
A fuse is a short piece of wire or thin strip which melts when excessive current
flows through it for sufficient time. It is inserted in series with the
circuit to be protected. Under normal operating conditions the fuse element
it at a temperature below its melting point. Therefore, it carries the normal
load current without overheating. However when a short circuit or overload
occurs, the current through the fuse element increases beyond its rated capacity.
This raises the temperature and the fuse element melts (or blows out),
disconnecting the circuit protected by Init. electronics and electrical engineering
a fuse (short for fusible link) is a type of sacrificial over current protection
device. Its essential component is a metal wire or strip that melts when too much current
flows, which
interrupts the circuit in which it is connected. Short circuit, overload or
device failure is often the reason for excessive current.
Fuse Ratings:
Ampere Rating
Each fuse has a specific ampere rating, which is its continuous current-
carrying capability. There are different types of fuse used in MPS, rating start from 2A.
Voltage Rating The voltage rating of a f use must be at least equal to the circuit
voltage. The voltage rating of a fuse can be higher than the circuit voltage, but
never lower. A 500 volt fuse, for example, could be used in a 450 volt circuit, but a 350
volt fuse could not be used in a 500 volt circuit.
Manual Change over Switch
The Manual change over switch is wired into your Electrical Distribution Board in
your home or office allowing it to power particular appliances in your home
or office by providing power to specific circuits.
77
The manual change over switch can be used with the remote start button. The Generator
does however need time to get up to speed before the Manual Change
Over Switch can be placed on “Generator.” The recommended time for this is 5
Seconds. Hence when used in conjunction with a remote start button, the generator
should be started whilst the Manual Change over Switch is in the “Off” position.
Once started and run for the recommended time the
switch can be moved to “Generator” providing power to the relative circuits which
the generator has been wired up to provide power to.The Following are the
respective Model numbers associated with the Manual change over switches
and their capability of single or three phase power. The key on the generator
has to be in the ON position for the manual change over switch to work.
The manual change over switch does not charge the battery so should the key
be left in the on position the battery will go flat, if
the generator is not used on a regular basis.
Departmental use of Machines
78
79
Grev Fibres
Gilling
Spinning
Scouring
Dyeing
Drying
Weaving
Mending
Finishing
Inspection
Cutting
Packing
Dispatching
3.2 MANUFACTURING PROCESS
SPINNING:
In new spinning section gilling, combing, post combing gilling, drawing, roving and gilling
and steaming is done.
G ILLING:
Doubling, drafting, evenness, entanglement is removed up to some extent.
COMBING:
Remove short fibres entanglement, neaps are removed.
POST COMBING GILLING:
It manages wt/unit length.
DRAWING:
This process draws twists and winds the stock, making the salivers more impact and thinning
them into slubbers.
ROVING:
It is actually a light twisting operation to hold the thin slubbers intact. The final stage before
spinning.
STEAMING:
It is to set the twist.
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AUTO-CONNING MACHINE
In it the yarns in smaller cones are converted into larger cones. The capacity of the machine
in it can convert 360 small size cones into 60 large size cones.
POST SPINNING
The sequence of process in the post spinning department is as follows:
Assembly winding
Two for one twister
Autoclave
Conditioning
Winding
MACHINES ARE:
a) Precombing gill box GC-14
b) Comber PB-31
c) Post combing gill box GC-14
d) Autoleveler GC-14
ZENSER 421 is mainly used for spinning and AUTOCORNER 238 is used for winding
81
DYEING
Three types of dyeing done are:-
1) Top dyeing 2) Yarn dyeing3) Fabric dyeing
The machine used for top and yarn dyeing are HTHP (High Temperature High Pressure) and for fabric dyeing there are 2 jet dyeing machine. Dyes are mainly bayed from ciba a Switzerland company and tops are buyed from australia.AC motors are used for all the machine used for dyeing. Dyes used for polyester disperse
The sequence of processes while dying in HTHP machine
There are various types of machines which perform all these process.
There is paper press machine, k-d machine, Conti blow machine, super finish machine, vaporizing machine, rotatory machine, back purch machine, hammer washing, etc.
In mat and rotor mat machine dc motor drives are used.
84
INSPECTION
Received civil export material from finishing
For back side perching
Conti blow or super finishing
Face side perching
Table measurement and cutting
Weighing
Double folding rolling, zig zag ,back folding
Stamping wrapping
Voucher making book entry
Ware house
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DEFECTS FOUND IN CLOTH
Broken color end
Tight end
Loose end
Wrong twisting
Wrong draft
Temple cut, temple mark, temple abrasion
Reed mark
Missing pick
Double pick
Double missing pick
Pick variation
86
3.3 INDUSTRIAL CONTROL SYSTEMS
Industrial control system (ICS) is a general term that encompasses several types of control
systems, including supervisory control and data acquisition (SCADA) systems, and other
control system configurations such as skid-mounted Programmable Logic Controllers (PLC)
often found in the industrial sectors and critical infrastructures. ICS are typically used in
industries such as electrical, electronics etc. These control systems are critical to the
operation of the infrastructures that are often highly interconnected and mutually dependent
systems. It is important to note that approximately 90 percent of the nation's critical
infrastructures are privately owned and operated. This section provides an overview of
SCADA and PLC systems, including typical architectures and components. Several diagrams
are presented to depict the network connections and components typically found on each
system to facilitate the understanding of these systems.
Overview of SCADA and PLCs
SCADA systems are highly distributed systems used to control geographically dispersed
assets, often scattered over thousands of square kilometers, where centralized data acquisition
and control are critical to system operation. They are used in distribution systems such as
electrical power grids. A SCADA control center performs centralized monitoring and control
for field sites over long-distance communications networks, including monitoring alarms and
processing status data. Based on information received from remote stations, automated or
operator-driven supervisory commands can be pushed to remote station control devices,
which are often referred to as field devices. Field devices control local operations such as
opening and closing valves and breakers, collecting data from sensor systems, and monitoring
the local environment for alarm conditions.
PLCs are computer-based solid-state devices that control industrial equipment and processes.
While PLCs are control system components used throughout SCADA and DCS systems, they
are often the primary components in smaller control system configurations used to provide
operational control of discrete processes such as automobile assembly lines and power plant
soot blower controls. PLCs are used extensively in almost all industrial processes.
87
ICS Operation
Key components include the following:
Control Loop: A control loop consists of sensors for measurement, controller
hardware such as PLCs, actuators such as control valves, breakers, switches and motors, and
the communication of variables. Controlled variables are transmitted to the controller from
the sensors. The controller interprets the signals and generates corresponding manipulated
variables, based on set points, which it transmits to the actuators. Process changes from
disturbances result in new sensor signals, identifying the state of the process, to again be
transmitted to the controller.
Human-Machine Interface (HMI): Operators and engineers use HMIs to monitor
and configure set points, control algorithms, and adjust and establish parameters in the
controller. The HMI also displays process status information and historical information.
Remote Diagnostics and Maintenance Utilities: Diagnostics and maintenance
utilities are used to prevent, identify and recover from abnormal operation or failures.
A typical ICS contains a proliferation of control loops, HMIs, and remote diagnostics and
maintenance tools built using an array of network protocols on layered network architectures.
Sometimes these control loops are nested and/or cascading –whereby the set point for one
loop is based on the process variable determined by another loop. Supervisory-level loops
and lower-level loops operate continuously over the duration of a process with cycle times
ranging on the order of milliseconds to minutes.
88
Figure 3.3.1 ICS Operation
Key ICS Components
To support subsequent discussions, this section defines key ICS components that are used in
control and networking. Some of these components can be described generically for use in
SCADA system and PLCs, while others are unique to one.
Control Components
The following is a list of the major control components of an ICS:
Control Server. The control server hosts the PLC supervisory control software that
communicates with lower-level control devices. The control server accesses subordinate
control modules over an ICS network.
SCADA Server or Master Terminal Unit (MTU). The SCADA Server is the device
that acts as the master in a SCADA system. Remote terminal units and PLC devices (as
described below) located at remote field sites usually act as slaves.
Remote Terminal Unit (RTU). The RTU, also called a remote telemetry unit, is a
special purpose data acquisition and control unit designed to support SCADA remote
89
stations. RTUs are field devices often equipped with wireless radio interfaces to support
remote situations where wire-based communications are unavailable. Sometimes PLCs are
implemented as field devices to serve as RTUs; in this case, the PLC is often referred to as an
RTU.
Programmable Logic Controller (PLC). The PLC is a small industrial computer
originally designed to perform the logic functions executed by electrical hardware (relays,
switches, and mechanical timer/counters). PLCs have evolved into controllers with the
capability of controlling complex processes, and they are used substantially in SCADA
systems. Other controllers used at the field level are process controllers and RTUs; they
provide the same control as PLCs but are designed for specific control applications. In
SCADA environments, PLCs are often used as field devices because they are more
economical, versatile, flexible, and configurable than special-purpose RTUs.
Intelligent Electronic Devices (IED). An IED is a “smart” sensor/actuator containing
the intelligence required to acquire data, communicate to other devices, and perform local
processing and control. An IED could combine an analog input sensor, analog output, low-
level control capabilities, a communication system, and program memory in one device. The
use of IEDs in SCADA and DCS systems allows for automatic control at the local level.
Human-Machine Interface (HMI). The HMI is software and hardware that allows
human operators to monitor the state of a process under control, modify control settings to
change the control objective, and manually override automatic control operations in the event
of an emergency. The HMI also allows a control engineer or operator to configure set points
or control algorithms and parameters in the controller. The HMI also displays process status
information, historical information, reports, and other information to operators,
administrators, managers, business partners, and other authorized users. The location,
platform, and interface may vary a great deal. For example, an HMI could be a dedicated
platform in the control center, a laptop on a wireless LAN, or a browser on any system
connected to the Internet.
Data Historian. The data historian is a centralized database for logging all process
information within an ICS. Information stored in this database can be accessed to support
various analyses, from statistical process control to enterprise level planning.
90
Input/Output (IO) Server. The IO server is a control component responsible for
collecting, buffering and providing access to process information from control sub-
components such as PLCs, RTUs and IEDs. An IO server can reside on the control server or
on a separate computer platform. IO servers are also used for interfacing third-party control
components, such as an HMI and a control server.
Network Components
There are different network characteristics for each layer within a control system hierarchy.
Network topologies across different ICS implementations vary with modern systems using
Internet-based IT and enterprise integration strategies. Control networks have merged with
corporate networks to allow control engineers to monitor and control systems from outside of
the control system network. The connection may also allow enterprise-level decision-makers
to obtain access to process data. The following is a list of the major components of an ICS
network, regardless of the network topologies in use:
Fieldbus Network: The fieldbus network links sensors and other devices to a PLC or
other controller. Use of fieldbus technologies eliminates the need for point-to-point wiring
between the controller and each device. The devices communicate with the fieldbus
controller using a variety of protocols. The messages sent between the sensors and the
controller uniquely identify each of the sensors.
Control Network: The control network connects the supervisory control level to
lower-level control modules.
Communications Routers: A router is a communications device that transfers
messages between two networks. Common uses for routers include connecting a LAN to a
WAN, and connecting MTUs and RTUs to a long-distance network medium for SCADA
communication.
Firewall: A firewall protects devices on a network by monitoring and controlling
communication packets using predefined filtering policies. Firewalls are also useful in
managing ICS network segregation strategies.
Modems: A modem is a device used to convert between serial digital data and a
signal suitable for transmission over a telephone line to allow devices to communicate.
Modems are often used in SCADA systems to enable long-distance serial communications
91
between MTUs and remote field devices. They are also used in SCADA systems, DCS and
PLCs for gaining remote access for operational and maintenance functions such as entering
commands or modifying parameters, and diagnostic purposes.
Remote Access Points. Remote access points are distinct devices, areas and locations
of a control network for remotely configuring control systems and accessing process data.
Examples include using a personal digital assistant (PDA) to access data over a LAN through
a wireless access point, and using a laptop and modem connection to remotely access an ICS
system.
3.3.1 SCADA Systems
SCADA systems are used to control dispersed assets where centralized data acquisition is as
important as control. These systems are used in distribution systems such as electrical utility
transmission and distribution systems, and rail and other public transportation systems.
SCADA systems integrate data acquisition systems with data transmission systems and HMI
software to provide a centralized monitoring and control system for numerous process inputs
and outputs. SCADA systems are designed to collect field information, transfer it to a central
computer facility, and display the information to the operator graphically or textually, thereby
allowing the operator to monitor or control an entire system from a central location in real
time. Based on the sophistication and setup of the individual system, control of any individual
system, operation, or task can be automatic, or it can be performed by operator commands.
SCADA systems consist of both hardware and software. Typical hardware includes an MTU
placed at a control center, communications equipment (e.g., radio, telephone line, cable, or
satellite), and one or more geographically distributed field sites consisting of either an RTU
or a PLC, which controls actuators and/or monitors sensors. The MTU stores and processes
the information from RTU inputs and outputs, while the RTU or PLC controls the local
process. The communications hardware allows the transfer of information and data back and
forth between the MTU and the RTUs or PLCs. The software is programmed to tell the
system what and when to monitor, what parameter ranges are acceptable, and what response
to initiate when parameters change outside acceptable values. An IED, such as a protective
relay, may communicate directly to the SCADA Server, or a local RTU may poll the IEDs to
collect the data and pass it to the SCADA Server. IEDs provide a direct interface to control
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and monitor equipment and sensors. IEDs may be directly polled and controlled by the
SCADA Server and in most cases have local programming that allows for the IED to act
without direct instructions from the SCADA control center. SCADA systems are usually
designed to be fault-tolerant systems with significant redundancy built into the system
architecture.
Figure 3.3.1.1. shows the components and general configuration of a SCADA system. The
control center houses a SCADA Server (MTU) and the communications routers. Other
control center components include the HMI, engineering workstations, and the data historian,
which are all connected by a LAN. The control center collects and logs information gathered
by the field sites, displays information to the HMI, and may generate actions based upon
detected events. The control center is also responsible for centralized alarming, trend
analysis, and reporting. The field site performs local control of actuators and monitors
sensors. Field sites are often equipped with a remote access capability to allow field operators
to perform remote diagnostics and repairs usually over a separate dial-up modem or WAN
connection. Standard and proprietary communication protocols running over serial
communications are used to transport information between the control center and field sites
using telemetry techniques such as telephone line, cable, fiber, and radio frequency such as
broadcast, microwave and satellite.
MTU-RTU communication architectures vary among implementations. The various
architectures used, including point-to-point, series, series-star, and multi-drop , are shown in
Figure 3.3.1.2. Point-to-point is functionally the simplest type; however, it is expensive
because of the individual channels needed for each connection. In a series configuration, the
number of channels used is reduced; however, channel sharing has an impact on the
efficiency and complexity of SCADA operations. Similarly, the series-star and multi-drop
configurations’ use of one channel per device results in decreased efficiency and increased
system complexity.
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Figure 3.3.1.1 SCADA System General
Layout
The four basic architectures shown in Figure 3.3.1.1 can be further augmented using
dedicated communication devices to manage communication exchange as well as message
switching and buffering. Large SCADA systems, containing hundreds of RTUs, often employ
sub-MTUs to alleviate the burden on the primary MTU. This type of topology is shown in
Figure 3.3.1.1.
Figure 3.3.1.2 shows an example of a SCADA system implementation. This particular
SCADA system consists of a primary control center and three field sites. A second backup
control center provides redundancy in the event of a primary control center malfunction.
Point-to-point connections are used for all control centre to field site communications, with
two connections using radio telemetry. The third field site is local to the control center and
uses the wide area network (WAN) for communications. A regional control center resides
above the primary control center for a higher level of supervisory control. The corporate
network has access to all control centers through the WAN, and field sites can be accessed
remotely for troubleshooting and maintenance operations. The primary control center polls
field devices for data at defined intervals (e.g., 5 seconds, 60 seconds) and can send new set
points to a field device as required. In addition to polling and issuing high-level commands,
the SCADA server also watches for priority interrupts coming from field site alarm systems.
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Figure 3.3.1.2. Basic SCADA Communication Topologies
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Figure 3.3.1.3 SCADA System Implementation Example (Distribution Monitoring and
Control)
Figure 2-6 shows an example implementation for rail monitoring and control. This example
includes a rail control centre that houses the SCADA system and three sections of a rail
system. The SCADA system polls the rail sections for information such as the status of the
trains, signal systems, traction electrification systems, and ticket vending machines. This
information is also fed to operator consoles at the HMI station within the rail control centre.
The SCADA system also monitors operator inputs at the rail control centre and disperses
high-level operator commands to the rail section components. In addition, the SCADA
system monitors conditions at the individual rail sections and issues commands based on
these conditions (e.g., shut down a train to prevent it from entering an area that has been
determined to be flooded or occupied by another train based on condition monitoring).
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Figure 2.6 SCADA System Implementation Example (Rail Monitoring and Control)
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3.3.2 Programmable Logic Controllers
PLCs are used in SCADA systems as the control components of an overall hierarchical
system to provide local management of processes through feedback control as described in
the sections above. In the case of SCADA systems, they provide the same functionality of
RTUs. When used in DCS, PLCs are implemented as local controllers within a supervisory
control scheme. PLCs are also implemented as the primary components in smaller control
system configurations. PLCs have a user-programmable memory for storing instructions for
the purpose of implementing specific functions such as I/O control, logic, timing, counting,
three mode proportional-integral-derivative (PID) control, communication, arithmetic, and
data and file processing. Figure 2-8 shows control of a manufacturing process being
performed by a PLC over a fieldbus network. The PLC is accessible via a programming
interface located on an engineering workstation, and data is stored in a data historian, all
connected on a LAN.
Figure 3.3.2.1 PLC Control System Implementation Example
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Chapter 4
4.1 CONCLUSION
The productivity and the growth of an industry depends on the technology they implement to
ensure the effective production of their goods . Hence we see that Instrumentation and
Control department plays a very important role in the textile Industry with which we did our
training.
We got to see the working of various Machines involved in the manufacturing process of
their fabric and the Control System such as SCADA , it’s implementation and structure. This
training period had exposed me to the practical usage of what I have been studying. SCADA
systems are designed to collect field information, transfer it to a central computer facility, and
display the information to the operator graphically or textually, thereby allowing the operator
to monitor or control an entire system from a central location in real time. Based on the
sophistication and setup of the individual system, control of any individual system, operation,
or task can be automatic, or it can be performed by operator commands.
