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TELECOMMUNICATION SYSTEMS IN VISAKHAPATNAM STEEL

PLANT

A Mini Project report submitted in partial fulfillment of the requirement for the award of

the Degree of B.Tech.

BY

G. NEELIMA ANAND

Reg. No: 09JG1A0438

DEPARTMENT OF ELECTRONICS & COMMUNICATION ENGINEERING

GAYATRI VIDYA PARISHAD COLLEGE OF ENGINEERING FOR WOMEN

(Approved by AICTE, New Delhi and Affiliated to JNTU, Kakinada)

Madhurwada, Visakhapatnam - 530048.

Year: 2012-2013


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TELECOMMUNICATION SYSTEMS IN VISAKHAPATNAM

STEEL PLANT

Mini Project report submitted in partial fulfillment of the requirement for theaward of the

Degree of

BACHELOR OF TECHNOLOGY

IN

ELECTRONICS AND COMMUNICATIONS ENGINEERING

BY

G.NEELIMA ANAND

Reg. No: 09JG1A0438

Under the esteemed guidance of

Ms. K.KATYAYANI

Asst. professor (ECE)



Madhurawada, Visakhapatnam530048


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Madhurawada, Visakhapatnam - 530048

CERTIFICATE

This is to certify that the mini project entitled TELECOMMUNICATION SYSTEMS IN

VISAKHAPATNAM STEEL PLANT that is being submitted by G.NEELIMA ANAND

(Reg. No: 09JG1A0438) in partial fulfillment for the award of the degree of Bachelor of

Technology in Electronics and Communication Engineering to the Jawaharlal Nehru

Technological University, Kakinada is a record of bonafide work carried out under my guidance

and supervision.

The results embodied in this mini project report have not been submitted to any other University

or Institute for the award of any degree or diploma.

Head of the Department: Internal guide:

Prof. Dr. Madhusudhana Rao Ms. K.KATYAYANI

Professor and HOD (ECE) Assistant professor (ECE)


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ACKNOWLEDGEMENT

I express my profound gratitude acknowledgement and my deep indebtedness to my

external guide Mrs. M. Rama Devi(DM),Telecom, for her technical guidance and support in

carrying out my project TELECOMMUNICATION SYSTEMS IN VISAKHAPATNAM

STEEL PLANT whose valuable suggestions, guidance and comprehensive assistance helped

me a lot in completing my project.

I would like to express my sincere gratitude to my internal guide Ms. K.KATYAYANI;

she guided and encouraged me at every stage and aspect by including the spirit of understanding

the best ability for me. And for her guidance, constant encouragement and support in carrying

out my mini project at college.

I express sincere and heartfelt thanks and acknowledge our indebtedness to my Head of

the Department of Electronics and Communication Engineering, Prof. D.MADHUSUDHANA

RAO for his spontaneous expression of knowledge, which helped me in bringing up in this

project that has been excellent guide and also a great source of inspiration to my work.

I am grateful to our principal, Mr. GOPAL RAO who most ably run the institution and

has had the major hand in enabling me to do my project. I would like to thank all the other staff

members, both teaching and non-teaching, who extended their timely help and eased my task.

I would like to express my heart-felt gratitude to my parents without whom I would not

have been privileged to achieve and fulfill my dreams.

Above all I sincerely thank the Almighty, for giving us all the enthusiasm and courage for

doing this mini project.

G.NEELIMA ANAND

Reg. No: 09JG1A0438


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ABSTRACT

In this modern world of Industrialization and automation, energy plays a major role in the

growth of any organization. The utilization of energy plays an impacting and direct role in the

growth of organizations like Visakhapatnam Steel Plant.

The Telecommunication department plays a vital role in providing & maintaining

different electronic communication systems in various departments to achieve the assigned targets

and accomplishing the desired performance in VSP. In Vizag Steel Plant, the main objective of this

project is to automate the services provided by telecommunication systems, by which all the

utilization of energy sources services online.


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INDEX

S.NO CONTENTS PAGE NO

1. Introduction 10

1.1 Evolution 11

1.2 Turn Around 12

1.3 Vizag steel tomorrow 13

2. MAJOR DEPARTMENTS IN VSP 15

2.1 Raw material handling plant 15

2.2 Coke ovens 15

2.3 Sinter plant 16

2.4 Blast furnace 16

2.5 Steel smelt shop (SMS) 16

2.6 Rolling mills (RM) 17

2.7 Thermal Power Plant (TPP)..17

2.8 Main products of (Vsp) 17

3. COMMUNICATION SYSTEMS IN VSP 19

3.1 General purpose communication systems 19

3.2 Process communication systems 20

3.3 Motoring and signaling systems 23

4. APPLICATION IN MOTION CONTROLLING 25

4.1 Drive basics 25

4.2 Block diagram of a drive 25

4.3 Various types of drives used in industries 27


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5. DC DRIVES 28

5.1 Analog DC drive 30

5.1.1 Components of analog DC drives (MTE) 30

5.1.1.1 POWER SUPPLY UNIT 30

5.1.1.2Control supply unit 30

5.1.1.3Synchronous supply unit 30

5.1.1.4Regulation unit 30

5.1.1.5Protection unit 31

5.1.2Need for speed control 32

5.2 Digital DC drive 43

6. COMPARISION BETWEEN ANALOG & DIGITAL DRIVES 44

7. CONCLUSION 45


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LIST OF FIGURES

FIG.NO NAME OF THE FIGURE PAGE.NO

Fig 4.1 Block Diagram of an electrical drive 26

Fig 5.1 DC drive motor connections 29

Fig 5.2 Speed torque characteristics 30

Fig 5.3 Diode Bridge circuit 32

Fig 5.4 Diode Bridge output waveform 33

Fig 5.5 Thyristor Bridge circuit 34

Fig 5.6 Output waveforms of thyristor stack 34

Fig 5.7 Controller section of the drive with all the cards 35

Fig 5.8 Speed controller in a card 36

Fig 5.9 Current controller 37

Fig 5.10 Firing module 38

Fig 5.11 Basic drive circuit 39

Fig 5.12 Forward/Reverse speed controller circuit 40

Fig 5.13 Full Forward/Reverse controller 41

Fig 5.14 Digital drive 42


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LIST OF TABLES

TABLE.NO NAME OF THE TABLE PAGE.NO

Table 1 Products of steel plant vsp 18


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1. INTRODUCTION

Visakhapatnam Steel Plant, an integrated steel plant under the corporate entity of

Rashtriya Ispat Nigam Limited (RINL), is the first shore based integrated Steel Plant in the country,

constructed with the then latest state of the art technology.

The Plant with a rated capacity of 3.0 Mt is a producer of steel products in the longs

category like wire rods, re-bars, angles, channels, blooms and billets. The Visakhapatnam Steel Plant

strikes every one with a tremendous sense of wonder and arrangement as it presents a wide array of

excellence in technology, in manpower, in management, in science beauty and includes all these in

product quality.

The momentum decision to establish a steel plant at Visakhapatnam was announced in

the parliament in 1970 by the Prime Minister Smt. Indira Gandhi. The announcement stone for this

massive project was laid in 1971. The detailed project report was prepared in 1977. However it was

the only company in 1979 with the government of Soviet Union offering techno economic

corporation, the cabinet approved the proposal for setting up an integrated steel plant in

Visakhapatnam.

He plant is located on the coast of Bay of Bengal, 16Kms to the Southwest of

Visakhapatnam port. IT lies between the northern boundary of National Highway No.5 from Madras

to Calcutta and 7Kms to the South West of Howrah Madras railway line.


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1.1. EVOLUTION:

Visakhapatnam Steel Plant was conceived in the year 1970 as a unit of Steel Authority of

India Limited (SAIL) to augment its long products capacity and to service the southern markets.

Announcement for Visakhapatnam Steel Plant was made in the Parliament in the year 1970 and the

foundation stone was laid in 1971 by the late Prime Minister, Smt.Indira Gandhi.

The feasibility report of the plant was made in 1973 and the Indo-Soviet Agreement was

signed in 1979. The comprehensive detailed project report was made in 1980 and the project was

sanctioned by Government of India in 1982. In the same year, a separate company called Rashtriya

Ispat Nigam Limited was formed.

The plant was to be commissioned by 1986 as per original schedule. However, because of

severe cash crunch, in the year 1986, a rationalized concept was adopted to lower the capital costs.

Some of the envisaged facilities were dropped and the nameplate capacities of steel making and

rolling mills were increased for making revenue generation more attractive.

Finally, the plant was fully commissioned in the year 1992. Due to the long gestation

period of 22 years from concept to commissioning stage, the capital cost of the project went up from

original estimate of Rs.2256 crores in 1979 to Rs.8594 crores in 1992. As a result of high capital

cost and large borrowings the company had to bear high interest and depreciation burden resulting incontinuous losses. This has resulted in huge cost over runs and high capital related charges and

Visakhapatnam Steel Plant at the time of commissioning itself had a net loss of over Rs.2000 crores.

While the plant was picking up production, the South East Asian financial crisis severely

affected the steel market which led to continuous drop in steel prices both in domestic and

international markets. Also from 1998, the steel industry, worldwide, was affected by recession.

Steel demand declined, forcing the steel producers to throttle production levels. Many unviable

production units in the world had to close down. Indias exports were hit adversely and domesticconsumption remained almost stagnant. Sales realizations plummeted and profitability of the Indian

steel producers was adversely affected. All these conditions brought a tremendous pressure on the

financials of the company.


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1.2. THE TURN-AROUND:

Despite these adverse conditions, the Vizag Steel collective rose to the occasion and over

the last few years Vizag Steels performance has improved on all fronts including production,

techno-economics, marketing and financials. The emphasis initially had been towards total

employee involvement, then to technology up gradation and process management and then to

managing external environment.

At this juncture, the leadership played a crucial role in providing direction focusing on

critical issues and empowering employees. A number of sustenance and performance improvement

programs were initiated to put the company on the growth trajectory. The emphasis was on attaining

rated capacity at the earliest, improving techno-economic performance, improving health of

equipment, cost reduction and process innovations.

Systematic and standard operation practices and structured systems were developed and

Vizag Steel was the first integrated steel plant in the country to be accredited with all the three

International Standards for Quality (ISO 9001), for Environment Management (ISO 14001) and for

Occupational Health and Safety (OHSAS-18001).

All these initiatives gave positive results and the company started its journey to

excellence by crossing its rated capacity levels in the year 2001-02. Since then the company hasbeen operating consistently beyond the rated capacities. Currently, the plant is operating at 120% of

its rated capacity. The Plant turned around in the year 2002-03 by achieving for the first time a net

profit of Rs.521 crores. The improved performance saw Vizag Steel become a Zero debt company

and is a net positive company today having wiped off all its accumulated losses .

All these efforts of Vizag Steel were well recognized by one and all. For its excellent

performance in the year 2002-03, Vizag Steel was conferred with the Prime Ministers trophy for the

best Integrated Steel plant in the country. During the year 2002, Vizag Steel was awarded with

`SCOPE excellence award for turnaround for its outstanding performance. Vizag Steel has been

winning the National Energy Conservation award for the last seven years and has also won the

Special Prize for National Energy Conservation for successfully annexing the first prize for three

consecutive years.


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Vizag Steel has been constantly achieving excellent MOU rating from the government for

its excellent performance. It was bestowed with the World Quality Commitment Award at Paris. In

2005, Vizag Steel bagged six Vishwakarma Rashtriya Puraskar Awards out of the 28 awards

announced by Ministry of Labour, a tribute to the involvement of its employees and participatory

approach of the management. Best Water Management, Best Financial Management and Best Safety

& Occupational health awards from Confederation of Indian Industries are some of the prestigious

awards received.

1.3. VIZAG STEEL TOMORROW:

Armed with a vision to become world class integrated steel plant, the Vizag Steel Collective

is charged with a steely resolve to face a challenging tomorrow. Some of the initiatives taken to

make Vizag Steel a world class organization are:

Adoption of business excellence through CII-Exam Business Excellence Model.

Initiation for BPR & ERP.

Implementation of Six Sigma methodology.

Implementation of 5S for outstanding housekeeping.

Bench marking with world class companies.

Introduction of Knowledge Management to harness the inner potential of employees.

Introduction of e-commerce.

Acquisition of captive mines in India and abroad through joint venture, so as to have a level

playing field with its competitors.

In line with its vision to become a continuously growing company, Vizag Steel recast its

expansion plan to double its capacity from its present 3 mT to 6.3 mT by 2008-09. The approval for

its recast expansion plan was obtained on 28th

Oct 05 in a record time of 10 months.


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The expansion has been planned to further strengthen its long product leadership in the

country through production of special bars, wire rods and structurals, in view of its high brand

image and also envisaged demand in line with the infrastructure growth of the country.

A seamless tube plant has been planned for the first time in an integrated steel plant to cater

to the growing oil and gas industry and reduce dependence on imports of seamless tubes. The next

phase of expansion to 10 mT is planned for completion by 2012-13 which will include flat products

also to provide a rich product mix.

With excellent performance levels continuing during the current year also and the ensuing

expansion wherein Vizag Steel has set up an ambitious target of completion of its expansion in a

record 36 months at international standards, Vizag Steel looks to new horizons. Vizag Steel

collective has proved its mettle time and again and is all set to take up new challenges and soar to

new heights to emerge as a World Class steel plant.


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2. MAJOR DEPARTMENTS IN VSP

2.1. RAW MATERIAL HANDLING PLANT (RMHP):

The RMHP receives the basic materials iron ore, fluxes (lime stone, dolomite),coking and

non coking coals etc. required for the steel making process from various sources through wagons

which are stacked and reclaimed by stackers-cum re-claimers and distributed to various departments

of Visakhapatnam steel plant through conveyor systems.

2.2. COKE OVENS (CO):

Blast furnaces, the mother units of any steel plant require huge quantities of strong, hard

and porous solid fuel in the form of hard metallurgical coke for supplying necessary heat for

carrying of the reduction and refining reactions besides acting as a reducing agent.

Coke is manufactured by heating of crushed coking coal (below 3mm) is in the absence of air

at a temperature of 1000deg centigrade and above for period of 16 hrs to 18 hrs. A coke oven

comprises of two hollow chambers namely coal chamber and heating chamber in the heating

chamber a gaseous fuel such as blast furnace gas, coke oven gas, etc. is burnt. The heat so generated

is conducted through the common wall to heat and carbonize the coking coal placed into adjacent

coal chamber. Number of ovens built in series one after the other form a coke oven battery.

At VSP there are three coke oven batteries, 7 meter tall and having 67 ovens each. Each

oven is having volume of 41.6 cu meters and can hold up to 31.6 tones of dry coal charge. The

carbonization takes place at 1000 to 1050 deg centigrade in the absence of air for 16 to 18 hours.

Red hot coke is pushed out of the oven and sent to coke dry cooling plants for cooling to

avoid its combustion. There are three Coke Dry Cooling Plants (CDCP), each having four cooling

chambers. The capacity of each cooling chamber is 50 to 52 TPH. Nitrogen gas is used as the

cooling medium. The heat recovery from nitrogen is done by generating steam and expanding in two

back pressure turbines to produce 7.5Watts of power each.

The coal chemicals such as benzol, tar, ammonium sulphate etc. are extracted in coal

chemical plant from co gas. After recovering the coal chemicals the gas is used as a byproduct fuel

by mixing it with gases such as BF gas, LD gas etc. A mechanical, biological and chemical treatment

plant takes care of the effluents.


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2.3. SINTER PLANT:

Sintering is one of the most widely used and economic agglomeration techniques. Sinter is a

hard and porous lump obtained by agglomeration of fines of iron ore, coke, limestone, and

metallurgical waste. Sinter increases the productivity of blast furnace, improves the quality of pig

iron and decreases the consumption of coke rate .Two 312 square meter sinter machines with 420

square meter straight stand type coolers for annual production of 5.26 MT sinter.

2.4. BLAST FURNACE (BF):

Pig iron or hot metal is produced in the Blast Furnace .The furnace is named as BF as it is

run with blast at high temperature and pressure of 1500 deg. C. Raw materials required for pig iron

and iron are iron making ore, sinter, coke, and lime stone. There are two 3200 cubic meter blast

furnace to meet 3.0 MT annual metal requirements. With bell each furnace is provided with a set of

four hot blast furnace stoves designed for supplying air blast up to 1300 deg .C. Three turbo

blowers, one for each furnace and one stand by common to both furnaces are provided with 12 MW

top pressure recovery turbo generating power. BF gas is produced from each furnace is being

cleaned in gas cleaning plant comprising dust catcher, high pressure scrubber and is distributed

through out the plant as a fuel.

2.5. STEEL MELT SHOP (SMS):

Steel is an alloy iron and carbon, where carbon should be less than 2%. Hot metal produced

in B.F contains impurities like carbon, sulphur, phosphorous, silicon etc., these impurities will be

removed in steel making by oxidation process. These are the three L.D converters to convert hot

metal in to steel. The steel melt shop complex is comprising of two 1300-ton hot metal mixers, three

130-ton LD converters (two operating) and six 4-stand bloom casters. Each converter is being

provided with gas cleaning plant for cleaning and recovery of LD gas, which will be used as fuel in

plant.


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2.6. ROLLING MILLS (RM):

Blooms cannot be used as they are in daily like. These blooms have to be reduced in size

and properly shaped to fit for various jobs. Rolling is one of the mechanical processes to reduce

large size sections in to smaller ones. The cast blooms from CCM are heated and rolled in to long

products of different specifications like high capacity, sophisticated high-speed rolling mills. The

rolling mill complex comprises:

Light and medium merchant mill (LMMM)

Wire rod mill (WRM)

Medium merchant and structured mill (MMSM).

Each mill is well equipped with required number of walking beam furnaces for heating ofwalking beam furnaces for heating of blooms or billets and except for wire rod mills, each furnace is

provided with evaporative cooling system for generation of steel for plant consumption.

2.7. THERMAL POWER PLANT (TPP):

The estimated power requirement for V.S.P in 280 at 3.0 MT stages, the peak load being

292 MW essential loads being 49 MW. The generating capacities are 286.5MW. A captive power is

having 3x60 MW turbo-generator sets and 5x330 ton/hr steam generators. In this plant,

6000Nm^3/min turbo blowers are being provided for supplying cold air blast furnaces.

2.8. MAIN PRODUCTS OF VSP (PRODUCT MIX):

Unlike many other steel plants VSP is an integrated steel plant , producing many

products like Blooms, Channels, Angles etc., other than these VSP also produces many by-products

that are derived during the production of coke and iron .The main products and the by-products that

are produced are shown in the table below :


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TABLE1:

Table1: Products of steel plant vsp

Steel productsBy-Products

Angles Nut coke Granulated slag

Billets Coke dust Lime fines

Channels Coal tar Ammonium sulphate

Beams Anthracene oil

Squares HP naphthalene

Flats Benzene

Rounds Toluene

Re-bars Zylene

Wire rods Wash oil


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3. COMMUNICATION SYSTEMS IN VSP

In this modern age of industrialization telecommunications plays a very important role in

coordinating the activities of various departments/sections and in achieving the set targets and also in

improving the performance of the organization. In Visakhapatnam Steel Plant, different types of

communication systems are being used to meet the internal and external communication needs.

These are broadly classified as follow:

a) General purpose communication systems.

b) Process communication systems.

c) Monitoring & Signaling Systems.

Apart from the above facilities Telecom department maintains the following cable networks also

a) DATACOM cable network

b) .Telephone cable network in plant and township

3.1. GENERAL PURPOSE COMMUNICATION SYSTEMS:

The following facilities are provided under category of general purpose communication systems:

4000 lines IP based Telephone in Plant.

3000 lines Electronic Exchange in Township.

100 lines Electronic Exchange in Visakha Steel General Hospital.

44 lines Electronic exchange in Hill Top Guest House

2500 Lines Electronic Exchange of Bharat Sanchar Nigam ltd (BSNL) in Project Office

is catering to the needs of Plant area and Sectors-I to VII in township. Another 2000 Lines

Electronic Exchange of Bharat Sanchar Nigam ltd (BSNL) in Township is catering to the needs of

Sectors-VIII to XI in Township.

The 3000 Lines electronic exchange in plant and 3000 lines exchange in township are

having the following facilities: Extension (subscriber) to extension call, Auto call back, Hot lines,

Music on hold, Reminder Alarm, Automatic line testing facility, Faults man ring back, Call consult

facility, Malicious call tracing facility, 3 party conference Facility and Howler Tone alert etc.


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All exchanges working in the steel plant are interconnected by means of junction lines

and have closed numbering scheme. The 3000 lines exchange in township is interconnected to the

BSNL network. Due to this interconnection all the subscribers of this exchange can receive

incoming calls from any part of the world. A few subscribers are provided with facility to contact

subscribers connected to the BSNL network and cellular and mobile phones in and around

Visakhapatnam.

3.2. PROCESS COMMUNICATION SYSTEMS:

To facilitate coordination, operation & management activities of production, maintenance

& service departments, the following process communication systems are provided:

a) Dispatcher communication system

b) Loudspeaker intercom systems

c) Loudspeaker broadcasting systems

d) Loudspeaker conference communication system

e) Industrial public address system

f) Hotline communication systems

g) VHF communication systems

A) DISPATCHER COMMUNICATION SYSTEMS:

Initially dispatcher communication is provided with cordless switch board type manual

exchanges of electromechanical. Since manufacture of such systems and their spares is discontinued

in the country, these dispatcher systems are being replaced by Electronic exchanges progressively.

Except the ones in CCCP other systems have been replaced. These would also be replaced very

soon. Production coordination at plant level being conducted by ED (Works) with all HOD s in the

morning every day is facilitated with the help of the digital EXCOM system provided in the plant

control room.


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B) LOUD SPEAKER INTERCOM SYSTEMS:

Loudspeaker intercom systems are working LMMM & WRM. These systems are used

for communication between various sections of the same production shop. Communication is made

possible using microphones and loudspeakers provided in the subscriber stations. This system is very

useful in noisy environment where conventional telephones are ineffective. This system helps to

establish communication between any two stations having interconnectivity on selection basis. By

using group call facility it is possible to communicate to all the subscribers in the group at a time .

C) LOUDSPEAKER BROADCASTING SYSTEMS:

This system consistsof centralized amplifier rack with amplifiers, desktop micro phone with

press to talk switch and a network of loud speakers connected to the amplifiers .this is useful to

make general announcements to the entire working area as to pass on important instruction from the

control room. Loudspeaker broad casting systems are provided in C&CCD, BF, SP and SMS

departments.

D) LOUDSPEAKER CONFERENCE COMMUNICATION SYSTEMS:

Loudspeaker conference communication systems are working in CCCP. These systems

are provided with both paging and private channel communication facilities. In case of paging a

general announcement can be made which is heard on all the stations. In the private mode

communication is possible between two selected stations only. Here also communication is carried

out by means of microphones and loudspeakers provided in the subscriber stations.

E) INDUSTRIAL PUBLIC ADDRESS SYSTEM:

Industrial Public Address System is working in TPP. It is a combination of loudspeaker

broadcasting system and conference communication system. From the main control room it is

possible to make announcements which are heard on the shop floor. From certain locations the

communication can also be established through handsets in private mode with the main control

room.


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F) HOTLINE COMMUNICATION SYSTEMS:

To ensure direct telephone communication between closely related critical locations hot

lines are provided. By using the hot lines specified locations are connected permanently.

Communication is possible only between these two locations. When one subscriber lifts his

telephone the other will immediately get a ring and communication can be had without any loss of

time.

This is useful to pass-on urgent messages. These hot lines are initially provided with

direct line communication systems which are electro mechanical systems. Due to obsolescence

electronic systems are now being used for most of the locations. Hot lines are working in CCCP, BF,

SMS, LMMM, WRM, MMSM, TPP, PPM, DNW and WMD departments.

G) VHF COMMUNICATION SYSTEMS:

VHF communication systems are used in VSP to establish two way communications

between two or more when either or one of them is moving. There are three models working in our

plant. They are hand-held units (Walkie-talkie), vehicle mountedmobile units and base station

units.

Walkie-talkies are used by operation and service personnel in almost all of the production

shops. Vehicle mounted units are being used by DNW, CISF (Fire) and CISF (security). Base station

units are used by CISF (fire), CISF (Security), Administration, DNW and largely by CCCP

departments. In CCCP these can be seen in pusher cars, charging cars, door extractors, electric locos,

lifters and CDCP areas.

These sets are very essential and useful in answering proper communication and

coordination during alignment of oven machines while charging and pushing the ovens and carrying

out these operations safely.

Handheld VHF sets are extensively used for establishing instantaneous communicationand ordination of operation or maintenance activities on different departments throughout the steel

plant.


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3.3. MONITORING AND SIGNALING SYSTEMS:

To facilitate monitoring production, maintenance & service activities, the following

monitoring and signaling systems are provided:

a) Closed Circuit Television Systems (CCTV)

b) Central fire alarm signaling system

c) SCADA system

d) Shift change Announcement Siren System

A) CLOSED CIRCUIT TELEVISION SYSTEMS (CCTV):

For monitoring critical operations in different production units continuously from the

concerned control rooms/pulpits CCTV systems are used in SP, BF, SMS, LMMM, WRM and

MMSM departments. CCTV system comprises of CCTV camera with a lens and a CCTV monitor.

In some cases a video switcher, a central control console, pan and tilt head and zoom

lens are also used. These are interconnected by means of control cables and / or coaxial cables.

Necessary protection is provided for the CCTV equipment depending on the locations where they

are used.

B) CENTRAL FIRE ALARM SIGNALING SYSTEM:

The central fire alarm system is provided for communicating the exact location of

outbreak of fire in any part of the steel plant complex to the central fire station and simultaneous

actuation of sirens to alert personnel of the affected plant zone. The system employs manual call

points located all over the plant.


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C) SCADA SYSTEM:

To monitor the generation and consumption of various energies by various users in the

plant the SCADA system is provided. Scada system is located at Energy and Telecom centre. The

system comprises of a master servers, 23 Remote Terminal Units (RTUs) installed in different plant

units and display units. The RTUs will collect the signals from the transducers & electrical systems

and transmitting to the master servers by means of co communication channel. The RTUs are

connected to the master servers by underground laid telephone cables.

D) SHIFT CHANGE ANNOUNCEMENT SIREN SYSTEM:

The shift change announcement siren system is provided for ensuring uniform and

accurate shift timings throughout the plant. This system consists of two quartz crystal controlled

master clocks, in the Energy & Telecom Centre. The shift timings are programmed in the Master

Clock. At the specified time, the signal will be transmitted for energizing the sirens located at

strategic points in plant area simultaneously at the preset timings.


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4. APPLICATION IN MOTION CONTROLLING

4.1. INTRODUCTION TO DRIVES:

Motion control is required in large number of industrial and domestic applications.Systems employed for motion control are called DRIVES. It may employ any of the prime movers

such as diesel or petrol engines, gas or steam turbines, steam engines, hydraulic motors and electrical

motors, for supplying mechanical energy for motion control. Drives employing for electrical motors

are known as ELECTRICAL DRIVES.

4.2 BLOCK DIAGRAM OF AN ELECTRICAL DRIVE:

FIGURE 4.1 Block diagram of a drive

Electrical drive has the following major parts:

LOAD:

There are large no of loads and each load has its own specific requirements.

Each load has its own current and voltage rating. These ratings are to be observed carefully before

operating the motor or machine.


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MOTORS:Motors commonly used in electrical drives are:

DC MOTORS:

Shunt motors

Series motors

Compound motors

1. Cumulative compound.

2. Differential compound.

AC MOTORS:

Induction motors

1. Squirrel cage

2. Slip ring or wound rotor

Synchronous motors

POWER MODULATOR:

Modulates flow of power from the source to the motor in such manner that motor is

imparted speed-torque characteristic required by the load. It consists of converters, inverters etc., in

general a pulse modulator is used in drives to supply the required power to the DC motor.

CONTROL UNIT:

Controls for a power modulator are built in control unit which usually operates at much

lower voltage and power levels. It consists of firing circuits, which employ linear and digital

integrated circuits and transistors and a microprocessor when sophisticated control is required. Input

command of the signal, which adjusts the operating point of the drive, forms an input to the control

unit.

SENSING UNIT:

Sensing of certain drive parameters, such as motor current and speed may be required

either for protection or for closed loop operation.


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4.3. VARIOUS TYPES OF DRIVES USED IN INDUSTRIES:

DC DRIVES:These drives are used to regulate the speed of DC motors within the rated

current and voltages.

Analog AC drives

Digital DC drives

AC DRIVES:These drives are used to regulate the speed of DC motor within the rated

current and voltages.

Analog AC drives

Digital DC drives

The Drives are to be protected from over current and over voltage. This is to be done using

Chokes and snobbery circuits.

CHOKE: A choke is a coil of insulated wire often wound on a magnetic core used as a

passive inductor to block high frequency AC in a high frequency circuit.

SNUBBER: Snobbery are frequently used in electrical systems with an inductive load

where sudden interruption of current flow often leads to sharp rise in voltage across a

device creating interruption.


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5. APPLICATION IN MOTION CONTROLLING

DC DRIVE:

Drives employed for speed control of dc motors are called dc drives. DC Drives convert AC

line voltage into variable DC voltage with an SCR phase-controlled bridge rectifier, to power the DC

motor ARMATURE. A separate field supply provides the motor with DC FIELD excitation.

FIGURE 5.1: DC drive motor connections

Speed of dc motor can be written as

N = kEb / @ ; Eb=(@ZN / 60) (p/a)

EbBack EMF

@ - flux

Z - no. of turns

P- no. of poles

Ano. of parallel paths

Speed can be controlled either by varying armature voltage or field flux.

Armature controlled method is usedto vary the motor speed below base speeds

Field control method is used to vary the motor speed above base speeds.

LINE

INPUTMOTOR OUTPUT

Armature

Field

A1

A2

F1

F2


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The typical speed torque characteristics of dc motor are as shown in below figure.

FIGURE 5.2: Speed torque characteristics

Main drive:

The drive having both armature and field control is called main drive. In this the motor

can be operated in below & above base speeds.

Auxiliary drive:

The drive having only armature control is called auxiliary drive. The dc drives are of either

analog or digital. The power circuit is same for both. In analog drives all the control signals are inanalog form but in digital drives this controlling is through microprocessor controller.

100

50

25

75

750 500 750 1000

Base Speed Max.Speed

2 : 1 FIELD

WEAKENING

3 : 1 FIELD WEAKENING

4 : 1 FIELD WEAKENING

FIELD WEAKENED RANGE 4 : 1

CONSTANT HORSEPOWER

HO

RSE

PO

WE

R

CONSTANT TORQUE

TORQUE @ 100% ARMATURE AMPS

FULL FIELDTO

R

Q

U

E

&

H

O

R

SE

P

O

W

E

SPEED (RPM)

%


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5.1 ANALOG DC DRIVE:

5.1.1 Components of Motor Testing Equipment (Analog Dc Drive):

1. POWER SUPPLY UNIT

2. CONTROL SUPPLY UNIT

3. SYNCHRONOUS SUPPLY UNIT

4. REGULATION UNIT

5. PROTECTION UNIT

5.1.1.1. POWER SUPPLY UNIT:

Armature main incoming transformer is the primary of which is 11KV. The secondary of thetransformer is connected to thyristor converter through HT breaker. The converter output DC is

connected to armature of the motor through HSCB and DC contactor.

Field main incoming transformer the primary of which is 415 V. The secondary of the

transformer is connected to thyristor converter through AC contactor. The output DC is connected to

field of the motor directly.

5.1.1.2. CONTROL SUPPLY UNIT:

Armature control supply transformer with primary 415volts-3phase, generation of

unregulated +/-24v DC and regulated +/-15v DC for control electronics.

Field control supply transformer with primary 415volts-3phase, generation of

unregulated +/-24v DC and regulated +/-15v DC for control electronics. Primary of the transformer

is fed with a circuit breaker for the generation of auxiliary supply (60V DC) in armature and in field

separately for pulse generation.

5.1.1.3. SYNCHRONOUS SUPPLY UNIT:

This consists of armature synchronous transformer, primary of which is 415V-3 phase,

secondary of which is connected to pulse generator card for generation of 60V DC pulse power

supply for armature.


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5.1.1.4. REGULATION UNIT:

This consist of

Speed controller, current controller for armature

EMF controller, flux controller for field

5.1.1.5. PROTECTION UNIT:

This consists of fault monitoring, fault registering and tripping in armature for followingunits:

Main incoming transformer (over temperature, Bucholtz protection).

Thyristor converter (fuse, over temperature, over current protection)

Motor armature (over temperature, instantaneous over current, over speed, over voltage,

earth fault protection)


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5.1.2 Need for speed control:

In various applications we need to vary speed i.e. there is a need to run the motor at more

than one speed. At such applications we use drives. The speed of a dc motor can be controlled by

various methods.

Speed is directly proportional to the supply voltage & hence we can increase the speed of motor

only up to the rated voltage. Hence speeds below rated speeds are only possible.

Speed is inversely proportional to Field/flux. Field can only be weakened. Hence we can only

achieve speed above rated in this process.

The speed of a dc drive is varied by varying the input power (since the speed is proportional to

applied voltage to the motor terminals).

In general industries use three phase ac supply. But we need to convert the ac power to

corresponding dc power.i.e, we need to convert the Input three phase supply to dc voltage. This can

be done by using bridge rectifiers. We have many types of bridge rectifiers like

Basic diode bridges

Thyristor bridges.

Our main aim is to regulate the speed of motor. But in a diode bridge we cannot control the

output of the bridge where as we can control the output of the bridge by varying the firing angle at

the gate of thyrisor.


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Diode Bridge:

Figure 5.3: Diode bridge circuit

Figure 5.4: Diode Bridge output waveform


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Thyristor (scr) Bridge:

Figure 5.5: Thyristor bridge circuit

In a thyristor circuit unlike in a diode bridge rectifier we can control the output voltage to

be applied to the DC motor for obtaining various rated speeds. This principle is largely employednowadays.

From the below wave forms it is evident that the output of the Thyristor Bridge is

dependent on the position at which pulse fired. This is also known as firing angle. The complete

voltage output can be regulated by varying the firing pulse between an angle from 30-150.

30 degrees corresponds to maximum voltage firing angle.

150 degrees corresponds to minimum


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Reference generation:

A reference 0-10V is generated which is equated to gate pulse angle max to min (Eg:

1500 to 300) to generate the dc voltage zero to maximum (E.g.:0V to 400V DC) which is directly

proportional to speed (E.g.: 0 to 1000 rpm) of the motor.

Ramp function generation:

To overcome starting inrush current, the ramp function generator is introduced. It is also

called soft start circuit (Fig.). The input of the ramp function generator is 10V; the output of this

varies as 0-10V with set times called ramp up and ramp down.

Figure 5.7: Controller section of the drive with all the cards


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Speed controller:

Open loop:

In modern speed-control drives, open loop control proves inadequate because of sharply

drooping speed-torque characteristics.

Closed loop:

The closed loop control systems are widely used for maintaining the speed constant at a

desired value with better accuracy and dynamic response. A Tachogenerator is often used,

sometimes voltage feedback for closed loop system.

The output of the Tachogenerator is compared with a preset reference (output of ramp

function generator). The difference between these two voltages is fed as an actuating signal

to control elements of the system.

Figure 5.8: Speed controller in a card


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Current controller:

CT feed back or Shunt feedback is used for the actual current of the motor. It is compared

with the output of the speed controller, which actuates and controls the triggering of the

thyristors.

There are two feedback paths in the dc control system; one is called outer speed or voltage

feedback path and the other is called inner current feedback path. With the combination of

two feedbacks paths the overall performance becomes more precise.

Figure 5.9: Current controller


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GK cards:

The component in the GK (gate and cathode) card is pulse transformer, mainly to isolate the

control signal with Power circuit.

Figure 5.11: Basic drive circuit from a standard manufacturer


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Fig 5.12 forward/reverse controller


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Fig 5.13 full forward/reverse controller


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5.2 Digital Drives:

An advancement of technology is the present days digital drive. All the above blocks are

combined logically on a single board using program logic controls which provide output to motor

based on the parameters given as input. The program is fed into and operated via a micro

processor/controller. The code used in the micro controller is given to the staff so that it can be

reprogrammed at any time. Along with all the above blocks logically the firing pulse generator is

provided with necessary hardware. The block diagram of the digital drive is as shown in figure

below.

Figure 5.14 Digitaldrive


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6.COMPARISION BETWEEN ANALOG & DIGITAL DRIVES

Basic building block :op-ampsupported by other analog

components

Functional blocks are inter connectedthrough wire wrapping or mother

board

Set points and gains are adjusted usingpotentiometers provided.

When the temperature increases thevalues are changed.

Modification is difficult. All analogcomponents ratings has to be

changed.

Functional blocks are soft warebased program processed in a

microprocessor

Blocks are interconnectedthrough software connectors

Adjusted using parameter valuesdirectly using their parameter

number

They are independent oftemperature.

We can configure the drive toany application easily. Only by

changing the parameter values.

Chances for failures are less.

Repairing is not possible. Onlyreplacement is possible.

FUNCTIONALLY NO DIFFERENCE

ANALOG DIGITAL


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7. CONCLUSION:

In the time being the analog drives are being replaced by digital drives. Analog drives are

difficult to maintain and are costly unlike digital drives which are very easy to maintain and cheaper

cost. The repair of digital drive involves of simple steps like re programming unlike the analog

drives which require component wise attention and replacement. The digital drives also present a

large range of accuracy.

But in component wise the replacement of components in an analog drive is easy compared

to the Digital drive which involves finding out the specific IC to be replaced in case of physical

damage. Due to the functional efficiency and less probability of hardware failure digital drives are

replacing the analog drives in almost all the industrial applications.

Even modifying parameters of a digital drive is easy compared to the analog drive which

needs just changing the parameter values in the code whereas an analog drive requires the resistors

and other circuitry to be changed. Hence it is always a good choice to run the machines based on

availability of the drive.

a mini project_binding copy!

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