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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. In vizag steel plant , there is Supervisory Control And Data Acquisition (SCADA) systems present for monitoring of energy networks which are present throughout the plant. The objective of this proposed SCADA systems is to monitor the energy usage and demands of various consumers of the plant and exercise effective control over their energy consumption optimum utilization of in-house energy resources. In this modern world of competition the technology is changing very rapidly. To compete with the changes and to sustain the development, Visakhapatnam Steel Plant is going for up gradation of its existing SCADA systems with the latest state of art-technology with the features like using high speed processors having cache memory and using the powerful unix based OS. This project makes a brief study of existing “SCADA” systems present in Visakhapatnam Steel Plant and the changes that are going to come to in the
proposed SCADA systems that is to be installed in the near future.
GROWTH AND IMPORTANCE OF STEEL INDUSTRY IN INDIA.
Steel comprises one of the most important inputs in all sectors of economy. Steel industry is a basic core industry. The economy if any depends on strong base f iron and steel ingn that nation. History has shown base of iron and steel industry in that nation.
History has shown that countries having a string potentially for iron and steel production have played the prominent role in the advancement of civilization in the world. Steel is such a versatile commodity that every object we see in our day to day life has used steel either directly or indirectly
However its use is innumerable to mention a few, it is used for such small items as nails, pins, needles etc., through surgical instruments, agricultural implements, ships, boilers, frigates, railway materials, automobile parts etc.. The great investment that has gone into the fundamental research in Iron and Steel technology has helped both directly an indirectly many modern fields of todays civilization without steel. Steel is versatile and indispensable item. The versatility of steel can be traced through mainly these reasons :
It is the only material item which can be conveniently produced in tonnage quantity. It has got very good strength coupled with ductility and malleability. Its property can be changed over a wide range. It alloys easily with many of the common elements. The properties can be manipulated to any extent by proper heat treatment
techniques. Taking these factors into consideration, it can be said without committing a serious
error, that the type of steel available are innumerable.
“Visakhapatnam Steel Plant is an integrated steel plant.”
Characteristics of Integrated Steel Plant.
“Visakhapatnam Steel Plant is an integrated steel plant”
This integrated steel plant has large capacities, highly capital intensive, labor intensive and they would have all facilities including raw material resources, water supply, power supply, testing and inspection facilities, township facilities, medical, educational, recreational etc., all under one administrative control. This would reduce
the extent of dependency on outside agencies, which would help the smooth running of the plant.
Technology in Steel Plant
Visakhapatnam steel plant is the most sophisticated and modern integrated steel plant in the country modern technology has been adopted in many areas of production, some of them for the first time in the country. Among these are
Selective crushing of coal Evenching of coke Conveyor charging and bell les top for blast furnace Hundred percent continuous casting of liquid steel Gas expansion turbine for power generation utilizing blast furnace top gas
pressure. Hot metal desulphurization. Extensive treatment facilities for effluence for ensuring proper environment
protection. Computerization for process control Sophisticated, high speech and high production rolling mills.
MAJOR DEPARTMENTS IN VSP
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 reclaimers and distributed to various departments of
Visakhapatnam steel plant through conveyor systems.
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 tons of dry coal charge. The
carbonization takes place at 1000 to 1050 degrees 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 7.5 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 byprioduct 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.
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.
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 requirement. 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.
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 comprising 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.
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 of walking
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.
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 286.5 MW. A captive power having 3x60
MW turbo-generator sets and 5x330 ton/hr steam generators. In this plant, 6000 Nm^3/min turbo
blowers are being provided for supplying cold air blast furnaces.
COMMUNICATION SYSTEMS IN VSP
Role in co 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:
General purpose communication systems.
Process communication systems.
Monitoring & Signaling Systems.
In this modern age of industrialization telecommunications plays a very important
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
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. 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.
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 a 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.
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 consists of 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.
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 mounted – mobile 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 communication and
ordination of operation or maintenance activities on different departments throughout the steel
plant.
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.
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 tranducers & electrical
systems and transmitting to the master servers by means of communication channel. The RTUs are
connected to the master servers by under ground 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.
SCADA SYSTEM:SCADA is an acronym for Supervisory Control and Data Acquisition system, a computer system for gathering and analyzing real time data. SCADA systems are used to monitor and control a plant or equipment in industries such as water and waste control, energy, oil and gas refining and transportation. A SCADA system gathers information, such as where a leak on a pipeline has occurred, transfers the information back to a central site, alerting the home station that the leak has occurred, carrying out necessary analysis and control, such as determining if the leak is critical, and displaying the information in a logical and organized fashion. SCADA systems can be relatively simple, such as one that monitors environmental conditions of a small office building, or incredibly complex, such as a system that monitors all the activity in a nuclear power plant or the activity of a municipal water system.
SCADA systems were first invented in the 1960s.
The signals for a plant unit will normally be concentrated in the control room of the unit from where the unit is being operated. PLCs/RTUs of the SCADA will be installed in these main control rooms and the tele- transmission signals identified for the units will be wired to the PLCs/RTUS .
The PLCs/RTUs are micro processor based intelligent units , responsible for acquisition of inputs from the plant units and convert them in to digital code for Tele -- transmission to the Master station computer of SCADA through the 5 pair telephone cable . Some plant unit where few signals are available for tele-transmission , A junction box will be installed in the control room ( instead of an PLCs) for the termination of inputs and these inputs are further connected to the nearest PLCs through the multi – core control cables.
The 23 PLC s are located in different parts of the plant are connected to the center master station through modems. The Master station located in the E&T centre of the Visakhapatnam steel plant will acquire all Information through PLC and LAN and Process the information for
displays and report generation .
The SCADA system acquires various electrical & utility parameters for effective monitoring & control operation. The various parameters acquired are electric power , voltages , currents , etc., under electrical monitoring and parameters such as flows , temperatures, pressures , etc..
CATEGORY OF ENERGY FORMS IN VSP
Utility systems
Electrical systems WATER
UTILITY SYSTEMS:
The utility system covers the services like fuel , gases , stream , compressed air, water etc.. The services covered by the utility systems of CSCS are broadly classified in to following groups.
Fuel gases system: CO, BF, Mixed & converter gases.
Process gas system : Nitrogen, Oxygen ,Argon, Acetylene.
Steam Distribution system: Steam at 40 KSCG, 13 KSCG.
Compressed air system: Compressed air and instrumentation grade air
Chilled water system: Chilled water.
Fuel oil system: LSHS, LDO and LTF.
Water Water systems: make up water, fire and drinking water
ELECTRICALSYSTEM:
The electrical system covers the complete electrical distribution network inside the Visakhapatnam Steel Plant like 220 KV ,11 KV, 6.6 KV systems in MRS, LBSS , 1, 2 , 3 , 4 and 5 , LBDSS.
For centralized supervisory of above services in utility and electrical systems and also to exercise control over their optimum utilization, following types of signals are considered for the users.
Analog input (AI)
Digital input (DI)
EM SIGNALS
The input signals acquired by the PLCs are tele-transmitted to the Master station and are sorted out according to the above subsystem division i.e utility and electrical.
SCADA systems monitor a total of 4000 different signals originating at different depts. in VSP. Among these 4 000 signals, 150 0 signals are catered to monitor utility system and 2 500 signals are electrical system .
ARCHITECTURE OF THE SCADA
ARCHIECTURE OF THE FIELD PLC/RTU’S
PLC – Architecture:
The selected PLC has got powerful processor to take care of the data acquisition requirements of the
VSP. The PLC interfaces with field to acquire the data from various field instruments. The offered
PLC system supports maintenance from the Engineering station in master station. The PLC will be
supplied with ladder programming language for building local automation sequences. The offered
PLC is fully modular and supports distributed I/O for future expansion. The PLC supports a total of
20,000 I/O ports.
The functional architecture of the PLC system will be as follows. The offered architecture is latest
state-of-the-art in which the PLC processor communicates with individual I/O stations over a highly
reliable Ethernet ring. The extension racks will be available for any more expansion in I/Os. The
system will support a total of 20,000I/O’s.
The PLC presented above shall have the following characteristics:
High capacity controller for I/O signals
High memory capacity and expandable
Input digital signals cards
Input analog signal cards
Galvanic isolation for the signal.
Empty slots for future expansions
Ports to connect to field buses (RS232C/RS485)
Configurable to standard protocols (MODBUS RTU / Profibus DP)
Comprehensive self-testing and diagnostic facilities
SCADA Master Station over dedicated telephone cables.
HARDWARE COMPONENTS OF THE PLC :
1. Power Supply Unit.
2. Programming Unit.
3. Central Processing Unit.
4. Bus Controller Unit.
5. Communication unit to Interface with External Programming unit.
6. Input and Output modules.
1. POWER SUPPLY UNIT :
The power supply modules provide the power supply for each rack.
The required power supply standard format or double format model. The mains electrical
supply ~200..240V
Description of the Power Supply Unit:
1. Display blocks comprising.
OK lamp (GREEN), if voltages are present and correct.
BAT lamp (RED), if the battery is faulty or missing.
24V lamp (GREEN) when sensor voltage is present
2. RESET pencil-point push button causing a warm restart of the application.
3. Slot for a battery which protects the internal RAM memory of the processor.
4. Cover to protect the front panel of the module.
5. Screw terminal for connecting:
To mains supply.
The alarms relay contact.
The sensors power supply for a.c supplies.
6. Opening for cable clamp.
7. Fuse located beneath the module and protecting.
24VR voltage on the non-isolated d.c supply.
Primary voltage on the other power supplies.
8. 110/220 voltage selector
CHARACTERISTICS OF THE POWER SUPPLY
The characteristics of the power supply module are
Primary Power supply Module:
Voltage (in V)
Nominal ~100…240
Limit ~85..264
Frequency (in Hz)
Nominal /limit 50…60/47..63
Current (in A)
Nominal input 1ms 0.5 at ~100v
0.3 at ~240V
Secondary power supply Module:
Output
Nominal voltage 5V
Nominal current 5A
Power 25W
Output
Nominal voltage 24V
Nominal current 0.6A
Power (typical) 15 W
Description of the 12 slot Rack Power Supply Unit:
It is possible to constitute a PLC station with premium processors with just a single rack. These racks are connected to each other.
The Racks comprise :
1. Metal frame.
2. Slots for anchoring the Module pins.
3. 48-way female ½ DIN connectors for module-rack connections
4. Locating slot for the power supply module.
5. Trapped holes for mounting the module.
6. Four holes for mounting the rack.
7. Position for rack address label.
8. Position for station network address label.
9. Two earth terminals for earthing the rack.
10. Micro switches for coding the rack address
11. Two 9-way female SUB-D connectors for the remote connection of bus X to another rack.
Rack address:
Address 0: This address is always assigned to the rack which holds the processor.
This rack can be located in any position on the line.
Addresses 1 to 7: These can be assigned in any order to all other extendable racks of the station.
As the two racks with 4, 6 or 8 slots which make up each pair can have the same address on the bus X , position numbers are defined as follows:
Rack n “ less- significant “: position 00 to xx;
Rack n “ most-significant “; position 08 to yy;
Each rack with 12 slots holds an address
Specifications of power supply :
Type Modular
No.of Slots 12 slots inclusive of power supply slot
Dimensions in mm 482.6(W) x 151.5 (H)
Reserved slots Slot-1 for power supply
Slot -2,3 for processor
Functions of the power supply module:
Alarm Relay:
The alarm relay located in each power supply module has a volt-free contact which can be
accessed on the connection screw terminal of the module.
Principle:
Module alarm relay on the processor rack (rack 0): In normal operation, PLC in RUN, the alarm relay is activated and its contact is closed. Whenever the application stops, even partially, occurrence of a blocking fault, incorrect output voltages or loss of mains power, the relay de-energizes and the associated contact opens(state 0).
Alarm relay of power supply modules located on the other racks(racks 1to 7).when the module is powered up and if the output voltages are correct, the relay is activated and its contact is closed (state 1).when the mains power is lost or if the output voltages are incorrect, the relay de-energizes (state 0).
Back-up battery:
Each power supply module has a slot reserved for a battery which provides the power supply to the
internal RAM memory located in the processors, in order to ensure that data is saved when the PLC
is switched off. The duration of data back-up is one year. The battery must be changed as soon as
the BAT lamp(RED) on the front panel lights up.
RESET Push button:
Pressing this push button, which located on the front panel of the power supply module, triggers a
sequence of service signals which is the same as that for:
A power breaks when the push button is pressed.
A power up when the push button is released.
Sensor power supply:
The sensor power supply (a.c) modules have an integrated power supply which provides a voltage of
24V to supply the input sensors. Connection to this sensor power supply can be accessed via module
screw terminal.
2. PLC PROGRAMMING
PLC acronym for Programmable Logic Controller is an industrial computer control system that
continuously monitors the input devices and performs a sequence of operations depending of
inputs. The output is user defined through a set of instructions, integrating the process sequences
and interlocks.
Programmable Logic Controller is a solid state device, basically designed to perform logic decision
making for industrial control applications. Sincere their development in early 1970’s PLC have
evolved to challenge not only relays but also other discrete control devices such as stepping
switches, drum sequencers etc.
The PLC is composed of electric circuit with a microcomputer centered. However , it can be
equivalently regarded as an integrated body of ordinary relay, timer, counter etc.
There are different methods of programming PLC’s .They are
1. Ladder diagram programming.
2. Function blocks programming.
3. Instruction list programming.
4. Structure text programming.
Ladder diagram:
It is graphic and very easy to understand. It closely resembles the old relay logic diagram. Generally shop floor maintenance people easily understand and prefer it. The drawback of this language is, occupies more memory space and slow.
Function diagram:
It is also easy to understand and pictorial representation. It closely resembles the controller programming. This is also very slow. Most of the PLC’s use a combination of ladder and function block programming.
Instruction List:
It uses he mnemonic codes of a microprocessor. It is very fast but it requires familiarity with assembly language programming of microprocessor.
Structured text:
It is nothing but C language programming. It is a fastest of all languages. But it requires through knowledge of ‘C’ language programming.
Function of the PLC:
HOUSE KEEPING
INPUT SCAN
LOGIC SCAN
OUTPUT SCAN
SERVICE COMMUNICATIONS
House Keeping:
It consists of internal checksums and diagnostics that the processor executes every scan cycle. These can be done at the beginning or the end of the scan cycle or both depending upon the PLC.
Input Scan:
It consists of reading the current state for each input connected to the PLC system and updating the input memory tables.
Logic Scan:
It consists of reading the use program that ahs been stored in the PLC memory. These programs can be written in ladder logic, instruction list, sequential flow charts, function block, structure test, c code or state logic depending upon their manufacturer of the system. Some system supports programming using combination of languages within the same program.
Output scan:
It consists of adjusting the values of outputs connected to the system based upon the status of inputs and execution of the logic.
Service communications:
It consists of opening the window of time for the processor to communicate to other devices. These can be programming devices, operator interface devices,
remote IO controllers, other PLC’s or any devices having communication capability that is compatible with the PLC system.
3. CENTRAL PROCESSING UNIT:
This CPU is a double format high performance processor.
FIGURE 1
The CPU displays 6 additional display lamps
1.
RUN lamp (GREEN) : Ethernet TCP/IP port ready.
ERR lamp (RED) : Ethernet port fault
COL lamp (RED) : Collision detection.
STS lamp (YELLOW) : Ethernet link diagnostics.
2TX and Rx lamp (YELLOW) : Tx/Rx activity.
2. A “Memory Extract” button for extracting the PCMMCIA memory extension card.
The associated “Memory extract ready” display lamp indicates that this card can be extracted safely.
3. RESET button causing a cold restart of the PLC when it is activated.
4.An 8-way female mini-DIN connector marked AUX for connecting a programming adjustment.
5. A USB type connector marked TER for connecting a programming terminal.
6. A PCM CIA slot (no.0) for a memory extension card.
7. A PCM CIA slot (no.1) for a communication card or memory Extension card for storing additional data.
8. NOT APPLICABLE FOR THIS MODEL.
9. An RJ 45 type connector for connection to the Ethernet TCP/IP 10BASE-T/100 BASE-Tx network.
MEMORY STRUCTURE
The application memory is divided into memory areas physically distributed in the internal RAM memory and on 0, 1 or 2 PCMCIA memory extension cards.
1. The application data area, which may be one of 2 possible types, is always in the internal RAM.
Located Data: It is defined by an address (e.g. %MW237) which a symbol may be associated.
Unlocated Data: It is defined by the symbol. This type of symbol addressing removes the memory “memory management” constraints because address is assigned automatically.
2. Area in internal RAM or PCMCIA memory card for the program and symbols. In the event of this area being in internal RAM.
It also supports the area for modifying the program in online mode.
This area contains the program’s executable binary code and IEC source code.
The user selects the type of information to be stored in the PLC memory.
3. Constants area in the internal RAM or the PCMCIA memory card (slot no .0)
4. Storage area for additional data (slot no. 0 or no.1)
Ex: For production data and manufacturing recipes.
Application of the internal RAM:
In this case, the application is entirely loaded in the processor’s internal battery-backed RAM(2). It varies at 96 to 640 Kb.
Application in PCMCIA card:
IN this case, the internal RAM is reserved for the application data. The PCMCIA memory card (slotno.1) contains the program space (programs, symbols and constants areas). It varies at 224 to 7168 Kb.
The internal RAM memory is backed up by an optional battery (3 year’s life) located in the power supply module.
Extension of data storage area :
Memory cards reserved for data storage (4096 or 8192 Kb) are used to:
Access the data storage area when the application is entirely supported by the internal RAM. In this case, the data storage memory card is inserted into PCMCIA slot no.0
Free up memory space to provide additional program space when the application is in the PCMCIA card (slot no.0).In this case, the data storage memory card is inserted into PCMCIA slot no.1.
Protecting the application:
Regardless of the PLC memory structure (whether it is located in the internal RAM or in the PCMCIA memory card), it is possible to protect this order to prevent it being accessed (read or modify program) by only loading the executable code on the PLC.
A memory protection bit, set in configuration mode, is also available to prevent any program modification (via the programming terminal or downloads).
Program modification in online mode:
The function of this PLC is, it allows program code and data in different parts of the application to be added or modified in a single modification session.
Any program modification made in online mode.
CHARACTERISTICS AND PERFORMANCE
The characteristics and performance are
Functions:
Max No. in Rack
Discrete I/O 2048
Analog I/O 256
Process control channels 20 (up to 60 simple loops)
Application- specific channels (counter, serial links)
64
Integrated Connections
Ethernet TCP/IP 1
Serial link 1x12 Mbps USB link(TER)
1x19.2 Kbps (AUX) link
Maximum no. of connections
Network (Ethernet,TCP/IP,Fipway,Ethway,ModbusPlus)
4;3if integrated Ethernet is used
Memories:
Maximum capacity
Without PCMCIA card (in Kb) 320prog + data
With PCMCIA card (in Kb) 2048 prog, 440 data
Data Storage 16,384 Kb
Execution time: 11.4 Instructions /Ms
Execution time for 1K instructions: 1/11.4 =0.0877ms
Total memory: 324 kb (with CPU) +256kb (with PCMICA memory Card) = 580kb
Assuming 50% Program memory loading =290kb
Scan time 290*0.0877 = 25.433ms
Communication protocol with Scada: Modbus TCP/IP.
Communication with SCADA: Built –in-Ethernet module
INPUT AND OUTPUT MODULES:
1. Analog Module
2. Digital Module
Analog Module :
The front panels of analog module comprise
i. A display and module diagnostics block.
ii. A connector for receiving the screw terminal block.
iii. A rotating supports containing the module locating device.
iv. A removable screw terminal for direct connection of the I/O to the sensors and preactutators.
v. A pivoting cover for accessing the terminal block screws and holding the identification label.
vi. A screw terminal blocks encoder.
vii. A 25-way SUB-D connector for connecting the sensors.
Functions of Analog Module:
1. Scanning of input channels, protection against over voltages, adaptation of signals by analog filtering, scanning by solid state multiplexing.
2. Adaptation to input signals: Gain selection, drift compensation.
3. Digitization of signals: 12-bit analog/digital conversion.
4. Converting input measurements to user format: recalibration coefficient, filtering, scaling.
5. Module monitoring: conversion circuit test, range overshoot test, terminal block presence test, “watch dog “test.
6. Fast processing of inputs
Specifications:
Channels 16channels
Isolation
Between Bus and channels
Between channels and earth
1000 v RMS
1000 v RMS
Resolution 12 bits
Input operating range +/-10 V DC,0-10V,0-5V,1-5V,0-20mA,4-20mA
Maximum Over Voltage +/- 30 V
Maximum Over current +/- 30 mA
Digital Module :
The front panels of Digital module comprise
Functions of the Digital Module :
I/O assignment :
Each module is functionally organized into groups of 8 channels. Each group of channels can be assigned a specific application task.
Reactivation of Outputs :
If a fault has caused an output to trip, output can be reactivated if no other terminal fault is present.
The reactivation command, defined during configuration, can be automatic or controlled via
program. Reactivation is carried out in groups of 8 channels. This function can be accessed on
modules with solid state d.c outputs. For relay and triac output modules protected by fuse, the same
type of reactivation is necessary after replacement of one or more fuses.
RUN /STOP command :
An input can be configured to control the Run /STOP mode for the PLC.
The command is accepted on a rising edge. A STOP command via an input takes priority over a
change to RUN via the terminal or via a network command.
Output Fallback:
When an application is placed in STOP mode, Outputs must be set to a state which is not harmful to
the application. This state known as the fallback position is defined for each module when its
outputs are configured.
This configuration enables the choice between:
Fall back: channels are set to state 0 or 1 depending on the fallback value entered.
Maintain: outputs retain the state they were in before the PLC stopped.
Diagnostic functions:
Module diagnostics:
Any exchange fault preventing normal operation of an output module or fast input mode is signaled. Similarly, any internal module fault is signalled.
Process diagnostics:
Sensor/procurator voltage check, terminal blocks presence check, short –circuit and overload check, preactuator voltage check.
Specification:
Nominal Input Voltage 24 VDC
Input characteristics
Input voltage
On state voltage
Off state current
On state voltage
24 V DC
>=11 V
>= 3mA
=<5 V
Off state current =<1.5 mA
On response time
Off response time
4ms
Web servers:
The web server module is a standalone TCP/IP –module gateway module used to connect a Modbus device to a TCP/IP network. It is a standard device. It has a built in RS 232 serial link which can be used to connect an external modem.
Mainly this module is used to perform the following functions:
Modbus messaging over TCP/IP,
SMTP service
SNMP service.
Embedded Web server.
Option of having a user web site.
Specifications:
Functions Embedded web server ,
Option of having a user website
Modbus messaging over TCP/IP
SMTP service
SNMP service
No. of Ports 1-RJ 45 connector
1-RJ 45 connector for RS 485 link
A 9-pin SUB D connector for a modem link
No. of simultaneous connections 16 Internet browsers
Energy Meters:
The energy meter portable working is a 3 phase portable electronic meter test unit for use
as a working standard to test both single and 3 phase electricity meters on site. This device allows
checking of all meter installation parameters and associated circuits. The energy meters is available
in accuracy classes 0.1.The unit can be used either with a direct connection in the range 1mA..12A.
Function:
Active, reactive and apparent energy measurement for single phase and 3 phase, 3 or 4 wire circuits with integrated error calculator.
Advantages:
Wide measuring range with auto ranging.
Display of vector diagram for analysis of mains conditions and meter connections.
Measurements of wave from and harmonics with display.
Easy detection of circuit connection faults.
Data memory.
Small dimensions and light in weight.
Serial interface for data transfer.
Application:
On site test of electricity meters.
Specifications:
Power consumption 10VA
Current range 1mA….12A
Voltage range 10V…..300V
CABLES
In both interrogation and broadcasting mode there is a continuous transfer of
information between the PLC and the MS so there is a necessity of a physical medium
to facilitate the flow of information( Electrical Signal). Cables perform the job of
interconnected the field PLCs and MS.
The inter- connecting cables required for connecting various terminals can be
classified in to 3 categories and the technical specification of various cables are also given
below .
CATEGORY – I :
Telephone cables required for inter connection of PLCs and the MS.
5Pair Petroleum jelly filled.
Armored.
Over all polythene packed.
Solid annealed high conductivity copper.
Diameter 0.633mm.
Resistance 57 ohm /KM.
CATEGORY—II:
Twisted pair cables required for the inter connection of remote video terminal to the master stations .
5Pair.
Diameter 7/ 0.2 mm.
Individually and over all shielded.
Armored cables.
CATEGORY – III :
Control cables required for the inter connection of signals from plant units and junction boxes to the PLCs .
# Size 1.5 mm.
# Solid annealed copper conductor.
# Multi core control cable.
# Armored and unarmored.
# Thickness 0.8 mm.
# Resistance 12.1 ohm / KM.
# PVC Insulated.
The cables will be laid partly on cable trays in cable tunnels and balance the directly buried under ground .
LAN EXTENDERS
The RTU’s are connected to the MS by underground telephone cables with one pair of Lan extenders.
Descriptions of Modems.
The SHDSL (Single-Paired High Speed Digital Subscriber Loop) routers/lan extenders comply
with10/100 Base-T auto-negotiation. It provides business-class, multi-range form64Kbps to
2.304Mbps (for 2-wire mode) or 128kbps to 4.608Mbps (for 4-wire mode) payload rates over
exiting single-pair copper wire. The SHDSL routers are designed not only to optimize the service bit
rate from central office to customer premises also it integrates high-end Bridging/Routing. Because
of rapid growth of network, virtual LAN has become one of the major new areas in Internetworking
industry. The SHDSL routers support port-based and IEEE 802.1q VLAN over ATM network.
The firewall routers provide not only advanced functions, Multi-DMZ, virtual server mapping
and VPN pass-through but advanced firewall, SPI, NAT, DOS protection serving as a powerful firewall
to protect from outside intruders of secure connection.
The SHDSL routers allow customers to leverage the latest in broadband technologies to
meet their growing data communication needs. Through the power of SHDSL products, you can
access superior manageability and reliability.
Features:
1. Easy configuration and management with password control for various application
Environments
2. Efficient IP routing and transparent learning bridge to support broadband Internet services
3. VPN pass-through for safeguarded connections
4. Virtual LANs (VLANs) offer significant benefit in terms of efficient use of bandwidth, flexibility, performance and security.
5. Build-in advanced firewall (Firewall router)
6. Four 10/100Mbps network connectivity (4-port router)
7. Getting enhancements and new features via Internet software upgrade.
Specification
Bridging:
1. IEEE 802.1D transparent learning bridge
2. IEEE 802.1q VLAN
3. Port-based VLAN (4-port router)
4. Spanning tree protocol
Management:
1. Easy-to-use web-based GUI for quick setup, configuration and management
2. Menu-driven interface/Command-line interface (CLI) for local console and Telnet
Access
3. Password protected management and access control list for administration
4. Software upgrade via web-browser/TFTP server
LAN Interface:
1. 4-ports switching hub (4-port router)
2. 10/100 Base-T auto-sensing and auto-negotiation
LAN –LAN Connection:
Communication Types :
Citect SCADA supports four types of I/O device communication:
1. Serial communication
2. PLC interface board
3. Data acquisition board
4. Dynamic data exchange (DDE) Server
Whether the I/O device is local or remote, communicating with I/O devices is
Usually via a simple serial connection using the RS-232or RS-485 standard .
With Citect SCADA there are many I/O device communications options, through Citect
SCADA computer's COM port, through a high-speed serial board, or through a communications
board supplied by the I/O device manufacturer.
Whichever option you choose, use the Express I/O Device Setup wizard.
Advantages:
1. Flexible.
2. Scalable.
3. Reliable.
4. Reduce Implementation Time.
5. Low cost.
MASTER STATION/Master server
SERVERS:
WINDOWS based operating software shall be considered as SCADA servers. Servers shall
work on hot redundant server configuration. All the PLCs shall be communicating directly to both the
servers. The data updates taking place in any of the PLCs shall be updated in both the servers
automatically and simultaneously. In the other HMI stations, only client software shall be loaded.
Both servers shall update relevant data (process, configurations, history etc.) continuously.
Necessary
Dual redundant network interface modules shall be provided for communication with PLCs
and other peripherals. Other operator station, shall log on to these servers for system & process
operation, data access and other operations. Servers shall be considered with Oracle database. The
system software shall support 10000 tags.
PROGRAMMING SOFTWARE:
Each LAP TOP PC shall be loaded with licensed programming software. All software shall be licensed
version. The programming software shall be windows based and shall be compatible with the
systems proposed. The Programming software shall be suitable to program all the RTUs. In addition
to above one licensed RTU/PLC programming software shall be loaded in the HMI (Telecom) also. It
shall be ensured that the healthiness and fault diagnosis of PLC/RTU cards can be checked / accessed
from HMI (Telecom) only.
60” PLASMA Screen:
The HMI shall connect to the 60” PLASMA screen (Video mimic) for viewing of mimic pages
in the control room. The offered mimic screen shall be self-standing type.
INTELLIGENT COMMUNICATION INTERFACE UNIT :
The intelligent communication interface unit shall be serving the purpose of interfacing
between Master station and PLCs with high speed.
The PLCs shall be connected to the Master station utilizing existing telephone cables with
modems at the RTU/PLC end and at Master station end. In the control room of E&T centre the
modems shall be connected to the Intelligent Communication Interface unit. The data of the PLCs
shall be transferred by the intelligent Interface unit to the server without affecting the process
requirement. The communication
from each RTU shall be connected to the Intelligent Interface unit through separate module. The
retrieval of data from the PLCs shall be configured by the servers of Master station. The intelligent
communication interface unit shall be connected to the dual ETHERNET. The offered interface unit
shall connect to all RTUs and 3 no.s work station. Over and above the above 20% spare cards to be
provided for future expansion. If the offered interface unit is not capable of handling all the cards
then required number of Intelligent Interface units shall be included in the scope of work. All the
interface units to be connected to the dual ETEHRNET switch.
ETHERNET SWITCH:
The ETEHRNET SWITCHES shall be redundant. It shall have 24 ports in each switch. Layer-3
Ethernet switch supporting 10/100/1000 MBPS shall be considered. It shall be mounted in suitable
metallic enclosure.
DIGITAL ENERGY METERS :
The digital Energy Meters shall be with serial interface (RS485) to connect to the PLC. The
energy meters shall be mounted in the field and the maximum distance shall be considered from the
RTU location
This covers design, engineering, manufacture, assemble, inspection and testing before supply of
110V, 5A/1A and 3 element 4 wire CT
Meters of accuracy class 0.5 capable of performing the functions of metering in all 4 quadrants .The
scope also includes commissioning of the meters by dismantling the existing electromechanical
meters, TTB and suitably installing, wiring new meter and commissioning of the meters at VSP site.
Connection to RTU for SCADA connectivity using MODBUS protocol or otherwise by ensuring 10
meters per serial loop also is included in the scope of the supplier. The supplier is expected to bring
all tools/tackles and instrument etc. required for commissioning as mentioned in the specifications.
MODEMS:
The modems located at site shall be suitable for interfacing the PLCs to Master Station over
existing telephone cables. The selected Modem shall be able to send the signals up to a distance of
15 KM over telephone cables. For this purpose the existing 5 pair PJF telephone cables of RTUs shall
be utilized for connecting the modems as well. Point to point modems shall be considered. The
modems shall be housed in suitable metallic enclosure and mounted in the RTU/PLC panel in the
field and separate panel in E&T centre. The modems shall be duplex type The modems shall be
suitable for the ambient temperature of 45 Deg C and shall be UL certified. The modems shall be
dedicated line type for industrial applications. The interface shall be as required to connect to the
RTU. The modems shall be suitable for SCADA applications.
UPS SYSTEM:
For RTUs and remote work stations separate UPS systems shall be provided. Total 26 nos
UPS systems shall be provided. A feeder with 230V +10% / - 10%,1Phase,
50Hz+/-3% will be made available. UPS rating shall be as per the requirement of complete
equipment covered in tenderer scope + 25% spare capacity. In the proposed UPS system the
batteries should be sealed maintenance free lead acid type. In case of power failure the backup time
of the UPS to be 30 minutes with resistive load (Unity Power factor). The AH rating of the offered
batteries shall be selected accordingly. The batteries shall be mounted in a suitable metallic
enclosure.
COMMUNICATION CABLES:
The communication cables like ETHERNET bus network and Modbus cable shall be industry
standard for process control. All these communication cables shall be routed through suitable size GI
conduits and GI conduits to be included in the scope of work. The OFC cable between proposed
SCADA server and the existing IBM server shall support 1Gbps data transfer. Same shall be single
mode, 6-core armored type. The specifications of PJF armored cables shall be same as the existing
cables.
CONTROL CABLES:
All the control cables shall have spare cores of 20%. The control cable shall be of 1.5 sq.mm
size, 1100 V grade,Annealed tinned Copper core, multistrand conductor, PVC insulated, PVC
sheathed, un-armoured cables conforming to IS 1554.
The size of the cables/wires considered for the internal wiring of the PLC panels unto the
terminal blocks shall be as per the PLC manufacturer's standard only.
POWER CABLES:
The power cables shall be ATC copper core, multistrand,PVC insulated, PVC sheathed, un-armoured cables conforming to IS 1554. The size and voltage grade of power cables shall be done as per the requirement and PLC manufacturer's standard only.
Advantages of SCADA system are:
High availability of front-end processors to dual access hardware.
Scalability due to provision for expansion for Field Remote terminal units, front end processors, intermediate serial port cards and memory / processors of the host and other computer systems.
Upgradability of hardware and software
Standard interfaces like RS 232, LAN etc are provided for interfacing with other systems and applications.
Availability of standard interfaces for interoperability with other systems like central computer, power plant computer, etc.
Thus SCADA is system has proven that a better technology establishment is a one – time cost but the fruits we see from this are continuous and encouraging.
Summary :
The Supervisory Control And Data Acquisition system is a versatile network of intelligent sub systems, which has broad revolution in the field of monitoring and controlling systems. Earlier due to lack of sophisticated equipment it was very difficult to predict whether the channel corrupted the data coming to the monitoring station or it is the date pertaining to a functional error in a particular department. Further it was very time consuming process to undo the effect causing the problem( Only after making sure the data received is correct ). In the mean time a lot of energy is wasted and sometimes even unacceptable hazards also used to take place. Also there was no privilege to track the position that is responsible for the error.
The Supervisory Control And Data Acquisition systems overcomes all the above bottlenecks. It has host computer in the master station to store the data for a long period of time so that it can be used to take strategic decisions sat the time of crisis.
The proposed SCADA systems for Vizag Steel Plant shall acquire various electrical and utility parameters for effective monitoring and control operations. The various parameters acquired shall be such as electric power, voltages, currents etc., and electrical monitoring and parameters such as flows , temperatures pressures etc., under utility monitoring.
These parameters are locked into the systems using a suitable database management system. The data is processed and presented in the plant to the concerned officials and operators using user-friendly graphical interfaces.
