VOCATIONAL TRAINING REPORT ON

NTPC LIMITED FARIDABAD

COLLEGE OF TECHNOLOGY&ENGG. ,UDAIPUR

Submitted To: SubmittedBy: Mr. r. k. niranjan MONESH KUMAR SHARMA B.E.3rd

yr. (ECE) PREFACE

NTPC is one of the most important industry for producing the electricity. Every

3rd bulb in India is glown by NTPC. There are various divisions in NTPC for various branches like control & instruments (Electronics), mechanical, electrical division etc. The main objective of preparing this report has been to present the operations of electronics and mechanical division in a logical, innovative and lucid manner. The basic theory presented in this report has been evolved out of simple and readily understood principles. A sincere effort has been made to maintain physical concepts in various operations. An effort has been made to give a balanced presentation of this report with the help of figures, different types of data and related suitable theories as well as concepts. Eventually, again I would like to thank NTPC FARIDABAD.

MONESH KUMAR SHARMA B.E.3rd YEAR (ECE) Email: monesh.sharma23992@gmail.com

ACKNOWLEDGEMENT

I am extremely grateful and indebted to my training incharge Mr. R. K. Niranjan(Manger, HR Division), Mr. Kuldeep Singh (Teaching Assistant, HR Division), Mr. Anil Garg (Manager, Switchyard), Ms. Yogita (HR Division) , Mr. Anil Khanna (DGM, NTPC) and MR.N.N MISHRA (AGM ,NTPC) , for being a source of inspiration and for their constant support. I am thankful to them for his constant support which helped us a lot while our training.

They have been co-operative throughout this training period. Through this column, it would be my utmost pleasure to express my warm gratitude to them for his encouragement, co-operation and consent without which I wouldn’t have been able to accomplish this training.

I would also like to thank other engineers in NTPC FARIDABAD for their constant support throughout the training.

CONTENTS

CHAPTER 1: INTRODUCTION

1.1Location of NTPC plants with installed capacity

1.1.1Coal based (Owned by NTPC)

1.1.2Gas based (Owned by NTPC)

1.1.3Coal based (In Joint venture)

1.1.4Gas based (In Joint venture)

1.2NTPC Capacity & Generation

1.3NTPC Mission & Vision

1.4NTPC’s Core Values

1.5Faridabad Gas Power Station

1.5.1Locaton & Origin

1.5.2Brief Profile of NTPC Faridabad

1.6NTPC Overview

CHAPTER 2: TECHNOLOGY, EQUIPMENTS AND

FACILITIES

2.1Power Generation Process

2.2Overview of Combined Cycle

2.2.1Gas Turbine

2.2.2Steam Turbine

2.3General Description of Combined Cycle

2.4Heat Recovery System Generator

2.4.1Evaporator Section

2.4.2Superheater Section

2.4.3Economizer Section

2.4.4Deaerator

2.4.5Cooling Towers

2.4.6Condenser

2.5Overview of Gas Turbine

2.5.1Air Intake System

2.5.2Compresssor

2.5.3Combustion Chamber

2.5.4Turbine

2.5.5Generator

2.5.6Gas Fuel System

2.5.7Nephtha Fuel System

2.5.8Gas Turbine Operation

2.6Overview of WHRB

2.6.1LP Boiler Part

2.6.2HP Boiler Part

2.7Overview of Steam Turbine

2.7.1HP Turbine

2.7.2LP Turbine

CHAPTER 3AUTOMATION & CONTROL SYSTEM

3.1Automation: The Definition

3.2Automation: The Benefits

3.3Process Structure

3.4Control System Structure

3.5System Overview

3.6Control & Monitoring Mechanism

3.6.1Pressure Monitoring

Switches

Gauges

Transmitter Type

3.6.2Temperature Monitoring

Electrical

Feed System

Static

3.6.3Flow Monitoring

Rotameter

Venturimeters

Control Valves

CHAPTER 4 POWER EVACUATION FROM NTPC

FARIDABAD

4.1Switchyard

4.2Outdoor Equipments

4.2.1Wave Trap

4.2.2Circuit Breaker

4.2.3Isolator

4.2.4Capacitance Voltage Transformer

4.2.5Potential Transformer

4.2.6Current Transformer

4.2.7Bus Coupler

4.3Control & Protection Panels

4.4Power Line Carrier Communication

CHAPTER 5 CONCLUSION

CHAPTER 1

INTRODUCTION

National Thermal Power Corporation Ltd. (NTPC) was incorporated in 1975 by an Act of Parliament, to supplement the efforts of the states for quicker and greater capacity addition in thermal power generation. In 1997, the Department of Public Enterprises, Government of India granted ‘Navratna’ (Nine Jewels) status with powers of operational autonomy to the board of NTPC with an objective to turn the public sector enterprise into a global giant. This has helped NTPC in speedy implementation of power projects, adoption of new technologies and formation of Joint Ventures in the core generation as well as service businesses. Recently,NTPC has been awarded the ‘Maharatna’ status which has given it greater autonomy.

In line with its vision and mission over the last thirty five years NTPC has grown to become the largest power utility in India with a commissioned generation capacity of 34,754 MW (as on July, 2011) with power stations spread over the length and breadth of the country, covering portfolios in coal based and combined cycle power plants. Besides, being India’s largest power generation utility, NTPC has also grown to become the number one independent power producer in Asia and second globally in 2009 (by Platts, a division of McGraw-Hill companies), 5th largest company in Asia and 317 Largest company in the world (FORBES ranking – 2009) with Net Sales of Rs. 53721 crore during 2010-11 as against Rs.46169 crore during 2009-10, as increase of 16.36% as on 31.03.2011. NTPC has also the honour of becoming the 6th largest thermal power generator in the world and second most efficient in terms of capacity utilization amongst top 10 utilities in the world. In line with the changing business environment, NTPC has expanded its operations in the area of Hydro Power and covered substantial ground in the areas of Coal Mining, Oil & Gas Value Chain, Power Trading and Distribution. With these forward and backward integration plans, NTPC has been re-christened as “NTPC Limited” since 7th Nov, 2005. Today NTPC is more than a company. It is an institution, which has moulded the economy of India setting many landmarks particularly in Power Plant Engineering, Operation and Maintenance, Contract Management that other power organizations would strive to emulate. NTPC accepted the challenging task of taking over and running of the Ratnagiri Gas & Power Station (erstwhile Dabhol Power Plant). NTPC has drawn an ambitious programme to become a 56000 plus MW Company by 2012 and 75000 plus MW Company by 2017.With a share of 17.75% in the total installed capacity in the country, NTPC’s market share in the country’s power generation was 27.4% during FY 2010-11.

Map Showing All NTPC Plants

1.1 LOCATION OF NTPC PLANTS WITH INSTALLED CAPACITY:-

NTPC is having a number of Coal Fired Stations as well as Gas Fired Stations throughout the Country. Some of the Plants are constructed and run by NTPC in Joint Ventures with other organizations. The table below lists all of NTPC in India-

1.1.1 COAL STATIONS (OWNED BY NTPC):

Coal Fired Stations owned by NTPC

1.1.2 GAS STATION (OWNED BY NTPC):

Gas Stations owned by NTPC

1.1.3 COAL STATION (IN JOINT VENTURE):

Coal Fired Stations in JV

1.1.4 GAS STATION (IN JOINT VENTURE):

Gas Station in JV

1.2 NTPC CAPACITY AND GENERATION:-

Generation v/s Capacity

1.3 NTPC’s MISSION AND VISION:-

NTPC’s vision and mission are driving force in all our endeavors to ultimately produce and deliver quality power in optimum cost and eco-friendly manner through concerted team efforts and effective systems. Being a PSU, Faridabad has derived its mission and vision aligning with that of the Corporate Mission and Vision.

VISION: “A world class integrated power major, powering India’s growth, with increasing global presence.”

MISSION: “Develop and provide reliable power, related products and services at competitive prices, integrating multiple energy sources with innovative and eco-friendly technologies and contribute to society.”

1.4 NTPC’s CORE VALUES:-

The Core Values (BCOMIT), as of NTPC epitomizes the organizational culture and is central to every activity of the company. The values create involvement of all sections of the employees. The core values are widely communicated for the actualization among the employees.

Business Ethics

Customer FocusOrganizational and Professional PrideMutual Respect and TrustInnovation and SpeedTotal Quality for Excellence

1.5 FARIDABAD GAS POWER STATION:-

Rapid industrialization and growth in agriculture/domestic consumption of power in the North India was putting lot of strain on the power grid. To overcome the gap between supply and demand, NTPC set up its first Gas Power Station at Faridabad. Presently NTPC, Faridabad is one of the seven Gas Stations of NTPC. Faridabad’s journey towards excellence had started since inception. Today Faridabad is one of the best gas power plant in the country. It has achieved unique distinction of being the first power station of the country having Zero Forced Outage.

1.5.1 LOCATION AND ORIGIN :

With the findings of natural gas in Western Offshore fields of Bombay High, Central Government decided to take this gas up to North India and accordingly lay the HBJ Pipeline starting from Hazira. GOI directed to set up gas based combined cycle power plants along with HBJ pipeline. NTPC Faridabad is located at Faridabad in Faridabad district in the Indian state of Haryana. The power plant is one of the gas based power plants of NTPC. The gas for the power plant is sourced from GAIL HBJ Pipeline. Source of water for the power plant is Rampur distributories of Gurgaon canal.

1.5.2 BREIF PROFILE OF NTPC FARIDABAD:

Station: Combined Cycle Gas Based Power StationGas Turbines: 2 x 143 MWSteam Turbine: 1 x 144 MWTotal Capacity: 430 MW

1.6NTPC OVERVIEW:-

NO. OF PLANTS CAPACITY(MW)NTPC OWNEDCoal 16 30,855Gas/ Liquid Based 7 3,955TOTAL 23 34,810OWNED BY JV’sCoal & Gas 7 4.564TOTAL 30 39,174

CHAPTER 2

TECHNOLOGY, EQUIPMENTS AND FACILITIES

2.1 POWER GENERATION PROCESS:-

The Gas/Naphtha from pipeline is taken and supplied to GT Combustion Chamber where it is burnt as fuel along with air drawn from atmosphere. This heat is then converted into mechanical energy in the Gas Turbine. Gas turbine through a common shaft rotates a Generator, which produces electric power. Flue gas from the turbine exhaust is used to convert water into steam in the Waste Heat Recovery Boiler (WHRB). Water required for steam generation is circulated through the tubes in the boiler, where heat exchange takes place and water gets converted into steam. The steam generated from WHRBs is used to run a steam turbo generator and produce electric power. This power is supplied to customer through 220 KV line.

2.2 OVERVIEW OF COMBINED CYCLE:-

Combined cycle power plant integrates two power conversion cycles with the principal objective of increasing overall plant efficiency.

Bratyon cycle (for gas turbine) Rankine cycle (for steam turbine)

Let us have a look on How Combined Cycle works in a combined cycle power plant toincrease the efficiency of power generation process.Gas turbine exhaust is at temperature of 500-550 Celsius.Steam generation Process for Rankine cycle requires a temperature of 500-550 Celcius to generate steam. Gas turbine exhaust heat can be recovered using a waste heat recovery boiler togenerate steam in a water tube boiler so as to run a steam turbine on Rankine cycle.Efficiency of simple gas turbine cycle is 34%.The efficiency of Rankine cycle is 35%. The overall efficiency of power generation by combined cycle comes to 49%.

2.2.1 GAS TURBINE: The gas turbine (Brayton) cycle is one of the most efficient cycles for the conversion of gas fuels to mechanical power or electricity. The use of distillate liquid fuels,

usually diesel, is also common where the cost of a gas pipeline cannot be justified. Gas turbines have long been used in simple cycle mode for peak lopping in the power generation industry, where natural gas or distillate liquid fuels have been used, and where their ability to start and shut down on demand is essential.Gas turbines have also been used in simple cycle mode for base load mechanical power and electricity generation in the oil and gas industries, where natural gas and process gases have been used as fuel. Gas fuels give reduced maintenance costs compared with liquid fuels, but the cost of natural gas supply pipelines is generally only justified for base load operation. More recently, as simple cycle efficiencies have improved and as natural gas prices have fallen, gas turbines have been more widely adopted for base load power generation, especially in combined cycle mode, where waste heat is recovered in waste heat boilers, and the steam used to produce additional electricity. The efficiency of operation of a gas turbine depends on the operating mode, with full load operation giving the highest efficiency, with efficiency deteriorating rapidly with declining power output.

Gas Turbine is a heat engine, working on the air standard Brayton cycle.The Process Includes:Compression: Compression of working medium (air) taken from atmosphere in a compressor.Combustion: Increase of working medium temperature by constant pressure ignition of fuel in combustion chamber.Expansion: Expansion of the product of combustion in a turbine.Rejection: Rejection of heat in the atmosphere.

Simple Gas Turbine Cycle

2.2.2 STEAM TURBINE: The operation of the turbine of steam is based on the thermodynamic principle that expresses that when the steam expands it diminishes its temperature and it decreases its internal energy This situation reduction of the energy becomes mechanical energy for the acceleration of the particles of steam, what allows have a great quantity of energy directly. When the steam expands, the reduction of its internal energy can produce an increase of the speed from the particles. To these speeds the available energy is very high, although the particles are very slight. The action turbine, it is the one that the jets of the turbine are subject of the shell of the turbine and the poles are prepared in the borders of wheels that rotate around a central axis.

The steam passes through the mouthpieces and it reaches the shovels. These absorb a part of the kinetic energy of the steam in expansion that it makes rotate the wheel that with her the axis to the one that this united one. The steam enters in an end it expands through a series of mouthpieces until it has lost most of its internal energy.So that the energy of the steam is used efficiently in turbines it is necessary to use several steps in each one of which it becomes kinetic energy a part of the thermal energy of the steam. If the energy conversion was made in a single step the rotational speed of the wheel was very excessive.

Steam Turbine is a heat engine, working on Rankine cycle. The Process Includes:Pressurization: Pressurization of working medium (water) by Boiler feed water pump.Heating: Phase change of working medium (from water to steam) and superheating atconstant pressure in Boiler.Expansion: Expansion of the steam in a turbine.Condensation: Condensation of the steam by cooling water.

2.3 GENERAL DESCRIPTION OF COMBINED CYCLE:- The 430 MW Faridabad combined cycle power plant consists of three gas turbines generator sets of 138 MW each and one steam turbine generator set of 154 MW. The gas turbine are equipped with a dual fuel burner for gaseous fuel (natural) and liquid fuel (naphtha) & HSD. The station can be operated in the open cycle mode via their exhaust gas bypass stacks or as modules together with their waste heat recovery boilers and STG in the combined cycle mode. The WHRB’s is designed as dual pressure boilers with high pressure (HP) and low pressure (LP) sections and condensate preheating at the tail end. The condensate pumped from the condenser hot well is degasified in the Deaerator at constant pressure and stored in the feed water tank. From feed water tank, the boiler feed water is extracted by mean of separate boiler feed water pumps for the HP and LP system serving the 3 WHRB’s in common HP and LP main steam lines the turbojet is composed of a single flow HP turbine and one double flow LP turbine. The Generator is directly coupled to the shaft of LP cylinder. The exhaust steam of the STG is condensed in a surface condenser cooled by fresh water of the right main Gurgaon canal in the once through cycle. During the shut-down of canal, the condenser is cooled via a wet cooling tower in the closed cycle alternatively. For start up and shut down as well as trip of STG one common HP and LP steam bypass station for all 3 modules are provided leading the steam directly into the condenser. Additional steam charged air presenters are installed in front of the GT-compressor inlet to preheat the intake air for the gas turbine, improving the heat rate during part load operation.

2.4HEAT RECOVERY STEAM GENERATOR:-

In the design of an HRSG, the first step normally is to perform a theoretical heat balance which will give us the relationship between the tube side and shell side process. We must decide the tube side components which will make up our HRSG unit, but only it considers the three primary coil types that may be present, Evaporator, Superheater and Economizer.

2.4.1EVAPORATOR SECTION: The most important component would, of course, be the Evaporator Section. So an evaporator section may consist of one or more coils. In these coils, the effluent (water), passing through the tubes is heated to the saturation point for the pressure it is flowing.

2.4.2SUPERHEATER SECTION: The Super heater Section of the HRSG is used to dry the saturated vapour being separated in the steam drum. In some units it may only be heated too little above the saturation point where in other units it may be superheated to a significant temperature for additional energy storage. The Super heater Section is normally located in the hotter gas stream, in front of the evaporator.

2.4.3ECONOMIZER SECTION: The Economizer Section, sometimes called a pre heater or preheat coil, is used to preheat the feed water being introduced to the system to replace the steam (vapour) being removed from the system via the super heater or steam outlet and the water loss through blow down. It is normally located in the colder gas downstream of the evaporator. Since the evaporator inlet and outlet temperatures are both close to the saturation temperature for the

system pressure, the amount of heat that may be removed from the flue gas is limited due to the approach to the evaporator, whereas the economizer inlet temperature is low, allowing the flue gas temperature to be taken lower.

2.4.4DEAERATOR: The deaerating boiler feed water system eliminates the need of expensive oxygen scavenger chemicals and also offers the following advantages:· Removes carbon dioxide as well as oxygen.· Raises the boiler feed water temperature, eliminating thermal shock in boilers.· Improves overall boiler room efficiency.· Feed water pumps are sized for each individual application - assuring total compatibility and optimum operation.

HOW DOES IT WORK? Undeaerated fresh water is fed into the deaerator through the inlet water connection. This water passes through the steam-filled heating and venting section. The water temperature is raised and many of the undissolved gases are released. As the water passes through the assembly, it flows to a scrubber section where final deaeration is accomplished by scrubbing the water with oxygen free steam. This steam is induced through a stainless steel spray valve assembly which causes the high velocity steam to break the water down to a fine mist through a violent scrubbing action. The deaerated water spills over to the tanks storage compartment for use by the boiler, and the gases are vented to the atmosphere.

2.4.5COOLING TOWERS: A cooling tower is an equipment used to reduce the temperature of a water stream by extracting heat from water and emitting it to the atmosphere. Cooling towers make use of evaporation whereby some of the water is evaporated into a moving air stream and subsequently discharged into the atmosphere.The tower vary in size from small roof-top units to very large hyperboloid structures that can be up to 200 meters tall and 100 meters in diameter, or rectangular structure that can be over 40 meters tall and 80 meters long Cooling towers were constructed primarily with wood, including the frame, casing, louvers, fill and cold-water basin. Sometimes the cold-water basin was made of concrete. Today, manufacturers use a variety of materials to construct cooling towers. Materials are chosen to enhance corrosion resistance, reduce maintenance, and promote reliability and long service life. Galvanized steel, various grades of stainless

steel, glass fibre, and concrete are widely used in tower construction, as well as aluminium and plastics for some components.

2.4.6CONDENSER: The condenser condenses the steam from the exhaust of the turbine into liquid to allow it to be pumped. If the condenser can be made cooler, the pressure of the exhaust steam is reduced and efficiency of the cycle increases. The surface condenser is a shell and tube heat exchanger in which cooling water is circulated through the tubes. The exhaust steam from the low pressure turbine enters the shell where it is cooled and converted to condensate (water) by flowing over the tubes.

For best efficiency, the temperature in the condenser must be kept as low as Practical in order to achieve the lowest possible pressure in the condensing steam. Since the condenser temperature can almost always be kept significantly below 100 °C where the vapour pressure

of water is much less than atmospheric pressure, the condenser generally works under vacuum. Thus leaks of non-condensible air into the closed loop must be prevented. 2.5 OVERVIEW OF GAS TURBINE:-

A gas turbine plant in its most simple form consists of following main part.

Air intake systemCompressorCombustion chamberTurbineGeneratorGas Fuel systemNaphtha Fuel SystemGas turbine plant operation

2.5.1 AIR INTAKE SYSTEM:

Air enters the suction of compressor after passing through fine filters. There are 945filters arranged in three levels. These are self cleaning type filters. Compressed air from the instrument air compressors passes through diaphragm valves and into the blowpipes. A pressure pulse is given to the filter elements in the reverse direction (inside to outside) this impulse of air flow cleans the filters.Make: FARRMaterial of filter media: Resin Impregnated Media consisting of synthetic and Cellulose fibers andTotal no. of filter cartridges: 945Initiation of pulse cleaning: 6.4 m barStop of pulse cleaning cycle: 4.6 m barCompressed air pulse clean: 7 barTime interval b\w two pulses: 30 sec.Time of a pulse: 0.1 sec.

Air Intake Filters

2.5.2 COMPRESSOR:

It is 18 stages with additional inlet guide blade, axial flow, reaction compressor. The blade of the 18 rotor and 19 fixed rows are made of high tensile ferric chrome steel. The compressor casing is horizontally split at axis, and is made of spherical graphite cast iron. This material possesses high tensile strength and good expansion quality. Upper and lower halves of the compressor casing are provided with robust flanges and are held together by expansion studs with socket head. The compressor casing has three circular ducts at 4th, 7th, 10th row of fixed blades. These ducts are closed to the outside by four bleed valves. Bleed valves are kept open up to 2700 rpm, so that certain amount of compressor air can be blown off. These bleed valves reduces the external power input required running compressor during start up.

2.5.3 COMBUSTION CHAMBER: In combustion chamber, the air compressed and supplied by compressor is brought to the required process temperature by combustion of liquid/gas fuel. The single combustion chamber is fitted with only one dual fuel burner and mounted vertically on the compressor/turbine assembly. The combustion chamber is all welded steel plate fabricated. The main parts are jacket with cover, lower upper combustion chamber bodies, finned segment body, burner and inner casing. Combustion chamber jacket, which houses the components, is made of heat resistant, low alloy ferrite steel. The air from the compressor enter the combustion chamber from below and flow upward through the annular space between combustion chamber jacket and inner section of the lower combustion chamber body. Approximately 30% air flow enter the combustion chamber through eight mixing nozzles provided at the lower body as secondary and approximately30% air flow enter the combustion chamber through upper body via finned segment row (there are 5row) , the remaining40%flow as primary air for combustion, into the swirl insert and enter thecombustion space with turbulence. After the fuel has ignited these gases are thoroughly mixed with secondary air from mixing nozzles and brought to the permissible turbine inlet temp.

Cross Sectional View of Gas turbine

2.5.4 TURBINE:

Turbine is five stage reaction turbines. Due to high temperature of incoming gases, the first and second row of rotor and fixed blading are air cooled with air from compressor discharge. Cooling air passes along several holes made in blades and finally blowing out through numbers of slits in the trailing /leading edge of the blade. This method of cooling ensures that blades are thoroughly cooled, thereby avoiding cracks induced by thermal stresses. These cooled blades are fixed rotor blades which are made of cast and nickel based alloy. The turbine and compressor casing are bolted together at radial flange with expansion bolts, turbine casing is made of heat resisting ferrite steel in order to with stand thermal stresses.

2.5.5 GENERATOR:

Generator Rotor

Generator characterstics

Generator is three phases, two pole air cooled machine. The generator and turbine are placed on common and plain concrete foundation, with same centre line level for the turbine and generator rotor. The mechanical energy generated by turbine is converted to electrical energy by the generator and appear in the stator winding in the form of current and voltage. This balances the torque of the gas turbine. It lead the magnetic flux, and carries the field winding, the generator is self excited. The power required for the excitation is taken from the generator terminals and fed to the field winding through the excitation transformer and the thrust-controlled rectifier units.

2.5.6 GAS FUEL SYSTEM:

Gas comes from GRS at around 18 bars. Manual isolation valve is to be opened by operator. Motorized stop relief valve will be opened by GT program when required. In the gas control block there is an emergency stop valve (ESV). This opens with the help of power oil pressure against spring force. Whenever turbine trips, the oil is drained (depressurized) and spring force closes the valve, cutting off gas supply to combustion chamber.

2.5.7 NAPHTHA FUEL SYSTEM:

Naphtha comes from naphtha station via the forwarding pumps at around 15bar. Manual isolation valve outside GT hall is to be opened by the operator. Manual isolation valves before main fuel oil pump and also to be opened. Motorized valve will be opened by GT program when FG liquid fuel is selected. Naphtha then passes through duplex filter to the main fuel oil pump, which raises the press to aproox.80 bar. There is release valve which opens when firing speed is reached (600rpm). There is an emergency stop valve similar to one in the gas scheme. Finally there is the control valve directly coupled with the Naphtha nozzle. A minimum opening of the nozzle is already pre-set. Once stable flame is formed, the nozzle opening increases with the control valve opening.

2.5.8 GAS TURBINE PLANT OPERATION: The compressor sucks in air from the atmosphere through the filters called air intake filters. The compresses air at approx. 11 bar passes into the combustion chamber where it is used as primary air for combustion and secondary air for cooling of very hot parts. The gas turbine generates the necessary power to drive the axial-flow compressor and the generator. Start-up of the GT is drives with the help of starting equipment which runs the generator as a motor with speed increasing from 0to 600 rpm. At this speed a pilot flame is ignited in the combustion chamber, fuel (gas/naphtha) enters and combustion takes place.The speed increases further both with the help of generator motoring and the combustion of fuel up to about 2000 rpm. At this speed starting equipment is switched off and only generator is made ready for synchronization with the grid. After synchronizations,

the turbine load increases up to base load with more and more fuel entering the combustion chamber. The hot gases after combustion enter the gas turbine at about 1005 degree centigrade (at base load). The higher pressure and temperature gas pass through the turbine rotating it and generator, this produces the electrical power. The exhaust gas coming out of the GT is at about 500 degree centigrade, this can be utilized to produce steam in WHRB.

2.6 OVERVIEW OF WASTE HEAT RECOVERY BOILER:-

Wagner-biro supplied boilers for anta combined cycle power plant known as waste heat recovery boilers (WHRB), which are of non fired, dual pressure, forced circulation type. The boiler has two different water/steam cycles known as high pressure system and low pressure system. Each system has its own boiler drum and circulating pumps, and is feed by HP & LP feed water pumps from a common feed water tank. The HP&LP steam from the three boiler from four common headers HP live steam line, HP bypass line, LP live steam line and LP bypass line, the bypass line dump steam in the condenser through the HP and LP bypass system. The HP steam drives the HP steam turbine through stop valves and control valves. The LP steam after passing through stop valves and control valves mixes with the HP turbine exhaust and drivers the gas turbine. This dual system of operating utilizes the waste heavy from the gas turbine with maximum efficiency. From LP turbine steam enters the condenser where it get condensed to water with the help of cooling water .condenser is shell and tube, water flow through the tubes and steam flow out side. The condensate get collected in hot well, from hot well it enters the feed water tank through condensate. Each of the WHRB is feed with waste heat flue gas from the respective gas turbine (GT). The gas turbines are fired either with gas or naphtha. The energy from waste heat flue gas is transferred to water/steam by means of heating surfaces of super heaters, evaporators, economizers and condensate pre heater. The steam-water system consists of a high (HP) and low (LP) pressure system and in addition there is a condenser preheated in order to obtain a higher efficiency.

2.6.1 LP BOILER PART:

Economizer: The LP feed water, which flows from the 3 X 50% LP feed water pumps through the common feed water line to the WHRB’s in parallel, enters a WHRB at economizer gate valve. In the economizer the feed water is heated up by the flue gas. After the economizer the feed water enters the LP boiler drum through feed regulating station (FRS), where the feed water control valve ensures the correct supply of feed water to the boiler.Boiler Drum Evaporator: The feed water in the LP boiler drum is pumped through the evaporator by means of 2 x 100% LP circulation pumps. In the evaporator the water is partially steamed by the flue gas passing at the outside of the evaporator tubes. The steam and water mixture again enters the drum, where steam is separated and this steam flows to the LP super heaters and the water is circulated again.

LP Super Heater: The steam leaving at the top of the LP-drum flows through the flue gas heated super heater, where it reaches the end temperature of about 206 Centigrade.

2.6.2 HP BOILER PART: The principal design of the HP- boiler part is the same as for the LP- part. The basic difference is of operating pressure.

Economizer: The HP fed water, which flows from the 3 x 50% HP feed water pumps through the common the feed water line to the HP parts of 3 WHRB in parallel, enters a WHRB at the gate valve of economizer. This gate valve is equipped with a parallel bypass valve as in LP-economizer.Boiler Drum Evaporator: The feed water in the HP- boiler drum is pumped through the evaporator by means of 2 x 100% HP circulation pumps in the evaporator water is partially steamed as in LP part, this partially steamed water enters in HP drum where steam is separated, and water is circulated again. Theses steam is super heated in HP super heater. The HP circulation pumps ensure the correct water flow through evaporator for which differential pressure switches are provided.

HP Super Heater: The HP super heater consists of two parts with a spray attemperator between them. This configuration allows the temperature control of the super heated steam. The spray water which is the cooling medium is branched from the feed water line at the HP economizer inlet via a control valve to the attemperator if the temperature of super heater increases beyond the predetermined temperature.

Condensate Preheater: The main condensate is pumped by 3 x 50% condensate extraction pumps (CEP) to the feed water tank. Before entering the feed water tank the condensate is passed through the condensate preheaters which are situated at the tail end of the WHRB and heated by the flue gas to achieve the highest cycle efficiency.

Blow down Tank: One blow down tank is provided for each WHRB to collect drains e.g. CBD, IBD and drum over flow water from hp and LP system of the WHRB. The water level in this tank is maintained through an over flow pipe, which leads the water to hot drain collecting system. The steam flows via a silencer to the atmosphere.

2.7OVERVIEW OF STEAM TURBINE:-

Steam Turbine Floor The steam turbine plant consists of a single shaft condensing turbo set with HP & LP live steam admission and with HP & LP bypass steam system. The steam generating plant consists of three waste heat recovery boilers (drum type) with common live steam lines. Exhaust gases of one appropriate gas turbine heat each boiler. Normally, the whole steam generated in boilers flows through the turbo set. Part of steam can be bled via extraction lines to preheat the intake air for gas turbines. After expansion in turbine, the remaining steam is condensed in the condenser. From there on, the condensate is fed through the gland steam condenser to a common feed water tank. The common HP & LP feed water pumps supply the feed water to the three waste heat recovery boilers. The steam turbo set is composed of a single flow HP turbine and one double flow LP turbine arranged one after the other with tandem compounding. The HP turbine has 25 stages and LP turbine has 2 x 6 stages of reaction blading. The generator is directly coupled to the shaft of the LP turbine. The cross over piping between the HP & LP brings the expanded steam of HP Turbine to the reaction blading in the LP turbine, where it expands down to the condenser pressure.

2.7.1 HP TURBINE:

The high-pressure turbine is a single shell casing design. It consists of the turbine casing, the fixed blade carriers, the dummy piston and the HP rotor.

ROTOR OF H.P. TURBINE

2.7.2 LP TURBINE:

The LP turbine is a double flow design .It consists of the welded turbine casing, the fixed blade carriers and the LP rotor.

ROTOR OF L.P. TURBINE

The LP casing is a welded fabrication from steel plate and is flanged together along the horizontal plane at turbine axis height and LP rotor is a welded design mate of plain steel.

LINE DIAGRAM SHOWING GAS TO ELECTRICITY CONVERSION AT FARIDABAD GAS POWER PLANT

Siemens and One Steam Turbine from BHEL

CHAPTER 3

AUTOMATION AND CONTROL SYSTEM

3.1AUTOMATION: THE DEFINITION:-The word automation is widely used today in relation to various types of applications, such as office automation, plant or process automation. This subsection presents the application of a control system for the automation of a process / plant, such as a power station. In this last application, the automation actively controls the plant during the three main phases of operation: plant start-up, power generation in stable or put During plant start-up and shut-down, sequence controllers as well as long range modulating controllers in or out of operation every piece of the plant, at the correct time and in coordinated modes, taking into account safety as well as overstressing limits. During stable generation of power, the modulating portion of the automation system keeps the actual generated power value within the limits of the desired load demand.During major load changes, the automation system automatically redefines new set points and switches ON or OFF process pieces, to automatically bring the individual processes in an optimally coordinated way to the new desired load demand. This load transfer is executed according to pre- programmed adaptively controlled load gradients and in a safe way.

3.2AUTOMATION: THE BENEFITS:-The main benefits of plant automation are to increase overall plant availability and efficiency. The increase of these two factors is achieved through a series of features summarized as follows: Optimisation of house load consumption during plant start- up, shutdown and operation, via: Faster plant start-up through elimination of control errors creating delays. Faster sequence of control actions compared to manual ones. Figures 1 shows the sequence of a rapid restart using automation for a typical coalfired station. Even a well- trained operator crew would probably not be able to bring the plant to full load in the same time without considerable risks. Co-ordination of house load to the generated power output. Ensure and maintain plant operation, even in case of disturbances in the control system, via: Coordinated ON / OFF and modulating control switchover capability from a sub process to a redundant one. Prevent sub-process and process tripping chain reaction following a process component trip. Reduce plant / process shutdown time for repair and maintenance as well as repair costs, via: Protection of individual process components against overstress (in a stable or unstable plant operation). Bringing processes in a safe stage of operation, where process components are protected against overstress

3.3PROCESS STRUCTURE:-Analysis of processes in Power Stations and Industry advocates the advisability of dividing the complex overall process into individual sub-processes having distinctly defined functions. This division of the process in clearly defined groups, termed as FUNCTIONAL GROUPS,

results in a hierarchical process structure. While the hierarchical structure is governed in the horizontal direction by the number of drives (motorised valves, fans, dampers, pumps, etc.) in other words the size of the process; in the vertical direction, there is a distinction made between three fundamental levels, these being the: - Drive Level Function Group Level Unit Level.To the Drive Level, the lowest level, belong the individual process equipment and associated electrical drives.The Function Group is that part of the process that fulfils a particular defined task e.g., Induced Draft Control, Feed Water Control, Blooming Mill Control, etc. Thus at the time of planning it is necessary to identify each function group in a clear manner by assigning it to a particular process activity. Each function group contains a combination of its associated individual equipment drives. The drive levels are subordinate to this level. The function groups are combined to obtain the overall process control function at the Unit Level. The above three levels are defined with regard to the process and not from thecontrol point of view.

3.4CONTROL SYSTEM STRUCTURE:-The primary requirement to be fulfilled by any control system architecture is that it be capable of being organized and implemented on true process-oriented lines. In other words, the control system structure should map on to the hierarchy process structure.BHEL’s PROCONTROL P®, a microprocessor based intelligent remote multiplexing system, meets this requirement completely.

3.5SYSTEM OVERVIEW:-The control and automation system used here is a micro based intelligent multiplexing system This system, designed on a modular basis, allows to tighten the scope of control hardware to the particular control strategy and operating requirements of the process Regardless of the type and extent of process to control provides system uniformity and integrity for: Signal conditioning and transmission Modulating controls

3.6CONTROL AND MONITORING MECHANISMS:-There are basically two types of Problems faced in a Power Plant Metallurgical MechanicalMechanical Problem can be related to Turbines that is the max speed permissible for a turbine is 3000 rpm, so speed should be monitored and maintained at that level Metallurgical Problem can be view as the max Inlet Temperature for Turbine is 1060 OC so temperature should be below the limit.

Monitoring of all the parameters is necessary for the safety of both: Employees Machines

So the Parameters to be monitored are : Speed Temperature Current Voltage Pressure Eccentricity Flow of Gases Vaccum Pressure Valves Level

3.6.1PRESSURE MONITORING:Pressure can be monitored by three types of basic mechanisms Switches Gauges Transmitter type

For gauges we use Bourdon tubes: The Bourdon Tube is a non liquid pressure measurement device. It is widely used in applications where inexpensive static pressure measurements are needed. A typical Bourdon tube contains a curved tube that is open to external pressure input on one end and is coupled mechanically to an indicating needle on the other end, as shown schematically below.

Typical Bourdon Tube Pressure Gages

Transmitter types use transducers (electrical to electrical normally) they are used where continuous monitoring is required. Normally capacitive transducers are used

For Switches pressure switches are used and they can be used for digital means of monitoring as switch being ON is referred as high and being OFF is as low. All the monitored data is converted to either Current or Voltage parameter.The Plant standard for current and voltage are as under Voltage: 0 – 10 Volts range Current: 4 – 20 milli Amperes

We use 4mA as the lower value so as to check for disturbances and wire breaks.Accuracy of such systems is very high.ACCURACY: + - 0.1 %The whole system used is SCADA based

INPUT ALARM

We use DDCMIC control for this process.Programmable Logic Circuits (PLCs) are used in the process as they are the heart of Instrumentation.

Pressure

Electricity Start L L Pressure in line pump

StopHigh levelElectricity

Electricity

BASIC PRESSURE CONTROL MECHANISM

Hence PLC selection depends upon the Criticality of the Process

ANALOG INPUT MODULE

MICRO PROCESSOR

HL switch

LL switch

AND

OR

3.6.2TEMPERATURE MONITORING:We can use Thermocouples or RTDs for temperature monitoring Normally RTDs are used for low temperatures.Thermocouples selection depends upon two factors: Temperature Range Accuracy RequiredWe can classify them into three categories

Electrical Feed System Static

Normally used Thermocouple is K Type Thermocouple: Chromel (Nickel-Chromium Alloy) / Alumel (Nickel-Aluminium Alloy).This is the most commonly used general purpose thermocouple. It is inexpensive and, owing to its popularity, available in a wide variety of probes. They are available in the −200 °C to +1200 °C range. Sensitivity is approximately 41μV/°C.We pass a constant current through the RTD. So that if R changes then the Voltage also changes RTDs used in Industries are Pt100 and Pt1000Pt100: 0 0C – 100 Ω (1 Ω = 2.5 OC)Pt100: 0 0C - 1000Ω

Pt1000 is used for higher accuracy.The gauges used for Temperature measurements are mercury filled Temperature gauges.

3.6.3FLOW MEASUREMENT:Flow measurement does not signify much and is measured just for metering purposes and for monitoring the processes.

ROTAMETERS:A Rotameter is a device that measures the flow rate of liquid or gas in a closed tube. It is occasionally misspelled as 'rotometer'. It belongs to a class of meters called variable area meters, which measure flow rate by allowing the cross sectional area the fluid travels through to vary, causing some measurable effect. A rotameter consists of a tapered tube, typically made of glass, with a float inside that is pushed up by flow and pulled down by gravity. At a higher flow rate more area (between the float and the tube) is needed to accommodate the flow, so the float rises. Floats are made in many different shapes, with spheres and spherical ellipses being the most common. The float is shaped so that it rotates axially as the fluid passes. This allows you to tell if the float is stuck since it will only rotate if it is not.

For Digital measurements Flap system is used.For Analog measurements we can use the following methods : Flowmeters Venurimeters / Orifice meters Turbines

Massflow meters (oil level) Ultrasonic Flow meters Magnetic Flowmeter (water level)Selection of flow meter depends upon the purpose, accuracy and liquid to be measured so different types of meters used.

Turbine types are the simplest of all.They work on the principle that on each rotation of the turbine a pulse is generated and that pulse is counted to get the flow rate.

VENTURIMETERS :

Referring to the diagram, using Bernoulli's equation in the special case of incompressible fluids (such as the approximation of a water jet), the theoretical pressure drop at the constriction would be given by

(ρ/2)(v2 2 - v1 2).

And we know that rate of flow is given by: Flow = k √ (D.P)Where DP is Differential Pressure or the Pressure Drop.

CONTROL VALVES:A valve is a device that regulates the flow of substances (either gases, fluidized solids, slurries, or liquids) by opening, closing, or partially obstructing various passageways. Valves are technically pipe fittings, but usually are discussed separately.Valves are used in a variety of applications including industrial, military, commercial, residential, transportation. Plumbing valves are the most obvious in everyday life, but many more are used.Some valves are driven by pressure only, they are mainly used for safety purposes in steam engines and domestic heating or cooking appliances. Others are used in a controlled way, like in Otto cycle engines driven by a camshaft, where they play a major role in engine cycle control.Many valves are controlled manually with a handle attached to the valve stem. If the handle is turned a quarter of a full turn (90°) between operating positions, the valve is called a quarter-turn valve. Butterfly valves, ball valves, and plug valves are often quarter-turn valves. Valves can also be controlled by devices called actuators attached to the stem. They can be electromechanical actuators such as an electric motor or solenoid, pneumatic actuators

which are controlled by air pressure, or hydraulic actuators which are controlled by the pressure of a liquid such as oil or water.

So there are basically three types of valves that are used in power industries besides the handle valves. They are : Pneumatic Valves – they are air or gas controlled which is compressed to turn or move them Hydraulic valves – they utilize oil in place of Air as oil has better compression Motorised valves – these valves are controlled by electric motors

CHAPTER 4

POWER EVACUATION FROM NTPC FARIDABAD

4.1 SWITCHYARD:-

Switchyard is considered as the HEART of the Power Plant. Power generated can

be wrathful only if it is successfully transmitted and received by its consumers. Switchyard

plays a very important role as a buffer between the generation and transmission. It is a

junction, which carries the generated power to its destination (i.e. consumers).

Switchyard is basically a yard or an open area where many different kinds of equipments are

located (isolator, circuit breaker etc…), responsible for connecting & disconnecting the

transmission line as per requirement (e.g. any fault condition).

Power transmission is done at a higher voltage.

(Higher transmission voltage reduces transmission losses).

Therefore, the power generated by the Turbo generator of 1 to 5 units is 15.75KV and of 6&7

units is 21KV which is further stepped-up to 400KV by the Generating transformer & then

Transmitted to switchyard.

Switchyard mainly consists of:

(i) Outdoor equipments.

(ii) Protection and Control panels.

(iii) P.L.C.C (Power Line Carrier Communication).

4.2 OUTDOOR EQUIPMENTS:-

4.2.1 WAVE TRAP:

It is equipment used to trap the high carrier frequency of 500 KHz and above and

allow the flow of power frequency (50 Hz). High frequencies also get generated due to

capacitance to earth in long transmission lines.

The basic principle of wave trap is that it has low inductance (2 Henry) &

negligible resistance, thus it offers high impedance to carrier frequency whereas very low

impedance to power frequency hence allowing it to flow in the station.

4.2.2 CIRCUIT BREAKER:

It is an automatic controlling switch used in power house, substation &

workshop as well as in power transmission during any unwanted condition (any fault

condition-earth fault, over-current, flashover, single phasing,).

During such condition it cuts down the supply automatically by

electromagnetic action or thermal action. It can be used in off-load as well as on-load

condition. When a circuit breaker is operated by sending an impulse through relay, C.B.

contact is made or broken accordingly. During this making and breaking, an arc is produced

which has to be quenched; this is done by air, oil, SF6 gas etc….

Depending on the medium being used C.B.s can be categorized into

various types. For 400 KV/132 KV switchyard only 4 main types are being used:-

ABCB (Air operated circuit breaker):- operated as well as arc quenched through air.

Air operated SF6 circuit breaker: - operated through air but arc quenching done through

SF6 gas.

MOCB (Minimum oil circuit breaker):-operated through spring action but arc quenching

done through oil (Aerosol fluid oil).

Hydraulic operated SF6 circuit breaker: - operated through hydraulic oil and arc quenching

done through SF6 gas.

Hydraulic operated SF6 circuit breaker is the most efficient due to following reasons:-

1. Less maintenance.

2. Arc quenching capability of SF6 gas is more effective than air.

3. Heat transfer capacity is better in this C.B.

4.2.3 ISOLATOR:

An isolator is also a switching device used to disconnect the line. As the name

suggests it isolate the line from the supply. It is always used in OFF-LOAD condition.

Whenever any fault occurs in the equipments present in the line, in order to remove the fault

or replace the device first of all supply is disconnected. But even after the disconnection of

the supply, the line remains in charged mode so before working on the device (to remove

fault) isolator should be made open. Depending on the structure there are mainly two types of

isolators:-

Pantograph isolator.

Pantograph is generally used in buses

Centre-break isolator (also known as sequential isolator).

Centre-break (Sequential) is used in line.

Isolators may be operated in air (pneumatic), electrically or even manually.

4.2.4 C.V.T (Capacitance Voltage Transformer):

This Transformer performs mainly two major functions:-

Used for voltage measurement. The high voltage of 400 KV is impossible to measure

directly. Hence a C.V.T is used, (connected in parallel with the line) which step-downs the

voltage of 400 KV to 110 KV, comparatively easy to measure.

the other most important function of C.V.T is that it blocks power frequency of 50Hz and

allows the flow of carrier frequency for communication.

4.2.5 P.T (Potential Transformer):

This Transformer is connected in parallel with the line with one end earthed. It is only used

for voltage measurement by stepping-down the voltage to the required measurable value.

4.2.6 C.T (Current Transformer):

This Transformer is used for basically two major functions: -

Metering which means current measurement.

Protection such as over current protection, overload earth fault protection, Bus-bar

protection, Bus differential protection.

Secondary of the C.T should be kept shorted because (when secondary is kept open) even the

presence of a very small voltage in the primary of C.T will prove to be harmful as it will start

working as a step-up Transformer & will increase the voltage to such a high value that

primary would not be able to bear it & will get burned.

4.2.7 BUS COUPLER:

Bus coupler is used to couple two busses together. Bus coupler consists of a

circuit breaker and the isolator which are situated at both side of circuit breaker.

4.3 CONTROL AND PROTECTION PANELS:-

The control and relay panels associated with 400KV & 132KV switchyard are

installed in a control room. The equipments housed here are:-

Air compressors for compressed air supply to 400KV/132KV switchyard where

pneumatically operated isolators and ABCB are installed. The compressors develop a

pressure of 60 Kg.

Two independent D.C. batteries of 300 AH capacity, 220V each along with separate battery

chargers and distribution boards.

One P.L.C.C. battery of 400AH capacity, 50V with separate battery charger.

P.L.C.C. Panels.

A.C. distribution board for 415V A.C. supply inside the switchyard.

The control and relay panels installed in this room are:-

(i) Duplex type control and relay panels for 400/132KV feeders. The protective relays of

400/132KV feeders such as control relays, local breaker back-up relays, energy-meters, auto-

reclose relays for line feeders and breakers, pole discrepancy relays are housed on the back of

the relay panels.

(ii) Simplex type protection panels for 400KV feeders. On these panels protective relays of

line feeders are mounted. The common bus bar protection panels in a separate section house

the entire bus bar protection scheme relays except the C.T. zone switchyard relays that are

mounted in weather proof relay panel for each bay located in the switchyard.

Besides the above, the protection relays of generator feeders are located in a section of

simplex protection panels located in the unit control room for each generator.

4.4 POWER LINE CARRIER COMMUNICATION (P.L.C.C.):-

As the name suggests, P.L.C.C. is basically a method in which the line used

for power transmission is also being used for communication.

P.L.C.C is employed for performing following two functions:

(i) Communication purposes.

(ii) Line tripping.

Communication Purpose:

There are two types of electrical signals which flow in a line- 50Hz

power signal & 20 KHz of carrier signal. In order to isolate these two signals (so that they do

not hinder each other) tapping of the signals is done as per the requirement.

Since in the buses and bays we need only power signal, wave traps are being used to block

high frequency carrier signals.

Line Tripping:

Transmission line between two sub-stations is bi-directional. When a

fault occurs and a trip command is given at one end, the breaker gets opened. Now the other

end breaker should also be opened to completely isolate the line from supply. For this the

other end should also give the trip command. This is when the P.L.C.C. comes into play.

From the P.L.C.C. room present at the tripping end along with the carrier signal, a signal of a

lesser frequency is superimposed and sent to the P.L.C.C. room present at the other end. Now

this will be demodulated and the other end will come to know that tripping has occurred.

Now it will give a command, which will energize the relay, contact will be made

And the breaker will operate.

CHAPTER 5

CONCLUSION

Faridabad Gas Power station is situated in Faridabad District of Haryana .The Power Station

site is about 19 kms from Delhi and is about 45 kms from Gurgaon (Haryana). Total installed

capacity of the plant is 430 MW. It consists of two gas turbines of 138 MW each and one

steam turbine of 154 MW.

The principle raw material (Fuel) is Natural Gas and is obtained from HBJ pipe line through

GAIL terminal at about 25 bars. The gas pressure is reduced to about 19 bars at gas reducing

station (GRS) before it is fed to combustion chamber of gas Turbine. The power station can

also run on Naphtha or HSD as alternate fuel.

With the help of starting equipment the generator is made to run as motor up to the speed of

600 rpm, between 600 to 1880 rpm the firing starts and continue in the combustion chamber

and at 1880 rpm, starting equipment cuts off automatically and machines accelerates by itself.

The air from air intake filters goes to air compressor. The compressed air and the fuel (natural

gas) are then fed to combustion chamber, the hot gases at 1005*C then went to gas Turbine to

drive it. The Gas turbine exhausts flue gas at 500*C either may be diverted to bypass stack or

to waste heat recovery boilers (WHRB).

In WHRB water from H.P. drum after passing through evaporator accumulates in the same

HP drum as steam. The steam from here after super heating is fed to HPT at 67.5 bars and

488*C to drive it. The exhausted steam at 5.3 bars & 181.8*C from H.P.T. is then fed to

L.P.T.

At the same time in WHRB ,water from LP drum after passing through evaporator

accumulates in the same L.P.T. at 5.61 bars & 207 *C to drive it.

The exhausted steam of L.P.T. is condensed in condenser. The condensed water is then

pumped in to feed water tank. The condenser also gets it make up water from DM plant. The

water from feed water tank is then pumped in to HP drum and LP drum. The generator

connected with each Gas Turbine develop 138 MW at 10.5 KV while the generator connected

with steam turbine develops 153.2 MW at 15.75 KV, the voltage so generated are then

stepped up to 220KV through power transformers connected to each unit before transmission.

REFERENCES:

WWW.NTPC.CO.IN

NTPC PROVIDED MATERIAL

WWW.WIKIPEDIA .ORG