CHAPTER-1 INTRODUCTION
1.1 Dholpur combined cycle power project DCCPP is situated in the outskirts of Dholpur which is about 55Km. South West of Agra. Dholpur was considered an ideal location for setting up of a gas power plant having regards to the availability of land, water, transmission network, proximity to broad gauge railway , also well connected by roads (G.T. road passes through this city) and being an important load center for eastern Rajasthan.
Figure 1.1 Combined Cycle Power Plant, Dholpur The total estimated cost of the plant is Rs.1155 crore. The main equipment’s were supplied by M/s BHEL and it was also the main contractor for erection, testing and commissioning of the plant. The BOP (Balance of plant) was given to M/s GEA Energy System. The main fuel used (AIET/DOEE/2016-2017/PTS/1)
for this plant is R-LNG (liquefied natural gas) which will be supplied by M/s GAIL. The gas required per day for both unit is 1.3MM SCM at 9000Kcal. The unique feature of this plant is that waste heat from the gas turbine is recovered by a heat recovery steam generator to power a conventional steam turbine in a combined cycle configuration. And also a MARK-6 control system has been introduced for the first time in the northern region in INDIA.
1.1.1 General introduction
Figure 1.2 Gas Plant of DCCCP
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1.1.1.1
Method for transforming other power in to electrical power
Rotating turbines attached to electrical generators produce most commercially available electricity. Turbines may be driven by using steam. Water wind or other fluids as an intermediate energy carrier. The most common usage is by steam in fossil fuel power plants or nuclear power plants and by water in hydroelectric dams. Alternately turbines can be driven directly by the combustion of natural gas. Power plants are classified in the following categories according to the fuel used:
Coal based thermal power plant
Nuclear power plant
Hydroelectric power plant
Solar power plant
Wind power plant
Gas power plant
1.1.1.2
Electricity from Natural gas
Power plant uses several methods to convert gas into electricity. One method is to burn the gas in a boiler to produce steam, which is then used by a steam turbine to generate electricity. A more common approach is to burn the gas in a combustion turbine to generate electricity. Another technology that is growing in a combustion turbine and used the hat combustion turbine exhaust to make steam to drive a steam turbine. This technology is called combined cycle and achieves a higher efficiency by using the same fuel source.
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Figure 1.3 Electricity from Natural Gas
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CHAPTER-2 COMBINED CYCLE POWER GENERATION
2.1 Combined Cycle Electricity Generation
Growth in gas fueled combined cycle system will take place, Because of the attractive economic environmental and operating characteristics of this natural gas system. Combined cycle gas turbine plants generate electricity more. Efficiently than conventional fossil to percent compares with 30 to 50 percent for typical now biological units.
2.1.1 Advantage of Combined Cycle Gas Power Plant
High Thermal Efficiency
Low water Requirement
Environmental friendliness
Fast start-up
Low Gestation period
Low Installation Cost
2.1.2 Disadvantage of Combined Cycle Gas Power Plant
Low thermal Efficiency in Open cycle
Higher Cost of Generation
Higher Maintenance Cost
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2.1.3 Classification of Combined Cycle Gas Power Plant
TABLE NO. 2.1.3 Size
Plant Capacity
Gt Capacity
Small
Up-To 100 MW
30-40 MW
Medium
150-400 MW
60-120 MW
Large
> 400 MW
> 120 MW
2.1.4 Environmental effects of combined cycle electricity generation Natural-gas fueled combined cycle units are environmentally performable to conventional coal system the gas combined cycle unit produces none of the solid waste associated with coal units less than 1 percent of the sulfur dioxide and particulate matter and about 85 percent less nitrogen oxide produces by a similarity sized new coal unit equipped with pollution control equipment’s.
2.1.4.1 Cogeneration system Cogeneration is use of a primary energy like natural gas to sequentially produce heat and electricity. The concept is based on the recover and use of waste heat produced daring the generation of electricity. In most electric utility power plants. This waste heat is lost resulting in substantially lower operating efficiencies than with cogeneration.
2.1.4.2 Variety of natural gas Cogeneration technologies are currently being used. Including small prepackaged units that incorporate all the necessary components for a cogeneration system as well as high efficiency industrial gas turbines. These natural gas cogeneration system are available in sizes ranging from as small as 202 kW to as large as several hundred megawatts.
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2.1.4.3. Air emissions The average emissions rates in the united states from natural gas fired generation are 1135 ibid/meh of carbon dioxide 0.1 ibs/mwh of sulfur dioxide and 1.7 ibs/mwh of nitrogen oxide compared to the average air emissions from coal fired generation natural gas produces as much carbon dioxide less than a third as much nitrogen dioxide at the power plant in addition the process of extraction treatment and transport of the natural gas to the power plant generators additional emissions.
2.1.4.4. Design principle In a gas turbine set composed primarily of a compressor burner and the gas turbine proper. The input temperature to the gas turbine is relatively high but the output temp of the fuel gas temperature is sufficient for production of steam in the second steam cycle with live steam temperature in the range of steam cycle depends on the ambient temperature and the methods of waste heat disposal either by direct cooling by lake river or sea water or using cooling towers.
2.1.4.5 Efficiency of CCGT plants The thermal efficiency of a combined cycle power plant is normally in terms of the net power output of the plant as a percentage for the lower heating value or net calorific value of the fuel. In the case of generating only etc. Criticity power plant efficiencies of up to 59% can be achieved in the case of combined heat and power generation the efficiency can increase to about 85%.
2.2 Plant Design Input
Ambient temperature range
Ambient air quality
fuel specification
Environmental requirements
Peaking capability
Operational flexibility
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Plant water quality
Black start facility
Figure. 2.1 Working of Combined Cycle Power Plant
2.3 Fuel Specification
Natural gas/lng vs naphtha
Natural gas supply pressure
Bridge fuel - naphtha/ hsd
Sulphur content - low preferred
Cooling tower
Switch yard
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2.4 Working of the Combined Cycle Power Plant DCCPP located at Dholpur has a unique feature that the same energy source (i.e. natural gas) is used to rotate both gas and steam turbine without wasting much of energy. As the name implies it is a combined cycle i.e. waste heat from the gas turbine is recovered by a heat recovery steam generator to power a conventional steam turbine in a combined cycle configuration. Hence, the working of both gas and steam turbine is discussed here. The whole power plant consider the following main parts:
Fuel tank
Compressor
Combustion chamber
HRSG
Turbine
Generator
Exciter
Condenser
Deaerator
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CHAPTER-3 GAS TURBINE
3.1 Working of the Gas Turbine
Figure 3.1 Gas Turbine
This machine has a single-stage centrifugal compressor and turbine, a recuperator, and foil bearings. A gas turbine extracts energy from a flow of hot gas produced by combustion of gas or fuel oil in a stream of compressed air. It has an upstream air compressor (radial or axial flow) mechanically coupled to a downstream turbine and a combustion chamber in between. Gas turbine may also refer to just the turbine element. Energy is released when compressed air is mixed with fuel and ignited in the combustor. The resulting gases are directed over the turbine's blades, spinning the turbine, and, mechanically, powering the compressor. Finally, the gases are passed through a nozzle, generating additional thrust by accelerating the hot exhaust gases by expansion back to atmospheric pressure. Energy is extracted in the form of shaft power, compressed air and thrust, in any combination, and used to power aircraft, trains, ships, electrical generators, and even tanks. A gas turbine, also called a combustion turbine, is a rotary engine that extracts energy from a flow of hot gas produced by combustion of gas in a stream of compressed air. It has an upstream air compressor radial or axial flow mechanically
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coupled to a downstream turbine and a combustion chamber in between. Gas turbine may also refer to just the turbine element. Energy is released when compressed air is mixed with fuel and ignited in the combustor. The resulting gases are directed over the turbine's blades, spinning the turbine, and, mechanically, powering the compressor. Finally, the gases are passed through a nozzle, generating additional thrust by accelerating the hot exhaust gases by expansion back to atmospheric pressure. Energy is extracted in the form of shaft power, compressed air and thrust, in any combination, and used to power electrical generators.
3.2 Theory of operation Gas turbines are described thermodynamically by the Brayton cycle, in which air is compressed isentropic ally, combustion occurs at constant pressure, and expansion over the turbine occurs isentropic ally back to the starting pressure. In practice, friction, and turbulence cause:
Non-isentropic compression: for a given overall pressure ratio, the compressor delivery temperature is higher than ideal.
Non-isentropic expansion: although the turbine temperature drop necessary to drive the compressor is unaffected, the associated pressure ratio is greater, which decreases the expansion available to provide useful work.
Pressure losses in the air intake, combustor and exhaust: reduces the expansion available to provide useful work.
3.2.1 Gas Power Cycle Although any cycle may in principle be used as a heat engine or as a refrigerator and heat pump by just reversing the direction of the process in practice there are big difference and the study is split between power cycle and refrigeration cycle. Many gas cycle have been proposed and several are currently used to model real heat engines. From the academic point of view we will the Brayton cycle.
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Figure 3.2 Brayton cycle
3.2.2 Brayton cycle The bray ton cycle nomad after the American engineer George bray ton is a good model for the operation of a gas turbines engine. Now a days used by practically all aircraft except the smallest once by fast boast and increasingly been used for stationary power generation. Particularly when both power and heat are of interest the ideal Brayton cycle in the T-S and PV diagram and the regenerative cycle. As with all cyclic heat engines, higher combustion temperature means greater efficiency. The limiting factor is the ability of the steel, nickel, ceramic, or other materials that make up the engine to withstand heat and pressure. Considerable engineering goes into keeping the turbine parts cool. Most turbines also try to recover exhaust heat, which otherwise is wasted energy. The heat released from the exhaust gas has been absorbed by many kms of tubing which line the boiler. Inside these tubes is water, which takes the heat and is converted into steam at high temperature and pressure. The type of boiler is called heat recovery steam generation (HRSG) This steam at high temperature and pressure is sent to the turbine where it is discharged through the nozzles on to the turbine blades. The energy of the steam striking on the blades makes the turbine to rotate. Coupled to the turbine is the rotor of the generator. So when the turbine rotates the rotor of the generator turns. The rotor is housed inside a stator having heavy coils of copper bars in which electricity is produced through the movement of magnetic field produced by the rotor. Electricity passes from stator winding to the transformer, which increases its voltage level so that it can be transmitted over the lines to far off places. The steam, which has given away its energy, is changed back into water in the condenser. Condenser contains many kms of tubing through
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which cold water is continuously pumped. The steam passing over the tubes continuously loses heat and is rapidly changed back into water. But the two waters i.e. the boiler feed water and cooling water must never mix. Boiler water must be absolutely pure otherwise the tubing of the boiler may get damaged due to the formation of salts inside the tubes due to the presence of different impurities in water. To condense large quantities of steam huge and continuous volume of water is required. In some power stations same water has to be used again and again because there is not enough water. So the hot water tracts are passed through the cooling towers. The cooling towers are simply concrete shells acting as a huge chimney creating a draught of air. The design of cooling towers is such that a draught of air is created in the upward direction. The water is sprayed at the top of the tower. As it falls down the air flowing in the upward direction cools it .
3.3 Advantage and Disadvantage
3.3.1 Advantages
Very high power to weight ratio, compared to reciprocating engines
Smaller than most reciprocating engines of the same power rating
Moves in one direction only, with far less vibration than a reciprocating engines
Fewer moving parts than reciprocating engines implies a lower maintenance cost
Greater reliability, Particularly in applications where sustained high power output is required
Waste heat dissipated almost entirely in the exhaust. This results in a high temperature exhaust stream that is very usable for boiling water in combined cycle, or for cogeneration
Low operating pressure
High operation speeds
Low lubricating oil cost and consumption
Can run on a wide variety of fuels
Very low toxic emission of CO and HC due to excess air, complete combustion and no “quench” of the flame on cold surfaces
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3.3.1 Disadvantages
Cost is very high
Less efficient then reciprocating engines at idle speed
Longer startup than reciprocating engines
Less responsive to change in power demand compared with reciprocating engines
Characteristic whine can be hard to suppress
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CHAPTER-4 HRSG (HEAT RECOVERY STEAM GENERATOR)
A heat recovery steam generator (HRSG) is an energy recovery heat exchanger that recovers heat from a hot gas stream. It produces steam that can be used in a process (cogeneration) or used to drive a steam turbine (combined cycle).
Figure 4.1 HRSG
4.1 Salient Features of Hrsg
Horizontal Natural Circulation Design.
Steam generation at multiple pressure levels with or without preheater’s.
Modular construction with spiral finned tubes for compactness.
Fully drainable heat transfer section
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Short installation time.
Ease of operation.
Supplementary Fuel firing system to meet specific customer requirements. In duct firing/Furnace firing. Multiple Fuel firing (Oil/Gas).
Low NOx and CO emission.
Unfired boiler.
Exhaust gases are used to generate steam.
500 c lower portion.
High pressure circuit two.
6H bar upper portion economizer.
Low temperature portion.
6 bar 202 c (ragging)
Discharge pressure 1H bar steam
Water tube boiler.
Forced circulation boiler.
Vertical boiler.
At 100 c leaver boiler.
Deareater feed storage tank
Circuit feed regulating
Economizer station controls
Evaporator flow
Super heater H.P. turbine and L.P. turbine
Twin cylinder turbine.
Tendon compound turbine.
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HP steam (rated parameters) Pressure: 78.2 Kg/Cm2.
Temperature: 514+/- 5 Deg. C
Flow: 187.1 TPH.
LP Steam (rated parameters)
Pressure: 5.0 Kg/Cm2.
Temperature: 200 Deg. C
Flow: 39.8 TPH.
4.2 Arrangement of HRSG Dholpur CCPP The arrangement of HRSG show in below figure how a HRSG work in combined cycle power plant and produce the steam
Figure 4.2 Arrangement of DCCP
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CHAPTER-5 STEAM TURBINE
A steam turbine is a device that extracts thermal energy from pressurized steam and uses it to do mechanical work on a rotating output shaft. Its modern manifestation was invented by Sir Charles Parsons in 1884. Because the turbine generates rotary motion, it is particularly suited to be used to drive an electrical generator – about 90% of all electricity generation in the United States (1996) is by use of steam turbines. The steam turbine is a form of heat engine that derives much of its improvement in thermodynamic efficiency from the use of multiple stages in the expansion of the steam, which results in a closer approach to the ideal reversible expansion process.
Figure 5.1 Steam Turbine
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5.1 ADVANTAGE OF STEAM TURBINE
The thermodynamics efficiency of steam turbine is higher than that of steam engine because these work on rankine cycle whereas steam engine works on modified rankine cycle. A steam turbine can thus take advantage of expansion up to the lowest pressure. The lowest exhaust it is 15 to 20 cm of hg (.2 to .3 bar)
The mechanism is simple as intermediate links like piston, piston rubber, croos head, etc. are absent.
There is no initial condensation as the parts are subjected to constant temperature and at constant loads.
Power is generated uniform rate, has no fly wheels necessary.
No internal lubricant necessary, which reduce the cost of lubrication and supplies purer feet to the boiler.
Due to absence reciprocating parts, perfect balance is possible which avoids heavy foundations.
Steam turbine can carry considerable overloads with only a stile reduction in efficiency.
The thermal efficiency of steam turbines plants is 35 to 40 %, whereas for steam engine it is 15 to 20 %.
5.2 LOSSES IN STEAM TURBINE
1. Losses in the exit velocity of steam: The loss in the exit velocity of the steam due to blade efficiency not being 100%. This is because of obliquity of nozzles angle is zero, blade efficiency would be 100%. 2. Loss due to friction and turbulence: friction occurs in nozzles and blades and between steams rotating disc. Also due to centrifugal action steam is thrown radially towards the casing and dragged along the surface by moving blades these losses are the disc friction and wind edge losses.
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3. Loss due to leakage: in impulse turbine leakage occurs b/w the shaft and the stationary diaphragms carrying nozzles. In the reaction turbine the leakage is at the blade tips. 4. Losses due to mechanical friction to the bearing, etc., this losses less than 1% and it decreases with the size of the plant. 5. Loses due to radiation is negligible. 6. Governor Losses: it is due to throttling. This may in order to 5 to 10%. 7. Exhaust losses: the steam leaves the turbine with a finite. Absolute velocity which partially or wholly lost. In this plant steam turbine produces 110 MW electricity, running by combined steam of HRSG. So in this plant cost of coal handling and ash handling is zero.
5.3 WORKING OF A STEAM TURBINE The steam turbine is a Siemens Westinghouse KN turbine generator, capable of producing up to 240 MG .it is located on top of the condenser, across from the cooling tower.
Steam enter the turbine with temperature as high as 1000 degrees Fahrenheit and pressure as strong as 2,200 pounds per square inch. The pressure of the steam is used to spin turbine blades that are attached to a rotor and a generator, producing additional electrical, about 100 MG per HRSG unit.
After the steam is spent in the turbine process, the residual steam leaves the turbine at low pressure and low heat, about 100degrees. This exhaust steam passes into a condenser to be turned back into water.
By using this “combined –cycle” process, two gas turbines, we can produce a total of about 110MW of electricity.
5.4 STEAM TURBINE AUXILIARY (STA) H.P. & L.P. by pass system
shaft turning system
feed water system
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Air extraction water side.
CW make up and raw water system.
Hub oil system.
Tacking oil system.
Hydraulic oil system.
Glained steam system
Two Glained steam -
Fan
-
Cooler
Pressure can valve
Cooling water circuit- To create low back pressure
Cooling water pump - Two pump are in service one is service & second is stained
Cooling tower- Fans is use in cooling.
Hub water pump- 3 pumps one is service of two is stained.
Air extraction system- Steam side removes non condensable from steam turbine.
Air ph. System
5.5 TURBO-GENERATOR AND EXCITATION SYSTEM
Figure 5.2 Turbo generator
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A Turbo generator is an electromechanical device that converts mechanical energy to electrical energy, using a rotating magnetic field
5.5.1 Theory Behind the working of a Turbo Generator
A Turbo generator generally includes a rotor that rotates within a stator core to convert mechanical energy into electrical energy.
A frame-supported stator core provides a high permeability path for magnetic flux and a rotor assembly positioned to rotate continuously within the stator core so as to induce electrical current.
The resulting current is carried by high-current conductors through and out from the power generator, to connectors that provide the current to a plant bus for power distribution.
5.5.2 Main Components of Generator
Stator - Stator Frame (Fabrication & Machining)
Core Assembly – Stator Core, Core Suspension Arrangement
End Shield
Stator Winding Assembly – Stator Winding, Winding Assembly, Connecting Bus bar, Terminal Bushing
Rotor – Rotor Shaft, Rotor Wedges, Rotor Coils, Wound Rotor, Rotor Assembly
Completing Assembly – Bearing Assembly, Shaft Seal Assembly, Oil Catchers, Insert Cover etc.
Exciter
Auxiliary Systems
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5.6 Function of Excitation System
Generation of air gap flux to get electrical output.
To generate synchronous torque to keep the machine in synchronism.
To generate reactive power (MVAR)
Fast response to system disturbance.
Capability to generate field forcing condition for prompt clearance of faults
Figure 5.3 Excitation System
5.6.1 Brushless Excitation System
Contact less system
Eliminates all problem related to transfer of power between
Stationary and rotating elements
Completely Eliminates brush gear
Slip rings, field breaker.
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Eliminates the hazard of changing
Brushes on load
Brush losses are eliminated
Reliability is better
Ideally suited for large sets
Figure 5.6 Coupling of Turbo generator and excitation
5.7 Parameter of Generator TABLE 5.7 Parameters
Gtg
Stg
Type
Tari 1080
Tari 1080
Active Power (MW)
112.46
126.2
MVA
132.3
148.47
Speed/Frequency (RPM/Hz)
3000/50
3000/50
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Stator Voltage (Kv)
10.5
10.5
Stator Current (A)
7275
8164
Cont. Unbalance Current (%)
10
10
Rated Power Factor
0.85 Lag
0.8 Lag
Y-Y
Y-Y
Rated Field Current (A)
756
825
Rated Field Voltage (V)
319
368
Internal Cooling
Air
Air
External Cooling
Air
Water
Inner Connection of Stator Winding
5.8 220 KV Switchyard And Transformer
Figure 5.8 220 KV switchyard
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Figure 5.8 Transformer
5.8.1 220 Kv Switchyard and Different Equipment’s Installed and Bus Schemes 5.8.1.1 Bus Scheme Main Function of the Stations Is To Receive the Energy and Transmit It at the Required Voltage Level with the Facility of Switching. At DCCPP Following Are the Bays: GTG-1 Bus coupler Line-1 GTG-2 Line-2 Line-3 STG
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5.8.1.2 Bus System There Are Mainly Two Buses 1. Main Bus-1 2. Main Bus-2
5.8.1.3 Sf6 Gas Circuit Breakers In this type of breaker quenching of arc is done by SF6 gas. The opening and closing of the circuit breaker is done by air.
5.8.1.4 Type Designation e
:
S F 6 Gas Insulation
l
:
Generation
f
:
Out Door Design
sl
:
Breaker Construction
4
:
Code BIL Rated Voltage 4 - 245 / 460 / 1050 kv
The high voltage circuit breaker type ELF SL 4-1 comprises 3 breaker poles, a common Control. Cubicle and a pneumatic unit (compressed air plant) a breaker pole consists of:- Support (frame)
-
40000
- Pole column
-
41309 N
- Pneumatic actuator (pka)
-
90200
The actuator is operated with compressed air. A pneumatic unit (97200), an air receiver and a unit compressor is installed to supply the compressed air. The compressed air stored in the air receiver is distributor to the three actuator via pipeline and most of the monitoring instrumentation with The exception of the density monitor 98005 mounted on the middle breaker pole. The pressure switches are installed in the control cubicle. All three poles columns are filled with insulating gas and interconnected by means of pipe lines. The gas is monitored by a density monitor 98005 (temp. compensated pressure monitor) If all the poles of the circuit breaker do not close simultaneously then the pole discrepancy relay will operate and trip the breaker. Also at the time of tripping, if all the breakers do not (AIET/DOEE/2016-2017/PTS/27)
trip simultaneously, then again the tripping command through the pole discrepancy relay will initiate to trip the breaker and annunciation will appear in the substation control room and the UCB.
5.8.1.5 Isolators Isolators are used to make or break the circuit on no load. They should never be operated on load. The isolators installed in the substation have a capacity of 1250 amperes. They are double end break type, motor operated and can be operated from local as well as remote.
5.8.1.6 Current and Capacitive voltage Transformer These are used for metering and protection. It should always be kept in mind that a CT should never be open circuited and a PT should never be short-circuited.
5.8.1.7 Lightening Arrestor and Arc Horns Protection against lightening.
5.8.2 Maintenance Jobs to Be Done On 220 KV Switch Yard 5.8.2.1 Daily Job
Visual checking for any hot spot
Checking of air leakage from the breaker
Checking for any gas leakage from the breaker
Checking of air pressure of breaker
Checking of gas pressure of breaker
Checking of oil leakage form CT and CVT
Checking of oil level from CT and CVT
Checking of lubricating oil level in compressors
Checking healthiness of trip circuit for all breakers.
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5.8.2.2 Monthly Job Thermo vision scanning of conductor joints and attending to the hot spot on available Opportunity Breaker operation checking from local and remote Isolators operation from remote and local. Measurement of specific gravity and voltage of 220 V D. C> Battery cells.
5.8.2.3 Quarterly Job 5.8.2.3.1 Isolators
Tightening of the jumper clamps
Tightening of electrical connections
Cleaning of male female connections
Checking of fuses and replacement there F.
Checking of operation of isolators
5.8.2.3.2 Current transformers
Checking of oil level.
Checking of oil and leakage
Tightening of jumper clamps
Tightening of electrical terminal secondary connection
5.8.2.3.3 Lightning Arrestors
Tightening of jumper connections
Tightening of earthing connections
Checking of counter reading
Checking of porcelain part
Checking of grading current
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5.8.2.3.4 Capacitive Voltage Transformer
Checking of oil level and leakage
Tightening of HT jumper clamps.
Tightening of secondary terminal connections
5.8.2.3.5 Battery 220 V D. C.
Cleaning of battery terminals
Tightening of battery terminal connections
Recording of specific gravity and voltage of each cell.
5.8.2.4 During Annual Shut down Of Units 5.8.2.4.1 Breakers
Checking and cleaning of porcelain part of the breaker.
Tightening of breaker clamps.
Cleaning of breaker cubical
Tightening of all the terminal connection
Lubrication of I) C and D Roller (II) Locking pins (III) Anti Pumping pins (IV) Mechanism Shafts
Recording of closing and tripping of each phase
Recording of insulation resistance value of breaker
Checking of annunciator and inter locks. o Air pressure low o Air pressure very low trip circuit cut off o Gas pressure low o Gas pressure trip circuit off and other ann. of breaker
Checking of tripping through o Trip Coil I o Trip Coil II o Through both the trip coils o Anti-Pumping operation
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o Pole Discrepancy operation o Measurement of resistance of trip cells and closing coils
Checking of air leakage and its stoppage
Checking the gas leakage
Replacing the oil of compressors
Checking of auto operation of compressors
Complete maintenance of compressors
Checking of closing/tripping of breaker from local remote
5.8.2.4.2 Isolators
Cleaning of male female connections
Tightening of all the jumper clamps
Lubrication of control rotary post insulator with grease
Checking of proper operation of the isolator
Tightening of all the nuts and bolts
Cleaning the motor cubical
Tightening of all the terminal connections
Greasing the gear box of motor
Checking of all the fuses
Checking of operation of isolator from local/remote
5.8.2.4.3 Current Transformers
Checking of oil and level and stopping it if low
Checking of oil leakage and its stoppage
Checking of N2 pressure and maintaining it at 0.2 kg/cm2
Tightening of earthing connection
Checking of BDV value of CT oil
Tightening of all the secondary terminal connections
Cleaning of marshalling box and tightening of terminal connections
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Recording of IR values of primary and secondary side of CT
Tightening of bushing clamps.
Checking / cleaning of porcelain part of CT
5.8.2.4.4 Capacitive Voltage Transformers
Checking of oil level and topping thereof
Checking of N2 pressure and maintaining it at 0.2 kg/cm
Tightening of jumper clamps.
Tightening of secondary connection
BD value of oil
5.8.2.4.5 Lightning Arrestors
Cleaning of porcelain part and checking
Tightening of earthing connection
Tightening of jumper connection
Recording of IR values
Checking of counter readings
Checking of grading current
5.8.3 Earth Shielding It is a mesh of wire upon the tower. Its main purpose is to protect the substation equipment from direct lightning strokes. Metallic body of each equipment is properly earthed. The earthing resistance of any switch yard is about 0.2 ohm. Before the building up of the substation earthing material of G. I. wire is buried in the ground whose depth depends upon the moisture content of ground. Earthing electrodes are provided at various points. This increases the number of parallel provided at various points. This increases the number of parallel paths and hence resistance of earth decreases.
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5.8.4 Power Line Carrier Communication This is a technique in which power lines are used as communication lines by which we can make contact with other substation. The range of frequency used for communication is 300 KHz to 500 kHz.
5.8.4.1 Working The voice frequency if converted into electrical signal. These signals are super imposed on a carrier frequency and transmitted on the line through a coupling capacitor. At the receiving Wave trap does not allow the modulated signal to enter the power circuit whereas the coupling Capacitor provides a low resistance path to this signal. This signal is then given To the line matching unit. In the LMU this frequency is matched and after wards filtration Of signal is done.
5.8.5 Different Transformer Installed In Transformer Yard Transformer is a static device which is used to change the voltage level keeping the power and frequency same. In the plant transformer is one of the most important equipment. In the whole plant, there are about 83 transformer installed at various places to operate the auxiliaries. Main transformers which are necessary:
To step up the generated voltage.
To supply power to the auxiliaries from the generator.
To start the plant by taking the supply from the grid.
5.8.5.1 Generator Transformer (GT - 1) It steps up the voltage from 10.5 KV to 220 KV. It connects the plant with the 220 KV Switchyard.
5.8.5.2 Generator Transformer (GT -2) It steps up the voltage from 10.5 KV to 220 KV. It connects the plant with the 220 KV
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Switch Yard.
5.8.1.3 Generator Transformer (GT -3) It steps up the voltage from 10.5 KV to 220 KV. It connects the plant with the 220 KV Switch Yard.
5.8.5.4 Unit Auxiliary Transformer (UAT-1) It is a step down transformer with 12/15 MVA capacity. It steps down the voltage from 11.5 KV to 6.9 KV.
5.8.5.5 Unit Auxiliary Transformer (UAT-2) It is a step down transformer with 12/15 MVA capacity. It steps down the voltage from 11.5 KV to 6.9 KV
5.8.5.6 Unit Service Transformer (UST) It is a step down transformer with 2 MVA capacity. It is used to step down from 6.6 kV to 0.4333 KV. There are 6 No’s of UST.
5.8.6 Transformer There are 3 generator transformers in the plant. One for each unit. The output from the Generator is fed to the generator transformer which steps up the voltage from 10.5 KV to 230 KV and supplies power to grid. Generator transformer winding connected in star\delta with a Phase displacement of 30 degrees. Three - phase supply from the generator is connected to the Low voltage side bushings and the output is taken from the opposite side. Neutral point on the H.V. side is provided at the side of the tank. Neutral is solidly grounded. In case neutral is solidly connected to the earth a very small current flowing through the neutral causes the Tripling of the transformer. So in this case more care is to be taken. The main parts of a transformer are:
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5.8.6.1 Steel Tank Whole of the transformer winding is immersed in the oil in the tank. The tank is airtight. The tank should be strong enough to bear the pressure generated inside the tank without Bursting. To avoid bursting of the tank two pressure relief valves are provided on both Sides of The tank. In case pressure inside the tank exceeds 0.39 kg/cm2 these valves operate. The diaphragm inside bursts and oil spills out thus tripling the generator 5.8.6.2 Bushing Porcelain bushings are provided on both sides of the tank from which L.V. and H. V. winding is connected to the external circuit. These bushings insulate the winding v terminals from the body. Bushings are also filed with transformer oil, which helps in cooling as well as insulation
5.8.6.3 Cooling System During the operation of the transformer, which raises the temperature of both the oil and the winding? For proper operation the temperature should be kept within limits. To cool the oil separate cooling system is provided. It consists of radiator, cooling fans and motor pump. Hot oil number of radiating fins from the top. There are a large enters the radiating fins from the top. There are a large number of radiating fins provided. When oil flows through this radiator fins it cools down and again enters the main tank from the bottom. The large number of fins increases the surface area thus increasing rate of heat dissipation. In transformer there are three types of cooling systems:
5.8.6.3.1 Oil Natural Air Natural (ONAN) In t8his type cooling of oil is done by the natural flow of the oil. It is done when the load on the transformer is below 160 MVA
5.8.6.3.2 Oil Natural Air Forced (ONAF) When the load on the transformer is between 160 MVA to 240 MVA, natural air striking the fins is not able to cool down the oil properly due to increase in the heat generation. So air is forced on the radiating fins. This is done by using the fans installed below the radiator fins.
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5.8.6.3.3 Oil Forced Air Forced (OFAF) With further increase in load, more heat is generated which necessary forced cooling of oil. This is done by energizing the pumps placed in the bottom pump near the main tank. These force the oil to flow which results in the cooling of the oil. G. T. is provided
5.8.6.4 Conservator Tank and Breather If some space is provided above the oil level in tank. As the tank is complete so stresses will develop on the tank due to the expansion of oil. So a ventilating system is provided which avoids stresses in the tank and helps in the proper expansion of the oil. A conservator tank with a breather is provided on the top of the tank. Conservator contains oil to some level and air cell. During expansion of the oil level inside the conservator tank increases. Due to this air cell contracts and air inside is pushed out. When the oil cools down, oil level decreases. Air cell expands and sucks air inside. The atmospheric air contains moisture and if oil comes in contact with this moist air its properties degrade. This is avoided by placing a drying agent in the breather. Calcium chloride or silica gel in the breather absorbs the moisture from air. Thus moisture less air enters the tank. In normal conditions the color of silica gel is blue. When its color changes to pale pink, it should be replaced immediately.
5.8.6.5 Buccholz relay It is the most important protective device for internal faults. It is a gas-activated relay. During any fault inside the winding light gases like hydrogen are generated. The Buccholz relay is connected on the pipe between the conservator and the main tank. These gases get struck in the Buccholz relay and cause the level of oil in the relay to go down. Due to this a mercury switch is operated which makes the contact and given a signal. In the beginning only an alarm is there. But if the fault persists and becomes serious there is a second mercury switch, which gets operated and trips the transformer. The various readings for the alarm and trip signal are: Alarm Signal -
220 mm Hg
Trip Signal -
500 mm Hg
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5.8.6.6 Tap changer Tap changers are provided in the transformer to get the desired output voltage by changing the number of turns. The tap changers are of two types: 1. On load tap changer 2. Off load tap changer
5.8.6.6.1 On load tap changer In this we can change the tapping of the transformer on load. The tap changer is
generally
provided on the H.V. side as current on this side is very less. These are installed on S.T.
5.8.6.6.2 Off load tap changer These are installed on GT. The tap is changed mechanically after disconnecting the transformer from the circuit. To monitor the temperature of oil as well as winding two temperature gauges are provided. In the gauge two capillary tubes are provided. One is dipped in oil to measure its temperature and the second one is dipped near the winding.
5.8.7 Unit Auxiliary Transformer Each unit has two unit auxiliary transformers. When the unit starts generating electricity these transformers are energized and then supplies power to the auxiliaries. Before starting of the unit, UAT bus is connected to the station bus. Auxiliaries of all three units take about 7 mw of power. UAT is connected between the generator and the GT. A tapping is taken from the power coming from the generator to the GT. UAT relieves GT from extra load of about 7 MW which is to be supplied to the auxiliaries via GT and ST thus increasing the efficiency. It is a step down transformer, which steps down the voltage from 10.5 kV to 6.9kV. The rating of UAT is 12/15 MVA. UAT bus supplies only those auxiliaries, which are not necessary to be energized in case of sudden tripping of generator.
5.8.8 Unit Service Transformer It is also a 6.6 kV/ 415 V transformer which is used to supply the auxiliaries connected to the unit secondary switchgear bus. (AIET/DOEE/2016-2017/PTS/37)
Figure 5.8 Single Line Electrical Layout Diagram of DCCP Dholpur
5.8.9 Detail of 220Kv C.B. TABLE NO. 5.8.9 Voltage
245 KV
Normal current
2000 amp.
Lighting impulse withstand voltage
1050 KV
Short circuit breaking current
40 KV
Short time withstand current & duration
40 KA , 3 sec.
Operating sequence
o-0.3sec.-co-3min-co.
Gas pressure(sf6)
7.0
Closing & opening supply voltage
220 v dc
Auxiliary circuit supply voltage
415 v ac
Air pressure
21.5 bar
Frequency
50 HZ
Mass (approx.)
3800 kg
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5.8.10 Unit Auxiliary Transformer TABLE NO. 5.8.10 Power
12/15 MVA
Hv voltage
10.5 KV
Lv voltage
6.9 KV
Transformer percentage impedance
10 %
Transformer vector
DYN 1
Tap
+/- 10% of rated voltage
5.8.11 Generator Transformer TABLE NO. 5.8.11 Power
90/120/160 MVA
Hv voltage
230 KV
Lv voltage
10.5 KV
Transformer percentage impedance
12.5 %
Transformer vector group
YND 11
Tap
+/- 5% of rated voltage
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CHAPTER 6 TEMPERATURE AND PRESSURE MEASUREMENT CONTROL Temperature and pressure are measured and control through many devices so then there will not be any damage to machines. This whole process is being done in C & I room.
6.1 TEMPERATURE MEASUREMENT Temperature of turbine has to be measured from time to time. So to measurement of temperature is done by temperature measuring instrument. For this purpose mainly measuring instrument used are Thermocouple, RTD, Thermistors etc. These measuring devices are then connected to carts through logic gates. Carts gives information about the temperature to control and information room. These carts also provide the limit to temperature. Whenever temperature reaches above the limit, an indication will be given to connected system then the machine will be automatically turned off. So due to increase in temperature there will not be any damage to turbine and other machine.
THERMOCOUPLE A thermocouple consists of two conductors of different materials (usually metal alloys) that produce a voltage in the vicinity of the point where the two conductors are in contact. The voltage produced is dependent on, but not necessarily proportional to, the difference of temperature of the junction to other parts of those conductors. Thermocouples are a widely used type of temperature sensor for measurement and control and can also be used to convert a temperature gradient into electricity. They are inexpensive, interchangeable, are supplied with standard connectors, and can measure a wide range of temperatures. In contrast to most other methods of temperature measurement, thermocouples are self-powered and require no external form of excitation. The main limitation with thermocouples is accuracy; system errors of less than one degree Celsius (C) can be difficult to achieve.
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Any junction of dissimilar metals will produce an electric potential related to temperature. Thermocouples for practical measurement of temperature are junctions of specific alloys which have a predictable and repeatable relationship between temperature and voltage. Different alloys are used for different temperature ranges. Properties such as resistance to corrosion may also be important when choosing a type of thermocouple. Where the measurement point is far from the measuring instrument, the intermediate connection can be made by extension wires which are less costly than the materials used to make the sensor. Thermocouples are usually standardized against a reference temperature of 0 degrees Celsius; practical instruments use electronic methods of cold-junction compensation to adjust for varying temperature at the instrument terminals. Electronic instruments can also compensate for the varying characteristics of the thermocouple, and so improve the precision and accuracy of measurements.
Thermocouples are widely used in science and industry; applications include temperature measurement for kilns, gas turbine exhaust, diesel engines, and other industrial processes.
Figure 6.1
THERMISTORS
A thermistor is a type of resistor whose resistance varies significantly with temperature, more so than in standard resistors. The word is a portmanteau of thermal and resistor. Thermistors are widely used as inrush current limiters, temperature sensors, self-resetting overcurrent protectors, and self-regulating heating elements.
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Thermistors differ from resistance temperature detectors (RTD) in that the material used in a thermistor is generally a ceramic or polymer, while RTDs use pure metals. The temperature response is also different; RTDs are useful over larger temperature ranges, while thermistors typically achieve a higher precision within a limited temperature range, typically −90 °C to 130 °C. Thermocouple symbol
Figure 6.2 Basic operations Assuming, as a first-order approximation, that the relationship between resistance and temperature is linear, then:
Where:
= change in resistance = change in temperature = first order temperature coefficient of resistance
Thermistors can be classified into two types, depending on the sign of . If
is positive, the
resistance increases with increasing temperature, and the device is called a positive temperature coefficient (PTC) thermistor, or posistor. If
is negative, the resistance decreases with
increasing temperature, and the device is called a negative temperature coefficient (NTC) thermistor. Resistors that are not thermistors are designed to have a
as close to zero as
possible, so that their resistance remains nearly constant over a wide temperature range. Instead of the temperature coefficient k, sometimes the temperature coefficient of resistance
(alpha sub T) is used. It is defined as
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RESISTANCE THERMOMETER
Resistance thermometers, also called resistance temperature detectors (RTDs), are sensors used to measure temperature by correlating the resistance of the RTD element with temperature. Most RTD elements consist of a length of fine coiled wire wrapped around a ceramic or glass core. The element is usually quite fragile, so it is often placed inside a sheathed probe to protect it. The RTD element is made from a pure material whose resistance at various temperatures has been documented. The material has a predictable change in resistance as the temperature changes; it is this predictable change that is used to determine temperature.
As they are almost invariably made of platinum, they are often called platinum resistance thermometers (PRTs). They are slowly replacing the use of thermocouples in many industrial applications below 600 °C, due to higher accuracy and repeatability. Common RTD sensing elements constructed of platinum copper or nickel have a unique, and repeatable and predictable resistance versus temperature relationship (R vs T) and operating temperature range. The ∆R Vs ∆T relationship is defined as the amount of resistance change of the sensor per degree of temperature change.
Figure 6.3
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6.2 PRESSURE MEASUREMENT Pressure of turbine has to be measured from time to time. So to measurement of pressure is done by pressure measuring instrument. For this purpose mainly measuring instrument used are bourdon tube, u tube, diaphragm pressure gage etc. these measuring devices are then connected to carts through logic gates. Carts gives information about the pressure to control and information room. These carts also provide the limit to pressure. Whenever pressure reaches above the limit, a indication will be given to connected
system then the machine will be
automatically turned off. So due to increase in pressure there will not be any damage to turbine and other machine.
BOURDON TUBE The Bourdon tube is a no 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.
Figure 6.4 Typical Bourdon Tube Pressure Gages.
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The external pressure is guided into the tube and causes it to flex, resulting in a change in curvature of the tube. These curvature changes are linked to the dial indicator for a number readout. Alternatively, a strain gage circuit can be attached on the tube to convert the pressureinduced deflections into electric voltage signals. These signals can then be output electronically, rather than mechanically with the dial indicator.
U TUBE The U Tube contains water or mercury in a U-shaped tube, and is usually used to measure gas pressure. One end of the U tube is exposed to the unknown pressure field and the other end is connected to a reference pressure source (usually atmospheric pressure), shown in the schematic below.
Figure 6.5 Typical U Tube To automate the pressure measurement in a mercury-filled U tube, a Wheatstone Bridge can be fabricated by connecting two external resistance to a high-resistance wire threading the interior of the U tube, as shown in the schematic below.
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Figure 6.6 U Tube Pressure Sensor The resistance of the U tube wire is proportional to its current-carrying length. The two parts of the wire external to the mercury will carry current and therefore will impart resistances to the circuit. However, the immersed portion of the wire carries no current, since the current will instead travel through the highly-conductive mercury. The U tube wire is effectively separated into two separate resistances, each resistance dependent upon the wire len gth above the mercury. As a result, the difference in the resistance of these two wire segments will be proportional to the pressure difference across the U tube,
Where c and k = cRw are factors that can be obtained during calibration.
6.3 DIAPHRAGM PRESSURE GAGE
The Diaphragm Pressure Gage uses the elastic deformation of a diaphragm (i.e. membrane) instead of a liquid level to measure the difference between an unknown pressure and a reference pressure.
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A typical Diaphragm pressure gage contains a capsule divided by a diaphragm, as shown in the schematic below. One side of the diaphragm is open to the external targeted pressure, PExt, and the other side is connected to a known pressure, PRef,. The pressure difference, PExt - PRef, mechanically deflects the diaphragm.
Figure 6.7 Typical Diaphragm Pressure Gage
The membrane deflection can be measured in any number of ways. For example, it can be detected via a mechanically-coupled indicating needle, an attached strain gage, a linear variable differential transformer (LVDT; see the schematic below), or with many other displacement/velocity sensors. Once known, the deflection can be converted to a pressure loading using plate theory.
Figure 6.8 LVDT-Based Diaphragm Pressure Gage
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CHAPTER 7 STARTER FOR INDUCTION MOTORS
7.1 Introduction Different starting methods are employed for starting induction motors because Induction Motor draws more starting current during starting. To prevent damage to the windings due to the high starting current flow, we employ different types of starters. 1. Direct On Line starter 2. Star Delta Starter
7.2 Direct On Line starter The simplest form of motor starter for the induction motor is the Direct Online starter. The Direct Online Motor Starter (DOL) consist a MCCB or Circuit Breaker, Contactor and an overload relay for protection. Electromagnetic contactor which can be opened by the thermal overload relay under fault conditions.
Typically, the contactor will be controlled by separate start and stop buttons, and an auxiliary contact on the contactor is used, across the start button, as a hold in contact. I.e. the contactor is electrically latched closed while the motor is operating.
7.2.1 Principle of Direct On Line Starter (DOL) To start, the contactor is closed, applying full line voltage to the motor windings. The motor will draw a very high inrush current for a very short time, the magnetic field in the iron, and then the current will be limited to the Locked Rotor Current of the motor. The motor will develop Locked Rotor Torque and begin to accelerate towards full speed. As the motor accelerates, the current will begin to drop, but will not drop significantly until the motor is at a high speed, typically about 85% of synchronous speed. The actual starting current curve is a function of the motor design, and the terminal voltage, and is totally independent of the motor load. The motor load will affect the time taken for the motor to accelerate to full speed and therefore the duration of the high starting current, but not the magnitude of the starting current. Provided the torque developed by the motor exceeds the load torque at all speeds during the start cycle, the motor will reach full speed. If the torque delivered by the motor is less than the torque of (AIET/DOEE/2016-2017/PTS/48)
the load at any speed during the start cycle, the motor will stops accelerating. If the starting torque with a DOL starter is insufficient for the load, the motor must be replaced with a motor which can develop a higher starting torque. The acceleration torque is the torque developed by the motor minus the load torque, and will change as the motor accelerates due to the motor speed torque curve and the load speed torque curve. The start time is dependent on the acceleration torque and the load inertia.
7.2.2 Main Parts of Direct online starter Direct online Starter consists of following parts:
Electromagnetic Contactor
Overload relay
Main MCB
ON/OFF switches
All Starters has two circuit diagrams:
Power circuit Diagram
Control circuit diagram
1. Power circuit diagram Power circuit is usually also called three phase diagram. In That diagram Overload relay comes at end of circuit and is below:
Figure 7.1
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Above diagram is known as power circuit diagram as ON/OFF switches are not shown in this diagram, instead only 3-Phase wiring is shown. In this diagram you can easily see that Overload relay is connected nearest to motor end so that if any abnormality occurs then Overload get tripped immediately and protects both motor and circuit.
2. Control Circuit diagram In control circuit O/L Relay comes at starting of circuit and is shown as below:
Figure 7.2
In this circuit as we see O/L Relay NC is used and Stop Push Button NC is used. Whenever start PB is pressed Phase 1st goes through Overload relay NC and then goes through Stop PB and Start PB and thereafter holds power contactor now as soon as Power contactor get holds it’s NO becomes NC and thereafter power supply continue to flow to power contactor through 13-14 point and Start PB goes to initial position. In above control circuit 220V circuit is shown but it may be 440V circuit depends upon Power contactor coil voltage supply.
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Advantages of DOL Starter
These are most simple type of starters.
Most economical and cheapest starter.
Maintenance cost is very low.
Disadvantages of DOL Starter
Draws very high inrush current at starting i.e. 6-8 times rated current of motor which restricts its use to motors up to 7.5 KW only.
It will put high Thermal Stress on motors that will reduce motor life.
High starting current will leads to dips in voltage.
7.3 Star Delta Starter Motors up-to 7.5 KW are started using direct online starters but above 7.5 KW induction motors are started using Star-Delta Starters as if motors above 7.5 KW are started directly then there will be voltage disturbances in line due to large starting current surges. So let’s discuss how this Star-Delta Starter works.
7.3.1 Working Principal of Star-Delta Starter: First of all you must know what Star and Delta connections are:
Star Connection or Wye Connections: In Star connections, Phase current= Line current and Phase voltage= Line voltage/ √3. This means that during starting voltage get reduced by factor 1/√3. So Torque also gets reduced by factor 1/3 as Torque is directly proportional to square of voltage. Current also get reduced by 1/√3 in induction motor if motor is started in Star connections. Delta Connections: In Delta connections Phase Voltage = Line Voltage and Phase current= Line Current/ √3. After starting motor in star connections then transition is done from Star connections to Delta connections after certain delay. (AIET/DOEE/2016-2017/PTS/51)
Star-delta Starter Consists following components:
Main, star and delta contactors Timer Star-Delta. Overload relay Main MCCB or Fuse Unit
Power Circuit of Star Delta Starter: In that circuit when Start PB is pressed Star and Main contactor gets holds and motor get started in Start connections and after certain delay which was set in timer star contactor get disengage and delta contactor comes in line. Star and Delta contactor NC’S are take in line both in Delta and contactor line so that only 1 contactor either star or Delta may come in line. In Star Delta Starter since Six leads goes at Motor end so in each lead phase current will flow so Overload relay used for Star-Delta circuit is usually for phase current not line current.
Figure 7.3
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Application of Star-Delta Starter: In Most of industries for motors above 7.5 KW Star-Delta Starters are used. Star Delta Starters are used as during starting start current get reduced by 1/3 times and also torque get reduced by 1/3 times. They have low maintenance cost compared to VFD or Soft-Starters which will be discussed late
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CHAPTER 8 DC BATTERIES
Figure 5.8 Battery Room
8.1. Batteries 8.1.1. Main Building
Wet cell battery bank -125 V Battery Bank – 1 -125 V Battery Bank – 2 -125 V Battery Bank – 3 -125 V Battery Bank – 4 -220 V Battery Bank – 1 -220 V Battery Bank – 2
Dry cell battery - Battery Bank
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8.1.2. Switchyard Building Battery Bank
220 V Battery Bank – 1
220 V Battery Bank – 2
48 V Battery Bank – 1
48 V Battery Bank – 2
8.1.3. Battery room
Battery room should be well ventilated, clean, dry and temperature moderate
Dangerous due to possibility of earth leakage from the battery
Smoking is prohibited
Battery get best result at the room temperature between 20 – 35o C
8.1.4. Electrolyte
It is a mixture of Acid and Pure Water (Distilled) with proper portion.
General value of proportion is 85 % water and 15 % acid.
Gravity to be maintained 1.200 + 0.005 in all the cells.
8.1.5. Caution 8.1.3 Battery Room
Batteries and Battery Room should be clean, dry and well ventilated.
Never allow a flame, cigarette near the batteries.
Wear old clothes or Terylene when working with acid or electrolyte (Terylene is resistant to Dilute acid).
Never add water to acid. It will spurt dangerously
8.1.6 Temperature Correction
The specific gravity of the electrolyte works wth temperature. Any reading observed on the hydrometer should therefore be corrected to 270o C as all the specific gravity values indicated by use are at 27o C
For every 1o C above 27o C add 0.007 to the specific gravity as read on hydrometer
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8.2 Normal Operation of Batteries
Keep the battery on trickle charge continuously (25 hrs. each day) except where it is on
Discharge or on Boost charge.
The trickle charge current shown on milli ammeter should be so adjusted that the battery be
Kept fully charges without being over charged.
The trickle charging current should be so appropriate that it should neither be too much trickle
Charge not too little trickle charge.
The value above 2.3 and below 2.25 volts per cell during routine checking it found means
Adjustment of trickle charging current is required.
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CONCLUSION AND FUTURE SCOPE
Conclusion Hence we have analyzed how to power generate and what are the basic building blocks of the power generation project such as a compressor, combustion chamber, gas turbine, steam turbine and Turbo generator etc. How power is supplied to the transmission line. We also observe construction of gas turbine, steam turbine, Turbo generator etc. Power generation are very efficient, reliable, highly performance and give tremendous result. Power generation plants are very economical. There are the 8 plants working under the RAJASTHAN RAJYA VIDYUT UTPADAN NIGAM LTD. And present total installed capacity of RAJASTHAN RAJYA VIDYUT UTPADAN NIGAM LTD. Is 4097.35 MW and the present capacity of DHOLPUR COMBINED CYCLE POWER PLANT is 330 MW
Future scope In future every sector required the electricity a large amount of power produces by the power plant. Power plant generate the power and transmit power in bulk. In future many technologies are invent in electrical field and required the large amount of power which fulfil by power plant.
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REFERENCE
https://en.wikipedia.org/wiki/Steam_turbine
https://en.wikipedia.org/wiki/Heat_recovery_steam_generator
https://en.wikipedia.org/wiki/Gas_turbine
https://www.scribd.com/subscribe?action=BXRD2Exit
https://en.wikipedia.org/wiki/Dholpur_Combined_Cycle_Power_S
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