cea _construction of electric plants- reg

8/6/2019 CEA _Construction of Electric Plants- Reg

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Central Electricity Authority (Construction of Electrical Plants & Electric Lines) Regulations, 2007 -DRAFT

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CENTRAL ELECTRICITY AUTHORITYNOTIFICATION

New Delhi, the , 2007

No. -- In exercise of the powers conferred by clause (b) of Section 73read with sub-section (2) of Section 177 of the Electricity Act 2003, the CentralElectricity Authority hereby makes the following regulations namely:

1. Short title and commencement

(1) These regulations may be called the Central Electricity Authority(Construction of Electrical Plants & Electric Lines) Regulations, 2007.

(2) These regulations shall come into force on the date of their publication in theGazette of India.

2. Definitions

(1) In these regulations, unless the context otherwise requires,--

(a) Accuracy Class means a classification assigned to current or voltagetransformer the errors of which remain within specified limits underprescribed conditions of use.

(b) Act means the Electricity Act, 2003.

(c) Authority means the Central Electricity Authority established under sub-section (2) of Section 70 of the Act.

(d) Automatic Voltage Regulator (AVR) means a continuously acting automaticexcitation control system to regulate a generating unit terminal voltage.

(b) Base Load Operation means operation at Maximum Continuous Rating(MCR) or its high fraction.

(c) Basic Insulation Level (BIL) means the crest value of a standard lightningimpulse wave (1.2/50 s) which the insulation provided to an item of

electrical equipment/apparatus can withstand.(d) Black Start means the start up of first unit or a gas turbine following Grid

failure.

(e) Boiler Maximum Continuous Rating (BMCR) means the maximum steamoutput (tonnes/hour) the steam- generator (boiler) can deliver continuously atrated parameters.


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(f) Break time means interval of time between the beginning of the openingtime of a switching device and the end of the arcing time.

(g) Burden in relation to current transformer means the impedance of thesecondary circuit expressed in ohms and power-factor and in relation to

voltage transformer means the admittance of the secondary circuit expressedin mhos and power-factor (lagging and leading). The burden is usuallyexpressed as the apparent power in voltamperes absorbed at a specifiedpower-factor and at the rated secondary current.

(h) Cold start in relation to steam turbine means start up after a shut downperiod exceeding 72 hours (turbine metal temperatures below approximately40% of their full load values).

(i) Combined Cycle Gas Turbine (CCGT) module means gas turbinegenerator(s), associated heat recovery steam generator (s) and steam

turbine generator. (j) Combined cycle mode in relation to gas turbine based thermal generating

station means operation of gas turbine alongwith associated exhaust heatrecovery steam generator and steam turbine.

(k) Control Load in relation to coal/lignite based thermal generating unitsmeans the lowest load at which the rated steam temperature can bemaintained under auto control system.

(l) Current Transformer means an instrument transformer in which thesecondary current, in normal conditions of use, is substantially proportional tothe primary current and differs in phase from it by an angle which isapproximately zero for an appropriate direction of the connections.

(m) Design Head means the net head at which peak efficiency of hydraulicturbine is attained while operating at rated head.

(n) Extra high Voltage (EHV) means a voltage above 33,000 volts.

(o) FRLS Cable means Flame Retardant Low Smoke cable which emit lowsmoke and is resistant to fire for certain duration of time.

(p) Gas Turbine means a machine which converts thermal energy intomechanical work and includes compressor, combustion system andexpansion turbine.

(q) Generator means an equipment which converts the mechanical power ofthe prime mover into electrical power.


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(r) Governor means a device which regulates the speed and output of turbine-generator units.

(s) Gross turbine cycle heat rate in relation to coal/lignite based thermalgenerating station means the external heat energy input to the turbine cycle

required to generate one kWh of electrical energy at generator terminals.(t) Gross heat rate in relation to gas turbine based and diesel engine based

thermal generating stations means the external heat energy input required togenerate one kWh of electrical energy at generator terminals.

(u) High heat value (HHV) means the heat produced by complete combustionof one kilogram of solid fuel/liquid fuel or one standard cubic meter (Sm 3) ofgaseous fuel as per IS:1350 (Part-II) or IS:1448 (P:6) as the case may be.

(v) Highest system voltage means the highest r.m.s line to line value of voltage

which can be sustained under normal operating conditions at any time and atany point in the system. It excludes temporary voltage variation due to faultconditions an the sudden disconnection of the large load.

(w) Hot Start in relation to steam turbine means start up after a shut downperiod of less than 10 hours (turbine metal temperatures approximately 80%of their full load values).

(x) House Load means the unit is operating in isolation to the grid andgenerating electric power to cater to its own auxiliaries.

(y) Hydraulic Turbine means a machine which converts the potential energy ofwater into mechanical power to rotate the generator.

(z) Hydro-electric Generating Station means the generating station asdefined in the Act for generating electricity by water-power.

(aa) Impedance Earthed Neutral System means a system whose neutral point(s)is(are) earthed through impedances to limit earth fault currents.

(bb) Impulse means a unidirectional wave of voltage or current which, withoutappreciable oscillations, rises rapidly to a maximum value and falls, usuallyless rapidly, to zero with small, if any, loops of opposite polarity. Theparameters which define a voltage or current impulse are polarity, peakvalue, front time, and time to half value on the tail.

(cc) Impulse withstand voltage means peak value of the standard impulsevoltage wave which the insulation of the circuit-breaker withstands underspecified test conditions.


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(dd) Insulation co-ordination means the selection of the dielectric strength ofequipment in relation to the voltages which can appear on the system forwhich the equipment is intended and taking into account the serviceenvironment and the characteristics of the available protective devices.

(ee) Isolated Neutral System means a system where the neutral point is notintentionally connected to earth, except for high impedance connections forprotection or measurement purposes.

(ff) Lightning Arrestor (Surge Diverter) means a device designed to protectelectrical apparatus from high transient voltage and to limit the duration andfrequently the amplitude of follow-current. The term "lightning arrester"includes any external series gap which is essential for the proper functioningof the device as installed for service, regardless of whether or not it issupplied as an integral part of the device.

(gg) Load cycling means operation alternating at high and low level of load on aregular basis.

(hh) Maximum Continuous Rating or MCR

- in relation to coal/lignite based thermal generating units means the output atthe generator terminals (net of any external excitation power) as guaranteedby the manufacturer at the rated parameters.

- in relation to gas turbine based thermal generating stations means theoutput of the Gas Turbine Generator measured at the generator terminals(net of generator excitation power) in case of simple cycle and sum of outputof the Gas Turbine Generator(s) and Steam Turbine Generator measured atthe generator terminals (net of generator excitation power) in case ofcombined cycle, as guaranteed by the manufacturer for design fuel andcorresponding to site conditions.

- in relation to diesel engine based thermal generating units means theoutput at the generator terminals (net of generator excitation power) asguaranteed by the manufacturer for design fuel and corresponding to siteconditions.

(ii) Maximum heat input per burner means the heat generated from fuel firing inone hour divided by the total number of coal burners.

(jj) Mesh Voltage means the maximum touch voltage within a mesh of aground grid.


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(kk) Minimum tail water level means the water level in the tail race at the exitend of the draft tube corresponding to a discharge required to run onemachine at no load.

(ll) Motor Control Centre (MCC) means the switchgear which contains

modules for motor supply and its control.(mm) Net Head means the pressure head differential between the entrance to

the hydraulic turbine casing and the tail race water surface elevation.

(nn) Net heat input (NHI) available in furnace per unit plan area means the netheat input (i.e. heat generated by fuel/s fired in one hour plus the sensibleheat of combustion air above 27 0C minus the radiation loss, unburntcombustibles, moisture in the air, latent heat of moisture in fuel and thatformed by combustion of H 2 in the fuel) divided by the plan area of thefurnace.

(oo) On Load Tap Changer (OLTC) means a device provided on high voltageside of transformer, which is used for variation of voltage during chargedcondition of the transformer.

(pp) Off Circuit Tap Changer (OCTC) means a device provided on high voltageside of transformer, which is used for variation of voltage during OFFcondition of the transformer.

(qq) Overhead Line means any electric supply line which is placed aboveground and in the open air, consisting of conductors which are insulated orbare.

(rr) Owner means the company or body corporate or association or body ofindividuals, whether incorporated or not or artificial juridical person whichowns or operates or maintains Electric Plants/ Lines.

(ss) Performance coal means the coal quality for which steam-generatorperformance is guaranteed by the manufacturer.

(tt) Power Control Centre (PCC) means the switchgear which containsmodules for power supply to other switchboards/ switchgears/ distributionboards and its control.

(uu) Power House means the structure which houses hydraulic turbines,generators, including main inlet valves and/or gates, associated electro-mechanical and control equipment.

(vv) Power System Stabiliser (PSS) means a device for achieving the dynamicstability of the generating unit under most severe conditions of operation in


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case of disturbance created by short circuit condition, load rejection,switching ON/ OFF of transmission lines.

(ww) Pump Turbine means a hydraulic turbine having a runner capable ofrunning in one direction in generating mode and reverse direction in pumping

mode.(xx) Pumped storage plant means a system of generating electricity in which the

electricity is generated during the peak hours by using water that has beenpumped into upper reservoir during off-peak hours from the lower reservoir.

(yy) Resonant Earthed Neutral System means a system in which one or moreneutral points are connected to earth through reactances whichapproximately compensate the capacitive component of a single phase toearth fault current.

(zz) Runaway speed means the speed attained by a hydraulic turbine at fullgate opening when the generator is disconnected from the system and thegovernor is in-operative.

(aaa) Simple cycle mode in relation to gas turbine based thermal generatingstation means operation of gas turbine with exhaust gases vented toatmosphere.

(bbb) Solidly Earthed Neutral System means a system whose neutral point(s) is(are) earthed directly.

(ccc) Specific speed means the speed in rpm at which a given hydraulic turbinewould rotate, if reduced homologically in size, so that it would develop 1metric horse power (i.e. 736 watts) under 1 meter of head at full gateopening.

(ddd) Station means either the Thermal Generating Station or Hydro-electricGenerating Station depending upon the context.

(eee) Steam turbine means a machine which converts thermal energy from steaminto mechanical work to drive the electrical generator.

(fff) Step Potential means the difference in surface potential experienced by aperson bridging a distance of 1 m with the feet without contacting anygrounded object when ground currents are flowing.

(ggg) Subcritical unit in relation to coal/lignite based thermal generating unitmeans a unit designed for main steam pressure less than the criticalpressure (221.2 bars).


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(hhh) Subcritical unit in relation to coal/lignite based thermal generating unitmeans a unit designed for main steam pressure more than the criticalpressure (221.2 bars).

(iii) Substation means any premises or enclosure containing an assemblage of

electrical apparatus for conversion, transformation and control of electricalpower other than transforming or converting solely for operation of switchingor instruments and includes a pole mounted substation.

(jjj) Surface Power House means the Power House in which upper partstarting from the generator floor or service bay are above the ground.

(kkk) Switchgear means switching devices and their combination with associatedcontrol, measuring, protective and regulating equipment, also assemblies ofsuch devices and equipment with associated interconnections, accessories,enclosures and supporting structures, intended in principle for use in

connection with generation, transmission, distribution and conversion ofelectric power.

(lll) Switchyard means a sub-station associated with a generating station fortransforming electricity for further transmission.

(mmm) Thermal Generating Station means the generating station as defined inthe Act for generating electricity using fossil fuels such as coal, lignite, gas,liquid fuel or combination of these as its primary source of energy.

(nnn) Touch Potential is the potential difference between the object touched andthe ground point just below the person touching the object when groundcurrents are flowing.

(ooo) Transients means over voltage or over current phenomena prevailing in anelectrical system for a transient period of the order of a fraction of a secondor a few seconds not exceeding five seconds.

(ppp) Turbine setting in relation to hydro-electric generating station means theelevation of distributor centre line or runner centre line.

(qqq) Two Shift Operation means operation at MCR or its high fraction for aboutsixteen hours in a day, unit being shut down for the remaining time.

(rrr) Under Ground Power House means the Power House in which all majorcomponents of the turbine-generator sets are underground.

(sss) Unit in relation to a coal/lignite based thermal generating station meanssteam generator with interconnected steam turbine-generator and auxiliaries,operated as one single set/system to generate electric power.


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(ttt) Voltage Transformer means an instrument transformer in which thesecondary voltage, in normal conditions of use, is substantially proportionalto the primary voltage and differs in phase from it by an angle which isapproximately zero for an appropriate direction of the connections.

(uuu) Volumetric Heat Liberation Rate is defined as the heat generated from fuelfiring in one hour divided by the volume of the furnace.

(vvv) Warm Start in relation to steam turbine means start up after a shut downperiod between 10 hours and 72 hours (turbine metal temperatures betweenapproximately 40% and 80% of their full load values).

(2) Words and expressions used but not defined in these Regulations shall havethe same meaning respectively assigned to them in the Act.

3. Applicability of RegulationsThese regulations shall apply to all Electrical Plants and Electric Lines forwhich order is placed by the Owner after the date of notification of theseregulations.

4. Objectives

These regulations are intended to specify the Technical Standards forconstruction of Electrical Plants and Electric Lines with the objective that allElectrical Plants and Electric Lines to be constructed conform to minimumrequirements as laid down hereunder to ensure high level of performance inrespect of reliability, availability and efficiency over its lifetime.

5. Technical Standards

All Electrical Plants and Electric Lines to be constructed shall conform to theGeneral Requirements specified at Regulation (6) below and The TechnicalStandards for construction of Electrical Plants and Electric Lines asappended with these Regulations at Schedule -I to IV detailed hereunder:

a) Schedule I: Technical Standards for Thermal Generating Stationsb) Schedule II: Technical Standards for Hydro-electric Generating

Stationsc) Schedule III: Technical Standards for Sub-stations and Switchyardsd) Schedule IV: Technical Standards for Electric Lines


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6. General Requirements

(1) The Electrical Plants and Electric Lines shall be constructed consideringprudent engineering practices and optimal utilization of resources. Theseshall be complete and include all the equipment and systems necessary to

ensure high level of safety, maintainability, reliability and availabilitythroughout their life.

(2) The Electrical Plants and Electric Lines shall be suitable for full range ofambient and other environmental conditions.

(3) The various parts / components / assemblies of equipment and systems shallbe of proven materials with well established physical and chemical propertiesappropriate to the service as intended.

(4) All equipment and systems installed shall comply with latest statutes,

regulations and safety codes, as applicable in the area.(5) The Electrical Plants and Electric Lines shall be designed to comply with the

requirements stipulated in

a) Central Electricity Authority (Installation and Operation of Meters)Regulations, 2006

b) Central Electricity Authority (Technical Standards for Connectivity to theGrid) Regulations, 2006

c) Central Electricity Authority (Measures relating to Safety and ElectricitySupply), Regulations, 2007

c) Indian Electricity Grid Code issued by Central Electricity RegulatoryCommission (CERC) and

d) Applicable State Grid Code issued by appropriate RegulatoryCommission.

(6) The design, construction and testing of all equipment, facilities, componentsand systems shall be in accordance with standards/ codes issued by Bureauof Indian Standards (BIS) and/or reputed international standards/ codes. Anon-exhaustive list of reputed international standards is given below:

a) American National Standards Institute (ANSI)b) American Petroleum Institute (API)c) American Society of Mechanical Engineers (ASME)d) American Society of Testing and Materials (ASTM)e) American Water Works Association (AWWA)f) American Welding Society (AWS)g) British Standards (BS)h) Deutsches Institut fur Normung (DIN), Germanyi) Heat Exchange Institute (HEI), USA


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j) Hydraulic Institute Standards (HIS), USAk) International Electrotechnical Commission (IEC)l) Institute of Electrical and Electronics Engineers (IEEE)m) International Organisation for Standardisation (ISO)n) Japanese Industrial Standards (JIS)

o) National Electric Code (NEC), USAp) National Electrical Manufacturers Association (NEMA), USAq) National Fire Protection Association (NFPA), USAr) Tubular Exchanger Manufacturers Association (TEMA), USAs) VDE association for Electrical, Electronic and Information Technologies

(VDE), Germany

Other International Standards, equivalent or superior to the above Standardscan also be adopted. However, in the event of any conflict between therequirements of the International standards/codes and, and the requirementsof the BIS standards/codes, the latter shall prevail.

(7) All materials, components and equipment shall be tested at all stages ofprocurement, manufacturing, erection, commissioning as per comprehensiveQuality Assurance Programme to be agreed mutually between the owner andthe equipment supplier.

(8) The SI /MKS system of units shall be used for design, drawings, diagrams,instruments, etc.

(9) The Owner shall retain at the site and make available the followingdocuments for inspection, as may be required by a statutory body:

a) As-built drawings including, but not limited to the civil and architecturalworks;

b) Copies of the project design memorandum, technical description, datasheets, operating manuals and manufacturers warranties for all majoritems and / or equipment ;

c) Copies of the results of all tests performed on major items andd) Such other technical documents relating to the design, procurement,

engineering and construction as may be required for inspection


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SCHEDULE I: TECHNICAL STANDARDS FOR THERMALGENERATING STATIONS

This Schedule describes the minimum technical requirements for construction ofThermal Generating Stations of various types in following four parts:

Part A: Common to all types of Thermal Generating StationsPart B: Coal/lignite based Thermal Generating StationsPart C: Gas Turbine based Thermal Generating StationsPart D: Diesel Engine based Thermal Generating Stations

PART A: COMMON TO ALL TYPES OF THERMAL GENERATING STATIONS

1.0 GENERAL TECHNICAL REQUIREMENTS:

1.1 The coal/lignite based thermal generating stations shall be designed to givelife not less than twenty five (25) years. Gas turbine based Stations anddiesel generator sets based Stations shall be designed for life not less thanfifteen (15) years.

1.2 The Station shall comply with the environmental stipulations (such asambient air quality, gaseous emissions, liquid effluent discharges and solidwaste disposal) of the Ministry of Environment and Forests (MOE&F),Government of India and any other stipulation in this regard of the CentralPollution Control Board (CPCB) and State Pollution Control Board (SPCB).

1.3 a) Noise level at the Station boundary shall not exceed the Ambient AirQuality Standard in respect of noise as notified by MOE&F and anyother stipulation in this regard of the SPCB and CPCB.

b) Noise level for the continuously operating equipment shall not be morethan 85 dBA at a distance of 1 meter and at a height of 1.5 meter fromany equipment except in case of Turbine Generator for which noiselevel shall not exceed 90 dBA. For short term exposure, noise levelsshall not exceed the limits as stipulated in the Occupational Safety &Health Administration (OSHA) Standard.

c) Equipment/ machines shall be provided with acoustic enclosures,wherever required so as not to exceed the permissible noise limits.

1.4 Areas where a potential flammable atmosphere may exist shall be classifiedin accordance with the provisions of the internationally recognised standard.Certified equipment shall be used in the designated hazardous areas. To theextent practicable, equipment requiring operator attention and/or electricalequipment shall not be installed in hazardous areas.


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1.5 All the equipments/surfaces (excluding coal/lignite pulverisers and electricalequipment) having skin temperature more than 60 deg.C shall be providedwith required insulation along with cladding. The insulating materials,accessories and protective covering shall be non-sulphurous, incombustible,low chloride content, chemically rot proof, non-hygroscopic and shall

withstand continuously and without deterioration the maximum temperatureto which they will be subjected as per duty conditions. The use of insulationor finishing materials containing asbestos in any form is not permitted.

2.0 SITE SELECTION AND LAYOUT CONSIDERATIONS:

2.1 Site selection

The following criteria shall be considered in selection of site for thermalgenerating stations:

i) Availability of adequate land for the Stationii) Avoidance of proximity to geological faults, high flood zone of rivers or the

high tide zones of sea / backwaters

iii) Siting criteria prescribed by MOE&F

iv) Availability of required water

v) Feasibility of rail, road or other linkages for transportation of fuel andequipment to the site

vi) Feasibility of power evacuation

2.2 Layout considerations

General layout of the Station shall be developed considering spaceoptimization, functional requirements, future extensions (if envisaged) andprovision of space requirements during construction stage. Followingminimum layout requirements shall be complied with as may be applicablefor coal/lignite and/or gas turbine based Stations:

i) The layout of the Station shall be compact so as to optimise use ofland, materials and minimise losses in the system.

ii) Adequate provision shall be made in regard to space and access inorder to carry out the maintenance of various equipment.

iii) Due consideration shall be given for the wind direction while decidingon the relative location of the following:


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a) cooling tower and switchyard to minimize the moisture drift towardsthe switchyard.

b) chimney and ash disposal area with respect to township andadjoining habitation areas (applicable for coal/lignite based

generating stationsiv) Adequate space shall be provided for unloading and maintenance

purposes in Turbine - Generator (TG) area.

In case of coal/lignite based generating stations, two transverse baysshall be provided in TG area, at ground level at one end of the buildingfor unloading and maintenance purposes. For Stations with multipleunits, adequate space shall be provided to meet the requirement forsimultaneous maintenance of two units.

v) Requisite lay down area shall be provided for each unit on TG floorand same shall be approachable with electric overhead travelling(EOT) crane.

vi) Coal/lignite bunker bay shall preferably be located away from the TGbuilding to avoid the dust nuisance. In case bunker bay is locatedadjacent to TG area, suitable isolation arrangement shall be provided.

vii) Adequate fire escape staircases shall be provided in TG building withfire doors at each landing.

viii) For coal/lignite based generating stations, interconnecting walkwaysbetween TG building and steam generator shall be provided at TGoperating floor level and at deaerator floor level. Walkways at variouslevels shall also be provided for interconnection between steamgenerator and bunker bay.

ix) Provision of adequate space, as per stipulation of MOE&F, shall bemade for future installation of flue gas desulphurization plant.

x) One (1) no. of staircase, for each unit/ module, and minimum one (1)no. elevator shall be provided in the TG building. In addition, followingelevators shall also be provided for coal/lignite based generatingstations:

a) One passenger-cum goods elevator for each steam-generatorb) One passenger cum goods elevator for coal transfer point in

bunker areac) One elevator for chimney with suitable landings


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PART B: COAL/LIGNITE BASED THERMAL GENERATING STATIONS

1.0 OPERATING CAPABILITIES OF A UNIT IN THE STATION

1.1 The unit shall give Maximum Continuous Rating (MCR) under the following

conditions:- Maximum cooling water temperature- Worst fuel quality stipulated for the unit- Grid frequency variation of -5% to +3% (47.5 Hz to 51.5 Hz)

1.2 The steam flow through steam turbine under valves wide open (VWO)condition shall correspond to 105% of steam flow corresponding to MCRoutput.

1.3 The unit shall be capable of base load operation. However, the unit shall

also be capable of regular two-shift operation and load cycling.1.4 The design shall cover adequate provision for quick start up and loading of

the unit to full load at a fast rate. The unit shall have minimum rate of loading/ unloading of 3% per minute above the control load (50% MCR).

1.5 The unit shall be capable of automatically coming down to house load andcontinue to operate at this load in the event of sudden external load throw off.

1. 6 The unit shall be designed to give maximum possible efficiency for the fuelstipulated and other site specific conditions.

2.0 STEAM GENERATOR (BOILER) AND AUXILIARIES

2.1 The steam generator shall normally be based on pulverized fuel combustionand shall be of sub-critical or super critical type with single /two pass or anyother proven flue gas path configuration. However, wherever very low gradefuel or coal/lignite with high sulphur content is stipulated, fluidized bedcombustion (FBC) based steam generator may be used.

2.2 The steam generator and its auxiliaries shall be suitable for outdoorinstallation.

2.3 Boiler Maximum Continuous Rating (BMCR) shall correspond to at least102% of the steam flow at turbine inlet under VWO condition plus continuoussteam requirement for auxiliary systems of the unit (e.g. turbine driven boilerfeed pumps, fuel oil heating etc.) when unit is operating above control load.The steam generator shall be capable to give BMCR output for the worst fuelquality stipulated.


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2.4 The steam generator including pressure parts, vessels, piping, valvesincluding safety valves and fittings shall meet the requirements of IndianBoiler Regulations (IBR).

2.5 All start up vents shall be provided with two valves in series - one motorized

isolating and one motorized regulating type.2.6 The typical characteristics of indigenous coal (high abrasive ash, slow

burning, high ash resistivity etc) should be given due consideration whiledesigning the steam generator and auxiliaries. The following criteria forfurnace sizing may be used for typical Indian coal for unit sizes upto 500MW. :-

S.No. Description Value @ i) Maximum Net Heat Input (NHI) per unit plan

area of furnace5x10 6 kcal/hr/m 2

ii) Maximum Volumetric Heat Liberation Rate 1.1x105

kcal/hr/m3

iii) Maximum Heat input per Burner 55 x10 6 kcal/hr/burner@ (Not applicable for fluidized bed boilers)

2.7 Pressure withstand capability of the furnace shall correspond to minimum +/-660 mmwc at 67% yield strength or maximum expected pressure/draft offans, whichever is higher.

2.8 The pulverized coal/lignite burners shall be low NO X type with NO X emission(both fuel NO X and thermal NO X) not exceeding 260 gms per gigajoule ofheat input.

2.9 For pulverized coal/lignite based steam-generators, fuel oil firing system shallbe provided for start up and low load flame stabilization. Fuel oil systemshall comprise of light diesel oil (LDO) for black start condition and heavy fueloil (HFO/LSHS/HPS) for start-up & low load operation.

2.10 The steam generator shall not require oil support above 40% unit load.

2.11 Coal/lignite preparation system for pulverized fuel system shall havesufficient spare mills. (e.g. one spare mill when using worst coal and twospare mills when using performance coal corresponding to BMCR condition

in case of medium speed mills). Coal supply to the mills shall be from theindividual coal bunkers having storage capacity of about 16 hours.

2.12 The coal fineness achieved from the pulverisers shall be at least 70% thru200 mesh (75 microns) and 98% thru 50 mesh (300 microns) at ratedcapacity of the pulveriser, with an input coal size up to 50 mm.


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2.13 2x60% forced draft (FD) fans and 2x60% induced draft (ID) fans shall beprovided to maintain balance draft conditions in the furnace over the entireload range while burning the stipulated range of fuels.

2.14 Suitable air pre-heating system shall be provided for recovery of useful heat

from the exhaust flue gases. Steam coil air pre-heater (SCAPH) may also beprovided for maintaining air temperature within safe limits to preventcorrosion during start up or very low ambient air temperature conditions.

2.15 The soot blowing system shall be provided for the waterwall, superheater,reheater, economizer and air preheater.

2.16 The dust collecting system (electro static precipitator, bag filter etc.) shall beprovided for removing suspended particulate matter (SPM) from the fluegases to meet the statutory stipulations. In case electro static precipitator(ESP) is provided, the following requirements shall be complied with:

i) ESP shall be able to meet the stipulated SPM emission requirement evenwhen one electric field in each pass of the ESP is out of service whilefiring worst fuel.

ii) ESP shall be provided with effective ash evacuation system havingcontrols for ash temperature and ash level in the hopper. Each hoppershall have a storage capacity of minimum of eight (8) hours.

iii) Specific weight of ash may be considered not more than 650 kg/m fordetermining hopper storage capacity and not less than 1350 kg/m for

ESP structural design.iv) Pressure withstand capability of the ESP casing shall correspond to

minimum +/- 660 mmwc at 67% yield strength and flue gas temperatureof 200C.

3.0 STEAM TURBINE AND AUXILIARIES

3.1 The steam turbine shall comply with latest versions of IEC-45 or equivalent.

3.2 The gross turbine cycle heat rate as guaranteed by the equipment

manufacturer shall not exceed the following values:Unit rating (MW) Gross turbine cycle heat rate*

(kcal / kWhr) at 100% MCR 100 MW to less than 200 MW 2000 @

200 MW to less than 250 MW 1970 @ 250 MW to less than 500 MW 1950 @ 500 MW to less than 660 MW 1950 $


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Supercritical units 1890 ( with turbine driven BFP)

* corresponding to reference conditions of 33 O C cooling water temperatureand 0% de-mineralised water make up

@

corresponding to sub-critical units with motor driven BFP. In case turbinedriven BFP is envisaged, the indicated gross heat rate shall be increasedby 40 kcal/kWhr

$ corresponding to sub-critical units with turbine driven BFP. In case motordriven BFP is envisaged, the indicated gross heat rate shall be reduced by40 kcal/kWhr

3.3 The steam turbine shall be of tandem/cross compound construction, reheattype, condensing, single/multi-cylinder design with number of uncontrolledextractions as optimized for regenerative feed heating. Steam turbines of

less than 100 MW rating may be non-reheat type.3.4 The steam turbine shall be designed for a minimum of 3000 hot starts, 700

warm starts and 100 cold starts during its life.

3.5 A self-contained lubricating oil system shall be provided for each steamturbine-generator. A main oil pump (MOP) shall be provided which may beeither directly driven by turbine shaft or by AC motor. In addition, a minimumof one AC motor driven auxiliary oil pump shall be provided as standby forthe main oil pump. Provision shall also be made for one DC motor drivenemergency oil pump for meeting lubricating oil requirement during non-

availability of AC motor driven pump.3.6 Jacking oil system, with 2x100% jacking oil pumps, shall be provided to

supply high pressure oil to each bearing of steam turbine-generator to lift therotor during starting or turning gear operation.

3.7 The oil used for turbine governing (control) shall be either from the lubricatingoil system or from a separate control oil system. In case of separate controloil system, the pumps provided shall be 2x100%.

3.8 The steam turbine shall be provided with electro-hydraulic governing system.However, units more than 200 MW shall be provided with back up governingsystem of mechanical hydraulic or electro hydraulic type.

3.9 The turbine shall be provided with protective devices as per IEC-45 orequivalent, including the following:


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i) Separately actuated over-speed trip device.

ii) Emergency hand trip devices to facilitate manual tripping of theturbine locally and from control room.

3.10 Turbine vibrations shall be minimized and shall be within limits as per ISO10816 and ISO 7919.

3.11 Non-return valves shall be provided in the steam extraction lines as requiredfor protection from overspeed that may result from sudden load throw off orturbine trip.

3.12 Hydraulic/pneumatic/D.C. operated device shall be provided for rapidreduction of vacuum in condenser to bring turbine rotor to rest as quickly aspossible under emergency conditions.

3.13 The start up and drainage system shall comply with ANSI/ASME StandardTDP-1 Recommended practices for the prevention of water damage tosteam turbines used for electric power generation.

3.14 For steam turbines with rating more than 100 MW, turbine by - pass systemof adequate capacity shall be provided for fast hot & warm start ups of unit,dumping steam in condenser during sudden turbine trip (without tripping theboiler), unit house load operation etc.

3.15 Condensate polishing system shall be provided in the steam turbine cycle forthe following:

a) units with rated pressure 170 kg/cm2 and above at turbine inletb) units using sea water for condenser cooling

3.16 Suitable feed water regenerative system consisting of low pressure heaters,deaerator and high pressure heaters shall be provided for optimized cycleefficiency.

3.17 Condenser

i) The design, manufacturing and testing of condenser shall be as per HeatExchange Institute (HEI) or equivalent.

ii) Condenser tubes shall be of titanium when using sea water and stainlesssteel for other sources of water. On load condenser tube cleaning systemmay be provided, as required, depending upon the quality of cooling water.


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iii) Vacuum pumps or steam ejectors shall be provided as per HEI or equivalentfor evacuating air steam mixture and non-condensable gases from thecondenser.

3.18 Condensate Extraction Pumps (CEPs)

i) 3x50% or 2x100% condensate extraction pumps shall be provided for eachunit. The design shall meet the requirements of Hydraulic Institute Standards(HIS) or equivalent.

ii) The required net positive suction head (NPSH) at 3% head drop shall bewell below the available NPSH under all operating regimes with lowest hotwell level and maximum pressure drop across suction strainer.

3.19 Boiler Feed Pumps (BFPs)

i) The unit shall be provided with boiler feed pumps of adequate capacity togive rated output. The following configurations may be considered in order toprovide redundancy and start up requirements for various unit sizes:

a) 500 MW and above: 2x50% or 1x100% turbine driven BFPplus

1x50% or 2x25% motor driven BFP

b) 100 to 300 MW: 3x50% motor driven BFP

c) Less than 100 MW 2x100% or 3x50% motor driven BFP

ii) The required net positive suction head required NPSH at 3% head drop shallbe one third of available NPSH at design point with lowest deaerator leveland maximum pressure drop across the strainer.

4.0 ELECTRICAL SYSTEM

4.1 General Requirements

4.1.1 For the purpose of design of electrical equipment/systems, an ambienttemperature of 50 deg. C and relative humidity of 95% shall be considered.The equipment shall be suitable for operation in a highly pollutedenvironment. However, for equipment in air conditioned areas, designambient temperature shall be 35 deg.C .

4.1.2 The Owner shall install and maintain the necessary communicationequipment to transmit the required data of the Power Station to the procurerof electricity, Regional/State Load Despatch Centre and TransmissionCompany.


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4.2 Generator

4.2.1 The turbo-generator shall comply with IS-4722/ IEC-60034 or theirequivalent. The efficiency of generator shall be more than 98% at rated load.

4.2.2 Insulation shall be thermal class-F for stator and rotor winding as per IEC60034. However, temperature rise shall be limited corresponding to thermalclass-B insulation. Generator shall be either hydrogen cooled, hydrogen &water cooled or air cooled type . The generator shall be capable of deliveringat least two third of its rated output with one hydrogen gas cooler out ofservice.

4.2.3 Generator Instrumentation

Resistance temperature detectors (RTDs)/ thermocouples shall be providedat suitable locations for monitoring the temperatures of stator core, stator

windings and bearings. Suitable arrangements shall also be made formonitoring the temperature of the rotor winding in case static excitationsystem is provided.

4.2.4 Hydrogen gas system

Hydrogen gas system shall be provided with driers of 2x100% duty tomaintain dryness of hydrogen inside the machine. Suitable system shall beprovided to prevent condensation during long shut down. The system shallhave the provision of on-line dew point measurement as well as gasanalyser.

4.2.5 Water system

Stator water cooling system shall be closed loop type with 2x100% ACmotor driven circulating water pumps, 2x100% de-mineralised (DM) waterheat exchangers, 2x100% filters, one mixed bed de-mineraliser and onealkalizer unit (as applicable).

4.2.6 Seal oil system

In case of hydrogen cooled machines, the seal oil system provided shall beequipped with 2x100% AC motor driven pumps and 1x 100% DC motordriven pump. The system shall be provided with coolers and filters having2x100% duty .

4.2.7 Excitation System

4.2.7.1 Suitable generator excitation system as well as automatic voltageregulator (AVR) shall be provided with the generator as per regulations of


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the Authority on Grid Connectivity. Power system stabilizer (PSS) shall beprovided in AVR for generator of 100MW and above.

4.2.7.2 The rated current of the excitation system shall be at least 110% of themachine excitation current at the rated output of the machine. The rated

voltage shall be at least 110% of the machine excitation voltage.4.2.7.3 Generators of 100 MW and above rating shall be provided with AVR

having 2x100% auto channels and automatic changeover. In the event offailure of auto channels, manual control shall be possible. At least 100%redundancy shall be provided for the converters. In case of brushlessexcitation system, rectifier assembly shall be provided with eithercomplete bridge as redundant or at least one redundant parallel branch ineach of the six arms of the bridge.

4.2.8 Instrument Transformers

4.2.8.1 Current Transformers

Current Transformers shall comply with IS: 2705/IEC: 60044-1 in general.The accuracy class shall be as under:

a) not less than 0.2 for low forward power relay, acceptance testing,energy accounting and audit meters.

b) not less than 0.5 for reverse power relay, generator AVR, ElectroHydraulic governor (EHG) and other measurements.

4.2.8.2 Voltage Transformers

Voltage transformers shall comply with IS:3156/IEC: 60044-2 in general.The accuracy class shall be as under:

a) not less than 0.2 for acceptance testing, energy accounting and auditmeters.

b) not less than 0.5 for generator AVR, Electro Hydraulic governor (EHG)and other measurements .

4.3 Power Transformers

4.3.1 The power transformers (Generator/ Unit Auxiliary /Station Transformers)shall comply with latest versions of BIS: 2026 or relevant IEC.

4.3.2. The generator transformer shall be provided to step up generating voltage forconnection to the grid. It shall also be used to provide start-up power from


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the grid in case circuit breaker is provided between the generator andgenerator-transformer in generator circuit breaker (GCB) scheme.

It shall be mineral oil filled with oil forced air forced (OFAF) (100% rating)/ oilnatural air forced (ONAF) (80% rating)/ oil natural air natural (ONAN) (60%

rating) cooling. It shall be provided with 2x50% cooling radiator banks. Eachradiator bank shall be provided with suitable number of working fans plus one(1) stand-by fan and 2x100% oil pumps.

It shall be provided with on-load tap changer (OLTC) or off-circuit tapchanger (OCTC) type depending upon system requirements.

4.3.3 The unit auxiliary transformer(s) (UAT) shall be used to meet the unit loadrequirement during normal running of the unit. However, in case of GCBscheme, it shall provide power requirement of the unit and station auxiliariesduring start-up and normal running of the unit.

It shall be mineral oil filled with ONAF (100% rating)/ ONAN (80% rating)cooling. It shall be provided with minimum 2x50% detachable cooling radiatorbanks. Each bank shall be provided with suitable no. of working fans plusone (1) stand-by fan. UAT, in case of GCB scheme, may be provided withOFAF/ONAF/ONAN cooling.

The tap changer for UAT shall be of OCTC type in case generatortransformer is provided with OLTC and vice versa.

4.3.4 The station transformer (s) shall provide the start-up power requirement andstation auxiliary load requirement during normal operation of the unit(s). Thismay not be applicable in case of GCB scheme.

It shall be mineral oil filled with OFAF (100% rating)/ ONAF (80% rating)/ ONAN (60% rating) cooling. It shall be provided with 2x50% cooling radiatorbanks. Each radiator bank shall be provided with suitable number of workingfans plus one (1) stand-by fan and 2x100% oil pumps.

It shall be provided with OLTC.

4.3.5 The transformers shall be suitable for continuous operation at rated MVA onany taps with voltage variation of +10% in accordance with IS: 6600.

4.3.6 The insulation levels for the transformer windings and bushings shall be asper Schedule III (Table-5).


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4.4 HT Switchgear

SF6 or vacuum type of circuit breakers shall be provided in HT Switchgear(11/6.6/3.3 kV) which shall be of draw out type, re-strike free, trip free, storedenergy operated and with electrical anti-pumping features. The protective

relays shall be preferably of numerical type with self monitoring anddiagnostic features.

4.5 LT Switchgear

Air break type of circuit breakers shall be provided for LT switchgear (415 V)which shall be of draw out type, trip free, stored energy operated and withelectrical anti-pumping features. The protective relays shall be preferably ofnumerical type with self monitoring and diagnostic features.

4.6 Generator Busducts

4.6.1 The busducts shall be of standard size as per BIS and designed to carrymaximum continuous current under normal site conditions without exceedingtemperature rise limits.

4.6.2 The busducts shall be segregated or isolated phase type. The busduct ratedmore than 3150 A shall be isolated phase type. Busduct rated more than6000 A shall be continuous isolated phase type. A hot air blowing system orair pressurization system shall be provided to prevent moisture deposition incase of isolated phase ducts while space heaters may be provided in case ofother busducts.

4.6.3 The bus assembly shall be designed mechanically to withstand ratedcontinuous current as well as the specified shortcircuit current withoutdamage or permanent deformation of any part of the bus structure.

4.6.4 Lightning arresters and voltage transformers connected to generatorbusducts shall be located in separate cubicles for each of the three phases.Voltage transformers shall be accommodated in draw-out type compartmentsin phase-isolated manner in a cubicle. The lightning arrestors and voltagetransformers cubicles shall comply with relevant BIS / IEC or equivalent.

4.7 Power Supply System

4.7.1 All auxiliaries dedicated to the unit shall be fed from unit bus connected toUAT(s). During start -up and shut - down of units, the unit auxiliaries shallbe supplied power from the station bus connected to station transformer(s).However, in case of GCB scheme, the same shall be provided by the unitbus.


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4.7.2 All the loads pertaining to balance of plant facilities shall be fed from stationbus connected to Station Transformer (s). Station bus shall also be capableof supplying power to largest unit in the Station during start-up and shut-down. However, in case of GCB scheme, the loads pertaining to balance ofplant facilities shall be fed from unit bus.

4.7.3 Power supplies, buses, switchgear, interlocks and standby supply systems tostation and unit auxiliaries shall be designed in such a way that the mainequipment and auxiliaries are not endangered under all conditions.Transformer voltage ratios, type of tap changers and tap ranges, impedancesand tolerances thereon, shall be so optimized that the auxiliary systemvoltages under various grid and loading conditions are always withinpermissible limits and equipments are not subjected to unacceptablevoltages during operation and starting of motors. The vector groups of thegenerator transformers, unit auxiliary transformers and station transformersshall be so selected that the paralleling at 11/ 6.6/ 3.3KV buses shall be

possible. Further, the vector group of other auxiliary transformers shall haveidentical vector groups.

4.7.4 In thermal power stations with unit sizes more than 100 MW, automatic bustransfer system (consisting of fast, slow, etc. transfer in auto mode ) shall beprovided to minimise time for transfer from unit to station bus and vice versaat 11/ 6.6 kV levels. Bus transfer scheme shall also have manual mode toinitiate transfer command manually.

The 11/6.6/3.3 kV switchgear buses for balance of plant facilities shall beprovided with auto reserve closure (ARC) facility between main incomer andreserve breakers. Critical 415 V switchgear buses shall also have ARCfeature.

4.7.5 Auxiliary transformers, as required, shall be provided to meet the demand atvarious voltage levels of auxiliary power systems, with the criteria that eachswitchgear, motor control centre (MCC), distribution board (DB) shall be fedby 2x100% transformers/ feeders. The auxiliary transformers shall bedesigned to carry the maximum expected load.

4.8 Neutral Earthing

Generator neutral earthing equipment shall be designed duly taking intoaccount the normal rise of the generated voltage above the rated value dueto load throw off and field forcing, ferro - resonance, etc.

Generator neutral shall be earthed through dry type distribution transformerwith secondary loaded with a resistor.


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Neutral earthing of other systems shall be such that it is possible to provideearth fault protection with proper discrimination.

4.9 Earthing System

The earthing system shall be designed for a life expectancy of at least forty(40) years, for maximum fault current or EHV system fault current of 40kA,whichever is higher for 1.0 sec. The minimum rate of corrosion of earthingconductor shall be considered as 0.12 mm per year while determining theconductor size.

Grounding and lightning protection for the entire Station shall be provided inaccordance with IS: 3043, IEEE : 80 and IEEE : 665.

4.10 Protection

Fully graded protection system with requisite speed, sensitivity and selectivityshall be provided for the entire Station. Generator, generator transformer,unit auxiliary transformers (UATs) shall be provided with protectionsconnected to two independent channels/ groups, such that one protectionsystem shall always be available for any type of fault in the generator/ generator transformer/ UAT(s). The protections for the generator/ generatortransformer/ UAT(s) shall be provided as under:

SN Protection Function Remarks1 Generator differential protection,

(87G)2 Overall differential protection

(87OA).3 Generator transformer differential

protection (87GT) for single phasebank

4 Restricted Earth Fault protection forGenerator transformer (87NGT)

5 Over head line connectiondifferential protection (87 L)

To be provided, ifdistance betweenGenerator Transformerand Switchyard is about200 mtrs and above.

6 100% stator earth fault protection(64G1).

For units of 100 MW andabove

7 95% stator earth fault protection(64G1).

For units less than 100MW

8 Standby stator earth fault protection(64G2)

9 Inter-turn fault protection (87TG) Applicable where split


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winding in Stator isprovided and if sixterminals are available.

10 Loss of field protection (40G). To be duplicated forunits of 500 MW and

above.11 Back up impedance protection, 3pole (21G)

12 Backup earth fault protection ongenerator transformer HV neutral(51NGT)

13 Negative sequence currentprotection, (46G)

14 Low-forward power and Reversepower interlock for steam turbine

generator (37/ 32G)

Preferably 3-ph powerrelays shall be provided.

Both the relays shall beduplicated for units of500 MW and above.

15 Rotor earth fault protection - twostages (64F1/F2).

16 Definite time over-voltage protection(59G)

17 Generator under frequencyprotection (81G)

18 Over-fluxing protection for generator(99G)

To be provided for unitsof 500 MW and above induplicate.

19 Over-fluxing protection for generatortransformer (99GT)

To be duplicated forunits of 500 MW andabove.

20 Accidental back energisationprotection (50GDM)

21 Overload protection for generator(51G)

22 Overheating (winding and/ orbearing) (49G)

Alarm only

23 Time graded IDMT type back non-directional over-current protection inall phases on HV side of generatortransformer (51GT)

24 Instantaneous and time delayedOver Current protection to be usedon HV side of excitation transformer

25 Generator pole slipping protection(98G)


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26 UAT differential protection, (87UAT)27 UAT LV back-up earth fault

protection (51NUAT)28 UAT LV restricted earth fault

(87NUAT)

29 UAT back-up over-current protection(51UAT).30 Generator transformer OTI (49Q)

and WTI (49T) trip31 Generator transformer Buchholtz

(63), PRV / other mechanicalprotections

32 UAT OTI(49Q) and WTI (49 T) trip

33 UAT Buchholtz (63) , PRV/ othermechanical protections

.

34 Pole discrepancy protection ofgenerator transformer breaker (162) To be provided if singlepole breakers are used35 Breaker failure protection of

generator transformer breaker (50Z)

4.11 Synchronization

Automatic as well as manual facility alongwith check synchronizing andguard relay features shall be provided for closing of generatortransformer/generator circuit breaker for synchronization of generator withthe grid.

4.12 Cables and cabling

Cables shall be flame retardant low smoke (FRLS) type. Cables to be directlyburied shall be essentially armoured type.

Derating factors for site ambient and ground temperatures, grouping and soilresistivity shall be considered while determining the size of cables.

Fire protection barriers shall be provided for cable galleries, cable shafts etc.at various suitable locations. Fire resistant penetration seals shall beprovided for all openings in floors, ceilings, walls etc.

4.13 Diesel Generator Set

Automatic mains failure (AMF) Diesel generators (DG) shall be installed forfeeding emergency loads in the event of failure of station supply. One DG setshall be provided for each unit of 200 MW and above. In addition there shallbe one common standby DG set of same rating to serve a block of two units.


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For unit sizes less than 200 MW, one DG set may be provided for every twounits.

4.14 D C System

Standard levels of DC system shall be 220 volts, 48 volts and 24 volts forcontrol and protection of various equipment. Two sets of batteries shall beprovided for each DC system each catering to 100% load. One float -cum-boost chargers shall be provided for each battery.

4.15 Illumination System

Adequate illumination shall be provided in accordance with IS: 3646.Emergency AC and DC illumination shall also be provided at importantplaces. Energy conservation measures shall be adopted while designing thelighting system.

4.16 Motors

AC motors shall be squirrel cage type induction motors suitable for direct on-line starting. Crane duty motors shall be slip ring/ squirrel cage typeinduction motor. DC motors shall be shunt wound type.

All motors shall be either totally enclosed fan cooled (TEFC) or totallyenclosed tube ventilated (TETV) or closed air circuit air cooled (CACA) orclosed air water cooled (CACW) type. Temperature rise shall be limited to 70deg C by resistance method for both class B and F insulation.

Enclosures of the motors located in hazardous areas shall be flame prooftype conforming to IS:2148 as per details given below:

a) Fuel oil area Group II B

b) Hydrogen generation plant area Group-IIC

5.0 CONTROL & INSTRUMENTATION SYSTEM

5.1 General

5.1.1 Control & Instrumentation system provided for the Station shall be consistentwith modern power station practices and in compliance with all applicablecodes, standards, guidelines and safety requirements in force.

5.1.2 The complete thermal, mechanical and electrical functions of the Stationshall be remotely controlled from the central control room/ respective localcontrol room of various auxiliary systems, as provided, during normal as well


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as emergency conditions. The number of control areas shall be kept tominimum with a view to optimize manpower.

5.1.3 All stand-by auxiliaries shall be designed to start automatically as quickly aspossible on failure of running auxiliaries.

5.2 Control System for Steam Generator and Turbine Generator

5.2.1 The state of art microprocessor based digital control system (DCS) shall beprovided for monitoring and control of steam generator, turbine generatorand auxiliaries and shall include monitoring & information, sequential controlfor drives, closed loop control for regulating drives, interlocking & protection,historical data storage, alarm annunciation system, sequence of event(SOE) recording system etc. DCS system shall be independent for eachunit.

5.2.2 Control systems integral to steam- generator and turbine- generator shallpreferably be implemented as part of DCS system.Control systems integral to steam-generator shall include burnermanagement system (BMS)/ furnace safeguard supervisory system (FSSS)which shall comply with latest version of NFPA 85. The Master Fuel Trip(MFT) system shall comply with VDE0116, VDE 0160 etc.

Control systems integral to turbine -generator shall include turbine protectionsystem, electro-hydraulic governing (EHG) system, turbine stressmanagement system, turbine supervisory system, automatic turbine run upsystem (ATRS).

5.2.3 Human machine interface system (HMIS) configured around latest state-of-the art redundant workstations with open architecture shall be provided tooperate the unit under all operating conditions. Minimum number ofhardwired devices shall also be provided for safe shutdown of unit.

5.2.4. DCS system shall be provided with 100% redundancy for processors, control& input/output bus and network components.

5.2.5 All input modules for control, interlocking and protection shall be redundant.Output modules for all HT drives and critical LT drives shall also beredundant. Redundant inputs/outputs shall be connected to different

input/output cards of DCS i.e. triple redundant inputs shall be connected tothree separate input cards. The logics for redundant drives shall not be in thesame processor.

5.2.6 The design of the control systems and related equipments shall adhere to theprinciple of fail safe operation wherever the safety of personnel / plantequipment is involved. fail safe operation signifies that the loss of signal,loss of power or failure of any component shall not cause a hazardouscondition. However, it shall also be ensured that occurrence of false trips are


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minimized. No single failure either of component or power source of DCSshall cause loss of generation.

5.2.7 The control system shall include on-line self-surveillance, monitoring anddiagnostic facility giving the details of the fault on the human machineinterface system (HMIS).

5.2.8 It shall be possible to remove and replace various modules (like anycontroller, input/output module, interface module, etc.) on-line from its slot formaintenance purpose without switching off power supply to thecorresponding rack and without jeopardizing safety of the Station equipmentand personnel.

5.2.9 The historical storage & retrieval system shall store and process system datafor future analysis. The data shall be transferred to removable storage mediafor long term storage and retrieval. The binary data to be stored shall includestatus of SOE (1millisecond resolution), alarm and other binary inputs. All

important analog data shall be stored at one second interval. Selected logsviz. start up log, trip analysis log shall also be stored.

5.3 Control system for Balance of Plant

Programmable logic controller/ PLC based control system with independentHMIS shall be provided for all the balance of plant facilities like coal/lignitehandling plant, ash handling plant, water treatment plant etc. PLCs shall belatest state of the art system with redundant processors.

5.4 Local Area Network (LAN)

A redundant station-wide LAN shall be provided for information exchangebetween DCS of each generating unit, PLCs for balance of plant as well asgateway for connecting to the other off-line services of the Station (inventorymanagement, maintenance management etc.).

5.5 Measuring Instruments

5.5.1 Primary instruments like transmitters, thermocouples, resistance resistancetemperature detectors (RTDs), local gauges, flow elements, transducers etc.shall be provided as required for comprehensive monitoring of variousparameters of the Station.

5.5.2 Microprocessor based vibration monitoring and analysis system shall beprovided for monitoring and analysis of vibration of critical rotating equipment(i.e. turbine-generator, boiler feed pumps, ID/FD/PA fans etc.)

5.5.3 Flue gas analysis instruments including sulphur-di-oxide (SO 2), nitrogenoxides (NOx), oxygen, carbon mono-oxide (CO) and dust emissionmonitoring systems shall be provided.


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5.5.4 The triple sensors shall be provided for critical binary and analog inputsrequired for protection of steam generator and steam turbine as well as forcritical control loops (e.g. furnace draft, drum level, condenser vacuum).Redundant sensors shall be provided for other important applications.

5.5.5 All electrical instruments and devices like switches, transmitters, controllers,analyzers, solenoid valves which are located in the hazardous locations likehydrogen generation plant shall be provided with explosion proof enclosuresuitable for hazardous areas as per NFPA/NEC.

5.6 Power supply system

Independent, redundant and reliable 230 V AC through uninterrupted powersupply system (UPS) and/or DC power supply at standard voltage levels(e.g.220V/48V/24V) shall be used for control & instrumentation systems.

5.7 Control Valves

The control valves and accessories shall be designed, constructed andtested as per IBR, ASME code for power piping (B 31.1) and ASME Boiler &pressure vessel code or equivalent.

5.8 Steam & Water Analysis System (SWAS)

An online analysis system shall be provided for continuously monitoring thepurity of condensate, feed water, steam etc. The on-line chemical analysisshall be carried out in the plant cycle at strategic points as per therecommendation of manufacturers of steam-generator and steam turbine.The system shall be generally designed as per ASME PTC 19.11.

6.0 BALANCE OF PLANT

6.1 Coal/lignite handling system

The arrangement for transportation of coal/lignite from supply source to theStation may be by rail or other captive systems such as merry go round(MGR), belt conveyor system, ropeway system etc. Further handling shallcomply with the following requirements:

6.1.1 The coal/lignite handling plant capacity shall be such as to meet the days

fuel requirement by its operation in 14 hours. Days fuel requirement shall beworked out at 100% BMCR using worst coal/lignite and a margin of 10%.

6.1.2 Coal/lignite handling plant shall be provided with 100% standby streams.Each coal/lignite stream shall be provided with 2x75% or 3x50% paddlefeeders (in case of track hoppers) or vibro feeders (in case of wagon tippler)and 2x50% crushers with belt feeders. Single set of coal/lignite conveyersfrom the stockyard to the bunkers shall not cater to more than three units.


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6.1.3 In case of rail based transportation, marshalling yard for handling of wagonsand unloading system shall be designed to facilitate return of empty wagonswithin the prescribed time by the Indian Railways.

6.1.4 The minimum storage capacity of coal/ lignite stockyard shall be as under:

Non-pit head stations: 30 daysCoastal stations: 30 daysPit-head stations 15 days

6.1.5 Provision of proper dust suppression facility shall be made for coal at variouslocations i.e. receiving point, stockyard and discharge points of conveyors, toavoid dust nuisance and spontaneous fire.

6.1.6 The provision for measurement of weight of coal/lignite shall be madethrough weighbridges at the receiving point. The weight of coal/lignite shallalso be measured through belt-weighers.

6.1.7 The arrangement shall be made for sampling of coal/lignite alongwithassociated instruments/equipment to monitor quality of coal/lignite on as-received basis as well as as-fired basis before the bunkers.

6.2 Fuel Oil System

6.2.1 Necessary arrangement shall be provided for unloading and storage of heavyfuel oil (HFO) and light diesel oil (LDO).

6.2.2 The capacity of fuel oil storage facilities shall be adequate for therequirement of fuel oil for at least 30 days operation of the Station.

6.2.3 Suitable heating arrangement shall be made for heating the HFO by steamto maintain its flowability.

6.2.4 The aspects regarding proper storage and handling of fuel oil shall be as perstatutory requirements of Chief Controller of Explosives.

6.3 Ash Handling System

6.3.1 For pulverised fuel based steam-generator

i) Arrangement shall be provided for extraction and transportation to silos indry form for 100% of fly ash produced

ii) Dry fly ash storage silos of adequate capacity (about 16 hours of ashgeneration) to collect dry fly ash shall be provided in a separate area nearthe Station boundary with provision for independent access.


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iii) In addition to fly ash disposal in dry form, the provision shall also be made for100% ash disposal through slurry system. Ash slurry concentration shall beminimum 25%. Suitable ash water recirculation system shall be provided torecycle and reuse water.

iv) Furnace bottom ash alongwith economizer ash shall be extracted anddisposed in wet/semi-wet form.

v) The capacity of ash handling systems, as a percentage of maximum ashgenerated corresponding to firing of worst coal/lignite at BMCR, shall not beless than the following:

a) Fly Ash System

ESP fly ash & chimney ash 90%Air preheater ash 5%

b) Bottom Ash System

Furnace bottom ash 25%Economiser ash 5%

vi) Ash removal rate shall meet the following criteria:

a) Fly Ash System 8 hour collection in 6 hours


Furnace bottom ash 8 hour collection in 90 minutesEconomiser ash Continuous

vii) Ash handling system shall have the provision for following standbyarrangement :Bottom Ash System - 100% standby for jet pumps with 2x100 %

pipelines for each jet pump outlet

or 100 % standby for submerged scrapperconveyor (SSC)

Fly Ash System - 100% standby for vacuum pumps, collectortanks, wetting heads

- 100% standby blowers for intermediate andstorage silos

- 50% standby for air compressors to beused for transporting ash

Ash slurry disposal - One pump stream as operating standbyand one pump stream as maintenancestandby


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6.3.2 For fluidized bed type steam-generator

i) Dry fly ash extraction, transportation and storage system shall meet therequirements as stipulated above for pulverized fuel based system

ii) In addition to fly ash disposal in dry form, the provision shall also be made forwet ash disposal through slurry system. Ash slurry concentration shall beminimum 16%. Suitable ash water recirculation system shall be provided torecycle and reuse water.

iii) Furnace bottom ash shall be extracted in dry form by means of drag linkchain conveyor and further disposed in wet/semi-wet form.

iv) The capacity of ash handling systems, as a percentage of maximum ashgenerated corresponding to firing of worst fuel at BMCR, shall not be lessthan the following:

a) Fly Ash System

ESP fly ash & chimney ash 80%Air preheater ash 5%Economiser ash 5%


Furnace bottom ash 30%

v) Ash removal rate shall meet the following criteria:

a) Fly Ash System 8 hour collection in 6 hours

b) Bottom Ash System Continuous

vi) Ash handling system shall have the provision for following standbyarrangement :

Bottom Ash System - 100% standby for drag link chain conveyor

Fly Ash System - 100% standby for compressors an blowers

Ash slurry disposal - One pump stream as operating standbyand one pump stream as maintenancestandby

6.3.3. Ash pond management shall be judiciously planned to optimize the area and

facilitate use of pond ash. It shall also conform to MOE&F requirements.6.4 Station Water System

6.4.1. Station Water scheme

i) The Station water scheme shall be designed to meet the total clarified waterrequirement of the Station consisting of cooling tower make up (for non-


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coastal stations), de-mineralisation system, equipment cooling system,service water, potable water and miscellaneous requirements.

ii) For coastal Stations, sea water shall be used for condenser cooling. In casewhere source of non-saline (sweet) water is not available, sea water shall be

used for production of demineralised water, potable water and service waterthrough desalination plant.

iii) Raw water for production of clarified water shall be drawn from identifiedsource of water and supplied to the Station site by raw water pumps withadequate standby provision and 2x50% capacity pipelines. Provision for de-silting and traveling water screens shall be made at the raw water intakepoint. Adequate storage of raw water/sweet water shall be provided at theStation site considering the period of non-availability of input water from thesource.

iv) In case of sea water, de-silting arrangement and traveling water screen shallbe provided at the sea water intake. Further, debris filter shall also beprovided at condenser inlet

6.4.2 Pre-Treatment System

The raw water shall be treated in pre-treatment plant to produce clarifiedwater for meeting the requirement of clarified water of the Station. Adequateprovisions for raw water chlorination, chemical dosing and sludge handlingshall also be made.

6.4.3 Cooling Water System

i) The cooling water (CW) system for condenser and secondary cooling systemfor Station equipment shall be of closed cycle type using cooling towers.However, for coastal Stations using sea water, once through condensercooling system may be used which shall conform to MOE&F requirements oftemperature rise.

ii) The cooling tower shall be of mechanical induced draft type or natural drafttype depending upon site specific techno-economics. The design wet bulbtemperature of the cooling tower shall correspond to the ambient wet bulbtemperature which is not exceeded by more than 5% duration over one yearperiod. Adequate recirculation allowance shall be considered for arriving atdesign wet bulb temperature for induced draft cooling tower.

The relative humidity, to be adopted for design of natural draft cooling tower,shall be appropriately selected considering annual variation of relativehumidity in combination with annual variation of wet bulb temperature.


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iv) All major and minor fire risks in the Station such as transformers, cablegalleries/shafts, fuel oil storage & handling, coal/lignite handling plant,coal/lignite conveyors/galleries, control rooms etc. should be protectedagainst fire by suitable automatic fire protection systems.

v) Automatic fire detection and alarm system shall be provided to facilitatedetection of fire at the incipient stage and give warning to the fire fightingstaff.

vi) Portable and mobile fire extinguishers shall be envisaged to extinguish fire inits early phase to prevent its spread.

vii) Fire station/fire tenders shall also be provided for the Station.

viii) Passive fire protection such as fire barriers, fire retardant coatings,penetrating sealing systems, fire proof doors etc. shall be envisaged to

prevent spreading and containment of fire.6.6 Compressed Air System

i) Compressed air system comprising of instrument air and service air shall beprovided to cater to the requirement for operation of various pneumaticallyoperated valves/dampers and general purpose cleaning & maintenanceservices.

ii) At least one no. service air compressor and two nos. instrument aircompressors shall be provided as standby. Air dryers shall be provided forinstrument air to achieve desired dryness.

6.7 Ventilation & Air-conditioning System

i) Suitable ventilation and air-conditioning system shall be provided to achieveproper working environment in the Station.

ii) Normally central control room, switchyard control room, local control roomsand service building for O&M personnel shall be air conditioned. Air-conditioned areas shall be maintained at about 25C and 50 % relativehumidity for comfort conditions.

Water chilling unit or condensing units shall have 100% standby equipment.Package type air-conditioners shall have 2x100% capacity or 3x50%capacity equipment. For window/ split air conditioners, if used for smallcontrol rooms, at least one unit shall be kept as standby.

iii) The type of ventilation systems to be provided for non-air conditioned areasshall be as under:


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All floors of TG building, switchgear rooms Evaporating cooling systemand cable gallery:

Other buildings Mechanical ventilation

6.8 Mill Reject System

The mill reject system shall be provided to collect reject from coal mills. Thesystem shall be mechanized i.e. drag chain conveyor or pneumaticallypressurized conveying system. The system shall consist of collection ofrejects from each coal mill and transport to silos for final disposal.

6.9 Electric Overhead Travelling (EOT) Crane

i) The EOT cranes shall be provided for maintenance and general station

services of various TG cycle equipment. These shall comply with therequirements and standards of latest versions of relevant BIS / IEC. Thecategory of cranes shall be M 5 as per IS 3177.

ii) Two identical capacity EOT cranes shall be installed in a T-G hall overoperating floor. The crane capacity shall be taken as 10% more than thesingle heaviest equipment to be lifted.

6.10 Workshop Equipment and Laboratories

6.10.1 Mechanical workshop equipment shall be provided for maintenance work andon-site repairs. The standard workshop equipment like centre lathe,universal milling machine, pedestal drilling machine, pedestal grindingmachine, hacksaw machine, cutter, grinder, tool grinder, hydraulic press,oxy-acetylene cutter and welding, fitters, benches/ racks, miscellaneousmeasuring & cutting tools etc. shall normally be provided.

6.10.2 Station shall be provided with following laboratories:

i) Electrical laboratory with necessary equipment/instruments for testingand maintenance of electrical equipment.

ii) Control & Instrumentation laboratory with necessary equipment/ instruments for testing, calibration and maintenance of control &instrumentation systems.

iii) Chemical laboratory with necessary equipment/instruments/reagentsfor chemical analysis, steam & water analysis and coal/ash/flue gasanalysis.


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7.0 CIVIL WORKS

Civil aspects are site specific and depend upon topographical, geo-technicaland other studies. The design philosophy needs to be based on techno-

economics of various alternatives of the construction techniques.7.1 Geotechnical Investigations

Geo-technical investigations are required for elastic assessment offoundation geology and needs to be carried out during investigation stageprior to taking up construction activity. The geotechnical investigations shallinclude determination of the sub soil type, ground water table etc.

Based on above, the type of foundation system, the bearing capacity, the pileparameters, requirement of soil stabilization/ compaction etc., shall be

established.7.2 Site Levelling:

The formation level of the Station shall be kept minimum 1.0 m above theHigh Flood Level (HFL) of the site.

It is preferable to keep the entire Station at the same level. However, to keepthe leveling cost to minimum, different levels may be adopted for variousblocks. The optimization of excavation and filling quantities may be donewhile fixing the levels of different blocks. The whole area of plant should notbe raised at the initial stage itself to avoid double handling of the earth work.

7.3 Foundations:

Open foundations or pile foundations or a combination of two keeping in viewthe lightly/heavily loaded foundations may be suitably adopted. In certaincases, ground improvement/stabilization methods may also be considered.

The foundations for turbines, boiler feed pumps and other rotating equipmentshall be suitably designed and the amplitude of vibrations shall be within thelimits recommended by the equipment supplier. To optimize the foundationsystem of rotating equipment, 3-D finite element analysis may be carried out.

Following loads shall be considered for the design of foundations:

a) Weight of equipmentb) Load of other accessoriesc) Dead load of foundation structured) Vacuum load


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e) Un balance forcesf) Loss of blade forceg) Short circuit forceh) Temperature forcesi) Torque loads

j) Frictional and other longitudinal forcesk) Live loadsl) Wind and Siesmic Loads

7.4 TG and other buildings :

All buildings shall be designed as RCC or steel framed super structures withmasonry or steel cladding. TG building shall have structural steel frameworkfor super structure with metal cladding on exterior face. Other buildings mayhave RCC or steel framework with masonry cladding of minimum onemasonry unit thickness on exterior face. The design of steel structures shall

be as per provisions of BIS.800 and other relevant standards.Considering the size, loadings and requirements of construction schedule,composite construction with steel supporting structures and RCC floors ispreferred for the TG and other buildings.

7.5 Structure System:

TG building shall preferably be moment resisting structures in transversedirection and braced in longitudinal direction. Mill and bunker building shallbe provided with moment resisting frame having adequate bracings in thetransverse direction and braced in longitudinal direction.

The structures shall be designed considering worst load combination of deadloads, super imposed dead loads, imposed loads, earthquake loads, windloads etc. The superimposed dead loads shall include the loads due toequipment and associated auxiliaries and accessories, duct loads as well ascrane loads with impact etc. Seismic forces shall be considered as per sitespecific seismic parameters.

7.6 Architectural Requirements:

Over all architectural character of Station building should be in harmony withnatural character of environment, climatic conditions and local landscape.Interior design should be given due consideration. The finishing works shallmeet the requirements of aesthetics, durability and functional aspects.

Adequate glazing shall be provided for natural light. Adequate ventilationshall be provided in all the buildings.


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7.7 Chimney:

Chimney may be single flue unitized or multiflue for two or more units.

The height of chimney shall be decided based on MOE&F guidelines and

shall also be got cleared by Airport Authority of India. The size of liner shallbe decided based on the exit velocity and temperature of flue gases.

Chimney windshield shall be of RCC construction. The flue liners shall be ofstructural steel or brick construction provided with suitable thermal insulation.The portion of liner above chimney shall be of acid resisting bricks protectedby RCC

cea _construction of electric plants- reg

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