SUMMER TRAININGAT

HUMAN RESOURCE DEVELOPMENT CENTRE

PROJECT REPORT ON CONSTRUCTION OF TURBOGENERATOR(600 MW)

BRUSHLESS EXCITER

TRANING PERIOD-(30th may-29th June 2011)SUBMITTED BY- SUBMITTED TO -Anuj Sinha SDGMVI SEM ELECTRICAL H.R.D.C S.G.V.U B.H.E.L HARDWARJaipur, Rajasthan UTTARAKHAND

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ACKNOWLEDGEMENT

My sincere thanks goes to Mr. A.K.DHIMAN or his prodigious guidance, precaution, painstaking, attitude reformative and suggestion throughout my summer training schedule.

Special thanks goes to Mr. P.S.Jangpangi who helped me a lot in giving minute details of the working of turbo generator, brushless exciter and enlightened me with the knowledge of essential equipments and their working.

Last but not the least, my sincere thanks to all the staff members of “BHEL HARDWAR”

Anuj Sinha B.Tech

EE (VIth SEM) S.G.V.U

Jaipur, Rajasthan .

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PREFACE

In the light of practical aspects of training for engineering. I am a student of B.Tech VI Sem had been completed my practical training at “BHARAT HEAVY ELECTRICALS LIMITED (BHEL) HARDWAR” for four weeks.

The objects of training in engineering course is to correlate the theory with practical aspects and to make students familiar with the difficulties arises during practical application so that they can face challenges boldly while working in the field.

As I am a student of electrical engineering so training at “BHEL” had been particularly beneficial for me. I observe various electrical machineries that are used in different large scale or a small scale industries and different types of power plants.

BHEL is very large industry for making the different types of electrical equipments as well as mechanical equipments.

I tried my best to get acquitted with over all plants. I hope that I have excited enough in the report of my training.

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CONTENTS

1. Company profile 05

2. BHEL’s contribution in Different Sectors 06

3. BHEL Hardwar 07

4. Products And Ratings 08

5. Different Blocks And Their Function 08

6. Turbo Generators 09

7. Construction of Turbo Generator 09

8. TARI & THRI Turbo Generators 10

9. Technical data of Turbo Generator 11

10. Turbo Generator Stator – 210MW 12

11. Turbo Generator Stator – 500MW 14

12. Control Panel Section 17

13. Stator Coil Construction – 500MW 18

14. Metal Coating 19

15. Rotor coil for THRI Generator 21

16. Brushless exciter for Turbo Generator 22

17. Block diagram of Brushless Exciter 23

18. Working of Brushless Exciter 23

19 Merits of Brushless Exciter 24

20. Conclusion 25

21. References 26

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COMPANY PROFILE

The first plant of what is today known as BHEL was established nearly 40 years ago at BHOPAL and was genius of heavy electrical equipment industry in India. BHEL is today the largest engineering enterprise of its kind in India with well recognized track records of performance making profits continuously since 1971-72 it achieved a sales turnover of 1023 crore in 1977-78. BHEL caters to core sectors of the Indian economy in power, industry, transportation, defence etc.

The wide network of BHEL’s 14 manufacturing divisions, 9 service centers & 4 power global players. BHEL has a wide network – 14 mfg. div.,4 power sct. Regional centers, 8 service centers,15 regional offices & large no. of project sites all over India & abroad. BHEL attained – ISO 9001 certification for quality management, ISO 14001 certification for environmental management & OHSAS-18001 certification for occupational health & safety management system.

Power sector comprises thermal, nuclear, gas & hydro power plant business today, BHEL supplied sets account for nearly 56, 318 MW or 75% of the total installed capacity of 86, 636 MW in as against nit till 1969-70.

BHEL has proven turnkey capabilities for executing power projectors from concept to commissioning. It possesses the technology and capability to produce thermal power plant equipments up to 1000 MW rating and gas turbine generator sets up to a unit rating of 240 MW. Cogeneration and combines cycle plants have been introduced to achieve higher plant efficiencies. To make efficient use of the higher ash content coil manufacturers 235 MW nuclear turbine generator sets and has commenced production of 500 MW nuclear turbine generator head discharge combinations are also engineered and manufactured is also competitive.

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BHEL’S CONTRIBUTION IN DIFFERENT SECTORS

POWER GENERATION :-

Power Generation sector includes Thermal, Gas, Hydro and Nuclear Power Plant business. BHEL supplied 75% of the total installed capacity in the country. BHEL has the capability to produce thermal sets up to 1000MW unit rating and gas turbine-generator sets of up to 250MW unit rating. The company manufactures 220/235/500 MW nuclear turbine-generator sets. Hydro sets of Francis, Pelton and Kaplan types for different head discharge combination are also manufactured by BHEL.

TRANSMISSION & DISTRIBUTION :-

BHEL also supplies a wide range of transmission products and system up to 400 KV class. These include high voltage power and distribution transformer, instrument transformers, instrument, transformers, dry type transformers, vacuum and SF6 circuit breaker, gas insulated switch gear, capacitor and insulator etc series and shunt compensation system have been also developed and introduced to minimize transmission losses.

INDUSTRIES :-

BHEL is a major contributor of equipment and systems to industries: cement, sugar, fertilizer, refineries, petrochemicals, paper, oil and gas, metallurgical and process industries. The company is a major producer of large-size thyristor devices. It also supplies digital distributed control system for process industries and control & instrumentation systems for power plant and industrial application.

TRANSPORTATION :-

A high percentage of trains operated by Indian Railway are equipped with BHEL’s traction and traction control equipments including the metro at Calcutta and Delhi. The company supplies broad gauge.

Electrical locomotive to Indian railway and diesel shunting locomotives to various industries 5000/6000 hp ac/dc locomotive developed and manufactured by BHEL have been leased to Indian railway, battery powered road.

RENEWABLE ENERGY :-

Technologies offered by BHEL for non-conventional and renewable sources of energy include: wind electric generators, solar photovoltaic system, stand alone and grid-interactive solar power plants, solar heating systems, solar lanterns and battery-powered road vehicles. The company has taken up R&D efforts for development of multi-junction amorphous solar cells and fuel cells based systems.

INTERNATIONAL OPERATIONS :-

BHEL’s product series and projects have been exported to over so countries ranging from UNITED STATES in the west to NEW ZEALAND in for east INDIA is over 3000 MW. A few motable ones are 150 MW gas turbine to GERMANY, utility boiler and open cycle gas turbine plant to MALAYSIA, Tripoli west, power station in Libya and Turkey. In Cyprus, hydro generator to New Zealand and hydro power plant to Thailand , Saudi Arabia, Oman , Greece and Egypt.

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BHEL HARIDWAR

At the foothills of the majestic Himalayas on the bank of the holy Ganges in Ranipurr“HARIDWAR” is located heavy electrical equipment plant of BHEL.

BHEL , wholly owned by the govt. of INDIA is and integrated engg. Complex consisting of several plants in INDIA, where about 70000 workers are busy in design and manufacturing of heavy electrical equipment.

At present 70% of the country electrical equipment is generated BHEL HARIDWAR.

BHEL HARDWAR is broadly divided in to two parts:A)- CFFP :– Central Foundry Forge Plant

B)- HEEP :– Heavy Electrical Equipment Plant

A)- CFFP is divided in to following shops: i)- Forge Shop ii)- Machine Shop iii)- Steel Melting Shop (SMS) iv)- Steel Foundry v)- Pattern Shop vi)- Cast Iron(CI) Foundry

B)- HEEP is divided into following blocks: i)- Block-1 ii)- Block-2 iii)- Block-3 iv)- Block-4 v)- Block-5 vi)- Block-6 vii)- Block-7 viii)- Block-8

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BHEL PRODUCTS

HEEP’s PRODUCT & RATINGS :

S.No. PRODUCT TYPE CAPACITY RATING

1. Turbo Generators Air Cooled500 MWHydrogen Cooled

Water Cooled2. Hydro Generators Umbrella

250 MWSemi-Umbrella

Suspension

Horizontal

3. MotorsAC Motors 35 MW

DC Motors 12 MW(70 rpm)

BLOCKS IN HEEP

Block-1 Turbo Generators, Brushless Exciters

Block-2 Fabrication (Steam, Hydro & Gas Turbine)

Block-3 Gas, Hydro & Steam Turbine

Block-4 CIM & ACM

Block-5 Heat exchangers, forging & fabrication

Block-6 Electrical repair & maintenance of motor & transformer

Block-7 Wooden packing works

Block-8 Fabrication, seamless tuber and heat exchanges

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TURBO GENERATORS

1. They are all high speed machines, the usual value of speed being 3000 or 1500 rpm for 50 Hz. Systems.2. The machines have horizontal configurations.3. The rotor is made from solid steel forgings of high grade nickel chrome molybdenum steel4. The short circuit ratio is 0.4 to 0.65. The machines have cylindrical rotors wound usual for two poles or four poles outside diameter of rotor 175 m/s max. Speed. Modern turbo generator is designed such that first critical speed lies between 1250 & 1400 rpm and then second critical speed is not less than 3700 rpm.6. The machines reactances have following range.

Synchronous reactance 1.5 to 2.5 p.u.Transient reactance 0.1 to 0.35 p.u.Sub- Transient reactance 0.1 to 0.15 p.u.Negative sequence reactance 0.1 to 0.15 p.u.Zero sequence reactance 0.02 to 0.15 p.u.

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CONSTRUCTION PROCESS OF T/G STATOR BARS

500 MW

1. Conductor cutting2. Transposition3. Cross over insulation4. Stack pressing5. I.S.T. Testing6. Forming7. Coil lug brazing8. N2 and Helium testing9. Thermal shock testing10. Insulation11. Insulation baking12.Finishing13.Conductor varnish coating14.Tan and H.V. Test

210 MW

1. Conductor cutting2. Transportation3. Cross over insulation4. Stack Prssing5. I.S.T. Testing6. Forming7. Coil lug brazing8. Hydraulic test9. Insulation10.Resin rich, baking on mould11.Hydraulic test12.Finishing13.Conductor varnish coating14.Tan & H.V. test

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TURBO HYDROGEN RADIALLY INDIRECT (THRI) & TURBO AIR RADIALLY INDIRECT (TARI)

The latest Computer numerical control (CNC) technique used for the following purposes:

1. Conductor cutting2. Transposition3. Cross over insulation4. Stack pressing5. I.S.T. Testing6. Forming insulation7. Insulation baking8. Finishing9. Conductor varnish coating10.Tan and H.V. Test

THRI is the latest German technique which is more oftenly used now a days where as TARI the Russian Technique earlier is used.

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TECHNICAL DATA OF TURBO GENERATOR

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210 MW TURBO GENERATOR STATOR

No. of slots - 60No. of bar/set - 120 ( 60 upper & 60 lower)Winding pitch - 1-26Terminal Voltage - 15.75 KV

Lower bar solid conductor size 2.1*7.4*7300 mmHollow conductor size 7.4*1.5*7300 mmUpper bar solid conductor size 2.1*7.4*7000 mmHollow conductor size 7.4*1.5*7000 mm

210 MW Turbo Generator Bar manufacturing process :

The stator winding consists of 3 phase double layer bar type lap winding having 2 parallel paths. Each winding consists of glass insulated solid and hollow conductor wit cooling water (D.W.) passing through them the elementary conductor are transposed in the slots portion of winding to minimize eddy current losses. The winding insulation is of thermo reactive type and it is rated as class “f” for avoiding corona and other surface discharge stress grading coating of varnish is provided on the winding.

1. Transportation of bar

Copper conductor of required size is cut and edgewise bending is done to assemble the conductor in particular sequence as per drawing.The main reason for transportation is

1. To reduce eddy current losses.2. To generate equal voltage at any cross section in slots portion.3. To reduce skin effect.

2. Cross over insulationInsulation spacers are kept at bend portion so that short circuit between two strands is eliminated. Leveling spaces are also put in slots portion so that proper consolidation of slot portion is avoided during tack pressing.

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3. Stack pressingStack pressing of bars is done to have proper consolidation in slot portion so that all loose conductor become monolithic and stack size of bar is achieved during pressing the slots portion after pressing becomes rectangular in shape.

4. Inter turn testingAfter stack pressing the bar is tested for inter turn test so that any short circuit between conductor are checked and it eliminates local flow of current during operation. This is dome at 300 V A/C supply.

5. Forming of barsThe forming of bars are done on T/G forming M/C, the bars are given proper shape during formation and the brazing of coil lug is dome at the ends of bars. This brazing is done with electric brazing insulation with the help of carbon.

6. Hydraulic testingHydraulic testing at 15+5 Kg/cm2 is carried out on stack bars so that any leakage of lug joint may be detected. This test is carried out for 21/2 hrs and pressure drop of +-1 Kg/cm2 is allowed. N2 test at 15+-1 Kg/cm2 has been introduced on bars so that any leakage of fine nature may also be checked before insulation of bar.

7. Insulation of barsThe stator bar is insulated by epoxy mica tape (0.18*25 mm) from tip to tip and nos of layers and perepary of insulation bar is noted for cross checking on the top of insulation a release film tape is done so that during baking & pressing the bar is easily taken out from moulds.

8. Pressing & curing of barsThe bar is pressed and cured on baking moulds provided for lower and upper bars separately. Heating of bars is done by electric supply through the conductor itself and pressing of bar is done by mechanical clamps provided on moulds baking regime is followed for proper currying of bars.

9. Coil lug tinningTinning of coil lugs are done to achieve proper contact surface during ferruling og lugs and assembly stage.

10. Final hydraulic testingFinal hydraulic testing of bar is done to check any brazing leakage during the process. The final hydraulic test is carried out at 15+5 kg/cm2 for 10 hrs. Water flows test is also done to ensure any blockage of hollow conductor during the process.

11. Finishing of bars/ stress gradingThe bar slot portion is properly sanded and dimension are maintained. Then the conductor coating

is done in slot portion to check surface discharges and tan checking. Low tan ensure better quality of insulation and better consolidations.

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500 MW :

Conductor size- hollow conductor -8*4.6*1.5 mmConductor size- solid conductor - 8*2.8 mm

Lower bar

L – 10200 mm c -500 mmConductor No of bars hollow – 10 No

Upper barU-10050 mm c-5—mmConductor size 8*4.6*1.5 mm (hollow)

8*1.3 mm (solid)Conductor no in one bar hollow -10no

Solid - 20 no

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500 MW TURBO GENERATOR STATOR

No of slots -40Winding Pitch -1-21Voltage - 21KVCurrent - 16.2 KA

40 Lower -40 Upper

Full bar 20 solid copper conductor solid -2.8*8*10200 mm lower barFull bar 20 hollow copper conductor hollow -4.6*8*10200 mm lower barFull bar 40 conductor solid -1.3*8*10050 mm upper bar

1. Transposition of bars (540 Elect degrees)

1. To reduce eddy current losses.2. To equalize the voltage generator3. To minimize skin effect of ac current so small cross section of conductor is used and also hollow

conductor are used to effect colling by D.M. water2. Cross over insulation

To eliminate inter turn short at bends during edges wise bending and leveling of bars in slots portion for proper stack pressing.

3. Pressing of bars Pressing of stack bar is done to achieve proper size of bar and consolidation Of stack so that it becomes monolithic.

4. Inter turn testThis is done to ensure that no local current is flowing due to short circuit between conductors.(300 A/C supply)

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5. Radius milling At edges the radius is former R-3 by radius tool.

6. Forming of bars (stator core length 5850 mm) Lower bars – var 00 to 15 Upper bars - var 00 to 07

As per variants the bars are formed on universal formers as per drawing over hang baking of bars is done by electrical heaters provided on formers.

7. Pickling of ends and bars lug mounting details All the details and bar are to be pickled in shop before assembly.

8. Mounting of lugs/contact sleeve Mounting of lungs/contact sleeve are fitted at bar ends as per drawing

9. Brazing of lugs/contact sleeve/water boxThe brazing of details is done with gas brazing unit which has automatic temperature control.

10. Internal picking of barThis is done to ensure that hollow conductor is free from dust & clogging etc. Boroscope is used to check the choking of conductor during brazing operations.

11. Thermal shock testingThis test is done to simulate the site condition of bars and repeated for 25 cycles at temp difference of 55 c from ambient temp. After the test is over the dry N2 is passed through the bars to cleat the water in side of conductor.

12. Helium leak testHelium gas is filled in the bar at 11 kg/cm2 and is covered with polythene bag and locked on both sides. By helium leak detector prob, if any leakage at lug joint occurs, then the meter will show and it can be confirmed for repair of bar joint.

13. Reforming of barsThis is done to ensure that the bar profile is maintained and fixing of generator will be trouble free.

14. Insulation of barBar insulation is done as per drawing with eosin poor moralistic insulation material for internal corona protection, conducting tape is used in the initial layer as per drawing.

15. Vacuum impregnationAs per set regime, the bar are to be impregnated in vacuum tank and then the pressing and current of bar is done on baking wagon which is made specially for 500 MW TG bars.

16. Finishing of barsSize of bar are done to ensure the dimensions as per drawing. Slots portion is coated with SIB 643 varnish which is conducting coating. Surface resistively is checked.

17. H.V. test Bar are tested for H.V. test at 64.5 KV A/C for 1 minute.

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APPARATUS AND CONTROL GEAR MANUFACTURING SHOP (ACM)

1. Mechanical assembly section2. Control panel section3. Rotor coil section4. Governing rocks shop5. Machine shop6. Sheet metal shop

CONTROL PANEL SECTION

The control panels which are manufactured in this section are:

1. D.C. jacking oil panel: It helps in lifting the rotor during starting, this saving the damage of heavy rotor then lubrication during running.

2. D.C. seal oil panel: It helps in sealing of the h2 gas at the shaft of the generator.

4. D.C. emergency oil panel:It helps in emergency lubrication of generator.

5. Generator insulation:It helps in controlling the generator instruments during its operation.

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STATOR COIL

Rotor coil are manufactured for THRI, THDF and TARI generator.

STATOR COIL FOR 500 MW T.G. GENERATORS

There are two poles in the rotor 7 coils in each pole coils no (A,B,C,D,E,F & G) . One coil is made of half coils. There are 6 conductors in each half coil for A coil. For B-G coil there are 9 conductor in each half coil.

Material for the rotor is copper silver ally having 0.12 % silver and 0.007%( mixed) phosphorous.

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Manufacturing process:

1. No. of punching2. Marking3. Drilling4. Debarring of holes5. Chamfering6. Cleaning of channels by passing brunch through it.7. Fitting and caulking of fillers8. annealing of ends9. Edge wise bending10. Pressing of bends11. Annealing12. Radius bending13. End cutting, facing14. Debarring15. Checking of thickness16. Brazing of fillers17. Finishing18. Inspection

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PAINTING SECTION

Painting section deals with the painting of all jobs of mechanical assembly governing racks and varnishing of hylum plates of control panel section.

The paints used are of three types:

1. ORDINARY PAINTS: These paints are of general purpose.

2. EPOXY PAINTS:The ratio of hardener and resin is decided as per customer. These are mixed for half an hour is different shades and it becomes hard offer half an hour. It is used for 250 MW assembles the primmer is epoxy based zinc is stock item.

3. POLYURETHANE PAINTS:It is more hard resin and hardener as mixed as specified by customer used for 500 MW assemblies.

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METAL COATING

Metal coating is applied to surface of metal and alloy to protect them from corrosion or to improve certain properties like wear resistance, harness and other properties this is an electrochemical process in which the metal or alloys to be planted are made to cathode and the meal which coating is to be done come from anode of from the electrolytic which contain the solution of metal to be deposited. If a direct current is passed thought an electrolyte metal will be eaten away from anode the composition of electrolytes remains same.

In the electroplating process the object to be planted is mage the cathode and a solution containing a salt of the metal to be deposited is used as the electrolytes the anode may be made of metal to be deposited or some other conductor when the low voltage direct current is passed thought the solution electrolysis takes place as result of which the metal get deposited on the article which forms the cathode.

The thickness of deposit depends upon the current density current efficiency and the duration of deposition. They physical character of deposit depends upon the current density the tamp of the both composition the nature of the surface to be placed and the presence or absence of addition agents.

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METAL COATING SHOP

The processes that are being carried out are:

1. Electroplating2. Picking3. Preservation

These are three types of electroplating that are being carried out:

1. Silver coating2. Copper coating3. Tin coating

Pickling process is necessary to clean the surface which is rusted or greased generally pickling is necessary before electroplating is carried out.

Preservation work is mainly necessary for components required partially hardened surface through carbureting or intruding the surface not required hardening is too marked through preserving film.

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ROTOR COIL FOR THRI GENERATOR

These are two pole in rotor, 7 coils in each pole (A,B,C,D,E ,F & G) one coil is made of 2 half coils. These are 11 conductors in each coil.Material for the rotor coils is copper silver alloy having 0.12% silver & 0.007% (mixed) phosphorous.

Manufacturing process:

1. No of punching2. marking3. Slat packing4. Debarring5. Annealing of ends6. Pressing7. Edge wise bending8. Annealing9. Radius bending10.Filler grazing11. End cutter and facing12. Debarring and finishing13. Checking of thickness14. Inspection

BRUSHLESS EXCITATION SYSTEM FOR TURBO GENERATORS

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A important characteristic of large turbo- generator is that the excitation requirements increased sharply with the rating of the m/c. since excitation voltage is limited from insulation considerations, excitation current levels increase sharply.Brush- less excitation system connected through driven revolvingArmature a.c. exciter connected through shaft mounted rectifiers to the rotating field of the turbo generator with no coupling of excitation power between the source of generation and point of supply to the generator field. Today, leading manufacturers offer brush- less excitation with rotating diodes as the preferred excitation system.

CONSTRUCTIONAL FEATURES OF BRUSHLESS EXCITER

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The three phase pilot exciter is of revolving field type with permanent magnet poles. The three phase a.c. generated in the stator is fed to the field of revolving armature main exciter via a stationary regulator and rectifier unit. The three phase a.c. induced in the rotor of the main exciter is rectified in the rotating rectifier bridge. And fed into the field winding of the generator rotor through the a.c. lead in the rotor shaft.

A common shaft carries the rectifier wheels, the rotor of the main exciter and the permanent magnet rotor of the pilot exciter, arranged one behind the other. The shaft is rigidly coupled to the generator rotor at its driving end and supported on a journal bearing at its non- driving end. The generator and exciter rotors are thus supported in a total of 3 bearings.

BLOCK DIAGRAM OF BRUSHLESS EXCITOR

WORKING OF BRUSHLESS EXCITER

Brushless exciter has two parts :

A) - Pilot exciterB) - Main exciter Pilot exciter is PMG type i.e. Permanent Magnet Generator. When rotor rotates emf induced in the stator of pilot exciter. This induced emf is converted into dc in rectifier section of pilot exciter.

The dc produced by pilot exciter is supplied to main exciter poles which magnetize the poles of main exciter and a field is set up in main exciter. When rotor rotates an emf induced in the armature of main exciter. This ac is supplied to diode wheel rectifiers through ac leads and converted into dc by diode wheel rectifiers. This dc supplied to the rotor of turbo generator by the use of dc lead.

MERITS :

The merits of brushless excitation system are:

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a. Completely eliminates brush gear, slip rings, field breaker and excited bus or cable.

b. Eliminates the hazard of changing brushes and leads.

c. Carbon dust is no longer produced and hence the operation is fully dust free.

d. Brush losses are eliminated.

e. Operating costs are reduced.

f. The system is best suited for atmospheres contaminated with oil, salt, chemical etc. and where sparking may be a fire hazard.

g. The system is simple and requires practically no maintenance except for an occasional inspection. Maintenance costs are thus reduced. Ideally suited for locations where maintenance is likely to be rare due to continuous demand on the m/c.

h. Brush less system with shaft mounted pilot exciter is of self generating type and the excitation is unaffected by system faults and disturbances.

i. Reliability is better.

j. Ideally suited for larger sets.

k. Increasing popular system the world over.

CONCLUSION

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Here, in the end, where I would like to conclude my whole report with some short sign. I must say that, to rise in the field of Electrical Engineering, one must have the good knowledge of all the manufacturing processes. The most important thing is to study the construction and working of all the electrical machines. And in that way I prefer myself to get training at B.H.E.L, Hardwar. Because B.H.E.L is growing in the field of Manufacturing and is a very big manufacturing unit so it’s very good to learn at this place the electrical and the strategies of management too.

Electric power has always been an important part of the world's power supply, providing reliable, cost effective electricity, and will continue to do so in the future. The future of turbines will depend upon future demand for electricity and the future is very bright as we have no source to produce without turbines, be it Hydro Turbine, Steam Turbine or Gas Turbine.

In this report, you will find some very refined data, which is referenced from a number of books and manuals and websites. This is just an effort to make my report more efficient.

REFRENCES

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1. Electrical machines by B.L. Threja

2. Electrical Machines by V.K. Mehta

3. Electrical machines by Ashfaq Husain

4. Electro Mechanical Energy Conversion by P.S. Bhimra

5. Electrical Engineering by B.L. Threja

6. Reference data Available in Block-1

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