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TRANSFORMER OIL RELATED ASPECTS

TRANSFORMER OIL RELATED ASPECTS.

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TRANSFORMER OIL RELATED ASPECTS

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  1. TRANSFORMEROILRELATED ASPECTS • OIL PLANT CAPACITY 60KL/Day(Now we are enhancing to 120KL/Day from existing 60KL capacity)A) TOBS storage capacity-1000KL(600KL tank-1no,100KL tanks-4nos)B) In process Oil storage capacity-125KL(20KL filters-3nos,10KL filters-6nos and 5KL filter-1no)C) Finished Oil storage capacity-390KL(240KL tank-1no,100KLtank-1no and 25KLtanks-2nos.

  2. FUNCTIONS OF TRANSFORMER OIL • To provide dielectric strength of the transformer insulation system. • To provide efficient cooling. • To protect the transformer core and coil assembly from chemical attack. • To prevent the build up of sludge in the transformer.

  3. PRODUCTION OF TRANSFORMER OIL • Transformer oil is hydrocarbon product,mainly oil contains napthanic,parrafinic and aromatics. • To obtain the TOBS the crude oil which is burried from earth crust subjected in to the following sequence of operations . • Distillation-Acid treatment-Neutralization-Water wash-Hot air blowing. • Clay treatment process on TOBS will give us the finished transformer oil. • After the hot filtration operation transformer oil is ready for filling the transformers.

  4. DETORIORATION ASPECTS OF TRANSFORMER OIL • Deterioration due to the accidental leakage of water . • Deterioration due to the chemical decomposition. • Deterioration due to the oxidation. • Deterioration due to the contamination by gases. • Deterioration due to the electrical stresses. • Deterioration due to the thermal stresses. • Deterioration due to the effect of oxidation products. • Deterioration due to the physical contamination.

  5. PRECAUTIONS INVOLVED IN TRANSFORMER OIL SAMPLING. • The utmost care should be taken to avoid contamination of samples with external impurities such as dust and moisture. • Attention is drawn to the danger of sampling in rainy or foggy weather. • The hands of the sampler should not come into contact with the samples. • Care should be taken when sampling oil colder than the surrounding air, to avoid contamination by condensation.

  6. PRECAUTIONS INVOLVED IN TRANSFORMER OIL SAMPLING. • Only glass sample containers,preferably fitted with ground glass stopper,should be used. • Cotton waste or other fibrous materials should not be used to wipe the containers or apparatus. • Where practicable,if a bottom sample is required the contents of the tank or package,after movement,should be allowed for at least 8Hrs,preferably 24Hrs before sampling. • Before the actual sample is taken,the entire sampling apparatus and containers should be rinsed with the oil,which should then discarded

  7. PRECAUTIONS INVOLVED IN TRANSFORMER OIL SAMPLING. • To remove any moisture or dirt on the surfaces over which the oil sample will flow a small amount of oil should be allowed to flow from the tank or package and run to waste before the sample is taken. • Samples that are to be tested for sludge,corrosive sulphur or tan delta should be protected from light.

  8. TRANSFORMER OIL Specifications for Testing of transformer oil. • IS-335 • ASTM-D3487 • IEC-60296 • BS-148 • JIS-2320

  9. IS-335SPECIFICATION • APPEARANCE:Clear transparent and free from suspended matter and or sediments. • DENSITY:IS-1448 P(16) HYDROMETER/THERMOMETER DESIGN VALUE—0.89 gms/ml @29.5°C max • KINEMATIC VISCOCITY:IS-1448 P(25) CONSTANT TEMPERATURE BATH THERMOMETERS/STOP WATCH DESIGN VALUE—27cSt @ 27 °C max

  10. IS-335SPECIFICATION • INTERFACIAL TENSION:IS-6104 INTERFACIAL TENSIO METER DESIGN VALUE—0.04N/M max • FLASH POINT:IS-1448 P(21) PENSKY MARTINS CLOSED CUP FLASH POINT TESTER/THERMOMETERS. DESIGN VALUE—140 °C min • POUR POINT:IS-1448 P(10) CLOUD POINT&POUR POINT APPARATUS/THERMOMETERS DESIGN VALUE-- -6 °C max

  11. IS-335SPECIFICATION • NEUTRALIZATION VALUE:IS-1448 P(2) CONICALFLASKS/BURETTES/MEASURING CYLINDERS/BURETTE STANDS/ VOLUMETRIC FLASKS DESIGN VALUES-- A. TOTAL ACIDITY : 0.03mgKOH/gm B. INORGANIC ACIDITY: NIL • ELECTRIC STRENGTH(BDV): IS-6792 BDV TEST SET DESIGN VALUES A. UN FILTERD :30kv min B. FILTERD : 60kv min

  12. IS-335SPECIFICATION • DIELECTRIC DISSIPATION FACTOR (TAN DELTA):IS-6262 TANDELTA TEST SET/OIL CELL HEATER/OIL CELL. DESIGN VALUE : 0.002 max • RESISTIVITY : IS-6013 RESISTIVITY TEST SET/OIL CELL HEATER /OIL CELL DESIGN VALUES A. 1500*10E12 Ohm-cm @27 °C min B. 35*10E12 Ohm-cm @90 °C min

  13. IS-335SPECIFICATION • PRESENCE OF ANTI OXIDATIVE INHIBITOR :IS13631 MEASURING CYLINDERS/PIPPETES/ BURETTES/BURETTE STANDS DESIGN VALUE : NOT DETCTABLE • WATER CONTENT : IS-13567 AUTO MATIC KARLE FISHER TITRATOR/WEIGHING BALANCE DESIGN VALUE : 50PPM max

  14. IS-335SPECIFICATION • CORROSIVE SULPHUR : IS-335 ANNEX-B TEMPERATURE CONTROLLED OVEN/CONOCAL FLASKS/FORECEPS DESIGN VALUE : NON CORROSIVE • OXIDATION STABILITY :IS-335 ANNEX-C OXIDATION STABILITY BLOCK/ VACUUM PUMP/OXIDATION TUBES/G-4 FILTERS/BURETTES/BURETTE STANDS/ CONICAL FLASKS/WEIGHING BALANCE. DESIGN VALUES A.NEUTRALIZATION VALUE:0.4mgKOH/gm B. SLUDGE % BY MASS :0.1max

  15. IS-335 SPECIFICATION • AGEING CHARACTERISTICS: IS-12177 AGEING OVEN /WEIGHING BALANCE/ VACCUME PUMP/ G-4 FILTERS/ BURETTES/BURETTE STANDS/ CONICAL FLASKS. DESIGN VALUES • A.RESISTIVITY@27DegC-2.5Ohm-cm min B.RESISTIVITY@90DegC-0.2Ohm-cm min C.TANDELTA@90DegC-0.2 max • D.TOTAL ACIDITY -0.05mgKOH/gm • E. TOTAL SLUDGE –0.05%

  16. NABL RECUREMENTS IN OIL LAB • Equipment history cards • Measurement uncertainty calculations. • Regular calibrations of instruments from NABL accredited laboratories. • Interlab comparison Replicate testing

  17. APPEARANCE TEST • APPEARANCE • Measurement uncertainty calculation for transformer oil appearance test • Sources of uncertainty • a) Improper sampling b) Presence of sediments and suspended matter in the bottles used for sampling c) Persons skills

  18. APPEARANCE TEST • a) Improper sampling : To avoid the uncertainty due to improper sampling the following care should be taken 1) Don’t use the cotton waste while sampling 2) Don’t pickup the sampling in dust and foggy weather 3) Clean the sampling point (pipe end) before sampling

  19. APPEARANCE TEST • b) Presence of sediments and suspended matter in the bottles used for sampling : The test results may be effect due to the contamination of sediments and suspended matter, if any present in the sampling bottles. Bottles should be thoroughly clean before sampling by using the following cleaning agents as per the sequence 1) Tap water 2) Soap solution 3) Tap water 4) Hot distilled water 5) Acetone and allow for oven drying at 110°C for 1hr. And then vacuum with the vacuum pump.

  20. APPEARANCE TEST • Persons skills : Person skills may also be the one of the reason for effecting the test results. To avoid this problem . The following persons will take care in the bottles cleaning and reporting the results • 01) P.SRINIVAS RAO

  21. BRAKE DOWN VOLTAGE TEST • Measurement uncertainty calculation for BDV test on transformer oil • Sources of uncertainty 1) Test results obtained 2) BDV test set resolution 3) BDV test set calibration 4) Atmospheric condition

  22. BRAKE DOWN VOLTAGE TEST • Results obtained . Repeated measurements on sample transformer oil sample a) ( 68,74,72,60,68,64) = 67.6kv b) (66,72,80,64,68,62) = 68.6kv c) (68,70,70,68,80,76) = 72.0kv d) (72,62,76,68,82,68) = 71.3kv e) (64,66,78,72,68,70) = 69.6kv Average value = 69.82kv St. Deviation = (-2.22)2+(-1.22)2+(2.18)2+(1.48)2+(-0.22)2 / 4=  (4.9284+1.4884+4.7524+2.1904+0.0484) / 4 = 1.8308 Type A uncertainty = 0.818kv

  23. BRAKE DOWN VOLTAGE TEST • 2)BDV test set resolution : (B1)uncertainty due to BDV test set resolution = 2 / 2 3 = 0.577kv • 3) BDV test set calibration : (B2)uncertainty due to BDV test set calibration. = 1.9 / 2 = 0.95kv Type B uncertainty = (B1)2+(B2)2 = (0.572)2+(0.95)2 = 1.1115kv combined uncertainty = (Type A)2+(Type B)2

  24. BRAKE DOWN VOLTAGE TEST combined uncertainty = (Type A)2+(Type B)2 =  (0.818)2+ 1.1115)2 = 1.38kv Note :4 Room temperature and relative Humidity maintained at 27°C and 44% RH respectively so uncertainty due to Atmospheric Conditions is not Considered Expended uncertainty = 2 x 1.38 = 2.76kv At 95% confidence level with respeet to 69.82kv 69.82 ± 2.76

  25. INTERLAB COMPARISION • Brake down voltage Inter lab comparison • 1) PGCL values = 73.1kv • Vijai electrical value = 69.3kv • Difference = 3.8kv • Uncertainty = 3.01kv • Z = Difference / uncertainty = 3.8 / 3.01 = 1.26 • Z Value is less than 2 OK

  26. INTERLAB COMPARISION • ERDA VALUE = 64.0kv • Vijai electrical value = 69.3kv • Difference = 5.3kv • Uncertainty = 3.01kv • Z = Difference / uncertainty = 5.3 / 3.01 = 1.76 • Z Value is less than 2 OK

  27. INTERLAB COMPARISION • CPRI VALUE = 87.0kv • Vijai electrical value = 69.3kv • Difference = 17.7kv • Uncertainty = 3.01kv • Z = Difference / uncertainty = 17.7 / 3.01 = 5.88 • Z Value is higher than 2 (Not OK) • The value of BDV reported By CPRI Bangolure appears to be very high . Requested CPRI to examine the same

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