This document discusses transformer oil testing aspects at an oil plant. It provides details on: 1. The oil plant's storage capacities for transformer oil stock, in-process oil, and finished oil. 2. Specifications for testing transformer oil, including tests for appearance, density, flash point, water content, and breakdown voltage according to IS-335 standards. 3. Sources of uncertainty in breakdown voltage testing and steps to reduce uncertainty, such as repeating measurements and maintaining consistent atmospheric conditions during testing.

1. 1
TRANSFORMER OIL RELATED
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. 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. 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. 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. 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. 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. 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. 8
TRANSFORMER OIL
Specifications for Testing of transformer oil.
IS-335
ASTM-D3487
IEC-60296
BS-148
JIS-2320

9. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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