transformer oil specifications

TRANSFORMER OIL SPECIFICATIONS

BYCENTRAL INSULATING OIL TESTING LABORATORY


• NEW OIL:

• An unused mineral insulating oils intended to use in transformers for insulation and cooling purpose.

• IS-335/1993 – Specification for uninhibited

new insulating oils.

• IS-12463/1988 – Specification for inhibited

mineral insulating oils.


• IEC -60296/2003 – Specification for unused mineral insulating oils for transformers and switchgear. This standard cover both uninhibited and inhibited oils.

• ASTM – D3487/2000- Standard Specification for Mineral Insulating Oil used in Electrical apparatus. This standard also covers both uninhibited and inhibited oils.


• Unused Mineral Insulating oils filled in New transformers

• IS – 1866/2000 – Code of Practice for Electrical Maintenance and supervision of Mineral Insulating oil in Equipment.

(Refer Table.1 for limiting values of various parameters)

• IEC – 60422/1998 – Supervision and maintenance guide for mineral insulating oils in electrical equipment.


• In service Mineral Insulating oils:

• IS – 1866/2000 – Code of Practice for Electrical Maintenance and supervision of Mineral Insulating oil in Equipment.

(Refer Table.2 for limiting values of various parameters)

TRANSFORMER OIL SPECIFICATIONSIS-335/1993

• Appearance ------------• Density at 29.5˚C (Max)• Kinematic Viscosity (Max)

1) at 27˚C ------------------

2) at 40˚C ------------------• IFT at 27˚C (Min) ---------• Flash Point (Min) ---------• Pour Point (Max) ---------• Neutralization Value

1) total Acidity (Max) ----

2) Inorganic acidity ------• Corrosive Sulphur -------

• Clear and transparent• 0.89 g/cm2

• 27 cSt• Under consideration• 0.04 N/m• 140˚C• -6˚C

• 0.03 mg KOH/gm• Nil• Non-corrosive


• Electric Strength (BDV) 1) New unfiltered Oil(Min) 2) After filteration (Min)

• Dielectric dissipation factor (tan δ)at 90˚C(max)

• Specific resistance (Resistivity)

1) at 90˚C (Min) 2) at 27˚C (Min)• Oxidation Stability 1) Acidity (max) 2) total sludge (max)

• 30 KV (rms)• If the above value is not

attained, the oil shall be filtered to 60 KV (rms)

• 0.002

• 35 x 1012 ohm-cm• 1500 x 1012 ohm-cm

• 0.4 mg KOH/gm• 0.1 % by weight


• Ageing characteristics

a) Resistivity (Min)

1) at 27˚C

2) at 90˚C

b) Tanδ at 90˚C (Max)

c) Total acidity (Max)

d) Total sludge (Max)• Presence of Oxidation

inhibitor

• Water content• SK value

• 2.5 x 1012 ohm-cm• 0.2 x 1012 ohm-cm• 0.20• 0.05 mg KOH/gm• 0.05 % by weight• The oil shall contain

natural anti oxidant additives.

• 50 ppm• Under consideration

TRANSFORMER OIL SPECIFICATIONSIS-1866/2000-Recommended Limits of Unused Mineral Oil filled in New

Transformer

Property Highest voltage of Equipment (KV)

<72.5 72.5-170 >170

Appearance Clear, Free from sediment and suspended matter

Density at 29.5˚C (g/cm2),Max 0.89 0.89 0.89

Viscosity at 27˚C (cSt),Max 27 27 27

Flash Point (˚C),Min 140 140 140

Pour Point (˚C),Max -6 -6 -6

Total acidity(mgKOH/gm),Max 0.03 0.03 0.03

Water content (ppm), Max 20 15 10

IFT at 27˚C (mN/m),Min 35 35 35

Tanδ at 90˚C, Max 0.015 0.015 0.010

Resistivity at 90˚C(x10e12ohm-cm),Min

6 6 6

BDV (KV),Min 40 50 60

TRANSFORMER OIL SPECIFICATIONSIS-1866/2000-Violation Limits for in service oils

Property Highest voltage of Equipment (KV)

<72.5 72.5-170 >170

Appearance Clear and without visual contaminations

Water content (ppm), Max No Free water 40 20

BDV (KV),Min 30 40 50

Total acidity(mgKOH/gm),Max 0. 3 0. 3 0. 3

IFT at 27˚C (mN/m),Min 15 15 15


1 1 1


0.1 0.1 0.1

Tanδ at 90˚C, Max 1.0 1.0 0.2

Flash Point (˚C),Min Maximum decrease of 15˚C from initial value

Sediment and sludge No sediment or precipitable sludge should be detected. Results below 0.02% by mass may be neglected.

TRANSFORMER OIL SPECIFICATIONSIS-1866/2000-Frequency of testing

Property Frequency of testing

Appearance In conjunction with other Quantitative tests

Water content After filling or refilling prior to energizing, then after three and 12 months, subsequently along with DGA

BDV After filling or refilling prior to energizing, then yearly

Total acidity Yearly

IFT After filling or refilling prior to energizing, then yearly

Resistivity After filling or refilling prior to energizing, then yearly

Tanδ After filling or refilling prior to energizing, then yearly

Flash Point Yearly

Sediment and sludge Yearly

TRANSFORMER OIL SPECIFICATIONSIS-1866/2000-Recommended Actions

Property Recommended Actions

Appearance As dictated by other tests

Water content Check Source of water and consider reconditioning

BDV Recondition the oil or alternatively, if more economical or other tests dictate replace oil

Total acidity Replace or reclaim oil

IFT Replace or reclaim oil

Resistivity Replace or reclaim oil

Tanδ Replace or reclaim oil

Flash Point Replace the oil, equipment may require inspection

Sediment and sludge Where sediment is detected recondition the oil

TRANSFORMER OIL SPECIFICATIONSIS-1866/2000-Classification of oils in service.

• Group 1:

This group contains oils that are in satisfactory condition for continued use. The frequency can be followed as described earlier.


• Group 2:

This group contains oils that requires reconditioning for further service. (Low BDV and High water content). The frequency can be followed as described earlier after reconditioning.


• Group 3:

This group contains oils in poor condition that it can restore satisfactory properties only after reclaiming. Insulating oils this group should be reclaimed or replaced depending on economic considerations.


• Group 4:

This group contains oils, in such poor state that it is technically advisable to dispose of them.

TRANSFORMER OIL SPECIFICATIONSIEC -60296 – General Specification

• Functional Properties: Viscosity, Pour point, Water content, BDV,

Density, Tanδ.• Stability Properties: Appearance, Acidity, IFT, corrosive Sulfur,

Antioxident additive• Performance Properties: Oxidation Stabillity, Sludge• HSE Properties: Flash Point, PCB content, PCA content

transformer oil specifications

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