IEC 60296 Unused Mineral Insulating Oils for Transformers and Switchgear
IEC 60296 Fluids for Electrotechnical Applications - Unused Mineral Insulating Oils for Transformers and Switchgear
1 Scope
This International Standard is applicable to specifications and test methods for unused mineral insulating oils (see Clause 3 for definitions). It applies to oil delivered to the agreed point and time of delivery, intended for use in transformers, switchgear and similar electrical equipment in which oil is required for insulation and heat transfer. These oils are obtained by refining, modifying and/or blending of petroleum products and other hydrocarbons.

Oils with and without additives are both within the scope of this standard.

This standard is applicable only to unused mineral insulating oils.

Recycled oils are beyond the scope of this standard.

NOTE Definitions and specifications for recycled oils will be covered by IEC 62701.

This standard does not apply to mineral insulating oils used as impregnants in cables or capacitors.

2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
IEC 60076-2, Power transformers - Part 2: Temperature rise for liquid-immersed transformers
IEC 60156, Insulating liquids - Determination of the breakdown voltage at power frequency - Test method
IEC 60247, Insulating liquids - Measurement of relative permittivity, dielectric dissipation factor (tan δ) and d.c. resistivity
IEC 60422, Mineral insulating oils in electrical equipment - Supervision and maintenance guidance
IEC 60475, Method of sampling liquid dielectrics
IEC 60628:1985, Gassing of insulating liquids under electrical stress and ionization
IEC 60666, Detection and determination of specified additives in mineral insulating oils
IEC 60814, Insulating liquids - Oil-impregnated paper and pressboard - Determination of water by automatic coulometric Karl Fischer titration
IEC 60970, Insulating liquids - Methods for counting and sizing particles
IEC 61125:1992, Unused hydrocarbon-based insulating liquids - Test methods for evaluating the oxidation stability Amendment 1 (2004)
IEC 61198, Mineral insulating oils - Methods for the determination of 2-furfural and related compounds
IEC 61619, Insulating liquids - Contamination by polychlorinated biphenyls (PCBs) - Method of determination by capillary column gas chromatography
IEC 61620, Insulating liquids - Determination of the dielectric dissipation factor by measurement of the conductance and capacitance - Test method
IEC 61868, Mineral insulating oils - Determination of kinematic viscosity at very low temperatures
IEC 62021-1, Insulating liquids - Determination of acidity - Part 1: Automatic potentiometric titration
IEC 62021-2, Insulating liquids - Determination of acidity - Part 2: Colourimetric titration
IEC 62535:2008, Insulating liquids - Test method for detection of potentially corrosive sulphur in used and unused insulating oils
ISO 2719, Determination of flash point - Pensky-Martens closed cup method
ISO 3016, Petroleum products - Determination of pour point
ISO 3104, Petroleum products - Transparent and opaque liquids - Determination of kinematic viscosity and calculation of dynamic viscosity
ISO 3675, Crude petroleum and liquid petroleum products - Laboratory determination of density - Hydrometer method
ISO 12185, Crude petroleum and petroleum products - Determination of density - Oscillating U-tube method
ISO 14596, Petroleum products - Determination of sulfur content - Wavelength-dispersive X-ray fluorescence spectrometry
ASTM D971, Standard Test Method for Interfacial Tension of Oil Against Water by the Ring Method
ASTM D7150, Standard Test Method for the Determination of Gassing Characteristics of Insulating Liquids Under Thermal Stress at Low temperature
DIN 51353, Testing of insulating oils; detection of corrosive sulfur; Silver strip test
EN 14210, Surface active agents - Determination of interfacial tension of solutions of surface active agents by the stirrup or ring method
IP 346, Determination of polycyclic aromatics in lubricant base oils and asphaltene free petroleum fractions - Dimethylsulfoxide refractive method
IP 373, Determination of the sulphur content of light and middle distillates - Oxidative microcoulometry

3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1 transformer oil
mineral insulating oil for transformers and similar electrical equipment

3.2 low temperature switchgear oil
mineral insulating oil for oil-filled switchgear for outdoor application in very cold climatic conditions

3.3 mineral insulating oil
insulating oil obtained by refining, modifying and/or blending of petroleum products and other hydrocarbons

Note 1 to entry - This does not include insulating liquids such as esters, synthetic aromatics or silicone fluids.

3.4 additive
chemical substance that is added to mineral insulating oil in order to improve certain characteristics

Note 1 to entry - Examples include antioxidants, metal passivators, metal deactivators, electrostatic charging tendency depressants, gas absorbers, pour point depressants, anti-foam agents and refining process improvers.

3.5 antioxidant additive
additive incorporated in mineral insulating oil that improves oxidation stability

Note 1 to entry - A large number of additives which improve oxidation stability, including inhibitors, peroxide decomposers, metal passivators and metal deactivators, are available and may be used in oils if declared (see 6.11.1 and 6.11.2).

3.5.1 inhibitor
antioxidant additives of the phenolic-or amine- type, such as DBPC and DBP described in IEC 60666

Note 1 to entry - DBPC = 2,6-di-tert-butyl-para-cresol; DBP = 2,6-di-tert-butyl-phenol.

3.5.2 other antioxidant additive
antioxidant additive of the sulphur- or phosphorous- type

3.5.3 passivator
metal passivator additive used primarily as electrostatic charging depressant, but which may also improve oxidation stability

Note 1 to entry - Metal passivators are sometimes described as metal deactivators or corrosion inhibitors.

3.6 uninhibited oil
mineral insulating oil containing no inhibitor

Note 1 to entry - No inhibitor means that the total inhibitor content is below the detection limit of 0,01 % indicated in IEC 60666.

3.7 trace inhibited oil
mineral insulating oil containing less than 0,08 % of total inhibitor content as measured by IEC 60666

3.8 inhibited oil
mineral insulating oil containing a minimum of 0,08 % and a maximum of 0,40 % of total inhibitor content as measured by IEC 60666

3.9 unused mineral insulating oil
mineral insulating oil not recycled as delivered by the supplier

Note 1 to entry - Such an oil has not been used in, nor been in contact with electrical equipment or other equipment not required for manufacture, storage or transport. The manufacturer and supplier of unused oil will have taken all reasonable precautions to ensure that there is no contamination with polychlorinated biphenyls or terphenyls (PCB, PCT), used, reclaimed or dechlorinated oil or other contaminants.

Note 2 to entry - The definition of recycled oils will be given in IEC 62701 (in preparation).

Note 3 to entry - A blend of unused and recycled oil in any proportion is regarded as being recycled.