Tranoil Class aII-Rev

National Transformer Oils are developed from Napthenic Base Oils having excellent Electrical properties to meet British Standards and related specifications for Electrical Insulating Oil.


  • Ensures good insulation of Electrical Conductors.
  • Prevents arcing between Electrodes.
  • Minimizes di electric loss.
  • Effectively cools Transformer Coils.
  • Provides long service life.
  • Very high oxidation stability and outstanding reliability during prolonged service.

Performance Levels

  • Meets
  • International Electro Technical Commission Standard - IEC 296 (1982) Class II (Uninhibited)


Recommended for Electrical Insulating Oil applications such as Transformers & Oil immersed switchgear where an oil meeting BSI, IEC or other comparable specification is required by the equipment manufacturer or user.

Typical Characteristics

Characteristics Test Method Specified Values Guaranteed Values
(A) Physical Properties
Kinematic Viscosity, mm²/sec 7.3    
at 40 °C   ≤11.0 7.82
at -30 °C   ≤1800 263.88
Flash Point, (PMCC) °C 7.4 >130 152
Pour Point, °C 7.5 <-45 -45
Appearance 7.1 Clear, free from sediments & suspended matter. Clear, free from sediments & suspended matter.
Density, Kg/dm³ @ 20 °C 7.2 <0.895 0.8170
Density, Kg/ dm³ @ 29.5 °C     0.8120
Interfacial Tension @ 25 °C, N/m 7.6 >0.040 0.048
(B) Electrical Properties
Break down voltage; 7.12    
as delivered, KV   >30 78
after treatment, KV   >50 -
Dissipation factor, @ 90 °C and 40 Hz to 60 Hz 7.13 <0.005 0.0014
(B) Chemical Properties
Neutralization Value, mg KOH/g 7.7 <0.03 0.0013
Corrosive Sulphur 7.8 Non-Corrosive Non-Corrosive
Water Content, ppm 7.9 <40 13
Anti-oxidant Additives 7.10 Absent Absent
Oxidation Stability 7.11.1 Min 120 Hrs >150
a) Total acidity, mg KoH per gm of oil   <0.40 0.14
b) Sludge, % by mass   <0.10 0.008
Induction Period P.C.B. Content IEC 61619 NIL NIL

Handling, Health And Safety
Lubricant consisting of highly refined mineral oils with specific additives. In normal conditions of use this lubricant presents no particular toxic hazard. All lubricants, of any kind should be handled with great care, particularly avoiding any contact with the skin.

Prevent any splashing and keep away from combustible materials. Store under cover and away from any risk of pollution. Disposes off the used oil correctly, don’t pour down drains, into watercourses or the soil.


Shelf Life For Our Products Is Five Years From The Production Date