TRANSFORMER OIL2023-05-24T12:02:35+00:00

The lifeblood of a transformer

Benzoil is among Australia’s few specialised transformer oil suppliers, and we consider ourselves well placed in the oil market to offer helpful advice, particularly if you are looking to buy.  Transformer oil is a dielectric fluid is used in oil-filled electrical assets including:

  • Transformers
  • High voltage capacitors
  • Circuit breakers

The function of transformer oil is to insulate and cool, and serves to:

  • Prevent electrical discharges between the coils
  • Remove heat generated by the operation of a transformer

Transformer oil can be considered a technically complex product, and we can explain the meaning and significance of the various physical, chemical and electrical properties including:

  • Moisture Content
  • Interfacial Tension
  • Flash Point
  • Viscosity
  • Pour Point
  • Neutralization value
  • Oxidation Stability
  • Corrosive Sulfur
  • Dielectric Strength
  • Specific Resistance
  • Dielectric Dissipation Factor

Although vegetable and synthetic variants are available, Benzoil chiefly offers mineral based transformer oil for sale.  When your business needs to buy transformer oil, Benzoil can supply electrical insulating oil for all applications and meeting any international or Australian specification.  Depending on the purpose, transformer oil may be required to meet not just technical requirements, but also environmental and price points.

We offer 3 tiers of transformer oil comprising:

  • Virgin (i.e. refined from crude)
  • Re-refined (i.e. refined from previously refined (virgin) oil)
  • Regenerated (i.e. physio-processed from previously refined (virgin) oil)

We welcome one-off sales enquiries as well as ongoing supply requirements.  Typical users include power utilities, OEMs, and service and maintenance companies.  Transformer oil is usually ordered in bulk and delivered by specialised road tankers or ISO containers.  We can also supply in sizes including:

  • 1,000L (IBC or pallecon)
  • 205L (drum)
  • 20L (small drum)

We provide a NATA accredited laboratory certificate of analysis with all orders.

An oil for all occasions

Benzoil is among Australia’s few specialised transformer oil suppliers, and we consider ourselves well placed in the oil market to offer helpful advice. Read more about virgin and re-refined transformer oils.

Regenerated and made good as new

Regenerated transformer oil is a naphthenic transformer oil which has been regenerated to restore physical, electrical and chemical qualities back to “as new” condition.  Read more about regenerated transformer oils.  

Specifically designed oil for industry

In conjunction with leading transformer OEMs and electric utility companies, Benzoil has developed a unique product designed specifically for flushing and rinsing electrical transformer internals.  Read more about transformer flush oils.

Learning about oxidation, the primary mechanism of oil degradation

In a transformer, oil oxidation is a chemical process which must be readily be kept in check.  The culprit oxygen is introduced from the atmosphere and/or is released from the cellulose based transformer paper insulation in the presence of heat.  Oxidation is normally first associated with the oil as it deteriorates, and can be controlled but not eliminated.  Oil oxidation, heat and moisture work in combination.

Oxidation by-products will destroy the paper and cause the formation of sludge which will lead to overheating and ultimately, premature failure of the asset.

Oil degradation releases a range of chemical substances that react and breakdown the cellulose.  These reactions accelerate in a chain effect – each adding to the ongoing destruction of the cellulose.  The porous nature of insulating paper and board react to the decay products as adsorbents.

It is well recognised that even low acid levels in oil have a major effect on oxidation and the degradation of the paper insulation in transformers.  New oil has an acidity of less than 0.03mg KOH/g and it has been shown that oil with acidity 0.05mg KOH/g will start to cause decay of cellulosic insulation.  The most cost effective point at which to reclaim that oil is at this time and certainly should not be delayed beyond acidity 0.1mg KOH/g.

When acidity moves beyond 0.2mg KOH/g the oil and insulation degradation process is accelerated and will usually be accompanied by the formation of sludge on the core and coils of the transformer.  At these levels acidity will tend to increase exponentially with increased time at normal transformer operating temperatures.  These high acid numbers are devastating to the tensile strength of the paper.

Oxidation can be kept in check by regular monitoring of oil condition, and Benzoil can provide this service in conjunction with our partners.