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Oil Analysis And Testing

Transformer Oil Testing

Let’s change the way you think about Transformers…


The use of Transformer (or Insulating) Oils is fundamental to the way our society currently distributes power. Providing a resistive barrier for potentially catastrophic electrostatic discharges and cooling the incredible temperatures Transformers can reach when under heavy load. At Oil Check Laboratory Services we have recently expanded our repertoire of available services to be able to support such a fundamental part of our power generation services.

We provide three varieties of tests for our clients as disclosed below and for an effective program we would generally recommend our ‘Physicals’ tests bi-annually, with an annual Dissolved Gas Analysis to go with it.

We normally recommend PCB analysis should only be preformed when environmental concerns are raised about the condition of an old transformer or when decommissioning as PCBs are considered hazardous and toxic.

Oil Condition:

General ‘Physicals’ Analysis

Over time oil degrades and Transformer Oils are no exception and are especially sensitive to this. The intense electrical and thermal strain can catalyse or initiate undesirable changes in the properties oil which may turn it into a hazard further down the line.

At Oil check, we recommend bi-annual checks for changes in electrical and physical properties to ensure that the oil you use is kept up-to specification over time. Our tests include:

Visual inspection

Acidity of the Oil

Dielectric Constant


Water Content (ppm), etc


Polychlorinated Biphenyls

Originally used for their excellent electrical characteristics and not being flammable. Polychlorinated Biphenyls and similarly related compounds were quickly found to be detrimental to the environment and over the years since have been phased out of use.

At Oil check we have the capacity to test oil from an aged transformer whether it be for maintenance, checking for any carry over after an oil change, disposal or refurbishment for such PCBs; ensuring that your equipment is compliant with the European Directive 96/59/EC.

Fault Diagnosis:

Dissolved Gas Analysis (DGA)

Transformers undergo intense electrical loads frequently and over time the oil may fatigue under this repeated strain. Eventually this can cause a breakdown of the long chained Hydrocarbons naturally in the oil into smaller, more volatile gases (ranging from the relatively inert Nitrogen to combustible agents such as Hydrogen, Methane and Acetylene,) which can become a significant problem if left to accumulate in larger quantities. The production/distribution of these gases are a useful tool in frequent preventative maintenance, as they enable us to see the types and severity of certain faults as they occur in your transformer.

At Oil Check we recommend DGA every year with every other of our Physicals test to ensure your transformers are running well and continue to run in the future.

We always recommend contacting the lab first so we can understand your requirements and advise which of the above tests is relevant in developing a cost effective program for your equipment.