Oil Processing

Transformers require to be maintained for guaranteed uninterrupted power supply. Transformers are filled with insulating oil in order to function. The dielectric properties of the transformer must be maintained in order to keep the transformer up and running.

What is Transformer Oil processing?
Transformers are filled with insulating oil with maintained dielectric properties. During the usage of the transformer, it absorbs moisture from the surrounding air through leaks and gets degraded due to soots, paper fibers, dirt, etc which makes the dielectric property fall from its original state. The process of filtration, degassing and dehumidification of transformer insulating oil is called oil processing. Transformer oil processing removes excess dirt, soots, fibers, moisture from the oil and degasses the oil to retain the quality of the oil.

Most transformer failures happen due to contaminated and deteriorated oil. It is important to filter the transformer oil regularly to prevent:

• Arcing

• Overheating, which reduces electrical efficiency as well as the life of the transformer

• Corona Discharges

• Decrease in insulating strength of the transformer oil, and more

The Quality Parameters of Transformer Oil:

The fundamental quality parameters of transformer insulating oil are:

• Color; ASTM D1500

• Dielectric breakdown voltage; D 877, ASTM D1816

• Dissolved gas analysis; ASTM D3612

• Dissolved metals; ASTM D7151

• Flashpoint, fire point; ASTM D92

• Interfacial tension; ASTM D 971

• Furanic compounds; ASTM D5837

• Karl Fischer moisture; ASTM D1533

• Liquid power factor; ASTM D924

• Neutralization number; ASTM D974

• Oxidation inhibitor content; ASTM D2668

• Polychlorinated biphenyls content; ASTM D4059

• Relative density (specific gravity); D 1298, ASTM D1524

• Resistivity; ASTM D1169

• Visual examination; ASTM D1524

The Oil Treatment Processes:

Mainly there are three types of oil treatment processes:

• Filtering

• Purification with Drying Process

• Regeneration/Reclamation with Degassing

The Filtering Process involves transformer oil filtering at a temperature of about 40 degrees Celsius. This process filters fine contaminated particles with the help of a filtering device.

The Purification with Drying Process heats the oil to a maximum temperature of 90 degrees Celsius and removes acidic & polar components from the transformer oil. A process of degassing under vacuum follows.

The Regeneration/Reclamation with Degassing is similar to the Purification with Drying Process but uses extra oxidant additives. This is the most effective method by which the oil can be regenerated in a cost-effective manner. However, the safety of the environment must be considered before undertaking this process.