page_title: Transformer oil testing
section_title: Motivation for testing
hierarchical_section_title: Transformer oil testing / Motivation for testing
caption_attribution_description: English: High voltage breakdown in an electric arc during transformer oil testing on a BA75 Oil tester by b2hv!
context_page_description: Transformer oil, a type of insulating and cooling oil used in transformers and other electrical equipment, needs to be tested periodically to ensure that it is still fit for purpose. This is because it tends to deteriorate over time. Testing sequences and procedures are defined by various international standards, many of them set by ASTM. Transformer oil testing consists of measuring breakdown voltage and other physical and chemical properties of samples of the oil, either in a laboratory or using portable test equipment on-site.
context_section_description: The transformer oil (insulation oil) of voltage transformers and current transformers fulfills the purpose of insulating as well as cooling. Thus, the dielectric quality of transformer oil is essential to secure operation of a transformer.
  As transformer oil deteriorates through aging and moisture ingress, transformer oil should, depending on economics, transformer duty and other factors, be tested periodically. Electric utility companies have a vested interest in periodic oil testing because transformers represent a large proportion of their total assets. Through such testing, transformers' life can be substantially increased, thus delaying new investment of replacement transformer assets.
caption: Voltage breakdown during oil test
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