Evaluating Transformer Health
August 1, 2015
Regular assessment of transformer health is an important recommendation for any transformer owner, from large manufacturing utilities to owners of large capital equipment and wind farms. Instrumental to the assessment is looking for the presence of hydrogen gases in the insulating oil. The industry considers dissolved gas analysis or (DGA), one of the most informative detection methods and a key indicator of the overall health and reliability of the transformer.
Assessing Insulating Oil for Hydrogen
During the natural breakdown of insulating oil, hydrogen atoms and hydrocarbon fragments form. Regular evaluation of the gas concentrations tell the history of the transformer and its potential for faults. The presence of elevated hydrogen levels can point toward thermal decomposition and electrical disturbances in a liquid or solid medium at any point in the insulating system. This is a sign of partial discharge.
What is Partial Discharge?
Partial discharge is a localized dielectric discharge in an area of a solid or liquid insulation under high-voltage stress. Its existence is more prevalent at higher voltages and is a cause of deterioration within the transformer insulation. The Class II-required test determining the presence of partial discharge can occur through an oil sample, acoustic testing, or through on-transformer monitoring.
Causes of Partial Discharge
- Voids or imperfections in solid insulation
- Gas bubbles within liquid insulation
- At the interface of different layers of insulation
- Poor design methods and/or assembly
With regular DGA sampling during acceptance and routine tests, it’s easier to see hydrogen trends, which can allow more time to evaluate and address potential problems. This preventative action could help head off the occurrence of a catastrophic failure, something that could occur anywhere from days to years later.
A Reliable Source for Partial Discharge Testing
Because of the variable causes of partial discharge, it’s important to make regular annual checks a priority for continued transformer health. Leaving insulation problems unaddressed can lead to partial discharge activity that can further develop into surface tracking and electrical trees before the eventual breakdown between phase and ground. Solomon Corporation can perform partial discharge testing on a transformer energized to rated voltage while the unit is loaded. Partial discharge testing is also available in our shop. Contact Solomon Corporation to learn more.
Solomon Corporation specializes in sales and service of oil-filled transformers and distribution transformers. We also offer technical support to the electrical distribution industry, as well as repair, recycling, and disposal of transformers, reclosers, and regulators. For more information or to request a quote, please click here to contact our sales and procurement team.