Routine testing of transformer insulating oil is an essential maintenance function that ensures a safe working environment and helps eliminate the possibility of disrupted production resulting from a transformer failure or explosion. Analysis of the concentration of various gases contained in insulating oils and monitoring of the oil’s physical properties will tell you much about the operating condition of your power transformers.
By showing the effects of the transformer’s operation on the insulating oil, these analyses confirm the serviceability and condition of the oil in use and allow better scheduling of transformer maintenance to avoid unplanned outages. Basic screening tests indicate the dielectric strength, interfacial tension, water concentration, specific gravity, and acidity of the oil. Transformer Oil Analysis tests identify whether the insulating properties are acceptable by measuring degradation and contamination of the oil.
In addition, dissolved gases are extracted from the oil sample, separated, and quantified in a gas Chromatograph. Gases develop through high temperature degradation of transformer oil and other insulating materials. Faults in transformers occur in areas immersed in the insulating oil and/or are in close proximity to cellulose insulation. Should a fault be active, the degradation rate can be significant. Varying mixtures of degradation gases are generated for each type of fault. Depending on the type of transformer in service, any combination of different gas concentrations can indicate potential problems that must be avoided.
Dissolved Gas Analysis identifies the presence and levels of these gases: hydrogen, nitrogen, carbon monoxide, oxygen, methane, carbon dioxide, ethane, ethylene, acetylene. Concentration levels of these gases are measured in parts-per-million. By analyzing and monitoring the composition of gases, the three basic fault processes corona, sparking, and arcing are identified and quantified. Comparing the rate of gas generation to industry standards allows expert data analysts to assess the magnitude of each fault. Analysis of the concentration of various gases within transformer insulating oil and the monitoring of physical properties will indicate the condition of your power transformers.
NOTE: Trico requires that proof of Polychlorinated biphenyls (PCB) do not exist for testing of transformers. Please consult a Lubrication Program Manager for further details.
Screening Test Program (STP)
- Dielectric Strength
- Interfacial Tension
- Specific Gravity
- Acid Number
- Karl Fischer
Dissolved Gas Analysis Program (DGA)
- Hydrogen (ppm)
- Methane (ppm)
- Ethane (ppm)
- Ethylene (ppm)
- Acetylene (ppm)
- Carbon Monoxide (ppm)
- Carbon Dioxide (ppm)
- Oxygen (ppm)
- Nitrogen (ppm)
- Total Dissolved Combustible Gas (ppm)
- Equivalent Total Combustible Gas %
- Total Gas (ppm)
- Carbon Dioxide / Carbon Monoxide
- Oxygen / Nitrogen