Powertech Labs is offering a new sample testing service for analysis of volatile compounds in the mineral oil of in-service power transformers. Analysis results provide insights into fault occurrence, identify and quantify degradation compounds, and help guide the most effective mitigation measures.

Degradation of Transformer Components

Components of electrical transformers naturally degrade as they age. This natural degradation is accelerated with heavier electrical loads or oscillating loads on the transformer system. If a fault occurs inside a transformer, due to localized overheating, arcing, or partial discharge, that incident can produce multiple degradation products at variable concentrations. The amount and type of compounds generated are dependent on the mode of degradation, the materials that are degrading, and the amount of energy imparted to cause the degradation.

Analysis of Volatile Compounds

Transformers are dynamic systems. During a fault, degradation occurs, and the generated compounds disperse throughout the transformer system’s components. These compounds include some of the volatile products dissolving into the system’s mineral oil. Analysis of a mineral oil sample for volatile compounds provides an indication of whether a fault or significant degradation has occurred. The volatile compounds produced, and their ratios, can help identify the type and severity of the fault. The two most common volatile compounds studied are methanol and acetone.

Through years of research, Powertech has developed an effective sample testing method to accurately identify and quantify several volatile compounds associated with transformer health. In particular, volatile analysis can help distinguish if the fault involved significant paper degradation. Since the volume of oil required for this test is small, the volatile component analysis can be performed either independently or on the oil collected for Dissolved Gas Analysis (DGA).

Volatile compound analysis of in-service mineral oil can provide a powerful tool for transformer asset assessment. The added analytical refinement provided by volatile analysis can allow users to make an informed decision about the next course of action, e.g., more frequent monitoring, a repair/replace determination, or a shutdown. The addition of volatile component analysis to a standard oil test package can also help utilities make the change from time-based to condition-based maintenance of transformers. This change can help transformer owners respond appropriately to real-time conditions in transformers, thus helping avoid failures and saving both time and costs.


Stephen Varisco – 604.590.7462
Manager, Applied Chemistry and Environment
Substations Technology & Testing

Stuart Chambers – 604.590.6614
Manager, R&D Investigations
Substations Technology & Testing