Advancements in Dissolved Gas Analysis: NEI & Gassing Events

Normalized Energy Intensity chart

One of the most important steps when looking at DGA data is to decide whether the data support the existence of a fault that is actively breaking down the insulation before you try to use a triangle, pentagon, or gas ratio method to identify a fault type. Otherwise, you are diagnosing random measurement noise, not the transformer. Conventional methods assign limits to each of the gases to detect and assess abnormal gas formation. Formerly it was common practice to add gas concentrations together to get total dissolved combustible gas (TDCG). The hope was to simplify the task of detecting abnormal gas production and interpreting rates of change. This, however, was equivalent to counting U.S. Dollars, Mexican Pesos, Bitcoins, and Canadian Loonies and thinking that the sum represented “value”.
Chemistry dictates that each gas we observe requires a different amount of energy to break away from the original insulating material. Instead of trying to interpret several indi¬vidual gas concentrations, why not follow the energy associ¬ated with the gassing? The energies required to form the gas can be weighted by the gas concentrations and added up.

Read full article in the SPECIAL TRANSFORMERS ISSUE.

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