Standard Test Method for the Determination of Gassing Characteristics of Insulating Liquids Under Thermal Stress

Importancia y uso:

5.1 Generation of combustible gases is used to determine the condition of oil-filled electrical apparatus. Many years of empirical evidence has yielded guidelines such as those given in IEEE C57.104, IEC 60599 and IEC 61464. Industry experience has shown that electric and thermal faults in oil-filled electrical apparatus are the usual sources that generate gases. Experience has shown that some of the gases could form in the oil due to thermal stress or as a result of contamination, without any other influences.

5.2 Some transformer oils subjected to thermal stress and oils that contain certain types of contamination may produce specific gases at lower temperatures than normally expected for their generation and hence, falsely indicate abnormal operation of the electrical apparatus. Some new oils have produced large amounts of gases, especially hydrogen, without the influence of other electrical apparatus materials or electrical stresses. This renders interpretation of the dissolved gas analysis more complicated.

5.3 Heating for 164 h has been found to be sufficient to reach a stable and characteristic gassing pattern.

5.4 This method uses both dry air and dry nitrogen as the sparging gas. This is to reflect either an electrical apparatus preservation system that allows oxygen to contact the oil or one that is sealed from the outside atmosphere. Oils sparged with air generally produce much more hydrogen as a percentage of the total combustible gas content as compared to oils sparged with nitrogen as these produce more hydrocarbons in relation to hydrogen.

Subcomité:

D27.03

Referida por:

D0117-22

Volúmen:

10.03

Número ICS:

29.040.01 (Insulating fluids in general)

Palabras clave:

combustible gases; DGA; dissolved gases; dissolved gas-in-oil; insulating oil; low temperature gassing characteristics; stray gassing; transformer oil, clay treatment;