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Gas extractions from insulating liquids – Part I

Marius Grisaru

Puni tekst: engleski pdf 1.103 Kb

str. 46-52

preuzimanja: 201



The most recent IIS reports on comparison tests for the DGA clearly indicate that the participating laboratory on average has not achieved repeatability dictated by both ASTM and IEC standards.
This may be seen in the reference IIS report 2020 [11]. Although the headspace extraction method is the most widespread extraction methodology today, other options are favoured by online and portable devices, such as membrane extraction or bubbling. For more reliable, repeatable, and versatile results for different oil types, it is preferred to choose other techniques such as vacuum extraction, total and partial. Mercury vacuum extraction is the most reliable and cost-effective method. Although mercury accidents are very rare, most western laboratories have abandoned them in favour of automatic options. Pros and cons for each option will be described herein. The gas extraction process is not a process that is in thermodynamical equilibrium, and all the gas transfers from
liquid to gas are therefore time-dependent. An exception is the total vacuum extraction by the method described in section 7.2 of IEC60567. ASTM D3612 does not include this procedure.

Ključne riječi

DGA, extraction, Henry's coefficients, Ostwald's coefficients, standardisation

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