Symptoms

Thursday March 9th, 2017 By seamarconi Comments are Off

Symptoms (analysis)

The specific symptom of the “SF6 in oil – Bushing seal defects” criticality is correlated with values that do not conform for the following diagnostic indicator:

SF6 in oil*

There are other co-factors useful for completing the diagnostic picture:

Dissolved water (IEC 60814)
Dissolved gases (IEC 60567) [oxygen, nitrogen, carbon dioxide, carbon monoxide, hydrogen, methane, ethane, ethylene, acetylene] with indications of C3S [propane, propylene and methylacetylene or propyne (C3H4)]
Dielectric dissipation factor (IEC 60247)
Particles (IEC 60970)

*Analysis of SF6 in oil, sampling from the oil compartment in the insulator and diagnostic interpretation of analytical results are all devoid of a valid reference method and bibliography.

Sea Marconi has developed and validated its own analytical method in-house which bypasses the technical limits that would occur by using the classic DGA. In fact, the latter cannot return the content of SF6 in oil. The reason is very technical: in fact, SF6 contaminates the catalyst of the methanator; more simply, it pushes the normal analytical system out of calibration.

The same research and development approach taken by Sea Marconi for the development of the analytical method described above has also been used to validate the diagnostic interpretation of results model. This has led to establishing what the typical values, alerts and alarms should be in relation to the concentration and speed of formation of the SF6 in oil and the profile of the other dissolved gases (DGA) for each family of equipment (in relation to the manufacturer).