Instrument Transformers

WHAT TECHNOLOGY ARE PRESENT AVAILABLE FOR DIAGNOSIS INCIPIENT PROBLEM IN HIGH VOLTAGE INSTRUMENT TRANSFORMERS(POTENTIAL AND CURRENT TRANSFORMERS)IN OPERATION, OTHER THAN VISUAL INSPECTION AND THERMOVION.

 

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Hypothetically you could do dissolved gas analysis on oil-insulated units, and some HV CT/PTs have oil cocks but I've never heard of it being done. There is not a lot of oil in them to sample.

 

I´ve heard there´s a new sensor to get gas from selead High Voltage Instrument Transformer to perform gas dissolved analysis in oil, without the need of taking out oil samples?
Any Help.