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On- and Offline Tests

On- and Offline PD measurements on transformers are advanced analysis methods to get further information about the life cycle condition of the insulation system. Tests after commissioning a new transformer are helpful to detect transportation damages or assembling failures for instance.

On- and Offline Tests

Testing power or distribution in the field is a demanding task for service engineers or commissioning teams today. Such tests can be done online, means the transformer is energized and connected to the grid or offline, means it is powered by a mobile power system. Both methods do have advantages and disadvantages as listed below:

Online testing:

+ Transformer is under load condition (full current)

+ Rated voltage and frequency

- No variable voltage and frequency

- Mostly no access to the transformer tank

- difficult for fault investigations

- PDIV and PDEV cannot be distinguished


Offline testing:

+ Full variable voltage and switchable frequencies