Using the recovery voltage method to evaluate aging in oil-paper insulation

The recovery voltage method (RVM) provides detailed information about the aging process of oil-paper insulation. Regular testing (e.g. every 1-3 years) with RVM supports: tracking the measured transformer's aging; comparison between transformers; planning of maintenance or further use. The measured values from an RVM test provide a characteristic of the current state of the insulation regardless of whether standard or non-standard curves are produced. The correct interpretation of the result depends, however, on the form of the curve and requires more knowledge and experience in the case of non-standard curves.