An ultrasonic evaluation for degradation of insulating oil using fuzzy inference

Periodic inspection for degradation of insulating oil in transformers requires from preventing outage. However, conventional methods were not suitable for that, due to large size of the measurement system and requirement of sampling. This study aims to develop ultrasonic evaluation system satisfying these requirements aided by fuzzy interference. The system evaluates degradation, and it estimates kinetic viscosity. In the experiment, we applied our method into six kinds of insulating oils. As a result, correlation coefficient between our estimation and viscometer were over 0.92. thus, our method correctly determines degradation of insulating oil.