Correlation Between Online Partial Discharge Intensity (PDI) Using RTD Sensor And Voltage Breakdown Test At 30 Years Large Turbo Generator

Abstract

Inner Cooled Hydrogen Generator 474 MVA 23 kV Single Vapor Pre-Impregnated Insulation (VPI) has been operated from 1988 with average capacity factor more than 80% annually. In 2014, Partial Discharge Intensity (PDI) reached an alarming state on RTD no 8B slot 19 of 30 (phase B) and 12A slot 29 of 30 (phase A). The testing and justification from manufacturers showed that the activity of Partial Discharge (PD) is categorized to HIGH level. This paper proposed a correlation between indication of HIGH PDI and breakdown voltage value. Value of PDI from the 30 years operated bars has been compared with PDI value from the new bars. The result shows the PDI level of old bars lower than new bars, however, both of its breakdown voltage are similar. This result shows that HIGH PDI level has low correlation with voltage breakdown threshold. Hence, it is needed to redefine the level of PDI which contribute to voltage breakdown value