Behavior of post insulators during UHV dc test

This paper presents experimental results on post insulators subjected to ultra high dc voltages in the range of 1 to 4.8 MV. The behavior of new and aged insulators has been studied recently during diagnostic and accelerated aging tests, in order to characterize both their withstand and recovery voltages, as well as estimate their remaining life time. Estimation of their remaining life time enables a better prediction of maintenance intervals, thus avoiding unnecessary and costly downtime periods. Measurements of the recovery voltage also have been performed on insulators presenting defects, following dielectric failure in service. The results of the accelerated aging tests carried out demonstrates a faster assessment of the post insulators performance.