Streaming electrification dynamics in oil/cellulose systems

Streaming electrification phenomena have been blamed for the failure of over two dozen large power transformers, and the list continues to grow. While streaming electrification actually occurs in all oil filled transformers to one degree or another, the occurence of failures as a result of this effect has been sporadic and very difficult to predict. One commonality among most of these failures is the occurrence of the failure within several hours of the initiation of forced flow. This suggests that for predicting and avoiding failure modes, the electrification dynamics may be much more important than steady-state conditions. In consideration of that fact, a study was undertaken to investigate the dynamics of streaming electrification. That study, the results of which are presented in this paper, revealed the existence of at least two dynamics. Data is presented and the natures of the dynamics, together with the implication of the findings, are discussed