Flow electrification in high power transformers: BTA effect on pressboard degraded by electrical discharges

The flow electrification process occurring at the oil-pressboard interface in high power transformers seems to cause electrical discharge incidents and may cause failures. The goal of this experimental study is to measure and to compare the streaming current obtained from unused pressboard, pressboard artificially degraded by electrical discharges, and pressboard obtained from a damaged power transformer. The influence of additive 1,2,3 Benzotriazole (BTA) in oil is also analyzed. The results show that flow electrification is greatly increased by the degraded pressboards compared with the new one. On the other hand, adding of BTA significantly reduces flow electrification.

[1]  T. Patzek,et al.  A physicochemical explanation for flow electrification in low-conductivity liquids in contact with a corroding wall , 1996 .

[2]  Ibrahim A. Metwally,et al.  Influence of solid insulating phase on streaming electrification of transformer oil , 1997 .

[3]  Dan W. Crofts.  The static electrification phenomena in power transformers , 1986, Conference on Electrical Insulation & Dielectric Phenomena — Annual Report 1986.

[4]  Tapan Kumar Saha,et al.  Electrical and chemical diagnostics of transformers insulation. B. Accelerated aged insulation samples , 1997 .

[5]  G. Touchard.  Streaming currents developed in laminar and turbulent flows through a pipe , 1978 .

[6]  Ibrahim A. Metwally.  Characterization of static electrification in power transformers , 1996 .

[7]  Mat Darveniza,et al.  Aging of Transformer Insulation Paper , 1996 .

[8]  Markus Zahn,et al.  Flow electrification measurements of transformer insulation using a Couette flow facility , 1996 .

[9]  John Scheirs,et al.  Study of the mechanism of thermal degradation of cellulosic paper insulation in electrical transformer oil , 1998 .

[10]  J. Rungis,et al.  Electrostatic charging in transformer oils. Testing and assessment , 1994 .

[11]  J. K. Nelson,et al.  Development and calibration of a streaming electrification model for a cellulose duct , 1997 .

[12]  O. Moreau,et al.  Flow electrification in power transformers. Explanation of the wall-current measurements , 1994 .

[13]  Alexander Mamishev,et al.  Moisture equilibrium in transformer paper-oil systems , 1999 .

[14]  T. Oommen,et al.  Eelectrostatic Charging Tendency of Transformer Oils , 1984, IEEE Transactions on Power Apparatus and Systems.

[15]  J. Nelson,et al.  Method for repetitive measurement of the electrostatic charging tendency of liquid dielectrics , 1996 .

[16]  O. Moreau,et al.  Flow electrification in power transformers , 1995 .

[17]  Tapan Kumar Saha,et al.  A study of the degradation of cellulosic insulation materials in a power transformer. Part III: Degradation products of cellulose insulation paper , 1996 .

[18]  D. W. Crofts.  The electrification phenomena in power transformers , 1988 .

[20]  G. Touchard,et al.  Electrostatic charges convected by flow of dielectric liquid through pipes of different length and different radii, (Theoretical model and experimental results) , 1981 .