Different microscopic features of AC and DC electrical trees in insulating polymer

The understanding of electrical trees plays a crucial role in the development of reliable high voltage power systems. The AC electrical trees are different from DC ones, however, there are only limited studies dealing with this topic. For the first time, the differences between AC and DC trees are carefully compared in a systematic way. A photomultiplier tube (PMT) was used to collect the electroluminescence (EL) during the AC and DC tree initiation. Optical microscope, CCD camera and scanning electron microscope (SEM) were employed to image the micro-morphology during the electrical tree initiation and propagation. Ageing characteristics were acquired by the confocal Raman spectrometer and infrared thermal imaging. The experimental results indicated that the initiation and propagation of AC and DC trees are totally different. Based on these, the growth mechanisms of AC and DC trees have been proposed, which provides a better understanding of the electrical treeing processes.

[1]  John C. Fothergill,et al.  Photoluminescence, recombination induced luminescence and electroluminescence in epoxy resin. , 2001 .

[2]  John C. Fothergill,et al.  Electrical degradation and breakdown in polymers , 1992 .

[3]  K. Fukunaga,et al.  Behaviour of space charge correlated with electroluminescence in cross-linked polyethylene , 2004 .

[4]  Ute Ebert,et al.  Growing discharge trees with self-consistent charge transport: the collective dynamics of streamers , 2013, 1307.2378.

[5]  J. V. Champion,et al.  The correlation between the partial discharge behaviour and the spatial and temporal development of electrical trees grown in an epoxy resin , 1996 .

[6]  A. Diaz,et al.  Three-Dimensional Nanometer Features of Direct Current Electrical Trees in Low-Density Polyethylene. , 2017, Nano letters.

[7]  Jiandong Wu,et al.  Characteristics of initial trees of 30 to 60 μm length in epoxy/silica nanocomposite , 2012, IEEE Transactions on Dielectrics and Electrical Insulation.

[8]  R. J. Densley,et al.  Degradation of polymeric insulation due to photoemission caused by high electric fields , 1989 .

[9]  G. Chen,et al.  Electrical treeing characteristics in XLPE power cable insulation in frequency range between 20 and 500 Hz , 2009, IEEE Transactions on Dielectrics and Electrical Insulation.

[10]  A. Vaughan,et al.  On the structure and chemistry of electrical trees in polyethylene , 2006 .

[11]  C. Laurent,et al.  Ac and dc electroluminescence in insulating polymers and implication for electrical ageing , 2001 .

[12]  N. Shimizu,et al.  Electrical tree initiation , 1998 .

[13]  Ying Liu,et al.  Electrical tree growth characteristics in XLPE cable insulation under DC voltage conditions , 2015, IEEE Transactions on Dielectrics and Electrical Insulation.

[14]  Antonio Zaopo,et al.  Mechanism of electrical degradation and breakdown of insulating polymers , 2003 .

[15]  Toshikatsu Tanaka,et al.  Charge transfer and tree initiation in polyethylene subjected to AC voltage stress , 1992 .

[16]  Sang-wook Kim,et al.  Electrical tree initiation mechanism of artificial defects filled XLPE , 1998 .

[17]  Philip J. Withers,et al.  Imaging and analysis techniques for electrical trees using X-ray computed tomography , 2014, IEEE Transactions on Dielectrics and Electrical Insulation.

[18]  C. Laurent,et al.  Optical emission due to space charge effects in electrically stressed polymers , 1997 .

[19]  G. Stevens,et al.  Long-term light emission measurement and imaging during the early stages of electrical breakdown in epoxy resin , 1994 .

[20]  L. A. Dissado,et al.  Effect of tree channel conductivity on electrical tree shape and breakdown in XLPE cable insulation samples , 2011, IEEE Transactions on Dielectrics and Electrical Insulation.

[21]  Len A. Dissado,et al.  Understanding electrical trees in solids: from experiment to theory , 2001, ICSD'01. Proceedings of the 20001 IEEE 7th International Conference on Solid Dielectrics (Cat. No.01CH37117).

[22]  G. Montanari,et al.  Electrical Trees in Solids , 1999 .

[23]  L.A. Dissado,et al.  Model for electrical tree initiation in epoxy resin , 2005, IEEE Transactions on Dielectrics and Electrical Insulation.

[24]  J. Robertson,et al.  Raman spectroscopy of amorphous, nanostructured, diamond–like carbon, and nanodiamond , 2004, Philosophical Transactions of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences.