Accelerated Charge Dissipation by Gas-Phase Fluorination on Nomex Paper

The surface charge and space charge accumulation in paper used in oil–paper insulation system may distort electric field distribution and lead to the flashover and breakdown of insulation system. In this paper, the effect of gas-phase fluorination on the surface charge and space charge characteristics of oil-impregnated Nomex paper was investigated. Nomex T410 was fluorinated at 25 °C using F2/N2 mixtures with 20% F2 in volume at 0.05 MPa for 15, 30 and 45 min. Fourier Transform Infrared Spectroscopy (FTIR) proved that the molecular chain scission and cleavage occurred during gas-phase fluorination. Furthermore, the surface charge and space charge characteristic of the original and fluorinated oil-impregnated paper were measured using an electrostatic voltmeter and Pulsed Electroacoustic (PEA) equipment respectively. Furthermore, the hole and electron trap distribution of the samples were obtained by Isothermal Surface Potential Decay (ISPD) model. The results showed that both the positive and negative charge decay rates were accelerated by gas-phase fluorination and the hole, electron trap energy and density of the fluorinated samples were reduced by fluorination. It is suggested that the space charge dissipation was also accelerated by fluorination, indicating that gas-phase fluorination is an effective approach to modify the charge dynamics of oil-impregnated Nomex paper.

[1]  Hai-Bao Mu,et al.  Effects of paper-aged state on space charge characteristics in oil-impregnated paper insulation , 2012, IEEE Transactions on Dielectrics and Electrical Insulation.

[2]  R. A. Young,et al.  Surface fluorination of paper in CF4-RF plasma environments , 2002 .

[3]  Maria Lucia Pereira da Silva,et al.  Paper surface modification by plasma deposition of double layers of organic silicon compounds , 2001 .

[4]  Takashi Maeno,et al.  Measurement of spatial charge distribution in thick dielectrics using the pulsed electroacoustic method , 1988 .

[5]  Huei-Hsiung Wang,et al.  Modification of nylon-6 with wholly rigid poly(m-phenylene isophthalamide) , 1991 .

[6]  B. X. Du,et al.  Effect of surface fluorination on space charge behavior in multilayered polyimide films , 2014, Proceedings of 2014 International Symposium on Electrical Insulating Materials.

[7]  R. Liao,et al.  Space charge behavior in multi-layer oil-paper insulation under different DC voltages and temperatures , 2010, IEEE Transactions on Dielectrics and Electrical Insulation.

[8]  Feihu Zheng,et al.  Significant suppression of space charge injection into linear low density polyethylene by surface oxyfluorination , 2009 .

[9]  M. Zahn,et al.  Kerr electro-optic field mapping study of the effect of charge injection on the impulse breakdown strength of transformer oil , 2013 .

[10]  Mohamed A. Izzularab,et al.  Dielectric and Thermal Properties of Transformer Oil Modified by Semiconductive CdS Quantum Dots , 2016, Journal of Electronic Materials.

[11]  Zhenlian An,et al.  Significantly improved charge stability of cellular polypropylene films by fluorination and subsequent annealing , 2010 .

[12]  B. X. Du,et al.  Dynamic behavior of surface charge on double-layer oil-paper insulation under pulse voltage , 2016, IEEE Transactions on Dielectrics and Electrical Insulation.

[13]  Wenxia Sima,et al.  An application area of C60: Overall improvement of insulating oil's electrical performance , 2018 .

[14]  Jianying Li,et al.  The energy distribution of trapped charges in polymers based on isothermal surface potential decay model , 2015, IEEE Transactions on Dielectrics and Electrical Insulation.

[15]  Zhenlian An,et al.  Suppression of surface charge accumulation on Al2O3-filled epoxy resin insulator under dc voltage by direct fluorination , 2015 .

[16]  B. Du,et al.  Surface charge accumulation and decay on directfluorinated oil-impregnated paper , 2016, IEEE Transactions on Dielectrics and Electrical Insulation.

[17]  Nicholas Quirke,et al.  Molecular modeling of electron traps in polymer insulators: Chemical defects and impurities , 2001 .

[18]  Yuan Song,et al.  Reliability assessment of insulation system for dry type transformers , 2013, IEEE Transactions on Dielectrics and Electrical Insulation.

[19]  Shengtao Li,et al.  Understanding the conduction and breakdown properties of polyethylene nanodielectrics: effect of deep traps , 2016, IEEE Transactions on Dielectrics and Electrical Insulation.

[20]  Chao Tang,et al.  Fabrication of Al2O3 Nano-Structure Functional Film on a Cellulose Insulation Polymer Surface and Its Space Charge Suppression Effect , 2017, Polymers.

[21]  Feipeng Wang,et al.  Influence of monodisperse Fe 3 O 4 nanoparticle size on electrical properties of vegetable oil-based nanofluids , 2015 .

[22]  Chao Tang,et al.  Thermal stability and dielectric properties of nano-SiO2-doped cellulose , 2017 .

[23]  Meng Huang,et al.  Influence of voltage reversal on space charge behavior in oil-paper insulation , 2014, IEEE Transactions on Dielectrics and Electrical Insulation.

[24]  B. X. Du,et al.  Effects of direct fluorination on charge coupling behavior of oil-paper insulation under DC and pulse voltages , 2017, IEEE Transactions on Dielectrics and Electrical Insulation.

[25]  Lijun Yang,et al.  Influence of moisture on space charge dynamics in multilayer oil-paper insulation , 2012, IEEE Transactions on Dielectrics and Electrical Insulation.

[26]  Feihu Zheng,et al.  Suppression effect of surface fluorination on charge injection into linear low density polyethylene , 2009 .

[27]  Goodarz Ahmadi,et al.  Transformer oils-based graphene quantum dots nanofluid as a new generation of highly conductive and stable coolant , 2017 .

[28]  Kai Wu,et al.  Space charge behavior in the sample with two layers of oil-immersed-paper and oil , 2014, IEEE Transactions on Dielectrics and Electrical Insulation.

[29]  Weijiang Chen,et al.  Influence of voltage reversal on space charge behavior in oil-paper insulation , 2014 .

[30]  J. A. Casado,et al.  Quantification of Kraft paper ageing in mineral oil impregnated insulation systems through mechanical characterization , 2018, Cellulose.

[31]  Dennis W. Hess,et al.  Surface modification of paper and cellulose by plasma-assisted deposition of fluorocarbon films , 2005 .

[32]  Jian Li,et al.  Enhanced Electrical Insulation and Heat Transfer Performance of Vegetable Oil Based Nanofluids , 2018 .