Measurement of Breakdown Electric Field Strength for Vegetation and Hydrocarbon Flames
- 1 Department of Physics, University of Botswana, Gaborone, Botswana
- 2 Department of Physics, University of Botswana, Gaborone, Botswana
- 3 Department of Physics, University of Botswana, Gaborone, Botswana
- 4 Department of Physics, University of Botswana, Gaborone, Botswana
Abstract
A significant number of fire-induced power disruptions are observed in several countries every year. The faults are normally phase-to-phase short circuiting or conductor-to-ground discharges at mid-span region of the high-voltage transmission system. In any case, the wildfire plumes provide a conductive path. The electrical conductivity is due to intense heat in combustion zone of the fire which creates ion and electrons from flame inherent particulates. Increase in the ion concentration increases the electrical conductivity of the fire plume. The main purpose of this study was to measure dielectric breakdown electric field for vegetation and hydrocarbon flames. The experimental data is needed for validation of simulation schemes which are necessary for evaluation of power grid systems reliability under extreme wildfire weather conditions. In this study, hydrocarbon and vegetation fuels were ignited in a cylindrically shaped steel burner which was fitted with type-K thermocouples to measure flame temperature. The fuels consisted of dried weeping wattle ( Peltophorum africanum ) litter, butane gas and candle wax. Two pinned copper electrodes supported by retort stands were mounted to the burner and energized to a high voltage. This generated a strong electric field sufficient to initiate dielectric breakdown in the flames. Breakdown electric field strength ( E crit ) obtained from the experiment decreased from 10.5 to 6.9 kV/cm for the flames with temperature range of 1003 to 1410 K, respectively.
- Spalding-Fecher, R., Senatla, M., Yamba, F., Lukwesa, B., Himunzowa, G., Heaps, C., Chapman, A., Mahumane, G., Tembo, B. and Nyambe, I. (2017) Electricity Supply and Demand Scenarios for Southern Africa Power Pool. Energy Policy, 101, 403-414. https://doi.org/10.1016/j.enpol.2016.10.033
- Mphale, K., Adedoyin, A., Nkoni, G., Ramaphane G., Wiston, M. and Chimidza, S. (2017) Analysis of Temperature Data in Semi-Arid Botswana: Trends and Break Points. Meteorology and Atmospheric Physics, 1-24. https://doi.org/10.1007/s00703-017-0540-y
- Minnaar, U.J., Gaunt, C.T. and Nicolls, F. (2012) Characterisation of Power Systems Events on South African Transmission Power Lines. Electric Power Systems Research, 88, 25-32. https://doi.org/10.1016/j.epsr.2012.01.015
- Robledo-Martinez, A. and Guzman, E. (1991) Dielectric Characteristics of a Model Transmission Line in the Presence of Fire. IEEE Transactions on Electrical Insulation, 26, 776-782. https://doi.org/10.1109/14.83702
- Mousa, A.M. (1990) Protecting Firemen against Fire-Induced Flashovers. IEEE Transactions on Power Delivery, 5, 297-302. https://doi.org/10.1109/61.107288
- You, F., Chen, H., Zhang, L., Zhang, Y., Zhou, J. and Zhu, J (2011) Experimental Study on Flashover of High Voltage Transmission Lines Induced by Wood Crib Fire. Proceedings of the Chinese Society of Electrical Engineering, 31, 192-197.
- Wu, T., Ruan, J., Chen, C. and Huang, D. (2011) Field Observation and Experimental Investigation on Breakdown of Air Gap of A.C. Transmission Line under Forest Fires. 2011 IEEE Power Engineering and Automation Conference (PEAM), Wuhan, 8-9 September 2011, 339-343.
- Li, P., Huang, D., Ruan, J., Wei, H., Qin, Z., Qiu, Z. and Chen, X. (2015) Study on the Dielectric Characteristics of Simulation Transmission Line Gap under Fire Conditions. Proceedings of the 2015 Annual Reports Conference on Electrical Insulation and Dielectric Phenomena, Ann Arbor, MI, 18-21 October 2015, 233-236.
- Hirano, T. (1973) Breakdown Potential of Potassium Seeded Combustion Products. Combustion and Flame, 21, 231-240. https://doi.org/10.1016/S0010-2180(73)80027-6
- Xu, K.G. (2014) Plasma Sheath Behaviour and Ionic Wind Effect in Electric Field Modified Flame. Combustion and Flame, 161, 1678-1686. https://doi.org/10.1016/j.combustflame.2013.12.008
- Messerle, H.K., Sakuntala, M. and Trung D. (1970) Arc Transition in MHD Generator. Journal of Physics D: Applied Physics, 3, 1080-1088. https://doi.org/10.1088/0022-3727/3/7/312