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The Role of the Accumulated Surface Charge on Nanoparticles in Improving the Breakdown Strength of Liquid and Solid Insulation
 
 
Article

The Influence of Diethylaniline and Toluene on the Streamer Propagation in Cyclohexane between a Point-Plane Gap under Positive Impulse Voltage Stress

1
School of Electrical and Information Engineering, University of the Witwatersrand, Johannesburg 2000, South Africa
2
DSI-NRF Centre of Excellence in Strong Materials and Materials Research Institute, School of Chemistry, University of the Witwatersrand, Johannesburg 2000, South Africa
3
National Institute for Space Research, São José dos Campos 12227-010, Brazil
*
Author to whom correspondence should be addressed.
Academic Editor: Ayman El-Hag
Energies 2022, 15(13), 4861; https://doi.org/10.3390/en15134861
Received: 27 April 2022 / Revised: 1 June 2022 / Accepted: 2 June 2022 / Published: 2 July 2022
(This article belongs to the Section F6: High Voltage)
Liquid insulation is used in high voltage equipment such as power transformers as both dielectric medium and coolant. Breakdown in liquid insulation tends to be governed either by streamer initiation under more uniform fields, or by streamer propagation under more non-uniform fields. A model streamer propagation study, which screens the effectiveness of additives based on cyclohexane and mixtures with diethylaniline (DEA) and toluene, is presented in this paper. The effect of additives, at different concentrations, on streamer propagation velocity in cyclohexane under an applied lightning impulse voltage of positive polarity is studied. Cyclohexane (ionisation potential 9.88 eV) was chosen because, being a hydrocarbon, it shares similarities with the constituents of common insulating liquids. Previous studies have also shown how, in general, the addition of additives of lower ionization potential than the bulk liquid can slow down streamer propagation in insulating liquids. A point-plane electrode configuration of 70 mm gap with a 5 μm tip radius is used and subjected to an applied positive polarity impulse of 1.2/50 μs. A high velocity imaging system is also used to capture streamer images to validate a Time-To-Breakdown (TTB) measurement approach used in inferring approximate streamer velocity. The DEA (ionisation potential 6.98 eV) was found to be an effective additive to slow down positive polarity streamers in cyclohexane in the applied voltage range (≈220–280 kV peak) in concentrations above approximately 0.33% (by volume). Toluene (ionisation potential 8.82 eV) was found not to significantly slow down streamers in cyclohexane, even at 10% concentration, for the same voltage range. This is postulated to be due to the fact that toluene does not have a low enough ionisation potential (with respect to that of the cyclohexane) to change the streamer branching characteristics sufficiently during propagation. View Full-Text
Keywords: streamer; propagation; cyclohexane; additives; high-speed imaging streamer; propagation; cyclohexane; additives; high-speed imaging
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MDPI and ACS Style

Wolmarans, C.P.; Nyamupangedengu, C.; Schumann, C.; Coville, N.J.; Saba, M.M.F. The Influence of Diethylaniline and Toluene on the Streamer Propagation in Cyclohexane between a Point-Plane Gap under Positive Impulse Voltage Stress. Energies 2022, 15, 4861. https://doi.org/10.3390/en15134861

AMA Style

Wolmarans CP, Nyamupangedengu C, Schumann C, Coville NJ, Saba MMF. The Influence of Diethylaniline and Toluene on the Streamer Propagation in Cyclohexane between a Point-Plane Gap under Positive Impulse Voltage Stress. Energies. 2022; 15(13):4861. https://doi.org/10.3390/en15134861

Chicago/Turabian Style

Wolmarans, Carl P., Cuthbert Nyamupangedengu, Carina Schumann, Neil J. Coville, and Marcelo M. F. Saba. 2022. "The Influence of Diethylaniline and Toluene on the Streamer Propagation in Cyclohexane between a Point-Plane Gap under Positive Impulse Voltage Stress" Energies 15, no. 13: 4861. https://doi.org/10.3390/en15134861

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