Design of a Hand-Held, Clamp-on, Leakage Current Sensor for High Voltage Direct Current Insulators
Leakage current monitoring for high voltage transmission line insulators is of interest as a performance indicator. Presently, to the best of our knowledge, there is no commercially available, clamp-on type, non-intrusive device for measuring leakage current on energised high voltage direct current (HVDC) transmission line insulators. The South African power utility, Eskom, is investigating the development of such a hand-held sensor for two important applications; first, for continuous real-time condition monitoring of HVDC line insulators and, second, for use by live line workers to determine if it is safe to work on energised insulators. In this paper, a DC leakage current sensor based on magnetic field sensing techniques is developed. The magnetic field sensor used in the prototype can also detect alternating current up to 5 MHz. The DC leakage current prototype detects the magnetic field associated with the current flowing on the surface of the insulator. Preliminary HVDC leakage current measurements are performed on glass insulators. The results show that the prototype can accurately measure leakage current in the specified current range of 1-200 mA. The influence of external fields from the HVDC line itself on the leakage current measurements is mitigated through a differential magnetometer sensing technique. Thus, the developed sensor can perform measurements on in-service HVDC insulators. The research contributes to the body of knowledge by providing a sensor to measure leakage current on energised HVDC insulators non-intrusively. This sensor can also be used by live line workers to inform them whether or not it is safe to perform maintenance on energized insulators.
Digital Object Identifier (DOI): doi.org/10.5281/zenodo.2021531Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 303
 W. K. Glossop, “Performance comparison of existing AC and DC transmission lines within Southern Africa with predictions for lines above 765kv”, M.S. thesis, Dept. Eng. and built environment, Univ. of Witwatersrand, Johannesburg, 2008.
 C. Zchariades, S. M. Rowland, I. Cotton, “Real-time monitoring of leakage current on insulating cross-arms in relation to local weather conditions”, Electrical Insulation Conference, Ottowa, ON, Canada, pp. 397-401, June 2013.
 L. H. Meyer, C. R. P. Oliboni, T. I. A. H. Mustafa, H. A. D. Almaguer, F. H. Molina, G. Cassel, “A study of the correlation of leakage current, humidity and temperature of 25 kV insulators in urban and rural areas”, Conference on Electrical Insulation and Dielectric Phenomena, Cancun, Mexico, pp. 398-402, October 2011.
 Suwarno, J. Parhusip, “Effects of humidity and fog conductivity on the leakage current waveforms of ceramics for outdoor insulators”, WSEAS transaction on systems, Vol. 9, Issue 4, pp. 442-452, 2010.
 Fluke. “Leakage current measurements basics”, (Online). Available: http://www.fluke.com/fluke/uses/comunidad/fluke-news-plus/articlecategories/electrical/leakagebasics.
 L. Holtzhausen, J. P. Pieterse, H. J. Vermeulen, S., Limbo, “Insulator aging tests with HVAC and HVDC excitation using the tracking wheel tester”, International Conference. on High Voltage Engineering and Application (ICHVE 2010), New Orleans, LA, USA, pp. 445-448, October 2010.
 W. H. Schwardt, J. P. Holtzhausen, W. L. Vosloo, “A Comparison between measured leakage current and surface conductivity during salt fog tests”, 7th Africon Conference in Africa, Gaborone, Botswana, pp. 597 600, September 2004.
 M. M. Werneck, D. M. dos Santos, C. C. de Carvalho, F. V. B. de Nazare, R. C. S. Allil, “Detection and monitoring of leakage currents in power transmission insulators”, IEEE sensors journal, pp. 1-9, 2014.
 A. J. Phillips, F. F. Bologna, J. M. Major, C. S. Engelbrecht, “Development and demonstration of low cost robust leakage current sensors for evaluating contaminated insulators”, Proceedings of the 16th International Symposium on High Voltage Engineering, Cape Town, South Africa, paper 5-3, pp. 1-6, August 2009.
 W. Chen, C. Yao, P. Chen, C. Sun, L. Du, R. Liao, “A new broadband microcurrent transducer for insulator leakage current monitoring system”, IEEE Trans. on Power Delivery, Vol. 23, Issue 1, pp. 355-360, 2008.
 Z. Jia, C. Chen, X., Wang, H. Lu, “Leakage current analysis on RTV coated porcelain insulators during long term fog experiments”, IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 21, Issue 4, pp. 1547-1553, 2014.
 P. J. Pieterse, A. I. Elombo, G. N. J. Mouton, H. J. Vermeulen, J. P. Holtzhausen, W. L. Vosloo, “A coastal insulator pollution test station for the evaluation of the relative ageing performance of power line insulators under AC and DC voltage”, Proceedings of the 17th International Symposium on High Voltage Engineering, Hannover, Germany, C-007, pp. 1-5, August 2011.
 A. I. Elombo, J. P. Haultzhausen, H. J. Vermeulen, P. J. Pieterse, W. L. Vosloo, “Comparative evaluation of the leakage current and aging performance of HTV SR insulators of different creepage lengths when energised by AC, DC+, DC- in a severe marine environment”, IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 20, Issue 2, pp. 421-428, 2013.
 M. Roman, R. R. van Zyl, N. Parus, N. Mahatho, “A novel technique for measuring HVDC insulator leakage current using magnetic field sensors”, The 19th International Symposium on High Voltage Engineering, http://www.zcu.cz/pracoviste/vyd/online/FEL_ISH_2015_Proceedings.zip, OF1, ID-36, Pilsen, Czech Republic, pp. 1-6, August 2015.
 M. Roman, R. R. van Zyl, N. Parus, N. Mahatho, “Insulator leakage current monitoring: challenges for high voltage direct current transmission lines”, in Industrial and Commercial Use of Energy (ICUE), Cape Town, South Africa, pp. 1-7, August 2014.
 J. Sarkar, R. Patil. “Detection of partial discharges occurring in HVDC environment”, International journal of innovative science, engineering and technology, Vol. 1, Issue 4, pp. 424-428, 2014.
 A. J. Otto, H. C. Reader. “Wideband and narrowband HVDC conductor corona test methods for radio noise prediction”, IEEE Trans. on Power Delivery, Vol. 25, No. 4, pp. 2950-2957, 2010.
 E. Matandirotya, P. J. Cilliers, R.R. van Zyl R. “Methods of measuring and modelling geomagnetically induced currents (GICs) in a power line”, Proceedings of SAIP2013, the 58th Annual Conference of the South African Institute of Physics, edited by Roelf Botha and Thulani Jili (SAIP and University of Zululand), pp. 410-415, July 2013.