Comparison among different diagnostic systems for medium voltage cable lines

Abstract

The progressive liberalization of the market of electric power gives the user new opportunities in terms of selection of electrical and integrated services providers and motivates electric companies to increase the quality of services offered limiting their costs. In the medium voltage distribution networks, one of the most effective technical drivers to reach a higher level of power quality is the optimization of the cable network operation; this can be achieved through the application of diagnostic tools able of monitoring the conditions of cables and giving necessary indication to extend the expected life of lines, optimize maintenance operations and schedule, thus increasing their productivity. In the specific situation of Italy, where the presence of historic sites, medieval towns and incomparable landscapes are major restraints for the system operator, any preventive maintenance must be well documented and the selection of suitable cable diagnostic systems must be based on the firm belief that the line condition measured is credible, that the diagnostic process has not damaged or aged the tested line and, last but not least, that the system selected can be driven to the site without being blocked into small medieval roads. With this goal in mind, a collaboration between ENEL Distribuzione and CESI has been set up. In particular, a systematic comparison of the most advanced medium voltage cables diagnostic systems available on the market has been carried out, both in laboratory on short cables with simulated defects and in the field on real cables representative of several typical situations: the main results and findings are reported and discussed in this paper. The work reported in the paper addresses only the methods and systems aimed at identifying the presence and the position of specific weak points in cable lines; we do not consider here the integral methods, aimed at checking the overall conditions of the cable insulation, even if the experience in the application of such integral condition assessment techniques has proven to give irreplaceable information. The techniques experimented in the work documented hereafter are considered as complementary to the integral ones and not replacing them. N.4 medium voltage cable diagnostic systems were considered in the program. They were

Review on Detection and Analysis of Partial Discharge along Power Cables

“…A test on XLPE material showed that although differences are limited, PDIV seems to be lower when testing with a lower frequency rather than a higher one [88]. Field experiences (paper, EPR, and XLPE cable) [99] showed that neither 0. Energies 2021, 14, x FOR PEER REVIEW 8 of 21 circumstances.…”

“…A test on XLPE material showed that although differences are limited, PDIV seems to be lower when testing with a lower frequency rather than a higher one [88]. Field experiences (paper, EPR, and XLPE cable) [99] showed that neither 0.1 Hz nor DAC can always give close inception PD voltage compared with 50 Hz and the maximum difference is about 200%. The PD tests mentioned above are summarized in Table 3.…”

Напрями Удосконалення Засобів Моніторингу Технічного Стану Силових Кабельних Ліній Систем Електропостачання Військових Аеродромів

“…Величина випробувальної напруги перевищує величину робочої напруги кабелю в 2-6 разів, що може призвести до пробою ізоляції кабелю, який не мав небезпечних дефектів і в нормальних умовах міг би ще працювати певний час. В літературі [4][5][6][7][8][9] розглядаються сучасні способи та засоби періодичного та безперервного неруйнівного контролю технічного стану силових КЛ, однак можливість їх застосування для моніторингу високовольтних та низьковольтних кабелів систем електропостачання військових аеродромів до кінця не досліджена.…”

Advanced solution for on-site diagnosis of distribution power cables

“…The physics and causes for PD defects in XLPE and PILC cable systems is mainly well known and described in detail in several publications [1][2][3][4][5].…”