Assessment method applied to the significance of design and operational factor influence on the service life of 6 (10) kV power cable insulation in urban networks

The article deals with retrospective statistical data on failure intensity of 6 (10) kV cable lines in Neftekamsk and Chelyabinsk urban networks to show the necessity of assessment of the significance not only of regime parameters, but also of the design and operational factors accepted by the service personnel. We propose the method of assessment of the significance of these factors and algorithm of preparation and collection retrospective data for carrying out the statistical analysis. The method is implemented with the use of analysis of variance which is aimed to research the distinctions for considered groups of factors. Based on the results of research and method testing we defined the probable significant factors accompanying to regime parameters affecting the service life, for example, related to the depth and trajectory of the cable as well as the location of the cable in structure of the feeder scheme in the city distribution cable network.