Research overload capability power cables medium voltage of XLPE insulation

Abstract

The modern normative approach to determining the load capacity of power cables with cross-linked polyethylene insulation is considered and the application of the model of determining the allowable current loads of a specific medium voltage cable with cross-linked polyethylene insulation to study its overload capacity in production conditions. Power cables with cross-linked polyethylene insulation have clear advantages over traditional oil-filled ones, which has led to their widespread use in all developed countries and a significant reduction in the use of other types of cable. The relevance of the study is due to changes in voltage testing methods of cables with cross-linked polyethylene insulation around the world. In stationary thermal mode (100% load factor) according to current international standards IEC (series 60287) load capacity is defined as the maximum allowable (rated) current, which depends on the thermophysical parameters of a particular cable and the normalized thermophysical parameters of the environment. The use of mathematical model is proposed, which due to the combination of structural and thermophysical parameters of a particular cable with environmental conditions during laying in air allows to determine the parameters of stationary thermal regime of the cable for any long load current. The possibility of constructing nomograms for determining the parameters of permissible loads of cables with cross-linked polyethylene insulation of medium voltage in the range of long-term current loads in operation is shown. The work is aimed at further studies of the design of the outer protective coatings of cable with cross-linked polyethylene insulation on the dynamics of its heating in order to create a method of testing the overload capacity of a particular cable with cross-linked polyethylene insulation in production conditions.