Experimental and numerical studies of current load in power supply cables, depending on layout conditions

Abstract

A laboratory setup that simulates a variety of ways to lay cables in beams is designed and constructed for the experimental determination of current loads in the cables. The conductors of the test cable form a shading coil, which is a current transformer secondary winding. The required value of current in the cables is provided by the laboratory autotransformer. The temperature in the center of the cable beam is measured with a thermocouple. Numerical studies of heat-mass exchange processes in the cables are performed using mathematical models that take into account the natural air convection and heat radiation. The mathematical description of convective processes is considered in the Boussinesq approximation and based on the laws of conservation of energy, mass, and linear momentum. The problem of heat conduction of cables is solved together with the problem of convective heat exchange of the air flow in the cable channel. The resulting system of differential equations, which describes the thermal processes in the liable channel, is supplemented by the appropriate boundary conditions. The problem is numerically solved in the ANSYS simulation software. Four ways to lay cables in the beams, each of which is loaded with five different currents, is considered. The coincidence of the mathematical model to real processes is confirmed by the comparing the experimentally measured temperatures on the surface of the cable in the beam center with the results. The difference between the experimental and numerical data does not exceed 11%. The allowable current loads in the cables in the different layout variants are determined by a mathematical model with using an iterative procedure. It is noted that the allowed current load of the cable lines in many ways depends on the cables disposition in the beams.