Numerical Study of Temperature Fields of Cables for Connecting Electric Motors Controlled by a Frequency Converter with Various Laying Methods

In the oil and gas industry, frequency-controlled electric motors with pulse width modulation connected through special shielded cables with a split grounding conductor are widely used. The number of such cables in the tray of tier-type drilling rigs can reach 20. With dense laying of cables loaded with rated current, the temperature of the current-carrying strands can significantly exceed the permissible values. A mathematical model is proposed for determining the temperature field of such cables with various methods of laying them under conditions of convective heat exchange with the surrounding air, taking into account current loads. The equations of thermal convection of air are considered in the Boussinesq approximation in a two-dimensional formulation. The problem was solved by the finite volume method using the ANSYS Fluent software package. The verification of the mathematical model was carried out by comparing the results of numerical and full-scale experiments for a single cable laid in an air environment at rated load current. An experimental method of laying cables in three layers was investigated; it was found that with this arrangement, the temperature of the current-carrying strands does not exceed 90°С. Correction factors for reducing the current load of cables for the considered laying methods have been determined.