Sadales tikls AS Five most used MV cable type permissible loading possibilities at a critical environment in dependence of conductor temperature

Abstract

The paper presents results of Latvian distribution system operator Sadales tikls AS (ST), Riga Technical University (RTU) and Latvian transmission system operator Augstsprieguma tikls AS (AS) joint research to determine the maximum permissible loading level of five ST most used 10 kV and 20 kV cable types and development of MV cable loading control methodology which includes development of maximum achievable cable conductor temperature prediction model for n − 1 conditions (broken one MV network element). At AS laboratory five most used ST MV cable type samples were protractedly loaded at a special test bed to simulate most critical ambient environment conditions of operating cables from the heating point of view with currents from 0.3 I n to 1.1 I n to imitate normal and n − 1 conditions in the electrical network. Experimentally gained temperature measurement data was used to develop mathematical models for MV cable sheath and conductor temperature prediction in dependence of load current, loading duration and different ambient environment (air, spray foam, soil).