Short Circuit Currents Due to Thermal Instability on TR-XLPE 12/20 kV Ground Cable

Short circuit current constitutes one of the forms of disturbance on transmission system of electric energy, including transmission system through underground cable. Effects of short circuit current disturbance are, among other things: mechanical damage on cable due to electromagnetic force from repulsion between conductors or between conductor and wrapper; the sharp increased temperature due to joule heat on the conductor and wrapper causing thermal instability on the cable. This will further cause the occurrence of tree electric or the failure on insulation; the occurrence of aging on the cable. This is certainly of disadvantage since the continuity of voltage distribution may be disturbed and investment is of disadvantage. This paper explains calculation/ determination of short circuit currents by comparing two methods, namely adiabatic method and non-adiabatic method. Non-adiabatic method is applicable for all durations of short circuit. If compared to adiabatic method, non-adiabatic method will give significant addition to permissible short circuit currents in the case of choosing the type of backfill, cable burying depth, distance between cables and distance between lines