Calculation of Molten and Broken Characteristics of ACSR Strands Due to AC Fault Arcs

Some of the strands of aluminum conductor steel reinforced (ACSR) are sometimes molten and broken by arc discharges owing to short-circuit faults of overhead transmission lines. AC arc tests have been carried out to clarify the molten and broken characteristics of ACSR strands. A lot of arc tests have to be carried out because there are many combinations of test conditions regarding the arc and ACSR (e.g., arc current and duration, size of conductor and strand). This paper describes the molten and broken characteristics of strands, which are calculated taking into account the heat transfer and its area from the arc to the strands under the above-mentioned conditions. The influence of the arc current (1-50 kA) on the molten and broken duration of all ACSR strands is calculated for ACSR of 160, 330, and 610 mm2 used in 66/77 kV overhead transmission lines. The calculation results agree approximately with the AC arc test results. Furthermore, supposing that the calculation results will be used to assist the inspection/maintenance systems of utility companies, the molten and broken characteristics of some of the strands of ACSR are also calculated.