Calculation of melting/breaking of GW and OPGW strands struck by DC arc discharge simulating high energy lightning

• The breaking duration of ground wire (GW) strands depending on the lightning current is calculated.
• The calculation results show a good agreement with the experimental values.
• The breaking time for the polarity of GW negative is shorter than that for the positive.
• The IEC standard testing conditions are far more severe than those of higher current and longer gap.

Some metal strands of ground wire (GW) and composite fiber-optic ground wire (OPGW) are sometimes melted and broken by high energy lightning strikes. Direct current (DC) arc tests simulating high energy lightning strikes have thus been performed to obtain the melting and breaking characteristics of these strands. In this work, calculations regarding these characteristics are performed considering the transferred heat and its area from the arc to the strands. The melting/breaking characteristics of the strands are calculated for arc currents of 0.1–100 kA, considering the current prescribed in the IEC standard and the measured actual lightning current. The calculation results of the strand-breaking duration depending on the arc current show good agreement with the experimental values obtained in DC arc tests. Furthermore, the calculation results show that the IEC standard testing conditions are far more severe than those in the cases of a higher current and longer gap.