Lightning transient response of oil derrick and associated grounding system

Lightning seriously endanger safety operation of oil rig. The transient behaviour of oil derrick subjected to a lightning strike is investigated using the field theory approach. An oil derrick connected to two different grounding systems is studied. The lightning strike is simulated by injecting a 30kA current surge having a double exponential. Two different lightning strike scenarios are examined: (i) oil derrick with natural grounding system, (ii) oil derrick with manual grounding system. The results show that oil derrick with manual grounding system just has a little lower scalar potentials and step voltages. The reason is that the number of vertical ground rods of manual grounding system is too small and depth of burying is too shallow.