Lightning Current Performance of Conventional and Enhanced Rod Ground Electrodes

David Clark, Salah Mousa, Noureddine Harid, Huw Griffiths, Abderahmane Haddad

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


The correct operation of surge arresters under lightning and switching transient conditions requires that grounding be effective at high frequencies as well as at power system frequency. Effective high frequency grounding also limits the electrocution risk to substation personnel due to transient ground potential rise. This article assesses the performance of high frequency electrodes at typical lightning impulse current magnitudes. The enhancement of such electrodes by addition of bonded horizontal arms in cross and star arrangement is also investigated. The effective impulse resistances for electrodes having lengths up to 4.8 m are calculated over a range of impulse current magnitudes at the same location. The results obtained indicate that, for low impulse current magnitudes, the preionization electrode's resistance (R1) falls with increasing rod length, a behavior reflected in the measured dc resistance. The presence of horizontal enhancement was found to reduce R1 in all cases. The occurrence of soil ionization in the immediate vicinity of the electrode resulted in a reduced postionization resistance (R2) at higher currents, tending toward a common asymptotic value independent of both the length of the rod and the presence of electrode enhancements. The observed behavior is supported by numerical simulation of electric field and current density distributions, indicating that the high current performance of a grounding rod is heavily influenced by soil ionization and breakdown in high-field regions at the electrode extremities.

Original languageBritish English
Article number9380500
Pages (from-to)1179-1188
Number of pages10
JournalIEEE Transactions on Electromagnetic Compatibility
Issue number4
StatePublished - Aug 2021


  • grounding
  • High-frequency rods
  • impulse impedance
  • lightning
  • rod electrodes
  • soil ionization


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