Behaviour of backfill materials for electrical grounding systems under high voltage conditions

Backfill materials like Bentonite and cement are effective in loweringgrounding resistance of electrodes for a considerable period. During lightning,switching impulses and earth fault occurrences in medium and high voltagenetworks, the grounding system needs to handle extremely high currents eitherfor a short duration or prolonged period respectively. This paper investigatesthe behaviour of bentonite, cement and sand under impulse and alternating highvoltage (50Hz) conditions. Fulguritic;formation wasobserved in all materialsunder alternating high voltage. The findings revealthat performance ofgrounding systems under high voltage conditions maysignificantly changefrom the outcomes anticipated at design stage