INTRODUCTION
With the power systems becoming more and more complex, the fault levels in the system are going up. This has resulted in focusing greater attention to the healthiness of earthing system. The efficacy of an earthing system depends on various factors like resistivity of soil, duration & magnitude of fault and the maximum safe current that a human body can tolerate i.e. 116 mA for 1 sec (for 50 kg body weight) as per IEEE 80-2000. So, it is significant to do proper analysis and calculation of earthing system parameters i.e. step & touch potential, ground resistance, grid integrity etc. Once these parameters satisfy the safety requirements, the earthing system is considered adequate.
i) Older Stations: Existing earthing system adequacy in view of increasing fault level
ii) New stations: Check the grid integrity and implementation of earthing system as per design
BENEFITS OF EARTHING ASSESSMENT
i) Earthing assessment required for safety of assets and live stock
ii) It will help in design validation & benchmarking
iii) Assess the present earth grid condition for older stations
iv) Review the present practices/workmanship during erection for new stations
v) Reference for future assessment and determination of corrective actions