SUBSTATION EARTHING

 

 

Step Potential- The difference in surface potential experienced by a person bridging a distance of 1m with the feet without contacting any grounded object.

 

Touch Potential- The potential difference between the ground potential rise (GPR) and the surface potential at the point where a person is standing while at the same time having a hand in contact with a grounded structure.

 

Soil Resistivity- The unit of resistivity is the ohm meter (Ω.m). This corresponds to the theoretical resistance in ohms of a cylinder of soil 1m² cross-section and 1m long.

 

Methods for testing Earth Resistance (existing electrodes)

 

  • Fall of Potential Method
  • 61.8% method
  • Clamp On test method
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    Methods for testing Soil Resistivity (no earth grid)

     

  • Wenner 4 pole method
  • Schlumberger method
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    H.V. TEST (PTY) LTD
    Specialists in High Voltage Testing & Diagnostics

     

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