Awareness of step potential and touch potential risks, caused by an earth potential rise. Is vital for anyone working on high-voltage power transmission. Also, distribution systems above 1 kV.
Earth Potential Rise
Earth Potential Rise (EPR) is caused by electrical faults that occur at
- electrical substations,
- power plants,
- or high-voltage transmission lines.
Therefore short-circuit current flows through the plant structure and equipment and into the earthing electrode.
Since the Soil Resistivity is not zero. Therefore, any current injected into the earth at the earth electrode produces a Rise of Earth Potential. This EPR earth potential rise is concerning an infinitely distant reference point. The resulting EPR earth potential rise can cause hazardous voltage, many hundreds of metres away from the actual fault location. However, many factors determine the level of hazard. Including available fault current. Also, soil type, soil moisture, temperature, underlying rock layers. And the clearing time to interrupt the fault.[Read more…] about What is Step and Touch Potential And How Can You Reduce its Risk?