GreyMatters

Electrical Earthing System Design & Soil Resistivity Testing

Home » EPR

EPR

By Leave a Comment

Rise of Earth Potential (RoEP) Know the Risks

Awareness of step and touch potential, caused by a rise of earth potential. Is essential for anyone working on high-voltage power transmission and distribution systems above 1 kV.

A rise of earth potential

A rise of earth potential 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 earth potential rise (EPR) is concerning an infinitely distant reference point. The resulting rise of earth potential can cause hazardous voltage. And, many hundreds of metres away from the actual fault location. Thus, many factors determine the level of hazard. Including available fault current. And, soil type, soil moisture, temperature, underlying rock layers. Also, clearing time to interrupt the fault.

[Read more…] about Rise of Earth Potential (RoEP) Know the Risks

By Leave a Comment

Earthing Calculations for Safe System Design

Earthing Calculations regarding your safety – you’re overdue an update!

If 1-ohm is still in circulation on your documentation then this section applies to you.

Even though the Earthing Calculations for determining a safe System Earth (Ground) has shifted away from an arbitrary resistance figure, usually <1 ohm.  It’s still all too common to see this outdated measure of installed success appear on client/employer requirement specifications(ER’s). As part of the Earthing Calculations Design Safety brief.

[Read more…] about Earthing Calculations for Safe System Design

By Leave a Comment

What is Step and Touch Potential And How Can You Reduce its Risk?

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 an imbalance of electrical charges between the earth and an electrical system, it can 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. 

This imbalance can be caused by a variety of factors, including:

[Read more…] about What is Step and Touch Potential And How Can You Reduce its Risk?

By Leave a Comment

Myth Busting – 5 reasons why a hot-site does not mean it’s a dangerous site!

What is ‘HOT-ZONE’ or ‘Hot-Site’?

There are so many misconceptions surrounding the whole concept of a‘Hot-Site’ and ‘Hot-Zoning’ for Electrical Earthing Designs.  In this article, I attempt to simplify what ‘Hot Zone’ (or Hot Site) means in Power System terms AND crucially, explain what a ‘Hot Zone’ is not.

By the end of this article, you should hopefully understand that just because a site classified as a ‘Hot Site’. It does not mean it is necessarily unsafe.

[Read more…] about Myth Busting – 5 reasons why a hot-site does not mean it’s a dangerous site!

By Leave a Comment

When Electrical Earthing Science Actually Works

Electrical Earthing Science…

On a recent generation project, there was a need to connect a partially completed system to the network as part of a staged commissioning. This meant that the full electrical earthing system had not been fully installed. [Read more…] about When Electrical Earthing Science Actually Works