Why is earthing important?
Due to the miniaturisation and proliferation of electronic equipment, such as computer networks, security systems, communications, process equipment, etc.; the need for a noise free Earth is growing.
In addition to this, our electrical consumption has increased dramatically during the past decade, which means bigger loads are being handled by bigger transformers/generators which in turn means that larger potential fault currents need to be allowed for.
How do you earth something?
The term 'earthing' means trying to achieve a "connection" to earth itself...the lower the resistance between your earth system and earth (the planet!), the better the 'earth'.
So, the materials required naturally need to be highly conductive and because they are being buried in the ground, they also need to be resistant to corrosion. This is why copper is the preferred material.
The earth connection itself relies on the 'soil resistivity', which in turn is affected by several factors, namely:
Typical target values range from <1-5 ohms for a transformer or generator earth. This varies depending on the fault clearance time and the magnitude of the potential faulty current.
KEY POINT
One thing to bare in mind...the lower the desired reading the more problematic it is to achieve.
Why? Because the relationship between the reading and the amount of electrodes required to reach the reading is LOGARITHMIC!
This means for every drop in Ohmic value, you will need exponentially more electrodes to achieve it!
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Earthing...what is it?
Learn how to design better earthing systems FREE, from the best in the business!
Key point summary:
The relationship between value and no. of electrodes is NOT linear!
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