Why are Stones Used in an Electrical Substation?

In an electrical substation, there are multiple devices and equipment such as transmission lines, power and distribution transformers, potential and current transformers, Isolators, etc. are grounded. Therefore, reducing the Ground Potential Rise (GPR), Step Voltage, and Touch Voltage is essential. For that, they always use stones instead of sand in Substations.

GPR is the maximum electrical potential that a substation grounding grid may attain relative to a distant grounding point assumed to be at the potential of remote earth. (as defined by IEEE Standard 80 -2000) This voltage, GPR, is equal to the maximum grid current times the grid resistance.

GPR events are a concern wherever electrical currents of large magnitude flow into the earth which in this case substation.

Step Voltage is defined as the maximum potential difference that exists between the feet when a fault current flows in the body. A particular case of step voltage is the Transferred voltage where a voltage is transferred into or out of the substation from or to a remote point external to the substation site. It is usual to consider a distance of one meter between the metallic structure and the point on the ground.

Touch voltage can be defined as the maximum potential difference that exists between an earthed metallic structure capable of being touched by the hand and any point of the ground when a fault current flows.

Step and touch voltage increases during the short circuit current. On other hand, the resistivity of stones is considerably high as compared to other materials which are sand, soil, etc. That is the main reason for laying stones or gravel in the substation to reduce the step potential and touch potential in case of maintenance or working on live equipment. This way, it reduces the risk of electric shock hazards during general maintenance and operational works.

Thanks!

Madusha Athapaththu

Related posts:

Traditional marketing is any type of marketing that is done offline to promote your products and services or to satisfy your audience’s needs and wants using offline channels like newspapers…

Total CBD RX Gummies Reviews — Anxiety, chronic agony, and depression are becoming increasingly common. These are only a few of the challenges that a typical man suffers on a daily basis as a result…

Go ahead and install your Windows 10 enterprise. Next, download the real Windows 11 drivers for the Surface Pro 8 (MSI file). Extract the MSI installer. Next open the device manager and make it…