The substation is combined with many electrical devices like transformers, isolators, electric lines, etc. Electrical devices are sensitive and have to protect carefully. Usually, the protector of the substation is stone. Isn't it surprising? Have you thought it should be more advanced? In the world of technology why stone is used as a protector? You will be surprised to know the fact that stone is the perfect natural protector. Today I will explain this topic to you.
The most important part is the ground potential rise (GPR)
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. This voltage GPR is equal to the maximum greed current times the grid resistance.
Step voltage: It 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 site. This can cause an electric shock to the human body. It is considered a distance of one meter between the metallic structure and the point on the ground.
Touch voltage: It can be defined as the maximum potential difference that exists between an earthed metallic structure capable to be touched by the hand and any point of the ground when a fault current flows. This prevents accidents for the daily workers in a switchyard.
As we know that step and touch voltage increases during the short circuit current and the resistivity of the stones is considerably higher than compared to other materials which can be found easily and everywhere. This is why stones are laid in the substation to reduce the step potential and touch potential in case of maintenance or working on live equipment.
Grass and tiny plants are harmful to substations. The plant makes trouble in case of rain and humidity. The dry grass may catch fire during short circuits and there are high chances of short circuits during the operation.
Stones prevent the formation of puddles of water in the switchyard which is not good for electrical devices and signs in the case of high voltage equipment.
Pebbles and stones are more shock resistant and hard compared to grass and sand therefore, it will reduce the vibration in the transformer and special cases like earthquakes, etc.
Stones in the switchyards improve the overall working conditions and smooth operation of an electric substation and protection against electric shock in the existence of proper grounding systems.
To know more: WHY STONES USED IN SUBSTATION?
Reference: https://en.wikipedia.org/wiki/Electrical_substation
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