Have you got the chance to visit any Substation? You must have seen Stones or Gravel spread in the Switchyard. Right?
Ever wondered why the Switchyard Surface is Covered with Gravels?
Well, I’m working in 400KV Sub-station and I have explained every possible reason for it. Let’s see.!
Reasons Why We Use Stones/Gravel in Switchyard:
There are various benefits of using Stones/Gravel over the PCC (Plain Cement Concrete) in Switchyard. I’ve written the reasons into points for easy understanding. Every point is inter-related with another one. Without any further delay, Let’s Learn Why it is used in Electrical Switchyard:
#1 Gravel Increases Resistance between Our Foot and the Ground:
Substation Switchyard is already grounded by earthmates to provide a very low resistance path to the fault current to flow to the ground.
But, the Stones or Gravels are used in the Switchyard to decrease the Foot Surface Area. When the touch surface area decreases the resistance increases.
So, the main purpose of filling Switchyard with Stones/Gravels to provide an extra layer of high resistance and act as an insulator between our foot and the ground.
Thus, gravels in Switchyard increases the resistance between our foot and ground.
#2 Gravels Prevent the Accumulation of Rain Water in Switchyard:
Stones/Gravels in Switchyard prevents the accumulation of water over the PCC surface and even if some water accumulates over some part of PCC due to the non-uniform (not fully plain) surface then Gravel provides some breaks over the surface of the water.
It makes the current non-continuous through our body and finally, it increases the resistance.
Finally, the rainwater can drop faster and it doesn’t make any mud inside the Substation.
#3 Gravel Reduces Step Potential & Touch Potential when Operators Work on Switchyard.
Step and Touch potential increases during Short circuit current. Gravel/Stones in the Substation Switchyard is provided to reduce the step potential and touch potential when operators work on Switchyard.
Step Potential: It is the potential developed between the two feet on the ground of a man or animal when short circuit occurs. This results in the flow of current in the body lead to electrical shock.
Touch potential: It is the potential that is developed between the ground and the body of the equipment when a person touches the body during fault condition. When the person touches electrical equipment during short circuit condition, fault current flows through the human body. This is defined as a touch potential.
#4 Stone Prevents Vegetation & Growth of Small Weeds, Plants inside the Switchyard:
Do you know? Vegetation is already prevented by PCC and growth of small weeds and plants in the Switchyard is prevented.
But, if we don’t fill with gravels then after some days/months/years, some soils & water will accumulate in many parts on the Switchyard and grass will also grow.
Thus, Gravels prevents the growth of grass & other small plants inside the Switchyard and Substation remains nice & clean
#5 Prevents the Entry of Animals & Wildlife:
The entry of animals like Rats, Snakes, Lizards etc. are also prevented to some extent by spreading Gravels over the Switchyard surface.
#6 Improves Yard Working Condition
Gravels also improves the working condition in the Switchyard of a Substation.
#7 Protect from Fire when Oil Spillage Takes Place
In Substation, Power Transformers & Shut Reactors are filled with oil as cooling and insulating medium.
Oil leakage takes place during operation or when changing the oil in the transformer. The spillage oil which can catch fire is dangerous to the switchyard operation.
So, Stones/Gravel is provided to protect from fire when oil spillage takes place.
So, this was the top reasons why we use Stones & Gravels in the Switchyard Surface in a Substation. These are the benefits of using Gravel over the PCC surface in Switchyard.
Hope you have liked it. Please share this article with your Electrical friends to let him/her know. Share your views in comment to appreciate my work. If you know any more reason for using Gravel in Substation Switchyard then must share in the comment box, We will love to update this article.