Ok, you don’t need to be an Electrical Engineer to ask yourself that, Why They Use Stone in Outdoor Electrical Substation? But if you are an Electrical Engineer then you may need to answer this type of question to anyone.
I got one question like this from my top management that, Why We Will Use 2-2.5 inch size Stone and Why Not 0.5-1 inch Stone? In this post I will discuss “Why We Use Stone in Outdoor Electrical Substation?”
First of all we use stone in our electrical substation for reducing the Ground Potential Rise (GPR) and in electrical engineering it also called Earth Potential Rise (EPR) and it occurs when a large current flows to earth through earth grid impedance.
Stone increase resistance of soil for this reason step potential and the touch potential limit decrease. When people are working in substations stone reduces the possibility of electric shock during work.
Generally when we design an electrical substation that time step potential and touch potential is one of our first parity. Because there is no compromise with safety. If there is any small glitch then percentage of electrical shock will increase and we really don’t want that to happen with us.
Step Potential: The amount of potential present between a two or four legged animal is called step potential. If there is imbalance potential on substation areas and if we stand that place then between our two legs we will have a potential difference and this is the real step potential.
Touch Potential: When a person stand on ground and touch a machine then the potential between his hand and leg called touch potential.
Now there are some others and different benefit that we can get by using stone in electrical substation.
- By using stone in substation grass and weed does not grow, so it remains nice and clean for perfect visual observation from outside.
- Stone reduce the potential movement of wild animals like snakes, frogs, rats etc. For this reason it decreases the risk of short circuits when substation is operational.
- Rain water can drop fast so that it does make any mud inside the substation.
- If there is any oil fall from power transformers or circuit breakers then oil do not stay there if substation ground is covered by stone. But it also creates some problem. If you can’t see any oil under the transformer when there is an oil leakage then you may think everything is alright. So check the transformer oil reserve tank indicator during physical inspection.
- If we compare with concrete casting using stone in substation is cheap and remain clean.
- Stone can carry much higher capacity weight.
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