Answer / nilkanth

in substation foot potential is develops between to foot.
inorder to reduce this potential the pebbles are laid as
electricity always try to flow along the surface

Answer / d k sharma

there are two terms defined regarding floor of earthing system
1. touch potential(pot b/w hand and structurals (gnd) when a person is touching a grounded body like structurals in switchyard
2. step potential(pot diff b/w the feet of a person walking in the switchyard)

now to minimize these potentials we put pebbles in place of flat flooring.

the reptiles,moisture etc. are secondary reasons...

Answer / j.i.doddamani

There are following resons
1.To Raduce the magnatic field in between ground and
conductor.
2.To Reduce the growth of gress.
3.To aviode entry of animals like Rats, sneks etc..
4.To Reduce water storage in the yard in the rainey
seansion

Answer / dinesh

In a substation the conductors will be near in distance to
the earth, so that the flux of the conductor may cause a
shock to the person who enters the substation. so in order
to increase the resistance between the earth and
conductors, pebbels or gravels are used...

Answer / umesh

Gravels / Pebbles 40mm Size should be upto 75 mm thickess
is provided through out the switch Yard for the protction
of humanbeing & material . This Stone is reduced Step
Potential & Touch Potential to protect electric sock.

Answer / abk

I too thought abt it n done research on it.......

* minimizes step ground potential

* easy to clean once there is spill of oil and any chemicals

* uniformity of design criteria based on international requirements.

Answer / arindam sarkar

AS water beneath the substation may provide condutivity for
electricity ,so pebbles are provided to break the surface
of water since water surface has high conductivity ,so that
flow of electricity is not continous.

Answer / sreenadh

we use pebbles in substation for mainly to reduce the
reptile movement,increase soil resistivity and for drying
up of transformer oil in case of any leacage.

Answer / suresh kumar

pebbles is used to maintain moister below the ground level.
good the moisture better the earthing result

Answer / sukhvinder

for reducing the ground resistance of the foot

can anybody send me syllabus of rrb section engg (electrical). and also send previous question pepar...

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