To study carry out at plate earthing , pipe earthing ~ MONU TUTORIALS ACADEMY

Theory

This is also one of the common system of earthing. In this case the earthing is done by embedding GI aur copper plate in the earth sufficiency deep.the size of plate used should not be less than 60 × 6.36 mm in case of GI plate.the copper and account of its high cost in not used nowadays.

A pit is pug about 4 meters Deep and the earth electrode is placed in such a way that its face is vertical. The space around that plate is filled with layers of charcoal and salt for a minimum thickness of 15 CM. The electrode aur plate is connected to GI pipe of 12.7 mm diameter for carrying GI Earth wire for connection to earth electrode.the earth wire is security bolted to the earth plate with the help of bolt nut and washer and GI thimble the detail of which is shown in the diagram.

it should be remembered that the nuts and bolts and thimble and washer not be to copper for copper plates and should be of GI for galvanised earth plate or electrode.the pit fitted with charcoal and salt is also connected with the pipe for carrying water from concrete work to a pipe for that area for the purpose of thick increasing dampness and moisture which ultimately reduce earth resistance.

Pipe earthing

Pipe earthing is used for body earthing of the equipment.

Fan pipe type earthing normal pnactive is to use GI pipe of 75 mm diameter, 10 feet long welded with 75 mm diameter, 10 feet long having 6 number of holes for the connection of earth wires and inserted in ground. This type of earth pit are generally filled with alternate layer of charcoal and salt or Earth reactivation compound.a galvanized steel and performed pipe of approved length and diameter is placed vertically in a wet soil in this kind of system of earthing.the size of pipe to use depends on the magnitude of current and the type of soil. The dimension of the pipe is is usually 40mm in diameter and 2.75 m in length for ordinary soil or greater for dry and Rocky soil. The moisture of the soil will determine the length of the pipe to be buried but usually it should be 4.75 m.

Rod earthing

It is the same method as pipe earthing.Are copper rod 12.5 mm diameter on 16 mm diameter of galvanized steel and hollow section 25 mm of GI pipe of length above 2.5 mAbu read up night in the earth manually on with the help of a pneumatic hammer.The length of embedded electrodes in the soil reduce earth resistance to are designed value.

Some important parts of earthing

Earthing conductor wire strips

It is used to connect the equipment with earthing pit. It can be a GI wire insulated wire, aluminium strips and copper strips. The size of earthing conductor wire strips depend on the fault current of the equipment system. The GI means galvanized iron.

Earth electrode

It is defined as a conductor or group of conductors in intimate contact with and providing an electrical connection to earth. Earth electrodes are of two types pipe and plates.pipe electrode is used for plate earthing and plate electrode ensure the healthiness of earthing system. Therefore the earth electrode should remain in healthy condition in the soil.

Earthing pit

an earth pit is a 3 metre deep PIT in which pipe is placed for pipe earthing on plate is placed for plate earthing. The dire of the pit for pipe should be at least 1 feet and the opening of the pit for plate arthing should be 1.5 feet ×3ft. The earth pit is filled with 150 mm 4 core and 150 mm salt layer alternately. Charcoal and salt is filled in the pit 150 mm layer surrounding the copper plate in case of plate earthing.

Earthing chamber

It is the uppermost part of the earth pit where in a funnel and fish plate are visible. Earthing conductor wire is connected with pipe plate through a fish plate.

Funnel

funnel is used for fan watering the PIT in order to keep the soil wet and wet soil keeps the resistivity of the ground at lower level.

Charcoal and salt

flow of current depend on the value of resistance of the path so far better earthing system the value of earth resistance of pit should as low as possible. The value of earth resistance depend on the resistance value of the soil. This can be achieved by mixture of equal amount of charcoal and salt. How this is achieved is given below. The function of charcoal and salt is to keep the soil wet,when salt melt drips it create motion which is observed and maintained by charcoal being a good conduct a mixture of charcoal and salt increase the conductivity area around the plate and this decrease the necessity vati of the soils.

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