Earthing For 300 KVA DG

Almost all calculations require the value of your soil resistivity ? Ohm/centimeters

You need to measure it and post it. Along with the type of soil and moisture content information. Please define your terms body and earth pits. They are not (normally) used in US engineering terminology.

Then perhaps we may be able to help you...

Why are not all grounds bonded together at this point. (this is a point of generation, not a customer load point.

Snakers

Number of earth pits depends on the soil resistivity and the moisture content in the soil.

As per Indian regulations the distance between earth pits should be 3050mm and the earth pit away from the building structure should be 1525mm.

Geetha

You have not indicated the countery of yours.You need to refer your local earthing code.each countery will have its codes.

crm

I'm not sure you need to earth the neutral. Someone smarter than me should comment. Typically I don't earth the neutral of DGs, even 30 kW to 5 MW. For 'earth' earthing in dry soil, consider a Ufer Ground. To measure the earth resistance you need a special clamp on earth Resistance tester. For earth rods they need to be more than 2 meters apart, connected to each other then on-wards to the frame of the DG, and frame of the generator can, by exothermic weld connections for perfect conductivity.

if you dont earth the neutral, there is no ground return path to operate any GFI (ground fault interruper) or ground sensing relay in the system. This may become a safety related issue, depending on the codes for your area and country.

Snakers

You can go for pipe type earth station as per IS 3043 OR IEEE 80 fro constaint of space. You can bore the earth and carry out the installation.

Copper / or other metal is to be consided to be resistat to corrosion in the type of soil, the important factor is the restance should be minimum so that the fault current is clear in safe time.

The earth condition is important.

nacon

i agree both IEEE 80 and IS 3043 are the referance documents for DG earthing.At the same time soil chemistery report of your site is very impartent.

crm

the distance between two earth pit is 1.5 times of the length of electrode.