Transformer Earthing

Hello Guest,

USING CAPITALS IN A FORUM SITUATION, is the same as shouting at the reader, and is regarded as bad manners in every Forum.

Your transformer will have a Maker's Engraved Plate attached.

Your transformer will also have a Low Voltage and Tap Changer Junction Box.

It is normal for the Makers to supply two sets of full specifications, connection diagrams etc, one via courier, and the other in the Connection/Tap changer box (Low Voltage side).

They would normally advise specifically for your installation site, because when the transformer was ordered, they would normally ask for your local conditions.

In view of the fact you have not advised what other equipment is supplied with the HV 11kV Supply, nor the actual ground conditions at the proposed installation site, it is not possible to successfully answer your question, except in an extremely general way.

Nor have you advised re type of secondary distribution: Isolated, 3 phase + Neutral, or MEN system.

Any answer given, would be a guess, and in Electrical Engineering, that is not good enough, because of the safety to people, animals and equipment involved.

Reply here, with

Kind Regards....

I am surprised some one from Mumbai asking such a question.If you do not know the basic earthing requirement how can you install a transformer. You expect some one from CR 4 to tell you the size of the copper/ aluminium strip required to connect to your earth pit. Now who will design your earth pit and how many pits are required and how much should be the earth plate size and at what depth it should be buried and how many bags of salt and charcoal to be put inside the pit, how to measure the earth value of the pit and what size of nuts and bolts to be purchased.A good electrical shop fellow knows it in Mumbai. But it is better to calculate or get from an engineer.

Hope your company has a electrical consultant if not a regular electrical engineer employed. Hope you have an electrician's licence to do electrical job. Please for heaven sake go and buy an IE rule book and BIS standard where everything is clearly given. it does not cost you more than Rs.100/- Please do not devalue the standard of Indian Engineers in front of this global body.

Very good response sir. It is realy ridiculous that such a question is being posted. You are right - he should get the basic reference books if he is doing electrical work.

It is quite probable that the person initiating the question is a civil engineer or an architect and there are many who feel that they can do all that is associated with buildings. They do not realize the aftermath of work based on half-knowledge leading to accidents - both shock as well as fires.

1) check the system fault MVA level and calculate ohomic value of Z for system and transformer.

2) calculate total Z as Zt

3) fault current Ig=3E/Zt

4) Area of copper conductor required Ig/(sqt log₁₀ ((Tm-Ta / 234+Ta)+1)/(E x S))