EHV Transmission Distribution Planning / Design

Google can !

found this.

Wiki is also a good source. Start here.

Sounds like homework to me. As the CR4 FAQ states. Do your own homework. CR4 is not a homework cheat site.

The question you are pondering is part of the classic engineering "advantages versus disadvantages" test that anyone attempting to perform engineering must do on their own. IMHO this question is the very core of all engineering. A good engineer must be able to identify items in both categories before deciding on an engineering approach.

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This way you can do your own homework.

If it is not homework we are happy to help.

There is a good document High voltage transmission line design manual u can use that

I think there are people here who can advise better than me

Let us know if we can help

What's this for exactly as there is no single specific reference document, book or standard that can answer such a broad question (although there are many that can be of some assistance depending on what you are trying to accomplish).

What are you trying to accomplish exactly?