Design Specification of any Substation Based Upon IEC Publication

Was there a drawing with you're homework?

You're question is still meaningless

Hopefully tthere are IEC standard for Substation Installation which show busbar/substation voltage and recommanded specification for each voltage as i have shown to u.

Why are you using so many voltages and voltage conversions, do you not have even a basic idea and are just listing all the variations you can think of?

With so little information supplied and such a broad question asked, an answer cannot be given. Given your previous questions regarding substation equipment selection and VAR explanation, and your mention that you are a Hydro Engineer it appears you really shouldn't be doing this.

If you are not qualified to perform a feasibility study then you shouldn't be doing it (unless this is homework). Hire an engineering consultancy firm to perform this for you if you don't know where to start, otherwise you could face stiff legal prosecution if anything goes wrong.

But its necessary to answer if u know ,dont demoralize other who whant to share with us plse

But its necessary to answer if u know

For you to keep your job or pass whatever homework assignment you are doing then probably, but what have you done yourself so far other than ask us broad questions on something that should be done by a paid consultancy department? Do you even have copies of the appropriate standards to form the specification?

There are legal considerations to take into account for people offering advice in this situation, so don't expect a detailed answer from those of us that could offer it even if you provided all the necessary information.

Hire a consultant to do this for you. You say you are a maintenance Engineer at a Hydro plant, you should know better.

The question should read and I quote, "I have some home work that I do not understand. I would like someone to help me to understand"

Thank you for your kindness in sharing your knowledge.