If the current is zero, then the voltage drop will be zero, no matter what voltage or length and size of cable.

Nope he is referring to the voltage drop across the cable when the cable is loaded which can never be zero..

Mohd imran, I would like say check IEC standards for the voltage drop or any relevant standards in your country.. but generally I believe it should not exceed 5%

My point - the OP did not mention a load - and also asked if the voltage drop could be ignored.

GA from me on this. Is this also not a case where if one does not know these basics, he/she is unqualified to the point of being dangerous? While I understood your first answer perfectly and agree totally with both of your answers, I think the OP NEEDS a qualified person doing his specifying. Who knows what else he/she is ignoring. -- JHF

1. first size the cable based on the load current capacity

2. check the % voltage drop with in 5%

3. check the short circuit capacity is with in the cable rated value 5 cycles

4. there are many things to check. But, in your case, the 3 items are enough.

Forget volt drop - its not your major concern. HV cables are sized to withstand fault current. You can size from tables where you select a cable that will stand several thousand amps for maybe as long as 3 seconds. This is all determined by your protection settings. I would suggest you will be expecting something in the order of 185mm²

You should in the first instance contact the cable manufacturer and ask for the cable specifications, if you don't have them already.

They should have a table/graph chart showing the voltage losses per foot/meter per load(amps) at a certain temperature.

If you have this table/graph chart, then you should be able to work it our yourself.

Also you MUST take into consideration (as already stated by Sliverfox) the fault current, again the cable manufacturer will be able to advise you on this.

If you have problems understanding the manufacturers specifications & cable chart, then again contact them as it's their cable and they will know their cables better than anyone else.

volt drop really doesn't matter. Loosing 10V on an 11kV system is hardly going to dip the lights. Any shortfalls are usually sorted by tapping the transformers. Look to the current withstand. The manufacturer will advise.

The generally accepted practice is to have a maximum of 5% Steady State Voltage drop at the MCC Panel Bus bars.

Now, you decide the cable size accordingly.