substation

http://www.google.com/search?sourceid=navclient&aq=0&oq=substation++design&ie=UTF-8&rlz=1T4GGLL_en&q=substation+design+guide

if you mean the the substation withstand capacity. in simple way first calculate the max load capacity amperes.

Load Amp.= max. Load Watt/√3 Voltage (3 phase system)

Load Amp.= max. Load Watt/ Voltage (1 phase system)

and then you compare with the substation busbar max. capacity where the load take the power (the percentage of busbar capacity has been used).

Load Amp./ Busbar Rated Amp. x 100% = percentage of busbar capacity has been used

and then calculate the short circuit capacity with:

Load Amp. x 8 = Amp. (usually in kA) (this is the rate short circuit capacity)

compare the short circuit capacity with the circuit breaker short circuit breaking current. If the value is not exceed the CB value is still safe to operate.

in accurate way i usually doing the load flow & short circuit analisys using ETAP software.

to calculate you will need, the datas of :

1. Transformer from the substation feeder. completed with the impedance & x/r ratio datas.

2. Cables size, core & insulation material & the lenght.

3. the substation circuit breaker

4. busbar

5. Utility grid datas or the generator

after this you can determines the load demand with many variation, on complete, automatic report.

good luck

Download " Electrical Installation Guide" from the Schneider Website. And.... study it!