Base/P.U. calcs

[Redskinsdb21]

I have a problem statement:

A system has S_base = 100 MVA, calculate the base current for V_Base = kV 230.

They calculate it:

I_Base = (100 MVA* 1000) / ( sqrt (3) * 230 kV) = 251 amps......

The statement doesnt say its 3 phase...so I went I_Base = (1000 * 100 MVA) / 230 Kv = 434 amps

so which is correct?

 

[Flyer_PE]

Even though they don't state it, if it's 100 MVA, it's pretty much certain that it's a 3-phase system.

 

[Redskinsdb21]

I understand that...but am I right in my thinking of how to do it if its 3 phase or single phase is the question?

 

[Wael]

Ill echo what Flyer mentioned: for such high Voltage and Load, you can tell that it is 3 phase system.

 

[Redskinsdb21]

Even though they don't state it, if it's 100 MVA, it's pretty much certain that it's a 3-phase system.

If it were 1-phase, did I do it correctly?

 

[Flyer_PE]

^Yes. A single phase 100 MVA load at 230 kV will draw 434 Amps.