Which short circuit level can I assume for a 13.2 kV line?

[Dvhez]

I'm designing a project where the only information I have is the voltage level. Which short circuit level and X/R ratio can I safely assume in order to make a power flow and short circuit study in etap?

 

[iceworm]

Which short circuit level and X/R ratio can I safely assume

You can't.
The levels sort of depend on the utility/generation MVA and the transformer impedance.
Okay, that's wrong
The levels absolutely depend on the utility/generation MVA and the transformer impedance.

Harmless flakes working together can unleash an avalanche of destruction

 

[Dvhez]

Thanks for your answer!. So in other words the best we can do is to design a project assuming an infinite bus? As we don't know how 'strong' is the PCC we cannot assume a lower value.

 

[iceworm]

One of my clients has a 138kv service 385 MVA. The client owns the xfm,13.8kv, 20 MVA, 8%
Another has 69KV service, 100MVA, xfm 13.8kv, 20MVA, 8%Z.

These are both really little utilities and the clients are at the end of a long line. The xfm impedance pretty well overwhelms the effect of the utility. So, if the transformer data is available, proceed as you said - infinite bus and have at it.

And I'm thinking you already knew this. Was there some other issue in question?

Aside:
If you don't have it, get the Moon Yen paper on calculating SCC. IEEE will have it. It is from the 70s.

But wait, I have ETAP, why would I need some cobweb paper from the dark ages.
I have ETAP as well. And, there are still some times when it is convenient to do an SCC calc without taking a couple of hours to set it up in ETAP.

Harmless flakes working together can unleash an avalanche of destruction

 

[7anoter4]

According to IEC 60076-5/2000 Power transformers –
Part 5:
Ability to withstand short circuit
Table 2 – Short-circuit apparent power of the system
For system voltages between 7.2 to 24 kV 500 MVA is recommended.
This is the three-phase short-circuit at terminals of 55 MVA and 11% short-circuit impedance at 13.2 kV. If the apparent rated power of a transformer will be 20 MVA and 8% impedance the short-circuit power will be 250 MVA only.
X/R it could be as per ANSI 37.10 [for 55 MVA 30-32 and for 20 MVA 22]