# 1-phase Short Circuit Calculation In Etap

#### nene_gu

##### Newly Registered
Dear Sir Ver,

Good day to all and especially to Sir Ver.

Sir, I need your help with regards to the above mention subject.

I am working here in saudi arabia as an electrical engineer (site).

It so happen that i visit our main opis, I saw the ETAP software used by our
Indian engineer in our opis for design.

Due to my curiosity, I take a look @ power grid editor-utility-Short Circuit (as per sample by etap)
in version 12.5. The primary voltage is 34.5kv.

SC Rating
MVAsc MVAsc X/R KAsc
3phase 1200 45 20.082

1-phase 1387.218 462.406 45 23.215
sqrt(3)Vll If Vln If

Sir, how you can compute the value of single phase short circuit in a given example.

I ask my indian fellow engineer but he is very much madamot?

Can u help me Sir?

Thanks and regards,

Nene Gu

#### ver

Staff member
From your above example, the single short circuit is already given as 23.2 kA.

You can verify this from the given values under 1-phase:
$MVA_{SC}=1387.218~MVA$ - Singple phase short circuit MVA
$Voltage=34.5~kV$ - System voltage

To calculate single phase short circuit currrent:
$I_{SC}={MVA_{SC} \over {sqrt{3} \times KV}}$

$I_{SC}={1387.218 \over {sqrt{3} \times 34.5}} = 23.2148 kA$

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#### nene_gu

##### Newly Registered
Dear Sir Ver,

How about if all the data in single phase like MVAsc, X/R and single phase short circuit are not given?

How you can compute the single MVAsc, X/R and single phase short circuit current in the above example?

Thanks and regards.

Nene Gu