Scribd
Upload
43 views1 page

From Nepal

The document outlines the formulas for performing LV short circuit calculations according to the IEC 60909-0 standard, detailing the parameters involved such as voltage factors and equivalent reactances. It specifies the assumptions made for calculating total short circuit power at a grid node, including neglecting cable reduction and resistances, and using a voltage factor of 1.05. These criteria are intended for preliminary assessments, with potential optimizations during the detailed engineering phase.

Uploaded by

nakul.mehra18102024
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as DOCX, PDF, TXT or read online on Scribd
43 views1 page

From Nepal

The document outlines the formulas for performing LV short circuit calculations according to the IEC 60909-0 standard, detailing the parameters involved such as voltage factors and equivalent reactances. It specifies the assumptions made for calculating total short circuit power at a grid node, including neglecting cable reduction and resistances, and using a voltage factor of 1.05. These criteria are intended for preliminary assessments, with potential optimizations during the detailed engineering phase.

Uploaded by

nakul.mehra18102024
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as DOCX, PDF, TXT or read online on Scribd
You are on page 1/ 1

 LV short circuit calculations are performed using the following precautionary

formulas according to IEC 60909-0 standard:


c Ur
I cc ,3 p=
√ 3 x deq

3 c Ur
I cc ,1 p=
√ 3(x + x ieq + x oeq )
d
eq

Where
c voltage factor according to IEC 60909-0

Ur rated voltage [V]


❑
I cc ,3 p maximum three-phase short circuit current [A]
❑
I cc ,1 p maximum single-phase short circuit current [A]
d
x eq positive sequence equivalent reactance [Ω]
i
x eq negative sequence equivalent reactance [Ω]
o
x eq zero sequence equivalent reactance [Ω]

Total short circuit power at a specific grid node is obtained by means of


series/parallel combination of the above-mentioned component short circuit
reactance’s with reference to the worst configuration conditions.
Maximum short circuit power is calculated assuming the following precautionary
hypotheses:
 Short circuit reduction due to cables is neglected.
 Resistances are neglected.
 Sub transient reactance of generators is assumed equal to 10%;
 Voltage factor assumed is 1,05 according to IEC 60909-0 for LV systems.
 Short circuit power contribution is assumed equal to 70% of the total
supply transformer power with start-up factor equal to 6; relevant supply
transformer short circuit power reduction is neglected.
The above-mentioned criteria are assumed for preliminary scope; possible
optimization will be possible during detail engineering stage.

You might also like