Earthing cables acc. to IEC61230

[hhhansen]

Hello everyone
IEC 61230 states to Apply a peak current factor of 2,5 for the peak sc. current. From grid study analysis of the utility grid the R/X short circuit ratio is close to zero. Thus the peak current factor theoretically reaches 2x sqrt(2)=2,83.
I am a little confused as why IEC tends to define a factor of 2,5 potentially leading to unsufficient
sizing of the esrthing cables.
Feel free sharing your experience on this topic.
Regards
Hans-Henrik

 

[7anoter4]

According to IEC 60909-0 Standard chpt.4.3.1.2 Short circuits in meshed networks b) Ratio R/X or X/R at the short-circuit location
As long as R/X remains smaller than 0,3 in all branches, it is not necessary to use the factor 1.15. It is not necessary for the product 1.15xkb to exceed 1.8 in low-voltage networks or to exceed 2.00 in medium- and high-voltage networks
So if it is about low voltage the ip=1.8x√2xI"k=2.5456xI"k