Ever wondered Why 31.5kA not 31kA or 32kA in ratings?
Atham Soofi
Director | power systems study?? | Renwable energy?? | Testing and commissioning services?? | Test Equipment Rentals??
19 April 2024
You may have noticed electrical equipment have ratings which commonly seen 20kA , 25kA , 12.5kA , 63kA , 31.5kA
So the question is like why is 12.5kA? why not 12kA? or why is 63A rated current not 60A or 65A ? ( you may see this is because Renard number or R series of ISO standard you may see this in various IEC and IEEE related( E.g. in IEC 60059 you may see though IEC/IEEE does not mandate or state it) , So the ISO R series were followed in manufacturing and engineering to get compatibilities , Following R series makes interoperability between different vendors , It is better you search and read about this ISO Renard series Wikipedia , there are several series ,
Ex. Below is R10 and R20 series of ISO , (Source Wikipedia/ ISO website)
R10 : 0; 12; 15; 20; 25; 30; 40; 50; 60; 80; 100
R20: 10; 11; 12; 14; 16; 18; 20; 22; 25; 28; 30; 35; 40; 45; 50; 50; 55; 60; 70; 80; 90; 100
So when manufactures and standards organizations followed this Renard number in their manufacturing or standards to multi vendor compatibility and even system integrity , this weird numbers started in the industry it is being followed , So you see 160A, 63A, 25kA ,40kA, 31.5kA etc. you may see some number which does not fall in the R series too .
leave your thoughts or feedbacks if you have more information about it
Thanks for reading , cheers ,
Protection&Control Eng |O&M EHV.HV.MV Substations
10 个月For Rating current standard ISO use Renard series 10^(n/10) , n is integer
Testing and Commissioning Engineer || Electrical Engineer
10 个月Hi Atham thank you for sharing. If I am right this post talked about that the root of thes ratings is Renard series. But why IEC & IEEE use them on thier standards? Why they did not use any other series ? Does it has any relation with optimization in manufacturing? Or it is just arbitrary thing.
??????????????????????????????????.?????? platform & groups founder/Switchgear Senior Sales Engineer/ Switchgear Technical & Marketing Consult
10 个月Please share this post in the Switchgear Content group for many electrical engineers worldwide. Thanks