Max zs equations

[malcolmsanford]

Welcome to the forum Jon and nice work though to be honest personally I prefer to calculate the Zs = Uo/Ia and most of the time curve characteristics are in appendix 3 for BS 88-2.2 and 88-6.

Granted there are some sizes that are not covered, but I would use the manufacturers data for this.

 

[Hawkeye]

hi guys maybe im being silly here just had a read through your posts is the Uo always 230? like i mean even if you have a TP 60898 or would you divide the current by 400 in this case?

Cheers

 

[malcolmsanford]

Uo is the nominal line voltage to earth so in UK cases will always be 230

All the tables calculated in the BS 7671-2008 are to Uo so all Zs values will be at 230

There are no current calculations needed for Zs values and so no need to divide it or anything else for that matter