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Discuss 60947 Zs VALUE S in the UK Electrical Forum area at ElectriciansForums.net
in your case In = 80 A, Type B= X5, type C= X10, type D= X20
so
230/(80 X10) = 230/800 = A =0.02875
0.02875 X 0.8 for temperature correction = max Zs of 0.023 ohms
In Amd 3 we apply a C min factor of 95% for max Voltage Drop so this would be 0.023 X 0.95, this is not really necessary at the moment though, but this will be reflected in the new Max Zs tables when Amd3 comes fully into force.
Some of the gents on here have def got the knack of this theory malarky!!! I am very impressed. I always struggled with this in college. I watch this thread with admiration...
Applying it to fixed MCBs to 60947-2 will err on the side of caution as the manufacturers data will lead to a more accurate figure, and this may be slightly higher than this calc produces due to the way that standard is applied
Aaaaaaaaaaaaa!
Thanks, I was about half way working it out, but would of been wrong. The readings that I have on various circuits protected by these MCB's are in the region of 0.54 to 0.68 which is higher than 0.23.
So, doing calcs using "B" type MCB, the Zs readings would be more acceptable, would they not?
0.58
You were right the first time lol, I had added an extra zero while typing, I have now corrected the earlier post
230/800 = 0.2875
0.2875 X 0.8 = 0.23
Sorry my Typo :mad2:
Reply to 60947 Zs VALUE S in the UK Electrical Forum area at ElectriciansForums.net