Hi Please refer to attached pdf. C

[hhhansen]

Hi
Please refer to attached pdf. Can anyone tell me what is wrong considering my calculation of U2 potential when there is a single phase fault on HV in secondary substation. I am considering a TT-system with RE and RB not connected.

IEC 60364-4-442 table 44.A1 says U2=U0, however I reach the result U2=U0+(2x RE x IE).

Best Regards

hhhansen

 

[RedSnake]

U₀ is the potential between L1 and N, PEN

So the potential on the HV cabinet at a short circuit is U_E = I_E* R_E
so U₁ = I_E* R_E+ U₀
And the potential U₂ when R_E and R_B are not connected is the same as U₀.

Best Regard A