I suppose this should be posted here instead of in the other thread.
Wolfgang,
I don't see where you get the high figure of 50 ohms for the total impedance of a Fault loop from?.
Over here in New Zealand, the maximum fault-loop impedance for an Installation using a Main fuse size of 63A, would be 0.55 ohm.
Where this device is a circuit-breaker, the maximum would be 0.49 ohm.
This would provide the required 0.4s maximum disconnection time.
Even assuming the installation is protected by a fuse and at a maximum 5s disconnection time the maximum loop impedance would only be 0.94 ohms.
