hi,
Very thx for the response, yes I'm testing all the underground cables, but that's the problem, al the Medium voltages cabines are connected to each other and before the new current & voltage transformers there was a possibility to check in the beginning or the end of the line? I put the megger between R or S or T phase and ground and if there was no shortage I got a good result, if you know what I mean, difficult to explain, but now with the new current and voltage transformers the primary is also connected to the ground, this calls unipolar shielded in europe, the system is protected with a SIEMENS SJ5005 earth protective relay.
thx
