An other thing i forgot to tell is when the line is tested, de-energised and earthed after the fault is to megger or replace the other LA's as well.
I know their is alway pressure upon getting power back on but if i get called out then i take my time to test and record matters properly to avoid early call backs to the same job.
I forgot what voltage level we talking here
33 / 11 kV or 66 / 22 kV.
Most 11 kV LA's with a MCOV of 8.4 kV will give a 5 kV megger reading in the giga ohms ranges. 100 G.ohms or more.
33 kV LA's with a MCOV of 29 kV can read up to T. ohms.
It also depends upon moist conditions during testing. At night i have reclosed 11 kV polyloom cables feeding transformers with megger readings as low as 25 M.ohms without causing a trip or ddo blow out.
On the other side of the coin i have had polyloom cables blow out with megger readings of 1 G.ohm on one phase compared to the other 2 phases reading 100 G. ohms.
Part of the game of playing with the big stuff that the fireworks can be spectacular sometimes, and noisy too when a ddo blows under fault conditions.
