On Thu, 23 Feb 2012 12:06:16 +0000, The Other Mike wrote:

Some breakers on LV networks (and even more modern 132kV breakers)
work on a clockwork mechanism.

ISTR the linesmen mentioning clockwork and/or something mechanical.

Have persistent trips and not only is there DAR lockout after a
defined number of attempts but the breaker may not have any charge due
to the substation also losing supply.

Loss of the 33kV to the local upstream substation very, very, rarely
happens, that 33kV feed has an 11kV backup running in parrallel with
it. More often than not if the power our side of the valley has gone,
the other side and village still have theirs. Those are fed from the
same upstream 33kV substation.

--
Cheers
Dave.