Just in case you wanted some references to the subject of DC electrical grid
interconnections...

A decent overview, a little history and some good links can be found on the
Wikipedia entry:
http://en.wikipedia.org/wiki/High_voltage_direct_current

Allen Bradley supplies most of the hardware for these systems (at least here
in the USA), they have some decent material at:
http://www.abb.com/global/abbzh/abbzh251.nsf!OpenDatabase&db=/global/gad/gad02181.nsf&v=17EA&e=us&m=100A&c=D7779A6F38FCBDC0C1256F9D0046D2B0

Basically they're used anywhere they can be financially justified. Install
can be cheaper because the conductors are sized smaller. (AC conductors must
be sized for peak current, but only deliver RMS power - DC doesn't) And long
term can be cheaper due to capacitive losses in AC lines. (think of long
underground runs...) And of coarse what could be the biggest benefit, the
ability to interconnect unsynchronized electrical grids.



-Denny

-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist