Just take note that ABB is not Allen Bradley. ABB is an European company. I know that one of the HVDC system is in California. Still the major market is not in USA since the states has enough electrical power generation capacity (do not know why President Bush wants to build more nuke power stations). The problem is in the distribution/transmission systems which is quite backwards. It is also not so easy to integrate this to the national grids. The whole idea of distributed power generation (using wind power, fuel cell, ...) is not so easy with the conservative power companies. Regards, Xiaofan -----Original Message----- From: Denny Esterline [mailto:firmware@tds.net] Sent: Sunday, August 14, 2005 2:26 AM To: Microcontroller discussion list - Public. Subject: Re: [EE] Voltage drops 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/gad 02181.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. -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist