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MichaelSol: Amount of substations per sections does not matter really - the thing is that you cannot really go above ~2kA continuus without some major engineering in place. To lower currents you need to increase voltage. 6 kV DC - feasible, but anything more then this... I dunno. There might be problems with extinguishing arc with DC voltages so high and possible tight clearances. On 3kV DC a typical 8000 hp universal loco may go as high as 4 kA. Getting more of them on a single section - bad thing... But not a problem with 25 kV AC (or 15 kV AC - for that matter). I suspect that the 5 kV loco costs are not an issue now :) [quote]QUOTE: This was something we noted: AC locomotives appeared to have shorter economic service lives than standard DC equipment.[/quote] With many AC locos reaching 50 year time frame... Besides - noone builds straight DC locos anymore. [quote]QUOTE: This no doubt remains true for electric locomotives as well. And, as Alan points out, anything placing voltages on the order of 20k, 25k or 50k directly into the confines of a locomotive body shell that is then converting that power to DC and back to AC again, represents a lot of high voltage activity in a very small space.[/quote] Oh come on - you know it is not true. In a comparsion to a straight DC loco an interior of a modern AC loco is just a set of boxes. No 3kV relay boxes, switches etc. ANd the HIgh voltage goes as far as the transformer. Usually all connections are made on the roof of the loco. There is no live 25kV in the vehicle. [quote]QUOTE: Russian Railways reports 56 empoyee deaths per year related to electrification -- as opposed to other railway related causes -- apparently most of them occuring on AC sections.[/quote] Sources? Anyhoo - SZD employs about 1,5-2 million people. Stellar safety record... [quote]QUOTE: However, future planning does not seem to account for the fact that 100kv, 200 kv, 350 kv and 500 kv AC supply sources will not be available in the not-so-distant future, as these lines are converted to DC for its inherent long distance transmission efficiency and environmental advantages.[/quote] 3 phase AC is the cheapest form of moving energy. Period. HVDC is used where it is impossible to string typical high tension line - usually to connect an island to a mainland or to connect two off-phase systems. Cost of a high power converter is astronomical. [quote]QUOTE: Well, 3600 vDC costs about $45,000 per mile to electrify, heavy conductor and all. This $1 mi per mile figure sounds inordinately high.[/quote] Omg - check current prices. Recently, to upgrade an existing catenery to 200 kmh polish railways paid ~$250.000/km. That works out to $400k per mile (2 tracks) - that is sans substations, connection ot the power grid and masts. 1mil/mile is usual cost. $45k will not buy you the necessary wire, let alone the whole catenary ;) Townsend: Except for a few rare circumstances (like arc furnaces) noone uses 100+ kV for anything else then transmission. In this part of the world 3kV DC stations are fed from 6 to 20 kV 50hz, stepped down to 3,6 kV/50 hz then rectified, and smoothed. To get from 110 kV the voltage usually goes down 110 -> 40 -> 20 -> 10/6 kV.
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