tag:blogger.com,1999:blog-3287675141745937676.post2264708599170371671..comments2024-03-20T23:43:28.613+00:00Comments on Caroline's Miscellany: Sub-station with styleCarolineLDhttp://www.blogger.com/profile/00197813252586559665noreply@blogger.comBlogger2125tag:blogger.com,1999:blog-3287675141745937676.post-48247804779106840042012-12-04T14:40:28.528+00:002012-12-04T14:40:28.528+00:00Thank you! This is what comes of trying to summari...Thank you! This is what comes of trying to summarise too briefly, especially on a point I have only very basic knowledge of... <br />CarolineLDhttps://www.blogger.com/profile/00197813252586559665noreply@blogger.comtag:blogger.com,1999:blog-3287675141745937676.post-48062557836439199692012-12-04T14:00:31.121+00:002012-12-04T14:00:31.121+00:00"That produced alternating current at 12,000 ..."That produced alternating current at 12,000 volts (direct current won't travel long distances)."<br /><br />Not quite, Caroline. Metro trains with live rails need low voltages, but if you carry low voltages over long distances you lose a lot of energy. <br /><br />So you need to convert somewhere from high to low voltage, and this is a lot easier if you generate HV AC, deliver it to somewhere near the track, then convert to LV AC where short-range losses are small, and then convert AC to DC to feed into the track. <br />Alan Burkitt-Grayhttps://www.blogger.com/profile/17344807923068268667noreply@blogger.com