San Francisco’s Secret DC Grid
<i>"By the mid-20th century, large rectifiers installed at two downtown substations supplied the current, pushing 250-V DC onto a rectangular loop of 3.6-centimeter-diameter cable."</i><p>OK, can anyone explain why each of the drum-wind elevator motors does not have its own small rectifier and be run from local AC mains (possibly cross-phase for 1.4x voltage)?<p>As this interesting article goes on to say the local power company is splitting the DC distribution into smaller isolated networks anyway...