if I=E/R, then assuming the same resistance of the DC fan, halving E reduces I [even if the resistance might be lower at lower speed, current still drops]

one difference in the AC motors is the different wiring to provide different resistance to provide the same rated hp at either voltage, as in P=I*E .... not all AC motors are dual voltage and a 240 motor fed with 120 wouldn't even start

Bill

Moved over to the Passing Lane

"When we tug a single thing in nature we find it attached to the rest of the world" John Muir
"When we tug a single thing on an old truck, we find it falls off" me
Some TF series details & TF heater pics & Rust-a-holics Unanimous parking lot