[Amps] soft-start vs. autotransformer

[Tom W8JI]

> I always thought that once the auto transformer got to 
> 100%, the moving tap effectively rested on
> the input line and regulation didn't depend on the core 
> and windings at all.

That's true. All you have are lead resistances and the wiper 
contact resistance.

While the problem is mostly at voltages other than 100%, we 
have to remember the very high power factor causes peak 
primary current to be much greater than RMS current. That's 
why measuring voltage drop with a regular AC voltage meter 
rather than a true peak voltage detecting meter doesn't work 
well with capacitor input supplies.

73 Tom