Andy Burns wrote:

Chris J Dixon wrote:

Until the advent of power electronics in rail traction, then control
was generally either by tapchanger, for ac supplies, or series
resistors for dc schemes. In both cases the steps (or notches as they
are known) are finite, not continuously variable, and there will
always be jerks.

On more recent trains, I seem to hear the electronics "whistling" a set
of steps as they depart, why not continuous?

Or are those just more noticeable and the latest ones /are/ continuous?

I can't give you chapter and verse, but I think you are about
right there.

If you want to delve a little deeper into the whole subject, this
can be a good starting point.

http://www.railway-technical.com/trains/rolling-stock-index-l/train-equipment/electric-traction-control-d.html

Chris
--
Chris J Dixon Nottingham UK


Plant amazing Acers.