Zak wrote...

Winfield Hill wrote:

The problem with switching transformer primaries with triacs is
the high inrush current that can develop.

[snip]

There are several solutions, including zero-crossing switching,
or a two-stage switch with a series resistor in the first path,
or both.

It is 'maximum voltage switching' that should be used in this case,
isn't it? Switching on at zero crossing will start with a demagnetized
core handing the full voltage * time integral, where in operation it
would start out with the opposite magnetization.

Thanks, Thomas, I stand corrected.


--
Thanks,
- Win