>As long as the ramping starts below 15% and the ramp is long enough, this
>scenario should never happen. With large and more costly loads, I like
>longer ramps, say as much as 5 sec full-scale. This gives the tungsten time
>to heat a bit more and the heat sink time to actually do something since
the
>resistance increases significantly along the way up the ramp. I haven't
>followed this thought from start to finish, nor have I done the analysis,
>but I do a fair bunch of AC power controllers for tungsten, and when I use
a
>5 second soft start with a 7:1 inrush, I have gotten into the practice of
>using devices at/near their rated power level without inrush failure.
>Besides, with a 1 or 2 second soft-start, most non-geeks wouldn't even
>notice it, and the 'wow-factor' would be mostly lost.

I would think that you probably do not want a linear ramp up anyway. Most of
the preheat to stop inrush current will happen in the first 15-20% of a long
ramp, so shortening the time for the last portion where the current is
highest may improve the average dissipation in the FETS. You will need to do
a bit of calculating in a spreadsheet or similar to produce a graph to prove
or disprove this, but it is my gut feeling.

The geek factor may be enhanced by having the bulbs sit there with an orange
glow for a couple of seconds, and then zoom up rapidly to white anyway.

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