```> I understand the amps.. i understand the max volts.. I assume the
> resistance is another way of saying saturated voltage drop..
>
> what I don't understand is the watts.
>
> Like this: if this device can really switch 15A @ 100V, that's 1500W,
> not 60 - or are they saying it can _dissipate_ 60W? I just flat out
> don't beleive that...
>
> S.
>
Yup it power dissapation. I have Igbt in to-247 cases that will
dissapate 500 watts and Igbt modules that will dissapate 4200 watts
while switching 400 amps of 1200 volts.

Not bad switch 1500 loose 60, that's  a pretty fair deal.

Oh yea Fets is RsDon, calculate as a resistor I2r.
Igbt are straight voltage drop amps times Vsat.

These are DC ratings.
Swithing losses are a whole nother ballgame.
```
From a EVDL post on Dec 31
```>Rich Rudman wrote:..
>
>6.7s are very happy at 5500 to 8K RPM, If you can find the volts to spin
>them that fast and still make enough torque to get any real
>acceleration.
>
>8 inchers are OK to about 6500, Some say 8K, NOT me.
>
>9 inchers are Rated to 4500, I say 6000, Not much more.
>
>Also clearly a HOT motor should not be run at the extreme edge of it's
>speed range. 6000 would be too much on a hot day and 500 amps for hours.
>
>
>If you use 5500 to 6000 as a design point and need to do any climbing or
>accelerating at this rpm, You will need more than 144 volts to make it
>happen.
>
>My XP-1263 144 volt AvDC motor in stock form would barley pull more than
>4500 with only 120 VDC on it. This gave me a nice speed limit of about
>70 mph on the flats.
>It would sag to 55 on a long hill, then the 400 amp curtis would over
>heat.
>
>Jumping to 156 and a 1200 amp Raptor, and it's still pulling pretty good
>at 5500 and 80 mph. It could pull a LOT harder, but that's for the
>racing side of me not the street EV side.
>
>Also the cooling of the AvDC motors is good enough above 4000 rpm to not
>worry about it. at 6000  it's not much better because of fan tip losses
>and windage losses. In fact the windage losses are getting to be
>dominante at 6K rpm.
>
>I would say that running at 6000 for long intervels is NOT a good design
>point. 3500 to 5000 is nice, for good pulling torque 2500 to 4000 or
>less. This depends on voltage of course. And in a big way.
```