> 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.