RE: SISG failure report

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: <dhmccauley@xxxxxxxxxxxxxxxxxxxxxxxxxx>

Terry,

One thing that I have found with TVS with my extensive experience in
designing high voltage supplies and radar transmitters is that the response
time of a TVS is directly proportional to the power rating of the device.
This has to do mostly with the surface area of internal junctions and
devices usually rated for 1.5kW or less, usually do poorly on fast
transients. They do clamp, however, not without delay and usually at a much
Higher voltage that rated on the datasheet.

This is the main reason I use exclusively 15kW and 30kW TVS devices for my
DRSSTC work.  I have even measured instances where those 220V 1.5kW devices
that most people use don't clamp until well over 300V during fast voltage
transients across the C-E of the IGBTs.

Of course, the 15kW and 30kW devices are pretty expensive, but they do
sample!  Of course, you have to speak directly with a sales rep there.

Dan