Re: SSTC Reliability

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: Terry Fritz <teslalist-at-twfpowerelectronics-dot-com>

Hi Steve,

You carefully design it for 100% and then run it at 25% ;-))

It would be as reliable as any IGBT generator.  Probably not a good super 
long term machine since electrolytic caps and all would die just from 
age.  Getting parts 50 years out would be a problem let alone finding 
anyone who knew how to fix it.  Trace bits of chlorine and such in the ICs 
would kill it in about 100 years...  Try to find parts they use in space 
craft.  I have a 486-50 Intel processor just like is in the Hubble ;-)   To 
this day, the Space Shuttles main engines use magnetic core memory from the 
60's.  It survived the Challenger explosion...

No problem for say 20 years out since the glass coating industry and all 
uses pretty darn reliable AC generators now.  Under sea com equipment is 
"burned in" for 5 years before installation...

You would have to build it like those super high end audio amplifiers whose 
parts simply don't degrade with time.  MiIitary/Space hermetic parts...

Document everything so those that have to make "modern" replacements, 100 
years from now, will know what to do. Be sure the "paper/ink" those 
documents are written on will last that long too!!

Today's parts are just made too cheap and short term so you have to get 
pretty extreme about finding super long term reliable parts.  This is one 
vast advantage of the old spark gap systems ;-)

Find an antique electronics store and note what fails, and what does 
not.  Older IC's from the 70's were much tougher, but not as capable.  Most 
modern plastics will fall apart after 100 years.  And all this is even 
before you turn it on...

I note we had tube based line carrier amps that were working perfectly fine 
after 50 years with zero care.  But they were "built" for it!!  Those tubes 
were running at about 10% ;-))  Modern version had three pound transistor 
heat sinks dissipating two watts...  The line power industry is pretty good 
at making equipment that lasts forever...

Heatsink grease turns to dust after 20 years...  Just don't use anything "wet".

Making machines that are designed to last and operate for say 500 years is 
really hard...  But a fascinating area of study!  I am making an autonomous 
robot that "lives" in the wilderness indefinitely.  Batteries are the 
limiter there along with temperature, humidity, animal attacks....

Cheers,

         Terry


At 07:57 PM 11/7/2004, you wrote:
>This is directed to those members that have experience with large SSTCs,
>high powered induction heaters, particle accelerator Klystron drivers and
>other applications using high power semiconductor arrays at RF.
>
>My question is, what is the likelyhood of being able to produce high powered
>SSTCs (e.g. 10 KVA or more) with museum quality reliability?   That is,
>coils that one can trust to run several times a day, day after day, year
>after year, without exploded IGBT bricks and other failures?  Can reliable
>"overload" monitoring, anti-shoot-through, shutdown and restart protective
>circuitry be developed?  We know the challenges - highly variable secondary
>loads and reflected impedance changes, severe RFI and EMI for the driver and
>protection circuits, etc.  Quite an engineering challenge.
>
>Thanks,
>--Steve Y.