It makes sense that if something isn't designed and tested for a particular 
use that there's a pretty good chance it won't work reliably for that use.

But vacuum inherently has larger resistance to corona/arcing than higher 
pressure areas. Perhaps Larry's failures were due to some kind of easily 
ionize-able gas evolving from his power supplies--maybe even due to a 
conformal coating oddity which is what this thread is about.

In any case, testing at very low pressures is pretty easy and relatively 
cheap.

Wayne

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Larry Dzaugis
Sent: Monday, January 19, 2015 4:48 PM
To: [log in to unmask]
Subject: Re: [TN] Conformal Coating vs Altitude

The voltage value matters.

When at a power supply manufacturer products would pass at a mountain top but 
would fail testing for space.

Found out when a small order for custom power supply was rejected when 
re-ordered. The catalog cut stated that the following configurations worked to 
14k ft. The initial order was placed and the prodcuct worked in a smart pebble 
firing. When more were ordered. they were rejected by the customer for corona 
testing at atmosphere values that were space based. We referred the customer 
to the catalog cut and told them of course they failed, not design intent.

Unfourtunetly, studies were closely held there.

For power supplies in the 100's to 10kv's it matters due to the corona that 
becomes more prevelant at the higher altitudes. These ps were all controlled 
leakage devices, low amperage.


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