Back in the era when I was fooling with military and space hardware I am
left with the following understandings.
Hi-Pot testing is always a potentially destructive process. Often slight
deterioration of insulation as a result of the applied high voltage will go
undetected at the time of testing and only show up after long term use.
The thought of _routine_ HiPot testing of modules containing sensitive
electronics makes my skin crawl!!
In all cases that I recall, HiPot testing was only conducted on
"qualification samples" of avionics modules. These usually went on to the
subjected to destructive tests (crash survival) or near destructive testing
(shock and vibration, etc.) an were eventually subjected to post-mortem
examination which finished destroying them. I cannot recall any instance in
which a HiPotted module was considered qualified to "fly".
For routine testing, you should consider sensitive leakage tests at or near
"high line" conditions but not exceeding maximum ratings. After some
experience, you should be able to characterize modules which are "normal"
and those that might have deteriorating insulation or have been subject to
excess moisture.
I you want expert opinion, I would suggest trying to contact someone in a
military electronics command unit or at NASA.
What does the FAA have to say about this?
Good luck, Bob Smith
--- Avoid computer viruses, Practice safe hex ---
-- Specializing in small, cost effective
embedded control systems --
Robert L. (Bob) Smith
Smith Machine Works, Inc.
9900 Lumlay Road
Richmond, VA 23236 804/745-1065
[EMAIL PROTECTED]
----- Original Message -----
To: "Multiple recipients of list CHIPDIR-L" <[EMAIL PROTECTED]>
Sent: Tuesday, October 29, 2002 7:48 AM
> Hi All,
>
> Apologies if this is off topic.
>
> We are evaluating the merits of Hi-Pot testing on aircraft black boxes as
> part of the return to service test after a shop repair visit.
>
> Most of our black boxes are embedded computer applications that live on
the
> avionics rack in an airplane and perform specific functions like autopilot
> computer for instance.
>
> Some of the box manufacturers specify Hi-Pot testing as part of their
return
> to service tests generally, at around 600 Volts RMS.
>
> We have issues with performing potentially destructive tests without
> restrictions as units that come through the shop for repair. No telling
how
> many times a lemon unit gets zapped. Where we are regulated, we need to
> have a solid case before we argue with the device manufacturers.
>
> What kind of experience do commercial manufacturers have with this sort of
> testing at manufacture or repair? Is it done commercially? What kinds of
> things do you find? All feedback on merits / drawbacks is welcome?
>
> Thank you.
>
>
> Bruce Torelli
> Delta Air Lines
> Sr. Avionics Engineer, Dept 556
> Atlanta, GA 30320-6001
> PH: 404 714 9508 FAX 404-714-3291
>
> --
> Author: Torelli, Bruce
> INET: [EMAIL PROTECTED]
>
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--
Author: Robert Smith
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