Failure of BASIC insulation.

[Rich Nute]

Hello from San Diego:


I have been studying failures of basic insulation in
electronic equipment.

Basic insulation is 

    the insulation that exists between mains (the 
    primary circuit) and ground, or 

    the first of the two insulations comprising double 
    insulation.

Basic insulation can be comprised of:

    Air insulation (clearance through air).
    Air-solid interface (creepage along the surface of 
        insulation).
    Solid insulation.

I have three sources of data:

    1.  Production-line hi-pot failure records.

        I have "good" data from this source.

    2.  Accelerated life test data.

        I have been performing some accelerated "life" 
        tests on basic insulation.  One failure.  I will 
        report on it in a follow-up message.

    3.  Field failure data.

        I have NO data whatsoever.

        I've never had a report of a failure of basic 
        insulation in a production unit that passed the 
        hi-pot test.  

        This implies that basic insulation is extremely
        reliable.

        Are you aware of any such failure?  If so, can you 
        please send me the details?

Please respond to me via e-mail.  I will compile the results
and report to this group.


Thanks, and best regards,
Rich



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 Richard Nute                             Quality Department 
 Hewlett-Packard Company           Product Regulations Group 
 San Diego Division (SDD)          Tel   :      619 655 3329 
 16399 West Bernardo Drive         FAX   :      619 655 4979 
 San Diego, California 92127       e-mail:  ri...@sdd.hp.com 
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