Re: SMPS mains circuit

From: legg (legg_at_nospam.magma.ca)
Date: 07/09/04 

Date: Fri, 09 Jul 2004 18:41:17 GMT

On Fri, 9 Jul 2004 17:25:41 +0100, John Woodgate
<jmw@jmwa.demon.contraspam.yuk> wrote:

>The problem I am working on is that products taken from the field and
>measured give significantly (in the mathematical sense) different
>results from the original type-test product on which the Declaration of
>Conformity was based. Many of these variations are of no significance in
>terms of passing or failing the test, but this has to be explained in
>the standard, and we need to find the best way of doing that, **and***
>justifying what we write.
>

If the variations have no signifigance, then perhaps it's because
there is already sufficient margin in the standard to cover variations
of this sort.

As the standards are written in absolute current value limits, the
assumption that worst case occurs at full load might be incorrectly
adopted. Loading tolerances might also be signifigant as product
inefficiencies are introduced, for economy's sake, after innitial
certification.

Has the testing body or representative ever been called to task for a
report that is unrepeatable? I doubt it.

Has retesting ever produced unexplainable non-compliant results in a
fully-functional product?

RL

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