Hi Amund:
> We want our IT product to be UL approved. We purchase a modified power
> supply
> (PS) which is not UL appoved. The original PS is UL approved. The only
> difference in the PS is the value of one resistor which means that we now
> can
> take 2.3A/28VDC out instead of 1.9/28VDC. It exist av TUV CB report on the
> original PS.
1. Even though only one resistor is changed, the
modified power supply is *NOT* UL certified.
The modified power supply needs to be re-
evaluated for safety.
Some of the original tests can be applied to
the new power supply, and some tests must be
repeated.
Generally, the electric shock requirements
and tests can be carried over from the
original power supply. For example, the
spacings and dielectrics of the original
power supply can be applied to the new power
supply.
However, the supply is changed from 53.2 watts
output to 64.4 watts output. This means that
the heating, short-circuit, overload tests,
and similar tests must be repeated.
> A local test lab tells us that thay can approve the total IT product
> (including
> the PS), but I feel we can get trouble with UL during the audits (4 times a
> year).
2a. The end-product can be safety-certified as package,
where the cert house does the applicable power
supply tests in the end-product. The cert house
can rely on *some* of the testing of the original
power supply.
This, however, has nothing to do with UL, which
is your objective.
2b. Since you want your end-product certified by UL,
then you *MUST* have a UL-certified power supply
(or UL must have tested the power supply as a
part of your product just as indicated by your
local test lab).
Best regards,
Rich
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