Hi Art:
You ask three questions:
A) Does a Class B or better transformer insulation system operating
at 65 C rise or more need to be UL 1446 Recognized to be qualified
for the NRTL mark?
In my opinion, regardless of the standard, if the transformer or
end-product is certified by UL, the transformer insulation system
will need to be certified in accordance with UL 1446. This is
the UL way.
If the transfomer or end-product is certified by any other NRTL,
then the transformer need only be made with Class B or better
insulating components.
B) Reading of the standard?
While there is no specific deviation associated with Sub-clause
2.2.2, there is a COMPONENT deviation associated with Sub-clause
1.5.1 which invokes Annex P.2. So either UL 1446 or CAN/CSA C22.2,
No. 0 applies.
A third-party certification house could apply either UL 1446 or
CAN/CSA C22.2, No. 0 in addition to component specs. This would
have to be negotiated with the certification house (insofar as
the certification house is willing to negotiate).
To my knowledge, CAN/CSA C22.2, No. 0 does not require insulations
to be tested as a system.
C) Correct interpretation?
Depends. Depends on who gets to make the final decision as to
the "correct" interpretation. If you are the one to decide, then
I believe you have a "correct" interpretation. If you are dealing
with a third-party certifier, then it is likely that they will be
the ones to decide and they would have the "correct" interpretation.
>From a safety point of view, the objective is to have an insulation
system rated for the temperatures, voltages, and mechanical strengths
found in the transformer.
UL 1449 presumes long-term chemical interactions among various insulating
materials when operated at high temperature and in intimate contact with
copper wire and for extend periods of time. Unfortunately, it is
difficult to predict if the particular insulations in your transformer
could incur chemical deterioration.
On the other hand, no other safety standards or third-party certification
houses, including CSA, have such requirements. This implies the long-
term, high-temperature deterioration is not of sufficient importance that
other certification houses need test for it.
Best regards,
Rich
Hewlett-Packard Company
San Diego, California
