Friends,
I'm looking at a commercial product certified to UL 1012 (Standard for Power
Units Other Than Class 2). The product outputs 150 Vdc power and control
signals to small motorized devices via proprietary connections. The downstream
devices can be powered at distances > 50m from the main unit, and are covered
by UL 61010-1. The NRTL claims that a downstream powered device can rely on
the main power unit's electrical isolation, if a "systems approach" is taken to
the certification (e.g. consider main unit & downstream powered device as one).
NRTL's presumption when using this approach is that the downstream device no
longer requires individual hipot test because it relies on the main unit's
construction for electrical protection.
*is the "systems approach" a practical one? I'm not convinced this is enough
and am considering dc-dc isolation on the downstream powered devices as well.
Also, there is a "reversed polarity test" required on the output of UL 1012
products:
*Does this test still apply if the only connections that can be made to the
main power output are "unique" to the proprietary downstream devices?
Thanks and best regards,
Chet Summers
1-580-572-1611
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