I read in !emc-pstc that Scott Lemon sle...@caspiannetworks.com wrote
(in 3be064c5.e48c3...@caspiannetworks.com) about 'Radiated Emissions
EUT Config', on Wed, 31 Oct 2001:
I am in search of opinions regarding the acceptable EUT configuration
for radiated emissions testing. If a system is comprised of one or more
independent shelf-level products (e.g. one shelf in a rack or several
racks full), at what level is it acceptable to test? Assume that the
system can be sold as one independent fully functional shelf or as
numerous interconnected shelves (interconnection just increasing
system capacity). For example, one shelf could be sold and deployed,
then 6 months later another shelf added (cabled up to the first), and so
on, etc.
1. Would it be acceptable to test at the shelf level?
2. If not, where is the line drawn? Two? Ten?
In a typical CO you may see racks and racks of the same equipment
shelves/chassis - chances are, they were not all tested together - where
is it reasonable to stop? FCC (ref. ANSI C63.4)/EN300386/GR1089 have
some guidance, differing slightly, but not clear. Any and all
opinions/experiences from the group are welcome.
Adopt a 'real world' approach. If the separate products could be simply
placed side-by-side or stacked on a table or shelf, instead of being
mounted in a rack, you do not need to measure the rack as a whole. See
IEC/EN61000-3-2, which says this explicitly.
In Europe, the question should not arise, because since each product can
be marketed separately, each requires to conform to applicable standards
and to be CE marked. Assembly into a rack could be carried out by anyone
- an installer or end-user - and clearly to then require re-testing
would be unrealistic.
The only snag is that if the **manufacturer** assembles the products
into a rack, **and then markets the rack as a single article of
commerce, i.e. at an inclusive price**, then it is classed as a system
under the EMC Directive and DOES need to conform as a whole to the
applicable standards, unless the product standard says differently, as
CISPR15/EN55015 does for dimmers.
Large assemblies and aggregations are almost always more or less 'site-
specific' and are thus 'installations' under the EMC Directive.
Installations need no a priori testing but the installation must be in
accordance with the product manufacturers' instructions, including the
correct use of appropriate cables. Installations are assessed for EMC
only in case of complaint (of either excessive emission or inadequate
immunity).
--
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk
Eat mink and be dreary!
---
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