Hello Tim,
I may be missing. Is there such a 40 cm height? Here is my 5 ยข worth.
These are some of the the special provision for conducted emission testing:
To meet EN 55011, I suppose since 1999?? the measurement may be carried
out:
- on the radiated emission test site (same EUT configuration)
- above a metal ground plane which shall extend at least
50 cm beyond the boundary of the equipment under test
and have a minimum size of 2m x 2m
- within a screened room; either the floor or one wall of
the screened room shall act as the vertical ground plane
.. CISPR 22 since (1993) and Amendment 1 (1995)
Table- top EUTis to be placed 40 cm from a vertical metal
reference plane (e.g. a wall of a screened room/enclosure)
"The EUT, where intended for table-top use, shall be placed 0,4
m from a vertical metal reference plane of at least 2 m by 2 m and shall be
kept at least 0,8 m from any other metal surface or other ground-plane not
being part of the EUT. If the measurement. is made in a screened enclosure, the
distance of 0,4 m may be referred to one of the walls of the enclosure."
Floor- standing EUT on a horizontal metal ground- plane, not in
metallic contact with the ground- plane. Metal floor of a screened room may
replace the reference ground- plane
best regards,
Tim Foo
Expert Witness, EMC and Product Safety
ECE, School of Engineering,
http://www.np.edu.sg/ece/ DID: +65 6460 6143
Ngee Ann Polytechnic,
535 Clementi Road, Fax: +65 6467 1730
Singapore 599489
[email protected] wrote on 23/09/2009 06:06:05 AM:
> Hello Group,
>
> I have a question about the conducted emission measurements
> performed in a semi-anechoic chamber.
>
> CISPR 22 requires the use of a vertical ground plane when testing
> tabletop EUTs, unless you mount your EUT on a non-conductive table
> 40cm above the horizontal ground plane (instead of the traditional 80cm)
>
> I did not find a requirement for a vertical ground plane when
> testing floorstanding equipment. If one opts to use the alternative
> method of not using the vertical ground plane, can floorstanding
> equipment also be tested without the vertical ground plane? The
> horizontal ground plane is always present since that is the chamber floor.
>
> What are most labs using? We have the option of making a removable
> vertical ground plane "wall" or mounting the equipment on a 40cm table.
>
> Thanks,
> Tim Pierce
> -
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