As an industry practice, which method is more commonly used? There would be
some setup time involved for testing tabletop equipment with either method. If
anyone has input on their preference it would be helpful.
Most standards are CISPR based so we must follow the CISPR methods so we have a
common test setup.
Thanks,
Tim Pierce
In a message dated 9/23/2009 8:01:56 AM Pacific Daylight Time,
[email protected] writes:
Before the CISPR standards included the level of detail they do now
about the test setup for emissions, we used the ANSI C63.4 standard for test
setup. The latest version I have in our library is the 2001 version which says,
ANSI C63.4:2001, Section 5.2.2 Vertical Conducting Plane
A tabletop device may be measured for AC powerline conducted emissions
without a vertical conducting plane while maintaining the 80 cm EUT elevation
specified in 6.2.1. However, in case of a dispute, ac powerline conducted
emission measurements made on a tabletop device with a vertical, conducting
plane in place shall take precedence.
Also, interesting enough, CISPR11 (EN55011:2006) doesn’t even mention a
vertical plane for conducted emissions testing. I interpreted it as allowing
you to perform conducted emissions on an OATS using the same setup as Radiated
Emissions which would include the 80 cm table and no vertical plane. It would
appear as if the 40cm table is only required for options b) and c) below.
CISPR11:2006, Section 7.1 Measurement of mains terminal disturbance
voltage
The measurement of the mains terminal disturbance voltage may be
carried out:
a) on the radiation test site with the equipment under test
having the same configuration as used during the radiation measurement;
b) above a metal ground plane which shall extend at least 0,5 m
beyond the boundary of the equipment under test and have a minimum size of 2 m
× 2 m; or
c) within a screened room. Either the floor or one wall of the
screened room shall act as the ground plane.
Option a) shall be used where the test site contains a metal ground
plane.
In options b) and c) the test unit, if non-floor-standing, shall be
placed 0,4 m from the ground plane.
Floorstanding test units shall be placed on the ground plane, the
point(s) of contact being insulated from the ground plane but otherwise
consistent with normal use. All test units shall be at least 0,8 m from any
other metal surface.
Does EN55022 allow conducted emissions to be performed on an OATS
without the vertical plane and with an 80 cm table? It sounds like it does as
an optional configuration (I’m not an expert on EN55022).
I would interpret a Semi-Anechoic chamber the same as an OATS.
The Other Brian
________________________________
From: [email protected] [mailto:[email protected]] On Behalf Of
Spencer, David H
Sent: Wednesday, September 23, 2009 7:50 AM
To: Wan Juang Foo; [email protected]; [email protected]
Subject: RE: Conducted emission measurements
Tim,
From EN55022:2006 +A1: 2007
Section 9.5.2 Tabletop equipment arrangement
2) "...........(for example on an open area test site (OATS) or in a
screened enclosure). The EUT shall be placed on a non-conductive table such
that it is 0,4m above the horizontal ground reference plane."
Regards,
David Spencer
EMC Engineer
Xerox Corp.
________________________________
From: [email protected] [mailto:[email protected]] On Behalf Of
Wan Juang Foo
Sent: Wednesday, September 23, 2009 1:46 AM
To: [email protected]; [email protected]
Cc: Wan Juang Foo
Subject: Re: Conducted emission measurements
Hello Tim,
I may be missing. Is there such a 40 cm height? Here is my 5 ¢
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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