I see length restrictions for CI only on cables *between* the UUT and the
coupling and decoupling devices -- and not elsewhere. Plus, the coupling
network can be only 0.1 to 0.3 meter from the UUT. I read that as saying the
cables must run through or to them as directly as possible, i.e.: short and
straight.
Cortland
KA5S
(posting from Downers Grove)
-----Original Message-----
From: Derek Walton
Sent: Feb 8, 2011 2:21 PM
To: [email protected], [email protected]
Subject: Re: EUT power cord length
Thanks to the folks that have replied so far.
Here's my dilemma, the EFT standard says:
If the manufacturer provides a non-detachable supply cable more than
0,5 m ± 0,05 m long
with the equipment, the excess length of this cable shall be folded to
avoid a flat coil and
situated at a distance of 0,1 m above the ground reference plane.
Surge is similar. However, CI is not.
On all cables to be tested, coupling and decoupling devices shall be
inserted (see 7.1.2). The
coupling and decoupling devices shall be placed on the ground reference
plane, making direct
contact with it at a distance of 0,1 m to 0,3 m from the EUT. The
cables between the coupling
and decoupling devices and the EUT shall be as short as possible and
shall not be bundled or
wrapped. Their height above the ground reference plane shall be between
30 mm and 50 mm.
So what this is telling me, I believe, is that the Surge and EFT must
be done first with the manufacturer supplied cable ( Or the connection remade )
and the cable bundled non-inductively. For CI, regardless of supplied cable
length, the cable must be cut to the minimum practical length.
I hear what is said about robust EUT's, but the requirement is to
follow the standard....
I think I have my answer...
Thanks everyone,
Derek Walton
L F Research
-----Original Message-----
From: Spencer, David H <[email protected]>
To: Derek Walton <[email protected]>; [email protected]
Sent: Tue, Feb 8, 2011 1:39 pm
Subject: RE: EUT power cord length
The obvious question: does it make a difference with respect to test
results
between .5M and 5M?
If the EUT is sufficiently robust, it may not make a difference.
If you determine a worse case I would go with that. Of course, hacking
bits off
at a time may not make the customer happy.
You could just directly inject into the in-let terminals of the EUT
(I'm sure
that's coming in a future revision of IEC 61000-4-4).
;)
Regards,
David Spencer
EH&S EMC Engineer
Xerox Corp
-----Original Message-----
From: [email protected] on behalf of Derek Walton
Sent: Tue 2/8/2011 2:22 PM
To: [email protected]
Subject: EUT power cord length
Hi Group,
I have a question concerning what to do with an EUT's non detaching
power cord
for EFT, Surge and CI.
Lets say the EUT comes with 5 metres of cable, what would I do with
this cable
between the coupling networks and the EUT?
Do I cut to a shorter length, bundle etc?
I'm stressing non detaching power cord....
Opinions welcome.
Thanks,
Derek Walton
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