Georg,
You were right on the money when you identified the requirement for post
installations. Similar to the case in many standards, the area of interest
is silent -- nothing is said about the application in 7.2.2. When I find
this lack of information, I begin my search for guidance in the next best
place. In this case, it was the instruction given in 7.3.1. Ultimately, a
CB answers the question. Our tests include "true common mode" as well as
individual lines.
We have found some problems in burn-in where the power source was dirty
similar to the effects caused by the EFT tests. We were able to observe the
same type of failures in the lab when common mode EFT signals were applied.
So this test does represent some real world possibilities.
Don Umbdenstock
> ----------
> From: Georg M. Dancau[SMTP:dan...@compuserve.com]
> Reply To: Georg M. Dancau
> Sent: Thursday, June 08, 2000 3:28 AM
> To: INTERNET:umbdenst...@sensormatic.com
> Cc: paolo.ronc...@compuprint.it; emc-p...@ieee.org
> Subject: RE: EFT/Burst
>
>
> Paolo,
>
> I agree with Don on the interpretation of "each" as opposite to "all"
> lines.
> I also confirm, that we find most faults when testing in common mode:
> -L AND N against "reference ground"
> -L, N AND PE against "reference ground"
> -(sometimes) PE against "reference ground"
>
> However, section 7.3.1 applies for tests made "at the installation place"
> (sorry, this is the translation for "Pürfungen am Aufstellungsort"). For
> test performed
> in a lab, you should apply section 7.2.2. There is no specification
> conerning "each" and
> "all".
>
> We always perform test including L+N, L+N+PE, PE only.
>
> Hope this helps.
>
> Best regards
>
> George
>
>
> Nachricht geschrieben von INTERNET:umbdenst...@sensormatic.com
> >
>
> Paolo,
>
> EN55024 does not directly address the issue, rather it refers you to EN
> 61000-4-4. Clause 7.3.1 states " . . . applied between a reference ground
> plane and each of the power supply terminals . . .". The key is "each"
> instead of "all". From a purely regulatory perspective, it appears you
> have
> a valid point the way I read the standard. Other standards do indicate
> "true common mode" as a requirement. By the way, the "reference ground"
> may
> be at a different potential than "protective earth". That's why a number
> of
> test sets have a test mode to test EFT between PE and ground reference.
> Check out the bonding and set up requirements carefully.
>
> However, a weakness in the design has been detected in "true common mode"
> test mode. Are you confident that your customer will not be bothered by
> the
> design weakness, whatever those manifestations are? Of course that is a
> quality issue, not a regulatory issue.
>
> Good luck,
>
> Don Umbdenstock
>
>
>
> > ----------
> > From: Roncone Paolo[SMTP:paolo.ronc...@compuprint.it]
> > Reply To: Roncone Paolo
> > Sent: Wednesday, June 07, 2000 11:45 AM
> > To: 'emc-p...@ieee.org'
> > Subject: EFT/Burst
> >
> >
> > Group,
> >
> > we are currently discussing with one OEM the interpretation of EFT/Burst
> > test requirements per EN55024 and EN61000-4-4 to a printer.
> > Specifically we are discussing the requirements of application of bursts
> > to
> > AC power lines. Our understanding is that they must be applied between
> > each
> > (single) power supply conductor and reference ground (or protective
> > earth),
> > as specified in EN61000-4-4 section 7.3.1. Also fig.4 and fig.11 in the
> > same
> > document seem to confirm this.
> > Our OEM customer says that all combinations of phase, neutral and
> > protective
> > earth should be tested. They actually tested both singular AC lines and
> > also
> > more than one AC line. The printer passed the test in the first mode and
> > failed in the second mode.
> >
> > Any comments / interpretations would be highly appreciated.
> >
> > Paolo Roncone
> > Compuprint s.p.a.
> > Italy
> <
>
>
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