Cameroon and Congo Regulatory Requirements

[RPickard]

Hello to all,

I have just been asked about the regulatory requirements that exist in
Cameroon and the Congo, if any actually exist.

If anyone knows what the EMC, safety and telecom regulatory requirements
are for these countries, please respond to this request with the details.
Regulatory contacts in these countries would also be very nice.

Oh, I think it would be beneficial to inform you that the products of
interest here are Customer Premise ITE.

Thank you very much in advance to those that can respond.

Best regards,
Ron Pickard
rpick...@hypercom.com


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IEC65 or IEC950 ?

[John Radomski]

Jess,

See my remarks below.





sb...@ctlsg.creaf.com on 08/20/99 05:47:50 AM

Please respond to sb...@ctlsg.creaf.com

To:   "EMC-PSTC (E-mail)" 
cc:(bcc: John Radomski/Chandler/Inter-Tel)
Subject:  IEC65 or IEC950 ?







Hi,

I have been troubled by some standard issue and sincerely hope that someone
could share their experience with me.

My company is selling multimedia products which is classified as Information
Technology Equipment(I.T.E.).
We used to OEM AC/DC adapter  to be bundled with our I.T.E. products.
So happen that one of the vendor tested his China  AC/DC power adapter to
GB8898(which is equivalent to IEC65) rather than GB4943(equivalent to IEC950)

My doubts are :
1)  Can I still declare my product as I.T.E., if it is bundled with adapter
tested to GB8898(IEC 65) rather than GB4943(IEC950)?


J.R.: Assuming it is an auto-ranging device:
  a. For the US and Canada, you need a formal NRTL approval,
  b. For the EEA (European Economic Area), you need to issue an EC
 Declaration of Conformity to the LV and EMC Directives (EN
 standards need to be used). If I were you I would ask the NRTL to
 verify the vendor test data.


2) Will there be any legal issue that I may face by using  IEC65 tested  adapter
   for I.T.E. products ?


3) Wonder is the testing criteria of IEC65  more stringent than IEC950 ?


J.R.: There is avery good chance it complies with IEC 950.


John Radomski
Compliance Engineer
Inter-Tel Integrated Systems







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Re: Concrete as an insulator???

[Rich Nute]

Hi Doug:


Some years ago I did some tests on my concrete garage
floor using aluminum foil laid down on the floor.

I applied 120 volts through an ammeter to the foil, 
and then measured the current from the 120 volts to 
the foil.  I wanted to learn how much current would 
be conducted by the concrete floor in the event 
someone was standing on the floor and touching a 
120-volt live wire.

As I recall, I put something on top of the foil to 
hold it in good contact with the concrete.

With dry concrete, the current was tolerably low --
in the microamps.

With wet concrete (I poured water onto the concrete,
mopped up the puddle, and placed the foil on the 
concrete), the leakage current was in the low 
milliampere region.

I would certainly caution about using as an insulator
a material that is not rated as an insulator.  Since
the material is not evaluated as an insulator, there
is no data on its performance.  I would be hard 
pressed to use such a material as a reliable insulator.


Good luck!
Rich





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Concrete as an insulator???

[POWELL, DOUG]

Hello all,
 
I have a very innovative engineer who has come up with a design idea that
uses concrete as an insulating compound in a very large inductor for a 200
kW switching power supply.  Yup, this is the stuff you buy down at the local
building supply company.  He was very proud of the idea, but until he came
up with it I think he was pretty desperate.  I'm thinking I should make him
desperate again but would like to be able to give him a clearly reasoned-out
explanation.
 
Has anyone ever had experience with using concrete or mortar in a high
voltage application?  What are the concerns here?  It is my understanding
that it does not actually "dry" but it cures with all the water contained
inside.
 
 
thanks,
 



-doug

===
Douglas E. Powell, Compliance Engineer
Advanced Energy Industries, Inc.
1625 Sharp Point Dr.
Fort Collins, Colorado 80525 USA
---
970-407-6410  (phone)
970-407-5410  (e-fax)
mailto:doug.pow...@aei.com  
http://www.advanced-energy.com  
===



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Colorado Product Safety Technical Committee (CPSTC) minutes for t he July 27, 1999 meeting.

[RichardG]

For those of you who are interested in the Colorado Product Safety Technical
Committee (CPSTC) minutes, please read on. Don't forget the Product Safety
Newsletter (PSN) can now be found at their new website:
http://www.ewh.ieee.org/soc/emcs/pstc/

The Product Safety Technical Committee of the IEEE EMC Society will have
updates regarding its annual meeting and Workshop that was held at the 1999
IEEE EMC Symposium in Seattle, WA this past August, on their new website.
===
The July 27, 1999 CPSTC meeting was held at the Hewlett Packard facilities
in Colorado Springs. Ron Duffy, HP safety engineer, hosted the meeting.

Review of the minutes:
1) Total attendance: Ten
2) The September 15, 1999 Wednesday, is tentative scheduled to be held at
the Exabyte facilities. Topics for the September meeting will include:
a. Update the chapter of the TC-8 annual meeting and Product Safety workshop
minutes from the 1999 IEEE EMC Symposium. The annual meeting and workshop
was held in Seattle, WA from August 2 to 6.
b. Future presentations to be developed by the chapter for future product
safety workshops or tutorials.
c. Next year's agenda.
d. Elections will be held at the January 2000 meeting. Presently, I will be
collecting nominations for chairman.

3) Reviewed with the chapter on the concepts that Ron Duffy and myself are
working on to be possibly submitted to next years IEEE symposium and/or the
Product Safety Workshop. The symposium and workshop are to be held in
Washington, D.C. The ideas and concepts will be submitted to the annual TC-8
meeting that is to be held on Aug. 2, 1999 in Seattle, WA, for their review
and inputs.

4) Glen Bolster, a CPSTC member, received a certificate that he successfully
completed the HP hazard base course. Good job Glen!

5) Ron Duffy presented a short version from his hazard base course. Ron
focused in on "Mitagators". His presentation included the following:
a. Insidious hazard - a hazard that exists but the operator, et al, are not
aware of. If the hazard is lethal, then use a mitagator to prevent the
hazard.
b. Belts and suspenders - two levels of protection
c. Grounding and insulation - examples were given: isolation ground free
environment, protective ground and additional insulation.
d. Hazard base sequence evaluations.
e. Standard fault tree analysis

Richard Georgerian, CPSTC Chair
PSTC Secretary
Product Compliance Engineer
Exabyte
1777 Exposition Drive
Boulder, CO  80301
USA
tel.: 303-417-7537  fax: 303-417-5710   e-mail: richa...@exabyte.com


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Re: 3-Meter Chamber for Emission Pre-Scanning

[ajmani]

Patrick,

In my company, we have a 10 meter semi-anechoic chamber (lined with cones).
However, sometimes I also need to use an outside EMC test facility.  I prefer a
chamber instead of an OATS, because I do only pre-scans, and it is a lot faster
in a chamber.  For the first couple of years, I was using a 3 meter fully
anechoic chamber lined with ferrite tiles.  This lab uses a BiLog antenna at a
fixed height (it is 1.5 or 2 meters), and applies a correction factor to account
for the reflections that are present in an OATS or a semi-anechoic chamber.  I
always had problem co-relating the data between our 10 meter chamber and this 3
meter chamber.  Now I use another EMC test facility with a 10 meter chamber,
similar to the one at our company.

The ferrite tiles generally work well to the frequencies of 500 MHz and then
their absorption drops down.  Also, keeping antenna at a fixed height does not
provide accurate data for horizontal polarization, where one sees more emissions
at higher antenna heights.  Still, a chamber is great for pre-scans and
trouble-shooting and saves you a lot of time.  Only once in a while you need to
verify your data at an OATS, or a 10 meter chamber.

Regards, Ravinder
PCB Development and Design Department

Email: ajm...@us.ibm.com
***
Always do right.  This will gratify some people and astonish the rest.  
Mark Twain



"Patrick, Al"  on 08/19/99 12:28:38 PM

Please respond to "Patrick, Al" 

To:   emc-p...@ieee.org
cc:   "Patrick, Al" , "'alpatr...@op9.com'"
  
Subject:  3-Meter Chamber for Emission Pre-Scanning





To all members of this distinguished group.  I now come to you not to make
commitment but to ask your for help.

My situation is this;  I had an OATS site to which I wanted to add a 3 Meter
chamber (ETS Model 20) for Immunity test per the EU requirements.

I started this quest in 1997 and have succeeded with the installation this
month.

Now my problem,  along the way my company moved into a new campus (Great!),
But now the CEO does not want an ugly OATS around his new campus.  Now just
before approving the new 3 Meter chamber, which took two years to get
thirteen signatures, he says "You can do your scanning in this chamber,
Right!" and looks at me just before he signs it.

Now my eyes roll back in my head and I say (the only thing which will save
this project) "Yes Sir"

Assumptions:  The chamber will only be used for pre-scans and diagnostics.

I already know that you can't correlate a 3 Meter chamber to a 10 Meter
OATS, but I have to try at least try until I can build a 10 OATS somewhere.

I would like to hear from members who have used, or tried to use a 3 meter
(10x10x22 FT. chamber lined with ferrite tile) for emission scans.

I have already found that 1 Meter is about the best distant to scan with out
to many reflections but it's easy to miss an emission too.

I'm "all ears" as they say.

Thank you,

Al Patrick, EMC Lab Manager
Scientific-Atlanta Inc.
al.patr...@sciatl.com




Title: 3-Meter Chamber for Emission Pre-Scanning 





To all members of this distinguished group.  I now come to you not to make commitment but to ask your for help.

My situation is this;  I had an OATS site to which I wanted to add a 3 Meter chamber (ETS Model 20) for Immunity test per the EU requirements.

I started this quest in 1997 and have succeeded with the installation this month.

Now my problem,  along the way my company moved into a new campus (Great!), But now the CEO does not want an ugly OATS around his new campus.  Now just before approving the new 3 Meter chamber, which took two years to get thirteen signatures, he says "You can do your scanning in this chamber, Right!" and looks at me just before he signs it.    

Now my eyes roll back in my head and I say (the only thing which will save this project) "Yes Sir"  

Assumptions:  The chamber will only be used for pre-scans and diagnostics.  

I already know that you can't correlate a 3 Meter chamber to a 10 Meter OATS, but I have to try at least try until I can build a 10 OATS somewhere.

I would like to hear from members who have used, or tried to use a 3 meter (10x10x22 FT. chamber lined with ferrite tile) for emission scans. 

I have already found that 1 Meter is about the best distant to scan with out to many reflections but it's easy to miss an emission too.   

I'm "all ears" as they say. 

Thank you, 

Al Patrick, EMC Lab Manager 

Scientific-Atlanta Inc.

al.patr...@sciatl.com


 

Re: ESD

[Leslie Bai]

Arun:

When I started dealing with EMC 13 years ago,
I always thought ESD is conductive
testing but later I found it is not only conductive
but also radiative! The way of doing testing looks
like conductive but the effect of ESD is beyond that.

Obviously, different dv/dt produce different field
distribution - James C. Maxwell told us about 150
years ago - unless you can prove it is wrong.

Different field distribution induces different current
intensity in different portion of the EUT and results
in different sympotum. That why if EUT can pass
higher test levels does not mean it can pass lower
levels due to the different susceptibility of the circuits
exposed to different field distributions.

If you only consider the conductive coupling ,
I guess you can not explain why EUT passed
hihger levels but may not pass lower levels, 
can you?

I also would like to share with you my experience
when I did a TCF job years ago when I was 
working in Singapore. 

We know it is not possible to perform radiated 
immunity testing at the customer's workshop.
It is just simply illegal!
But how would you verify the machine's radiated
susceptibility?  ESD gun can help - think about it.

Regards,
Leslie

--- Arun Kaore  wrote:
 
> I differ from this theory of radiated coupling in
> air discharges. There will
> be air discharge if the creepage/clearance is less
> (than say 7mm for 8kV)
> such that the disturbance voltage just arcs over, if
> there is a path. 
> 
> The discharge current flows then via the shortest
> path, corrupting
> everything in the way, if it is not immune. We note
> that the Immunity noise
> threshold for most ICs is less than a couple of
> volts. 
> 
> The easiest way we employ to fix air discharge
> problems is by artificially
> increasing the creepage by adding plastic foil or
> increasing spacing. 
> 
> Schaffner has different probes, "loop types", which
> are more suited for
> radiative coupling (near field types) as you
> suggest, but we use them for
> pre-compliance purposes only. These are the truly
> "radiative coupling
> types". They are a poor man's friend for MIL STD
> 461/462 CS06 (in air!!), or
> CS115/CS116/ RS02 pre compliance.
> 
> I cannot comment on your Fire Alarm system though,
> but I would hazard a
> guess and attribute it to HCP or capacitive coupling
> via unshielded cables
> spaced off the metal test sheet (the GRP).
> 
> Regards
> 
> 
> 
> Arun Kaore
> EMC Engineer
> 
> ADI Limited
> Systems Group
> Test & Evaluation Centre
> Forrester Road, St Marys NSW 2760
> P O Box: 315, St Marys NSW 1790
> 
> Tel: 61 2 9673 8375
> Fax: 61 2 9673 8321
> Email: kao...@sg.adi-limited.com.au
>  
> 
> 
> -
> This message is coming from the emc-pstc discussion
> list.
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> majord...@ieee.org
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> jim_bac...@monarch.com, ri...@sdd.hp.com, or
> roger.volgst...@compaq.com (the list
> administrators).
> 
> > 
> Leslie Bai wrote: ESD test is to verify the EUT
> immunity due to induced
> current (nonsense!). The current can be induced by
> conducted coupling
> (direct contact) or/and radiated coupling. My
> understanding of the test is
> that for contact discharge, conduct coupling is
> dominate and for
> air-discharge, radiated coupling is dominate.
> Thus for contactt discharge, if you can pass the
> higher level, you may not
> have much problem with lower levels, but although
> radiated coupling is not
> dominate for contact discharge, the effects have to
> be verified through
> testing.
> For air-discharge, ESD test is to verify the effects
> of electromagnetic
> field on the EUT - i.e. a kind of field immunity
> test. Different levels will
> have a different field distribution around the EUT
> due to the different
> dV/dt - Maxwell told us.
> Thus, the induced current is (mainly) generated
> by the electromagnetic field.
> I tested one Fire Alarm system years ago. This
> system has 128 ports all
> connected with (at least 5m) twisted wires. I
> noticed that the cable layout
> can affect result (pass or fail) significantly when
> doing air-discharge.
> However, there is no noticable difference by varying
> cable layout when doing
> contact discharge.
> That was my understanding comes from.
> Rgds,
> Leslie
> 

__
Do You Yahoo!?
Bid and sell for free at http://auctions.yahoo.com


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RE: Equipment designed and manufactured for use in-house

[Scott Douglas]

Carlos,

I do not worry too much about EMI or EMC issues for in-house test 
equipment. Reason being is - some engineer will probably de-skin it sooner 
rather than later anyway. I do always look at electrical, mechanical and 
laser safety issues. I will require changes to make things safe that way. 
But if your FM radio stops working, oh well

Scott
s_doug...@ecrm.com

-Original Message-
From:   carlos.perk...@eu.effem.com [SMTP:carlos.perk...@eu.effem.com]
Sent:   Friday, August 13, 1999 2:22 AM
To: emc-p...@majordomo.ieee.org
Subject:Equipment designed and manufactured for use in-house


Dear All,

A question from UK:

Does anyone have a strategy for handling the Low Voltage and EMC Directive
requirements relating to equipment made for use in-house?

By this, I mean test boxes, power supplies, break-out boxes, etc.

These products are not meant to be offered for sale (ie not 'placed on the
market'), but have been 'taken into service' by being switched on and used.
I think, therefore, that the protection requirements of the Directives must
be met, but CE marking is not necessary.

In terms of Safety, I think EN 60950 and EN 61010-1 are relevant.

Does anyone have a view on this?

Cheers,

Carlos Perkins



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RE: EN50082-1:1997 & EN55024

[Scott Douglas]

Hi Benoit,

I think that testing at voltage increments up to the standard limit (or 
beyond) is necessary. We too had several products that failed at 2 or 3 kV 
but never blinked at 8 kV. Testing to 8 kV only does meet the requirement 
of the standard, but if my customers keep asking for their money back, what 
good is the standard test? As for your hypothesis, I concur. Either one is 
possible. I never did go after figuring out why, just how to fix it. The 
solution would probably give a clue as to why, but it was long enough ago 
that I forget what it was.

Scott
s_doug...@ecrm.com

-Original Message-
From:   bnad...@matrox.com [SMTP:bnad...@matrox.com]
Sent:   Thursday, August 19, 1999 1:07 PM
To: hulbe...@pb.com; emc-p...@ieee.org
Subject:Re: EN50082-1:1997 & EN55024


Bonjour de Montreal,

In another life, I was working for a EMC Test lab and we always used the
step by step procedure which was in the ESD Standard. We tested using this
procedure for years and we did encounter some products who failed at low
level ESD but had no problem at higher levels.

We wondered what to conclude and had some hypothesis.

1) may be the current path was different at higher level or
2) Lower levels might have a slightly longer rise time which tends to
produce
more energy in the lower part of the frequency spectrum where the EUT was
more sensible.

Since the products were not staying in our hands for long we never had a
chance to investigate further.

Comments ?
At 10:07 19-08-99 -0400, Jim Hulbert wrote:
>>
>>
>>
>>Immunity test standards EN50082-1:1997 and EN 55024 call out the basic
standards
>>EN61000-4-2 and EN61000-4-5  for ESD and Surge.
>>
>>EN61000-4-2, Section 5 starts out "The preferential range of test levels
for the
>>ESD test is given in table 1.  Testing shall also be satisfied at the
>lower
>>levels given in table 1."   EN61000-4-5, Section 5 contains similar
>wording.
>>This is how we perform our compliance tests.   We start at the lowest
>test
>>voltage levels from the respective tables and step up to the test levels
called
>>out in EN50082-1/ EN55024 (or higher, depending on our own in-house
>product
>>spec.)
>>
>>However, I have noticed that some test labs go straight to the levels
called out
>>in EN 50082-1/EN55024 and skip testing at the lower levels.  I believe
>this
>>approach is incorrect because it does not conform to the requirements of
>the
>>basic standard and is simply not a complete test.   As explained in
EN61000-4-5,
>>the non-linear current-voltage characteristics of the equipment under
>test
>>should be considered and the test voltage should therefore be increased
>by
steps
>>up to the test level specified in the product standard or test plan.
>The
same
>>rationale applies to ESD testing where current-voltage characteristics
>are
also
>>non-linear.
>>
>>How do others approach these tests?  Are we adding unnecessary test time
>by
>>starting at lower test voltages and stepping our way up or are the test
>labs
>>that go straight to the maximum test levels overlooking an important
aspect of
>>the testing?
>>
>>Jim Hulbert
>>Senior Engineer-EMC
>>Pitney Bowes



--
Benoit Nadeau, ing. M.ing. (P.Eng., M.Eng)
Gerant du Groupe Conformite (Conformity Group Manager)
Matrox 
--

1055, boul. St-Regis
Dorval (Quebec) Canada
H9P 2T4

Tel : (514) 822-6000 (x2475)
FAX : (514) 822-6275
Internet : bnad...@matrox.com, 

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RE: re: EN50082-1:1997 & EN55024

[Mike Hopkins]

I'm not sure I'm the most appropriate person to answer, but here's my
opinion. Doug Smith at Auspex (also a member of this ieee group) is probably
the best qualified to talk about ESD and other noise phenomena:

Back in the mid '80's when we were demonstrating ESD simulators (air
discharge only), we saw a lot of cases where EUT's survived higer voltages
-- 8 to 10kV, but failed when tested at a few kV. With the scopes at the
time, we could see faster rise times at the lower voltages (about 2-5kV),
slower risetimes at intermediate voltages (5-10kV) and faster risetimes
again at the higher voltages (>10kV). We attributed these low voltage
failures to the faster risetimes with air discharges below about 5kV. I I
think this scenereo is still valid, and we see risetimes of a few hundred
pico seconds below about 3kV. Risetimes do get to be slower at higher
voltages. David Pommerenke at HP has done a lot of recent work to
characterize human ESD with modern scopes and high bandwidth
instrumentation.

With contact mode testing, I'm not sure the same argument applies. With a
simulator that has very clean risetimes, the risetime is held constant (IEC
is .7 to 1ns) with voltage. di/dt in fact increases with voltage, which
would be evidence for more failures at higher voltages, but this doesn't
seem to be the case in practice. Nevertheless, people keep coming up with
cases where lower voltages cause failures where higher voltages are okay.

Some possibilities for the problem with contact mode:
1. Some simulator have a considerable amount of ringing on the rising edge
of the current waveform -- ESD Association work under WG14 -- also papers
published at past ESD Symposiums by HP and others. This ringing could be
inconsistant with voltage and be a significant contributor to failures.

2. Breakdowns inside the EUT in air across very small gaps could produce
risetimes well under 400ps. 

3.  Other ideas  

In any case, it is still felt by members of IEC TC77B WG9 (now in the
process of completely re-evaluating IEC 61000-4-2) that testing at lower
voltages is required to insure a product is, in fact, immune to ESD. This
requirement will likely continue into any future version of the IEC
standard.

The latest draft of ANSI/IEEE C63.16- includes statements recommending
testing begin at the lowest voltage and progress to higher voltages -- 1kV
intervals for contact mode and 2kV intervals for air discharge. 

It's clear these requirements will go forward -- there's just too much
evidence for the existance of the phenomena, even though the reasons aren't
always clearly understood for a specific EUT.

Mike Hopkins
mhopk...@keytek.com

> -Original Message-
> From: b...@anritsu.com [SMTP:b...@anritsu.com]
> Sent: Thursday, August 19, 1999 6:56 PM
> To:   Mike Hopkins
> Subject:  fwd: re: EN50082-1:1997 & EN55024
> 
> Mike,
> 
> You are the most appropriate person to answer the question that why DUT
> could 
> fail at lower ESD voltage sometimes. Can you post your answer directly to
> the 
> emc-pstc group?
> 
> Thank you.
> Barry Ma
> b...@anritsu.com
> -- Original Text --
> 
> From: "Leslie Bai" , on 8/19/99 3:00 PM:
> To: Bailin Ma@MMDILAB@ACUS
> 
> Barry,
> 
> I agree with you but just wondering why
> "DUT got larger current at lower ESD 
> voltage. ...".
> 
> BTW, I called Anritsu early this week 
> requesting for a demonstration of "Site Master"
> but just couldn't get any reply yet. 
> 
> Rgds,
> Leslie
> 
> --- b...@anritsu.com wrote:
> > 
> > Jim,
> > 
> > You have been doing right thing. Those who directly
> > go to the highest ESD 
> > voltage level may thought if DUT can pass the
> > highest level it will certainly 
> > pass lower level. As a matter of fact, DUT could
> > possibly fail at lower level 
> > and pass at higher level. Because DUT got larger
> > current at lower ESD 
> > voltage. ...
> > 
> > Barry Ma
> > b...@anritsu.com
> > -- Original Text --
> > 
> > From: "Jim Hulbert" , on 8/19/99
> > 11:34 AM:
> > 
> > 
> > 
> > 
> > Immunity test standards EN50082-1:1997 and EN 55024
> > call out the basic 
> > standards
> > EN61000-4-2 and EN61000-4-5  for ESD and Surge.
> > 
> > EN61000-4-2, Section 5 starts out "The preferential
> > range of test levels for 
> > the
> > ESD test is given in table 1.  Testing shall also be
> > satisfied at the lower
> > levels given in table 1."   EN61000-4-5, Section 5
> > contains similar wording.
> > This is how we perform our compliance tests.   We
> > start at the lowest test
> > voltage levels from the respective tables and step
> > up to the test levels called
> > out in EN50082-1/ EN55024 (or higher, depending on
> > our own in-house product
> > spec.)
> > 
> > However, I have noticed that some test labs go
> > straight to the levels called 
> > out
> > in EN 50082-1/EN55024 and skip testing at the lower
> > levels.  I believe this
> > approach is incorrect because it does not conform to
> > the requirements of the
> > bas

RE: Question on internal ESD testing

[Scott Douglas]

Jack,

We also make large products and I insist on ESD testing every place an 
operator or maintainer can get to. I test in 2kV increments to 16 kV. There 
are even times when I will go beyond that, like testing the media path (we 
move polyester film around) to see what happens or to solve specific 
problems. Tedious, maybe. But cost effective in the long run.

Scott
s_doug...@ecrm.com

-Original Message-
From:   jack.c...@cax.usa.xerox.com [SMTP:jack.c...@cax.usa.xerox.com]
Sent:   Friday, August 13, 1999 4:54 PM
To: gra...@louisville.stortek.com
Cc: emc-p...@majordomo.ieee.org; jack.c...@cax.usa.xerox.com
Subject:RE: Question on internal ESD testing


Charles,

This is a contentious subject for us due to the time it takes to thoroughly
test a large product, so I'd be interested in hearing other's opinions and
practices.

A scenario where ESD can cause a genuine problem (in our business) is when
someone walks across a room to add paper to a printer tray.  In some
machines, the unit will be in standby mode.  In others, it may continue
printing from a different tray or cabinet.  In either case, a discharge to
the internal metal parts of the paper tray could conceivably cause problems
we would consider failures (and have).

Jack Cook
EMC Engineer,
Xerox Corp.
jack.c...@cax.usa.xerox.com
(310)333-5214


-Original Message-
From: Grasso, Charles (Chaz) [mailto:gra...@louisville.stortek.com]
Sent: Friday, August 13, 1999 9:35 AM
To: 'EMC Group'
Subject: Question on internal ESD testing



Hello,

Does anyone in this august group apply ESD discharges INTERNAL
to a product as required by EN55024.

I consider this just a tad egregious - don't you?

Thank you
Charles Grasso
Advisory Engineer
StorageTek
2270Sth 88th Street
Louisville CO 80027 M/S 4247.
Tel:303-673-2908
Fax:303-661-7115
email:gra...@louisville.stortek.com
Web Site:  http://www.ewh.ieee.org/r5/denver/rockymountainemc/




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Re: 3-Meter Chamber for Emission Pre-Scanning

[reheller]

Patrick, I don't understandplease explain your statement:

"you can't correlate a 3 Meter chamber to a 10 Meter
OATS."

The only "correlation" necessary is having the required site attenuation
and ground plane parameters. It is the same "correlation" that 10 meter
sites are required to show. If your chamber falls within plus or minus 4 dB
of the NSA tables using volumetric measurements, then you are deemed
"correlated". OATS have the same requirements except that linear
measurements are made instead of volumetric measurements (volumetric
measurements are harsher requirements).

We use independent commercial testing organizations to do our site
attenuation. Here is the process:

1. Site attenuation measurements are made on a 10 meter open area test site
(OATS) that is known to fall within plus or minus 4 dB of the normalized
site attenuation (NSA) tables.

2. If the OATS measures within 4 dB of NSA then the test equipment used to
measure NSA is determined to be "calibrated".

3. The same test equipment is then used to measure our chamber site
attenuation using volumetric measurements.

4. If the site attenuation data falls within 4 dB of NSA then we are deemed
"correlated".

Our site attenuation data has always been within plus or minus 4 dB of NSA.
It is not an inexpensive process either because we have to fly people and
equipment into our site and pay for two NSA measurements each time.

But to answer your question.yes, professionally built
chambers using state-of -the-art materials are quite good at measuring
emissions. In some respects, they are superior to OATS.

Bob
==





"Patrick, Al"  on 08/19/99 02:28:38 PM

Please respond to "Patrick, Al" 


To:   emc-p...@ieee.org
cc:   "Patrick, Al" 
  "'alpatr...@op9.com'"  (bcc: Robert E.
  Heller/US-Corporate/3M/US)
Subject:  3-Meter Chamber for Emission Pre-Scanning




To all members of this distinguished group.  I now come to you not to make
commitment but to ask your for help.

My situation is this;  I had an OATS site to which I wanted to add a 3
Meter
chamber (ETS Model 20) for Immunity test per the EU requirements.

I started this quest in 1997 and have succeeded with the installation this
month.

Now my problem,  along the way my company moved into a new campus (Great!),
But now the CEO does not want an ugly OATS around his new campus.  Now just
before approving the new 3 Meter chamber, which took two years to get
thirteen signatures, he says "You can do your scanning in this chamber,
Right!" and looks at me just before he signs it.

Now my eyes roll back in my head and I say (the only thing which will save
this project) "Yes Sir"

Assumptions:  The chamber will only be used for pre-scans and diagnostics.

I already know that you can't correlate a 3 Meter chamber to a 10 Meter
OATS, but I have to try at least try until I can build a 10 OATS somewhere.

I would like to hear from members who have used, or tried to use a 3 meter
(10x10x22 FT. chamber lined with ferrite tile) for emission scans.

I have already found that 1 Meter is about the best distant to scan with
out
to many reflections but it's easy to miss an emission too.

I'm "all ears" as they say.

Thank you,

Al Patrick, EMC Lab Manager
Scientific-Atlanta Inc.
al.patr...@sciatl.com




Title: 3-Meter Chamber for Emission Pre-Scanning 





To all members of this distinguished group.  I now come to you not to make commitment but to ask your for help.

My situation is this;  I had an OATS site to which I wanted to add a 3 Meter chamber (ETS Model 20) for Immunity test per the EU requirements.

I started this quest in 1997 and have succeeded with the installation this month.

Now my problem,  along the way my company moved into a new campus (Great!), But now the CEO does not want an ugly OATS around his new campus.  Now just before approving the new 3 Meter chamber, which took two years to get thirteen signatures, he says "You can do your scanning in this chamber, Right!" and looks at me just before he signs it.    

Now my eyes roll back in my head and I say (the only thing which will save this project) "Yes Sir"  

Assumptions:  The chamber will only be used for pre-scans and diagnostics.  

I already know that you can't correlate a 3 Meter chamber to a 10 Meter OATS, but I have to try at least try until I can build a 10 OATS somewhere.

I would like to hear from members who have used, or tried to use a 3 meter (10x10x22 FT. chamber lined with ferrite tile) for emission scans. 

I have already found that 1 Meter is about the best distant to scan with out to many reflections but it's easy to miss an emission too.   

I'm "all ears" as they say. 

Thank you, 

Al Patrick, EMC Lab Manager 

Scientific-Atlanta Inc.

al.patr...@sciatl.com


 

IEC65 or IEC950 ?

[sbtan]

Hi,

I have been troubled by some standard issue and sincerely hope that someone
could share their experience with me.

My company is selling multimedia products which is classified as Information
Technology Equipment(I.T.E.).
We used to OEM AC/DC adapter  to be bundled with our I.T.E. products.
So happen that one of the vendor tested his China  AC/DC power adapter to
GB8898(which is equivalent to IEC65) rather than GB4943(equivalent to IEC950)

My doubts are :
1)  Can I still declare my product as I.T.E., if it is bundled with adapter
tested to GB8898(IEC 65) rather than
 GB4943(IEC950) ?
2) Will there be any legal issue that I may face by using  IEC65 tested  adapter
for I.T.E. products ?
3) Wonder is the testing criteria of IEC65  more stringent than IEC950 ?


Thanks in advance !
Jess



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Re: Egon Vargu, where are you?

[Bill Lyons]

Hi Egon,

many thanks for your message, and apologies for my stupidity in 
mis-spelling your surname, naturally resulting in "not known at this 
address"!  

> Regarding the "Cenelec's List of Decisions," yes, I have cancelled my home 
> page.  Wasn't really using it (too busy with my day job), so it was a bit 
> of a waste of money.

Thanks for the clarification.

> In another message on this thread, Art Michael points to a URL that has 
> some of these decisions.  I took a quick look, but it doesn't seem to 
> include EN 60950.  If anybody wants a copy of the one I made up, I will be 
> glad to send a copy by e-mail.  Alternatively, if anybody wants to post 
> this on an easily accessible web site, they are welcome to do so (We need a 
> volunteer here.  Art?).  Just make sure the entire document is posted, 
> including my disclaimer.

I'd be very happy to put it on my personal (i.e. technical links) website 
www.lyons.demon.co.uk, which already has the ASCII versions of the FAQ 
files (Martin Rowe, technical editor of Test & Measurement World, kindly 
HTMLises it and puts that version on his site).

I already have a number of other useful documents on my site, which is 
distinct from (but naturally linked to) our commercial site 
www.claudelyons.co.uk - if you have the time, have a look.

If you'd like me to do this, tell me where I can download it, or email it 
to me.

Best regards, and glad to be back in contact.  My full sig(s) below for 
reference.

Bill.

P.S.  I now seem to have collected so many alternative or suggested
email addresses for you that it would be useful to confirm your preferred 
one is indeed e...@varju.bc.ca (if spelt correctly!!!).  Other offerings 
include:

>From: "Paul Smith" 

Try eva...@compuserve.com

The RCIC 'repository' for emc-pstc and treg has this listed as the email 
address.

>From: "Serge F Bousquet" 

Try his "Have Modem Will Travel" address

eva...@csi.com

>From: Art Michael 



[And thanks to all who kindly replied to my message - Bill.]

-- 
Bill Lyons
Claude Lyons Limited, Brook Road, Waltham Cross, Herts EN8 7LR, UK
Tel: +44 1992 768 888   email: b...@lyons.demon.co.uk
Fax: +44 1992 769 849   URL:   http://www.claudelyons.co.uk

Maintainer of the sci.engr.electrical.compliance (s.e.e.c) FAQ
Posted approx 15th of each month (d.v.), archived at:-
HTML:   http://world.std.com/~techbook/compliance_faq.html
ASCII:  http://www.lyons.demon.co.uk/seecfaq1.txt, seecfaq2.txt


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ESD

[Arun Kaore]

Leslie Bai wrote: ESD test is to verify the EUT immunity due to induced
current (nonsense!). The current can be induced by conducted coupling
(direct contact) or/and radiated coupling. My understanding of the test is
that for contact discharge, conduct coupling is dominate and for
air-discharge, radiated coupling is dominate.
Thus for contactt discharge, if you can pass the higher level, you may not
have much problem with lower levels, but although radiated coupling is not
dominate for contact discharge, the effects have to be verified through
testing.
For air-discharge, ESD test is to verify the effects of electromagnetic
field on the EUT - i.e. a kind of field immunity test. Different levels will
have a different field distribution around the EUT due to the different
dV/dt - Maxwell told us.
Thus, the induced current is (mainly) generated
by the electromagnetic field.
I tested one Fire Alarm system years ago. This system has 128 ports all
connected with (at least 5m) twisted wires. I noticed that the cable layout
can affect result (pass or fail) significantly when doing air-discharge.
However, there is no noticable difference by varying cable layout when doing
contact discharge.
That was my understanding comes from.
Rgds,
Leslie

Leslie:

I differ from this theory of radiated coupling in air discharges. There will
be air discharge if the creepage/clearance is less (than say 7mm for 8kV)
such that the disturbance voltage just arcs over, if there is a path. 

The discharge current flows then via the shortest path, corrupting
everything in the way, if it is not immune. We note that the Immunity noise
threshold for most ICs is less than a couple of volts. 

The easiest way we employ to fix air discharge problems is by artificially
increasing the creepage by adding plastic foil or increasing spacing. 

Schaffner has different probes, "loop types", which are more suited for
radiative coupling (near field types) as you suggest, but we use them for
pre-compliance purposes only. These are the truly "radiative coupling
types". They are a poor man's friend for MIL STD 461/462 CS06 (in air!!), or
CS115/CS116/ RS02 pre compliance.

I cannot comment on your Fire Alarm system though, but I would hazard a
guess and attribute it to HCP or capacitive coupling via unshielded cables
spaced off the metal test sheet (the GRP).

Regards



Arun Kaore
EMC Engineer

ADI Limited
Systems Group
Test & Evaluation Centre
Forrester Road, St Marys NSW 2760
P O Box: 315, St Marys NSW 1790

Tel: 61 2 9673 8375
Fax: 61 2 9673 8321
Email: kao...@sg.adi-limited.com.au  


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IEC945 for Apparatus?

[SM Ling]

IEC945 is a test for whole equipment.  Does it apply to apparatus,
like a processor card?  If it is applicable, what parts of it should
be used?  How should one decide?

After reading through IEC945 literature, I found it not applicable to
module or appartus.  However, recently I came across a mouse that
claims to be IEC945 tested.  Am I missing something here?

Comment please.

Ling


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1 GHz probe theory

[Douglas C. Smith]

Hi All,

I have added a theory of operation section to the 1 GHz probe plans on
my site at:

http://emcesd.com

The section discusses why the foil is needed and the underlying
limitation on the useful frequency range of the probe. Also added is
the ability to click on the probe pictures to blow them up to full
screen size, instantly. You can even clearly read the values on the
surface mount resistors!

I am interested in any comments on the theory addition (correctness,
readability, etc.)

Also posted is the discussion on this month's problem of how to
measure circuit voltages with a paper clip.

Thanks in advance,

Doug

-- 
---
___  _   Doug Smith
 \  / )  P.O. Box 1457
  =  Los Gatos, CA 95031-1457
   _ / \ / \ _   TEL/FAX: 408-356-4186/358-3799
 /  /\  \ ] /  /\  \ Mobile:  408-858-4528
|  q-( )  |  o  |Email:   d...@dsmith.org
 \ _ /]\ _ / Website: http://www.dsmith.org
---


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FW: EN50082-1:1997 & EN55024

[Arun Kaore]

EN 55014-2: 1997: Immunity standard for Household goods:

#5.1: ESD will be tested to the procedures of IEC 1000-4-2 but "tests with
lower voltages than those given in Table 1 (4kV Contact/ 8 kV Air) are not
required.:

# 5.6: Surges: Tests with lower voltages than those given in Table 12
(1kV/2kV) are not required, but tests will be carried out in accordance with
IEC 1000-4-5. 

What is right and what is wrong? At least for household we believe that EN
55014-2 takes precedence, and we belt the EUT with the stated levels. But we
do a few exploratory runs at lower voltages.

For all other immunity standards we start off gradually till we reach the
stated limit values, which is the way I believe it should be done. But it
increases the time, especially for Surge tests where you got to hit at
different points on the sine wave quadrant too. 



Regards

Arun Kaore
EMC Engineer

ADI Limited
Systems Group
Test & Evaluation Centre
Forrester Road, St Marys NSW 2760
P O Box: 315, St Marys NSW 1790

Tel: 61 2 9673 8375
Fax: 61 2 9673 8321
Email: kao...@sg.adi-limited.com.au  

-Original Message-
From:   Jim Hulbert [mailto:hulbe...@pb.com]
 
Sent:   Friday, 20 August, 1999 0:07
To: emc-p...@ieee.org  
Subject:EN50082-1:1997 & EN55024




Immunity test standards EN50082-1:1997 and EN 55024 call out the basic
standards EN61000-4-2 and EN61000-4-5  for ESD and Surge.
EN61000-4-2, Section 5 starts out "The preferential range of test levels for
the ESD test is given in table 1.  Testing shall also be satisfied at the
lower levels given in table 1."   EN61000-4-5, Section 5 contains similar
wording.  This is how we perform our compliance tests.   We start at the
lowest test voltage levels from the respective tables and step up to the
test levels called out in EN50082-1/ EN55024 (or higher, depending on our
own in-house product spec.)
However, I have noticed that some test labs go straight to the levels called
out in EN 50082-1/EN55024 and skip testing at the lower levels.  I believe
this approach is incorrect because it does not conform to the requirements
of the basic standard and is simply not a complete test.   As explained in
EN61000-4-5, the non-linear current-voltage characteristics of the equipment
under test should be considered and the test voltage should therefore be
increased by steps up to the test level specified in the product standard or
test plan.   The same rationale applies to ESD testing where current-voltage
characteristics are also non-linear.
How do others approach these tests?  Are we adding unnecessary test time by
starting at lower test voltages and stepping our way up or are the test labs
that go straight to the maximum test levels overlooking an important aspect
of the testing?
Jim Hulbert
Senior Engineer-EMC
Pitney Bowes




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Re: Pressurized Vessel Directive and "Nominal Size"

[Chuck Seyboldt]

On Thu, 19 Aug 1999, Crane, Lauren wrote:

> I am working to grasp the implications of the PED (Pressurized
> Equipment Directive) for our equipment. 
 
> I'm stuck on determining the "DN" value for tubing in our equipment.
 
> I gather from Article 1, 2.6 that DN is Nominal Size, and is a value
> assigned to piping system components.

Dear Lauren:

DN indeed refers to "Nominal Size" and may be thought of a
"Diameter Nominal" expressed in millimeters.  It refers basically to
the inside diameter of the tube or pipe.  The bigger the pipe, the
bigger the hazard.  Length of the pipe does not figure in placing
the piping system or piping run within the Tables.

> 1. 30 psi (2 bar) pneumatic systems in equipment for driving air
> cylinders and air valves and the like fall under the PED according to
> Article 3, 1.3, second indent (group 2 liquids)correct?

Maybe - see section 3.6 in Article 1, if the pressure
related equipment is no higher than Category I and is evaluated
under the Machinery Directive, then the PED does not apply.  Also,
the design of some devices (e.g. internal combustion engines, and
perhaps the cylinders in your equipment) is not determined by the
stresses due to pressure.  In those instances, even though the
device contains pressure, they are not expected to be covered by the
PED.  See section 3.10 of Article 1 for this exemption - although
the tubing system you referred to is likely to have been designed
with pressure being a controlling factor.

Even if the equipment is covered by the PED, the piping is
not likely to control the classification.  At 2 Bar, the piping size
needs to be greater than 500 mm (20 inches) before leaving "SEP" -
Sound Engineering Practices - and entering Category I.  2 Bar times
DN 500 -> 1000 PS*DN.
 
> . . . if you have a valve with DN=10 and a length of tube
> connected with DN=50, then the system total is . . . ? 

In this case, the system will be evaluated using a DN value
of 50, even though the valve is smaller.  Again, for piping, DN
refers only to the (largest) diameter, and placement of a piping
system in the tables is determined by the combination of diameter
and pressure.  A DN 10 valve with DN 10 tubing results in a DN 10
piping system. 

The entire system will be placed in a category that is
determined by the aspect that "earns the highest rating."  If the
system contains a vessel at Category II and piping at Category I,
the system is a Category II system.  

Regards,
Chuck Seyboldt


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Re: EN50082-1:1997 & EN55024

[Leslie Bai]

Hi, all

Just put a few words of my understanding of ESD.

ESD test is to verify the EUT immunity due to induced
current (nonsense!). The current can be induced by
conducted coupling (direct contact) or/and radiated
coupling. My understanding of the test is that for
contact discharge, conduct coupling is dominate
and for air-discharge, radiated coupling is dominate.

Thus for contactt discharge, if you can pass the higher
level, you may not have much problem with lower
levels, but although radiated coupling is not 
dominate for contact discharge, the effects have 
to be verified through testing.

For air-discharge, ESD test is to verify the effects
of electromagnetic field on the EUT - i.e. a kind
of field immunity test. Different levels will have
a different field distribution around the EUT
due to the different dV/dt - Maxwell told us.
Thus, the induced current is (mainly) generated
by the electromagnetic field.

I tested one Fire Alarm system years ago. This
system has 128 ports all connected with (at least 
5m) twisted wires. I noticed that the cable layout
can affect result (pass or fail) significantly when
doing air-discharge. However, there is no 
noticable difference by varying cable layout 
when doing contact discharge.

That was my understanding comes from.

Rgds,
Leslie
 

--- Hans Mellberg  wrote:
> 
> 
> --- Benoit Nadeau  wrote:
> > 
> > Bonjour de Montreal,
> > 
> > In another life, I was working for a EMC Test lab
> > and we always used the
> > step by step procedure which was in the ESD
> > Standard. We tested using this
> > procedure for years and we did encounter some
> > products who failed at low
> > level ESD but had no problem at higher levels.
> > 
> > We wondered what to conclude and had some
> > hypothesis.
> > 
> > 1) may be the current path was different at higher
> > level or
> > 2) Lower levels might have a slightly longer rise
> > time which tends to produce 
> > more energy in the lower part of the frequency
> > spectrum where the EUT was
> > more sensible.
> >
> 
> 
> Partly true. The risetime changes as the voltage
> increases. The
> risetime "slows" (dV/dt or dI/dt value gets reduced)
> down as you begin
> to go over 6-8kV. I also have seen products fail at
> 2-4 kV and pass at
> levels 8-10 kV. This ofcourse is on air discharge
> equipment where
> variability of the risetime is expected.
> Contact discharge equipment do not exhibit much
> risetime variability
> (at least not to a large degree)
> 
> Hans T. Mellberg
> EMC/ESD Consultant
> member ANSI/IEEE C63.16 WG on ESD
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