Dear Experts please help me to answer my question(s) I have since few years.
I planned to ask it later, but it looks very close to that conversation
subject so I ask now.
I plan to produce the electronic education system.
If I have the PCB with single transistor amplifier (or some OpAmp circuit) to
allow pupil to measure it I have to make all pins accessible at least to allow
for connecting the scope probe. I think I cannot protect each pin against ESD
because my protection elements will certainly disturb the measurement results
making them different from theory - for me unacceptable from education point
of view.
I expect during EMC tests ESD can destroy that transistor, or OpAmp (really
each education board can be destroyed by ESD). At the same time I don't expect
real problems in practical use of it.
In my opinion the right standard is 61326 which fortunately allows for
deviation for ESD criteria, but even it don't allow the DUT being destroyed by
ESD.
When I read here that new version don't allows for previously allowed
deviations I came to seeing no way how I can do that education equipment with
accordance with right standard.
On the other way I don't expect that in EU practical electronic education is
forbidden now and should be replaced with simulation only ;-)
If there is someone who knows what is the solution please tell me.
May be some notes in TCF and instruction are enough.
Each such experiment PCB is low price and low volume product so I don't
consider asking for external official opinion for each of it.
The other EMC problem with that design:
It is typical (and I assume also) to use unshielded short (10 - 15cm) wires to
make the connections by pupil at such devices.
The function generator (1Hz to 3MHz, better to 10MHz) is the standard part of
such system.
Do I have to hardly filter the main (sin/triangle/square) output to have
nothing above 30MHz making the square not being the square ?
But the generator should also have the TTL output which can also be connected
by such 15cm cable to some circuit under test.
I suppose (not sure) that such TTL signal in 15 cm unshielded wire will
violate allowed emission levels.
I have read 61326 two years ago and don't remember now.
Is there any point saying that if the generator is intended to generate the
signal that it's emission at generated frequency can be higher than limit ?
If yes than if the generator has square output the harmonics of the main
frequency are also considered the intended signal ?
As with the ESD I also expect no EMC problems with this generator in practical
use because the highest frequency will be used may be 10 minutes per year and
far away from neighbours with their TV sets.
I have planed to make such system since more than 10 years, but gave up in
2002 when I read that shortly (when we join EU in 2004) all devices on the
market will have to be ESD protected.
Now I'd like to realise my dream, but don't know how to solve two described
problems.
I believe you can help me.
Best Regards
Piotr Galka [email protected]
----- Original Message -----
From: Kunde, Brian <mailto:[email protected]>
To: Ted Eckert <mailto:[email protected]> ;
[email protected]
Sent: Wednesday, November 05, 2008 8:24 PM
Subject: RE: Deviation of Performance Criteria
As Doug mentioned in his email, the allowance of deviations appear to
have
been removed in the 2006 version of the EN 61326-1 standard which I believe
becomes mandatory in February 2009. Can anyone else confirm this or is there
some other statement in the 2006 version that I’m not seeing that allows the
deviation?
Thanks,
The Other Brian
________________________________
From: Ted Eckert [mailto:[email protected]]
Sent: Wednesday, November 05, 2008 1:53 PM
To: Kunde, Brian; [email protected]
Subject: RE: Deviation of Performance Criteria
As I read EN 61326, it allows the manufacturer to specify the
performance
criteria for each test. The standard only requires that equipment shall not
become dangerous or unsafe as a result of the application of the tests. Table
2 is only an example of evaluation of immunity test results. The note states
“…performance criteria B and/or C may be accepted provided that both the
specification and the test report highlight such deviation(s) for the relevant
combination(s) of function and test.”
The standard does require that the deviations be listed in the
specifications
in addition to the test report. If the published specifications do not
describe the deviations, the manufacturer may be considered in noncompliance
with the standard. If they have declared compliance via the standard, this
could be an issue. If the manufacturer has chosen not to use the standards
route but claims compliance with the essential requirements of the directive,
you may have an argument if the peripheral is not suitable for its intended
use because of the deviation.
I agree with David Spencer; you are the customer and the vendor needs
to meet
your requirements if they want you to buy their products.
Ted Eckert
Compliance Engineer
Microsoft Corporation
[email protected]
The opinions expressed are my own and do not necessarily reflect those
of my
employer.
From: Kunde, Brian [mailto:[email protected]]
Sent: Wednesday, November 05, 2008 9:59 AM
To: [email protected]
Subject: Deviation of Performance Criteria
Greetings Compliance Experts.
Something disturbing came across my desk today I thought I would get
your
opinion on it.
On a CE marked peripheral we buy/sell as part of our laboratory
equipment
system, failed several immunity tests when we tested it as part of our system.
When we notified the peripheral's manufacturer of the problem (yes, I'm being
purposely vague) they said the failures were ok and sent us a "Certificate of
Compliance" by a very very well know compliance lab with the following
statement:
Snip
EMC Immunity:
EN 61326-1:1997/A1:1998/A2:2001 EMC requirements for Electrical
equipment for
measurement, control, and laboratory use.
- General Use for the following test with deviation of performance
criteria
to Criteria "C" instead of "B".
EN 61000-4-2
EN 61000-4-3
EN 61000-4-4
Unsnip
The peripheral manufacture said the EMC test lab told them they can put
the
CE marking on their product as long as they included the above deviation
statement in their documentation and DOC.
Is this true or was there some kind of miscommunication between the
test lab
and the peripheral manufacturer?
With this line of thinking, our test lab will not have to fail anything
in
the future; just pass it with a deviation in the requirements. (just kidding).
Thanks to all for your opinion.
The Other Brian
_________________________
LECO Corporation Notice: This communication may contain confidential
information intended for the named recipient(s) only. If you received this by
mistake, please destroy it and notify us of the error. Thank you.
-
----------------------------------------------------------------
This message is from the IEEE Product Safety Engineering Society
emc-pstc
discussion list. Website: http://www.ieee-pses.org/
To post a message to the list, send your e-mail to [email protected]
Instructions: http://listserv.ieee.org/request/user-guide.html
List rules: http://www.ieee-pses.org/listrules.html
For help, send mail to the list administrators:
Scott Douglas [email protected]
Mike Cantwell [email protected]
For policy questions, send mail to:
Jim Bacher: [email protected]
David Heald: [email protected]
All emc-pstc postings are archived and searchable on the web at:
http://www.ieeecommunities.org/emc-pstc
_________________________
LECO Corporation Notice: This communication may contain confidential
information intended for the named recipient(s) only. If you received this by
mistake, please destroy it and notify us
of the error. Thank you.
-
----------------------------------------------------------------
This message is from the IEEE Product Safety Engineering Society
emc-pstc
discussion list. Website: http://www.ieee-pses.org/
To post a message to the list, send your e-mail to [email protected]
Instructions: http://listserv.ieee.org/request/user-guide.html
List rules: http://www.ieee-pses.org/listrules.html
For help, send mail to the list administrators:
Scott Douglas [email protected]
Mike Cantwell [email protected]
For policy questions, send mail to:
Jim Bacher: [email protected]
David Heald: [email protected]
All emc-pstc postings are archived and searchable on the web at:
http://www.ieeecommunities.org/emc-pstc
-
This message is from the IEEE Product Safety Engineering Society emc-pstc
discussion list. Website: http://www.ieee-pses.org/
To post a message to the list, send your e-mail to [email protected]
Instructions: http://listserv.ieee.org/request/user-guide.html
List rules: http://www.ieee-pses.org/listrules.html
For help, send mail to the list administrators:
Scott Douglas [email protected]
Mike Cantwell [email protected]
For policy questions, send mail to:
Jim Bacher: [email protected]
David Heald: [email protected]
All emc-pstc postings are archived and searchable on the web at:
http://www.ieeecommunities.org/emc-pstc
