RE: Kalmus Amplifier

[owner-emc-p...@majordomo.ieee.org]

From: Ahmad Fallah [mailto:emcesd2...@yahoo.com]
Sent: Wednesday, April 14, 2004 3:39 PM
To: emc-p...@majordomo.ieee.org
Subject: Kalmus Amplifier


Hello all,

Would anyone in the group know of a shop that can repair and calibrate
Kalmus amplifiers?  We have sent our broadband amplifier out for repairs,
but the response has been very slow.

Thanks,
Ahmad Fallah



Ahmad:

IFI claims that they repair all makes of amplifiers, so see them at

http://www.ifi.com


I only calibrate my pre-amplifiers; i.e., amplifiers in the emission
measurement signal chain.

All of my broadband power amplifiers are non-calibrated equipment. If I need
to apply a specific power level to a test fixture, I use a directional
coupler to measure the power directly. This method does not require
knowledge of the amplifier gain, eliminating the need for calibration. You
save money, and the amp always stays in-house.

Regards,

Ed

Ed Price
ed.pr...@cubic.com WB6WSN
NARTE Certified EMC Engineer & Technician
Electromagnetic Compatibility Lab
Cubic Defense Applications
San Diego, CA  USA
858-505-2780  (Voice)
858-505-1583  (Fax)
Military & Avionics EMC Is Our Specialty


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Re: Product Safety Symbol Legalities

[owner-emc-p...@majordomo.ieee.org]

Jo,
 
While I agree with Bob and Rich that the use of markings will not provide you
with an immunity from prosecution, some infer from such replies that providing
warnings on the product or in the user instructions is a waste of time: this
isn't so.  
 
Safety standards may require certain information to be provided (marked on the
equipment or contained in user or service documentation) and both product and
health and safety legislation (in Europe at least) has a duty to warn of
residual risks.  If you do not provide an adequate warning when such
information is required then you are certainly asking to be fined a higher
amount in any ensuing court case by virtue of your negligence.
 
 
Moderators,
 
Why is it that sometimes I only seem to get the replies to questions and not
the original questions?  Is this unique to my system (some anti-spam software
being over zealous perhaps?) or are others finding the same thing?
 
Regards,
 
Richard Hughes
 
 
 
 
In a message dated 04/14/2004 23:27:53 GMT Standard Time,
john...@itesafety.com writes:


Greetings,

A common product safety symbol, the exclamation point within a triangle, is
used to refer the user to the manual.

General questions:
As a manufacturer, are we covered from any liability as a result of the
user not being aware of what the symbol means?  Do we assume that users
know to refer to the manual when they see that symbol?  Are there any court
cases that have set precedents on this issue or related safety marking
issues?  Any personal experiences?

All responses are greatly appreciated.

Regards

Joe Martin
Applied Biosystems

 

Re: Defining an ESD Threat

[owner-emc-p...@majordomo.ieee.org]

After looking at the triboelectric series, it seems that the only time a human
would charge negatively is after falling off an airplane! Otherwise, you are
likely to be positevily charged.
 
Hans Mellberg

Kalmus Amplifier

[owner-emc-p...@majordomo.ieee.org]

Hello all,
 
Would anyone in the group know of a shop that can repair and calibrate Kalmus
amplifiers?  We have sent our broadband amplifier out for repairs, but the
response has been very slow.
 
Thanks,
Ahmad Fallah
 

Re: laminated capacitor source

[owner-emc-p...@majordomo.ieee.org]

Eric Lifsey wrote:

>
> At 11:50 AM -0700 4/13/04, Fred Townsend wrote:
>
>> John Woodgate wrote:
>>
>>> I read in !emc-pstc that Chris Maxwell 
>>>  wrote
>>> (in 
>>> <39F7
60a00b5e946b516261c077441c002a...@utexch1w.gnnettest.com>) 
>>>
>>> about 'laminated capacitor source' on Tue, 13 Apr 2004:
>>>
 I think that they gave the product a name something like
 the "Micro Q" series.

>>>
>>>
>>> A definite marketroid name. Do we want our decoupling capacitors to 
>>> have
>>> extremely low Q?
>>>
>> Yes, John, you want the bypass circuitry to be low Q!  [...]
>>
>> Fred Townsend
>
>
> And another GOTCHA if I may.
>
> Lossy caps (or anything lossy in this business) will dissipate some 
> heat.  If your power rail has high di/dt or RF currents, the cap will 
> heat up.  The cap life may shorten insignificantly, or given the 
> severe conditions end quickly and spectacularly.  Lossy caps may bring 
> down your predicted MTBF, but depending on other failure contributors 
> (such as stressed tantalum caps) it is probably a very acceptable 
> trade to reduce emissions.

I agree Eric.  That is one reason for using multiple bypass caps in 
parallel. There is another heat source called dielectric losses. (Try 
using a clay cup in a mircowave oven if you want to see an example.)  I 
have actually seen caps that were melted from excess current (not 
leakage current.  That is why transmitter caps have current ratings as 
well as voltage breakdown ratings.

Fred Townsend

>
> Eric Lifsey
> http://www.relia.net/~elifsey/
>
> ---
> This message is from the IEEE EMC Society Product Safety
> Technical Committee emc-pstc discussion list.
>
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>
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>






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RE: Defining an ESD Threat

[owner-emc-p...@majordomo.ieee.org]

http://esda.org/esdbasics1.htm   and   
ttp://www.rfcafe.com/references/electrical/triboelectric_series.htm give
further details of the effect of distance apart on the triboelectric series
chart.

 

 


From: owner-emc-p...@majordomo.ieee.org
[mailto:owner-emc-p...@majordomo.ieee.org] On Behalf Of Mike Hopkins
Sent: Wednesday, April 14, 2004 1:24 PM
To: 'Ken Javor'; Mike Hopkins; emc-p...@majordomo.ieee.org
Subject: RE: Defining an ESD Threat

 

Ah yes,  things get more complicated as usual...

 

There is something called the Triboelectric series, which gives you some idea
of the charging possibilities between materials There further apart two
materials are in the series, the more charge you get from rubbing them
together -- the more you rub, the more you charge... Look at:
http://www.school-for-champions.com/science/static_materials.htm for one

 

What you really need is an inexpensive charge meter and a volunteer -- see
what you can get on a person in various environments as the humidity increase
- it would be easy to do and maybe even some fun Use a MiniZap to charge
'em up to different voltages (standing on a rubber mat) and have him/her step
off and see if the charge stays(As I think about it, someone's probably
already done it, but not sure where to look...)

 

 

Best Regards, 

Michael Hopkins 
Control Technology Division 
Compliance Test Solutions 
Thermo Electron Corporation 
One Lowell Research Center 
Lowell, MA 01852 
Tel: +1 978 275 0800 ext. 334 
Mobile: +1 603 765 3736 
michael.hopk...@thermo.com 

 

One Thermo, committed to integrity, intensity, innovation & involvement 


From: Ken Javor [mailto:ken.ja...@emccompliance.com]
Sent: Wednesday, April 14, 2004 3:33 PM
To: Mike Hopkins; emc-p...@majordomo.ieee.org
Subject: Re: Defining an ESD Threat

That makes sense, but it only addresses half of the ESD environment question,
which is how high a potential can something be charged up to, and how long
will it hold the charge.  The other half of the question is the
charge-generating mechanism.  If the surfaces one walks on are largely metal
or concrete, how does that effect the amount of charge relative to a carpet? 
And more importantly, whether the charging surface is carpet or concrete or
metal, how can one simulate the charging mechanism in a repeatable fashion? 
How do you build a human body model not in terms of a capacitor and resistor,
but in terms of modeling scuffing one's feet and measuring the resultant
charge collection?


From: Mike  Hopkins 
List-Post: emc-pstc@listserv.ieee.org
Date: Wed, 14 Apr 2004 14:18:24 -0400
To: "'Ken Javor'" , emc-p...@majordomo.ieee.org
Subject: RE: Defining an ESD Threat

 


Simple thing to do is take an ESD simulator and try charging some objects in
that environment and see if they will hold a charge In high humidity, I'd
expect charges to bleed off very quickly on most objects, which is why the ESD
threat would be low 

In low humidity, of course, the charged surfaces and/or objects would tend to
hold a charge... 

If a person becomes charged due to triboelectric charging walking across a
carpet, I don't know that a high humidity prevents charging -- but it will
definately bleed a charge off quickly Maybe faster than the charging can
take place??? 

None of this is quantitative, of course 

Best Regards, 

Michael Hopkins 
Control Technology Division 
Compliance Test Solutions 
Thermo Electron Corporation 
One Lowell Research Center 
Lowell, MA 01852 
Tel: +1 978 275 0800 ext. 334 
Mobile: +1 603 765 3736 
michael.hopk...@thermo.com 

One Thermo, committed to integrity, intensity, innovation & involvement 

-Original Message- 
From: Ken Javor [mailto:ken.ja...@emccompliance.com] 
Sent: Wednesday, April 14, 2004 12:04 PM 
To: emc-p...@majordomo.ieee.org 
Subject: Defining an ESD Threat 


Esteemed List Members, 

I am working a problem where it would be helpful to define an ESD threat 
level in a particular high humidity, metallic surroundings environment - 
expectation is that ESD levels would be much lower than typical.  I have a 
very high level concept of how it might be done, some kind of Van de Graf 
model of a human discharge. 

Someone somewhere might have done a similar test to arrive at threats for 
IEC 1000-4-2 or other standards. 

Any pointers on how to do this? 

Thank you, 

Ken Javor 

--- 
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All e

Measurements under EN 61000-3-2 and 3-3

[owner-emc-p...@majordomo.ieee.org]

Did anyone already perform measurements under the directives EN 61000-3-2 and
3-3 using the equipment PHFx from Haefely? Other equipment suggestion?

 

Many Thanks,

 

Djonny

 

--

UFSC - Universidade Federal de Santa Catarina
GEMCO - Grupo de Engenharia em Compatibiliade Eletromagnética
Caixa Postal 476 CEP 88040-900, Florianópolis, SC - Brasil
Telefones: +55(48)331-7557 +55(48)331-9280

RE: Product Safety Symbol Legalities

[owner-emc-p...@majordomo.ieee.org]

You are not going to get a clear answer. You liability is a probability
calculation, no a yes or no answer. You can provide an attendant to
personally warn users as they do the wrong thing and still have liability.
If your product is attractive enough to distract someone's glance as they
walk through a second story window, they have the right to sue you no matter
how your product is designed. How much you are liable depends on the jury,
how much money you have, your legal defense and a lot of other things
unrelated to the product.

Getting down to your question, I am unaware of the exclamation in a triangle
label being part of any lawsuit. You will have to use judgment about your
application. If you are using it to prevent electrocution, you are on pretty
thin ice. If you are using it to prevent minor burns, you might be OK.
What's the probability and damage from misuse? Keep in mind an auto
manufacturer who lost an unbuckled seat belt suit in spite of the presence
of five labels in sight of the passenger. Labels aren't much defense.

>As a manufacturer, are we covered from any liability as a 
>result of the user not being aware of what the symbol means? 
No
>Do we assume that users know to refer to the manual when 
>they see that symbol? 
No
>Are there any court cases that have set precedents on this 
>issue or related safety marking issues? 
Yes, Definitive answers? No. Your lawyer can provide case law. If you have
to ask, you should reconsider.

Bob Johnson
ITE Safety



From: owner-emc-p...@majordomo.ieee.org
[mailto:owner-emc-p...@majordomo.ieee.org] On Behalf Of Joe P Martin
Sent: Wednesday, April 14, 2004 2:47 PM
To: emc-p...@majordomo.ieee.org
Subject: Product Safety Symbol Legalities 






Greetings,

A common product safety symbol, the exclamation point within a triangle, is
used to refer the user to the manual.

General questions:
As a manufacturer, are we covered from any liability as a result of the
user not being aware of what the symbol means?  Do we assume that users
know to refer to the manual when they see that symbol?  Are there any court
cases that have set precedents on this issue or related safety marking
issues?  Any personal experiences?

All responses are greatly appreciated.

Regards

Joe Martin
Applied Biosystems
marti...@appliedbiosystems.com



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RE: Rechargeable and Non-Rechargeable batteries

[owner-emc-p...@majordomo.ieee.org]

Chris -

You might be able to find a barrel connector with a switch
mechanism built in that will remove the batteries from the
circuit automatically, as the plug is inserted.  This won't
allow for charging NimH or other secondary cells, but it's
safer for primary cells.

Long ago, I owned a few pieces of consumer audio equipment
that allowed operation by batteries and by either a direct
plug-in or line voltage.  In these pieces, there were power
connectors that had switches built into them, so that the
batteries were removed from their circuits to prevent
charging currents from flowing.

In those days, consumer NiCd batteries were all that was
available and more rare, thus more costly, than today; most
batteries were nonrechargeable laclanche cells that got
messy when placed under 'significant' reverse charging
conditions.


Regards,

Peter L. Tarver, PE
ptar...@ieee.org


From: Chris Maxwell
Sent: Wednesday, April 14, 2004 10:44 AM

Where I'm really lacking in knowledge (among many areas) is
when it comes to handling standard sized, yet rechargeable
batteries.

For instance consider the following example:

1.  A case designed with a wall wart power input and a spot
for AA sized batteries.
2.  The product would be designed to recharge AA sized NiMh
batteries, if installed.
3.  Alternatively, the user could install AA sized alkaline
batteries; but they would have to set a switch in the
battery compartment to disable the charge circuitry.




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Re: Product Safety Symbol Legalities

[owner-emc-p...@majordomo.ieee.org]

Hi Joe:


>   As a manufacturer, are we covered from any liability as a result of the
>   user not being aware of what the symbol means?  Do we assume that users
>   know to refer to the manual when they see that symbol?  Are there any court
>   cases that have set precedents on this issue or related safety marking
>   issues?  Any personal experiences?

Liability arises after someone has been injured,
or after someone PERCIEVES that they have been 
injured.

Liability is determined in a court of law, and 
is a function of the lawyers, the legal theories,
the judge, and the jury.  Liability has been
levied even with specific, plain-language warnings
against the action that caused the injury.


Best regards,
Rich






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RE: Defining an ESD Threat

[owner-emc-p...@majordomo.ieee.org]

Ah yes,  things get more complicated as usual...
 
There is something called the Triboelectric series, which gives you some idea
of the charging possibilities between materials There further apart two
materials are in the series, the more charge you get from rubbing them
together -- the more you rub, the more you charge... Look at:
http://www.school-for-champions.com/science/static_materials.htm for one
 
What you really need is an inexpensive charge meter and a volunteer -- see
what you can get on a person in various environments as the humidity increase
- it would be easy to do and maybe even some fun Use a MiniZap to charge
'em up to different voltages (standing on a rubber mat) and have him/her step
off and see if the charge stays(As I think about it, someone's probably
already done it, but not sure where to look...)
 
 

Best Regards, 

Michael Hopkins 
Control Technology Division 
Compliance Test Solutions 
Thermo Electron Corporation 
One Lowell Research Center 
Lowell, MA 01852 
Tel: +1 978 275 0800 ext. 334 
Mobile: +1 603 765 3736 
michael.hopk...@thermo.com 


One Thermo, committed to integrity, intensity, innovation & involvement 


From: Ken Javor [mailto:ken.ja...@emccompliance.com]
Sent: Wednesday, April 14, 2004 3:33 PM
To: Mike Hopkins; emc-p...@majordomo.ieee.org
Subject: Re: Defining an ESD Threat


That makes sense, but it only addresses half of the ESD environment question,
which is how high a potential can something be charged up to, and how long
will it hold the charge.  The other half of the question is the
charge-generating mechanism.  If the surfaces one walks on are largely metal
or concrete, how does that effect the amount of charge relative to a carpet? 
And more importantly, whether the charging surface is carpet or concrete or
metal, how can one simulate the charging mechanism in a repeatable fashion? 
How do you build a human body model not in terms of a capacitor and resistor,
but in terms of modeling scuffing one's feet and measuring the resultant
charge collection?



From: Mike  Hopkins 
List-Post: emc-pstc@listserv.ieee.org
Date: Wed, 14 Apr 2004 14:18:24 -0400
To: "'Ken Javor'" , emc-p...@majordomo.ieee.org
Subject: RE: Defining an ESD Threat





Simple thing to do is take an ESD simulator and try charging some objects in
that environment and see if they will hold a charge In high humidity, I'd
expect charges to bleed off very quickly on most objects, which is why the ESD
threat would be low 

In low humidity, of course, the charged surfaces and/or objects would tend to
hold a charge... 

If a person becomes charged due to triboelectric charging walking across a
carpet, I don't know that a high humidity prevents charging -- but it will
definately bleed a charge off quickly Maybe faster than the charging can
take place??? 

None of this is quantitative, of course 

Best Regards, 

Michael Hopkins 
Control Technology Division 
Compliance Test Solutions 
Thermo Electron Corporation 
One Lowell Research Center 
Lowell, MA 01852 
Tel: +1 978 275 0800 ext. 334 
Mobile: +1 603 765 3736 
michael.hopk...@thermo.com 

One Thermo, committed to integrity, intensity, innovation & involvement 

-Original Message- 
From: Ken Javor [mailto:ken.ja...@emccompliance.com] 
Sent: Wednesday, April 14, 2004 12:04 PM 
To: emc-p...@majordomo.ieee.org 
Subject: Defining an ESD Threat 


Esteemed List Members, 

I am working a problem where it would be helpful to define an ESD threat 
level in a particular high humidity, metallic surroundings environment - 
expectation is that ESD levels would be much lower than typical.  I have a 
very high level concept of how it might be done, some kind of Van de Graf 
model of a human discharge. 

Someone somewhere might have done a similar test to arrive at threats for 
IEC 1000-4-2 or other standards. 

Any pointers on how to do this? 

Thank you, 

Ken Javor 

--- 
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Technical Committee emc-pstc discussion list. 

Visit our web site at:  http://www.ieee-pses.org/ 

To cancel your subscription, send mail to: 
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with the single line: 
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For help, send mail to the list administrators: 
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Dave Heald:   emc_p...@symbol.com 

For policy questions, send mail to: 
Richard Nute:   ri...@ieee.org 
Jim Bacher: j.bac...@ieee.org 

All emc-pstc postings are archived and searchable on the web at: 
   http://www.ieeecommunities.org/emc-pstc 

Re: Rechargeable and Non-Rechargeable batteries

[owner-emc-p...@majordomo.ieee.org]

Totally anecdotal reply.  I have  a Fluke 97 Scopemeter I purchased perhaps
ten years ago.  It has a wall-wart supply that recharges internal C-cell
batteries, but it can also run on alkaline or other non-rechargeable C-cells. 
 To the best of my knowledge, it is up to me to remember what batteries I have
in there, there is no switch at all.  If I want to run off mains power, I have
to either have rechargeable batteries, or remove the non-rechargeables.  I
don't know much about this, but I seem to recall that it took a long time to
recharge the Ni-Cds.  Maybe they got around the hazard by having a low enough
charging current it wasn't a hazard?



From: "Chris Maxwell" 
Reply-To: "Chris Maxwell" 
List-Post: emc-pstc@listserv.ieee.org
Date: Wed, 14 Apr 2004 13:44:29 -0400
To: "EMC-PSTC Internet Forum" 
Subject: Rechargeable and Non-Rechargeable batteries




Hello good people of the group. 



We generally test our equipment to EN 61010-1.  We usually have rechargeable
batteries in our product; and they¹ve never really been a safety problem,
other than adding diodes and ³approved² charging methods.  Usually the
batteries that we use are so oddly shaped, that there is a very small risk of
a customer putting in the wrong type of battery.  



Where I¹m really lacking in knowledge (among many areas) is when it comes to
handling standard sized, yet rechargeable batteries. 



For instance consider the following example: 



1.  A case designed with a wall wart power input and a spot for AA sized
batteries. 

2.  The product would be designed to recharge AA sized NiMh batteries, if
installed. 

3.  Alternatively, the user could install AA sized alkaline batteries; but
they would have to set a switch in the battery compartment to disable the
charge circuitry. 



Assuming all warning labels and documentation were in place?  Is this a
generally accepted practice; or is it too unsafe to require the customer to
throw a switch. 







That¹s my specific question.  Now a more general issue.  Up until now, I¹ve
learned about battery safety indirectly.  As in, I submit a product to the
lab, make any required changes (diodesŠ) and ship product.  I haven¹t yet
found a reference that outlines the safety requirements for batteries in EN
61010-1 or EN 60950 equipment.  Is there something that I¹m missing in the
standard?  Or, is this one of those issues that is handled by experience,
agreements and memoranda among the various safety certification agencies? 



Alternatively, is there a stand-alone IEC specification regarding battery
safety? 



As always, the collective time and energy of the group is appreciated. 



adTHANKSvance 



Chris Maxwell 

Design Engineer 

Nettest 

Re: Defining an ESD Threat

[owner-emc-p...@majordomo.ieee.org]

That makes sense, but it only addresses half of the ESD environment question,
which is how high a potential can something be charged up to, and how long
will it hold the charge.  The other half of the question is the
charge-generating mechanism.  If the surfaces one walks on are largely metal
or concrete, how does that effect the amount of charge relative to a carpet? 
And more importantly, whether the charging surface is carpet or concrete or
metal, how can one simulate the charging mechanism in a repeatable fashion? 
How do you build a human body model not in terms of a capacitor and resistor,
but in terms of modeling scuffing one's feet and measuring the resultant
charge collection?



From: Mike  Hopkins 
List-Post: emc-pstc@listserv.ieee.org
Date: Wed, 14 Apr 2004 14:18:24 -0400
To: "'Ken Javor'" , emc-p...@majordomo.ieee.org
Subject: RE: Defining an ESD Threat





Simple thing to do is take an ESD simulator and try charging some objects in
that environment and see if they will hold a charge In high humidity, I'd
expect charges to bleed off very quickly on most objects, which is why the ESD
threat would be low 

In low humidity, of course, the charged surfaces and/or objects would tend to
hold a charge... 

If a person becomes charged due to triboelectric charging walking across a
carpet, I don't know that a high humidity prevents charging -- but it will
definately bleed a charge off quickly Maybe faster than the charging can
take place??? 

None of this is quantitative, of course 

Best Regards, 

Michael Hopkins 
Control Technology Division 
Compliance Test Solutions 
Thermo Electron Corporation 
One Lowell Research Center 
Lowell, MA 01852 
Tel: +1 978 275 0800 ext. 334 
Mobile: +1 603 765 3736 
michael.hopk...@thermo.com 

One Thermo, committed to integrity, intensity, innovation & involvement 

-Original Message- 
From: Ken Javor [mailto:ken.ja...@emccompliance.com] 
Sent: Wednesday, April 14, 2004 12:04 PM 
To: emc-p...@majordomo.ieee.org 
Subject: Defining an ESD Threat 


Esteemed List Members, 

I am working a problem where it would be helpful to define an ESD threat 
level in a particular high humidity, metallic surroundings environment - 
expectation is that ESD levels would be much lower than typical.  I have a 
very high level concept of how it might be done, some kind of Van de Graf 
model of a human discharge. 

Someone somewhere might have done a similar test to arrive at threats for 
IEC 1000-4-2 or other standards. 

Any pointers on how to do this? 

Thank you, 

Ken Javor 

--- 
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   http://www.ieeecommunities.org/emc-pstc 

Re: Rechargeable and Non-Rechargeable batteries

[owner-emc-p...@majordomo.ieee.org]

I read in !emc-pstc that Chris Maxwell  wrote
(in <39f7060a00b5e946b516261c077441c002a...@utexch1w.gnnettest.com>)
about 'Rechargeable and Non-Rechargeable batteries' on Wed, 14 Apr 2004:

>We generally test our equipment to EN 61010-1.  We usually have
>rechargeable batteries in our product; and they've never really been a
>safety problem, other than adding diodes and "approved" charging
>methods.  Usually the batteries that we use are so oddly shaped, that
>there is a very small risk of a customer putting in the wrong type of
>battery.  
>
> 
>
>Where I'm really lacking in knowledge (among many areas) is when it
>comes to handling standard sized, yet rechargeable batteries.
>
> 
>
>For instance consider the following example:
>
> 
>
>1.  A case designed with a wall wart power input and a spot for AA sized
>batteries.
>
>2.  The product would be designed to recharge AA sized NiMh batteries,
>if installed.
>
>3.  Alternatively, the user could install AA sized alkaline batteries;
>but they would have to set a switch in the battery compartment to
>disable the charge circuitry.
>
> 
>
>Assuming all warning labels and documentation were in place?  Is this a
>generally accepted practice; or is it too unsafe to require the customer
>to throw a switch.

It specifically isn't allowed in IEC 60065, which is aimed at consumer
products, used by the general public. But for IEC 61010 equipment, it
MIGHT be considered acceptable to have a switch. However, for Europe (if
relevant) labelling is not an acceptable solution in many cases, because
it should be multilingual and that is impracticable.
>
> 
>
> 
>
> 
>
>That's my specific question.  Now a more general issue.  Up until now,
>I've learned about battery safety indirectly.  As in, I submit a product
>to the lab, make any required changes (diodes...) and ship product.  I
>haven't yet found a reference that outlines the safety requirements for
>batteries in EN 61010-1 or EN 60950 equipment.  Is there something that
>I'm missing in the standard?  

Not that I know of. But the Hazard-Based Standard, in development to
replace IEC 60065 and IEC 60950, will have published justifications for
all its requirements. However, it's a big task and the results won't be
published for a while yet. I'll look to see if there is anything about
batteries already written, but it won't be in the public domain. 

>Or, is this one of those issues that is
>handled by experience, agreements and memoranda among the various safety
>certification agencies?

Well, that's one important activity, but it's not the main way in which
IEC safety standards are prepared. Standards committees are composed of
**industry experts** and representatives of test houses and
certification bodies, with a few academics. The presence and active,
indeed often vociferous, participation by industry experts should dispel
any impression that the safety requirements are imposed from 'above' or
'elsewhere'. But it's still a widely-held impression.
>
> 
>
>Alternatively, is there a stand-alone IEC specification regarding
>battery safety?

You could try searching at http://www.iec.ch A vast amount of
information there is publicly available; it's not all behind passwords. 
-- 
Regards, John Woodgate, OOO - Own Opinions Only. 
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk 


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RE: Defining an ESD Threat

[owner-emc-p...@majordomo.ieee.org]

In addition to what Mike stated below the chances of an ESD even occurring
in a high humidity environment is less, not to mention the charges of an
even occurring in a high humidity environment will be smaller (ie not
likely to reach 25kV for example).

I agree with the comments made that the discharge will bleed faster also.

FYI the humidity requirement for most ESD Testing is 20-40% RH.

Hope this helps.


Rob Kado
EMC Engineer
VWS - Auburn Hills, USA
Tel: 248-340-3828 / Fax: 248-340-3316
Internal Location 3M2


  

   Mike Hopkins   

   ,
   m> 
emc-p...@majordomo.ieee.org 
   Sent by:  cc:  

   owner-emc-pstc@majordomo.iSubject:RE:
Defining an ESD Threat
   eee.org

  

   04/14/2004 02:18 PM

   Please respond to Mike 

   Hopkins

  

  

  





Simple thing to do is take an ESD simulator and try charging some objects
in that environment and see if they will hold a charge In high
humidity, I'd expect charges to bleed off very quickly on most objects,
which is why the ESD threat would be low


In low humidity, of course, the charged surfaces and/or objects would tend
to hold a charge...


If a person becomes charged due to triboelectric charging walking across a
carpet, I don't know that a high humidity prevents charging -- but it will
definately bleed a charge off quickly Maybe faster than the charging
can take place???


None of this is quantitative, of course


Best Regards,


Michael Hopkins
Control Technology Division
Compliance Test Solutions
Thermo Electron Corporation
One Lowell Research Center
Lowell, MA 01852
Tel: +1 978 275 0800 ext. 334
Mobile: +1 603 765 3736
michael.hopk...@thermo.com





One Thermo, committed to integrity, intensity, innovation & involvement






From: Ken Javor [mailto:ken.ja...@emccompliance.com]
Sent: Wednesday, April 14, 2004 12:04 PM
To: emc-p...@majordomo.ieee.org
Subject: Defining an ESD Threat






Esteemed List Members,


I am working a problem where it would be helpful to define an ESD threat
level in a particular high humidity, metallic surroundings environment -
expectation is that ESD levels would be much lower than typical.  I have a
very high level concept of how it might be done, some kind of Van de Graf
model of a human discharge.


Someone somewhere might have done a similar test to arrive at threats for
IEC 1000-4-2 or other standards.


Any pointers on how to do this?


Thank you,


Ken Javor






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"This e-mail message is intended only for the use of the intended
recipient(s).
The information contained therein may be confidential or privileged, and
its disclosure or reproduction is strictly prohibited.
If you are not the intended recipient, please return it immediately to its
sender at the above address and destroy it

Product Safety Symbol Legalities

[owner-emc-p...@majordomo.ieee.org]

Greetings,

A common product safety symbol, the exclamation point within a triangle, is
used to refer the user to the manual.

General questions:
As a manufacturer, are we covered from any liability as a result of the
user not being aware of what the symbol means?  Do we assume that users
know to refer to the manual when they see that symbol?  Are there any court
cases that have set precedents on this issue or related safety marking
issues?  Any personal experiences?

All responses are greatly appreciated.

Regards

Joe Martin
Applied Biosystems
marti...@appliedbiosystems.com



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Re: Rechargeable and Non-Rechargeable batteries

[owner-emc-p...@majordomo.ieee.org]

Hi Chris:


>   1.  A case designed with a wall wart power input and a spot for AA sized
>   batteries.
>   
>   2.  The product would be designed to recharge AA sized NiMh batteries,
>   if installed.
>   
>   3.  Alternatively, the user could install AA sized alkaline batteries;
>   but they would have to set a switch in the battery compartment to
>   disable the charge circuitry.
>   
>   Assuming all warning labels and documentation were in place?  Is this a
>   generally accepted practice; or is it too unsafe to require the customer
>   to throw a switch.

For the purposes of safety, the switch is useless
because the charger would be tested with all AA-
sized batteries with the switch in both positions.

Today, low-cost battery-chargers include circuits
that can detect the type of battery and charge or
not charge accordingly.  I believe commercial 
battery-charger ICs are available which will both
detect the type of battery and charge (or not
charge) accordingly.


Best regards,
Rich






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RE: Defining an ESD Threat

[owner-emc-p...@majordomo.ieee.org]

Simple thing to do is take an ESD simulator and try charging some objects in
that environment and see if they will hold a charge In high humidity, I'd
expect charges to bleed off very quickly on most objects, which is why the ESD
threat would be low

In low humidity, of course, the charged surfaces and/or objects would tend to
hold a charge... 

If a person becomes charged due to triboelectric charging walking across a
carpet, I don't know that a high humidity prevents charging -- but it will
definately bleed a charge off quickly Maybe faster than the charging can
take place???

None of this is quantitative, of course 

Best Regards, 

Michael Hopkins 
Control Technology Division 
Compliance Test Solutions 
Thermo Electron Corporation 
One Lowell Research Center 
Lowell, MA 01852 
Tel: +1 978 275 0800 ext. 334 
Mobile: +1 603 765 3736 
michael.hopk...@thermo.com 


One Thermo, committed to integrity, intensity, innovation & involvement 


-Original Message- 
From: Ken Javor [ mailto:ken.ja...@emccompliance.com] 
Sent: Wednesday, April 14, 2004 12:04 PM 
To: emc-p...@majordomo.ieee.org 
Subject: Defining an ESD Threat 



Esteemed List Members, 

I am working a problem where it would be helpful to define an ESD threat 
level in a particular high humidity, metallic surroundings environment - 
expectation is that ESD levels would be much lower than typical.  I have a 
very high level concept of how it might be done, some kind of Van de Graf 
model of a human discharge. 

Someone somewhere might have done a similar test to arrive at threats for 
IEC 1000-4-2 or other standards. 

Any pointers on how to do this? 

Thank you, 

Ken Javor 


--- 
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Technical Committee emc-pstc discussion list. 

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http://www.ieeecommunities.org/emc-pstc 

Job Opening: Sr. Compliance & Reliability Technician

[owner-emc-p...@majordomo.ieee.org]

Greetings,

Nokia Enterprise Mobility Systems has an opening for an experience technician
in Mountain View, CA.

Primary responsibility
The set-up of equipment for compliance and reliability testing. As such,
knowledge of commissioning networking equipment, primarily Ethernet/IP, is
very important.

Other Qualities
Any experience with Regulatory (EMC, Safety, Telecom Interconnect, NEBS) or
Reliability (HALT, vibration, temperature, voltage variation) testing is a
major advantage.

Of course we want the usual - good communication, team player, basic MS Office
skills, etc.

About the division
This division of Nokia develops Firewall, Intrusion Detection, IP VPN and
other similar products.

The pay and benefits are competitive and the vacation is (in my opinion!)
quite generous. Oh yeah - and you get a free cell phone + service.  8-)



Interested or want a complete job description?

Send your resume or questions to:

Marko Radojicic
marko.radoji...@nokia.com


Cheers,
Marko




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Rechargeable and Non-Rechargeable batteries

[owner-emc-p...@majordomo.ieee.org]

Hello good people of the group.

 

We generally test our equipment to EN 61010-1.  We usually have rechargeable
batteries in our product; and they’ve never really been a safety problem,
other than adding diodes and “approved” charging methods.  Usually the
batteries that we use are so oddly shaped, that there is a very small risk of
a customer putting in the wrong type of battery.  

 

Where I’m really lacking in knowledge (among many areas) is when it comes to
handling standard sized, yet rechargeable batteries.

 

For instance consider the following example:

 

1.  A case designed with a wall wart power input and a spot for AA sized
batteries.

2.  The product would be designed to recharge AA sized NiMh batteries, if
installed.

3.  Alternatively, the user could install AA sized alkaline batteries; but
they would have to set a switch in the battery compartment to disable the
charge circuitry.

 

Assuming all warning labels and documentation were in place?  Is this a
generally accepted practice; or is it too unsafe to require the customer to
throw a switch.

 

 

 

That’s my specific question.  Now a more general issue.  Up until now,
I’ve learned about battery safety indirectly.  As in, I submit a product to
the lab, make any required changes (diodes…) and ship product.  I haven’t
yet found a reference that outlines the safety requirements for batteries in
EN 61010-1 or EN 60950 equipment.  Is there something that I’m missing in
the standard?  Or, is this one of those issues that is handled by experience,
agreements and memoranda among the various safety certification agencies?

 

Alternatively, is there a stand-alone IEC specification regarding battery
safety?

 

As always, the collective time and energy of the group is appreciated.

 

adTHANKSvance

 

Chris Maxwell

Design Engineer

Nettest

Defining an ESD Threat

[owner-emc-p...@majordomo.ieee.org]

Esteemed List Members,

I am working a problem where it would be helpful to define an ESD threat
level in a particular high humidity, metallic surroundings environment -
expectation is that ESD levels would be much lower than typical.  I have a
very high level concept of how it might be done, some kind of Van de Graf
model of a human discharge.

Someone somewhere might have done a similar test to arrive at threats for
IEC 1000-4-2 or other standards.

Any pointers on how to do this?

Thank you,

Ken Javor



This message is from the IEEE EMC Society Product Safety
Technical Committee emc-pstc discussion list.

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http://www.ieeecommunities.org/emc-pstc

Re: zincor EMI contact

[owner-emc-p...@majordomo.ieee.org]

I read in !emc-pstc that Jan Vercammen  wrote
(in 
) about 'zincor EMI contact' on Wed, 14 Apr 2004:

>Because it is lower in the electrochemical table zinc oxide will protect 
>the iron.

No, it doesn't work like that. Zinc is a 'sacrificial coating', unlike
nickel, chromium etc. The zinc dissolves in the oxygenated water,
instead of the iron being converted to rust. 

>The steel is coated with a thickness of 2.5 to 5 microns (data from 
>manufacturers). 
>
>The question is about a zincor chassis which we want to contact with Be Cu
>fingers. Do the fingers penetrate the zinc oxide in a reproducible and 
>consistent
>manner?

There is no *hard* oxide layer on zinc, unlike on some other metals. The
fingers will rather easily contact the zinc metal itself. 

The electrochemical table Annex J in IEC/EN 60950 shows that zinc in
contact with copper or copper alloys is above the critical line, so
corrosion will occur in the presence of moisture and oxygen. This means
that contact will not necessarily be reliable.

Having said that, the electrochemical potentials are NOT a safe guide to
avoiding electrochemical corrosion, because they are determined under
laboratory conditions with no impurities present. But 'real life'
conditions (especially where chlorine ions are present, which is almost
everywhere) are usually less favourable that the table indicates, i.e.
even combinations below the line can suffer from corrosion. 
-- 
Regards, John Woodgate, OOO - Own Opinions Only. 
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk 


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zincor EMI contact

[owner-emc-p...@majordomo.ieee.org]

__ 

emc-pstc list, 


I have a question concerning Zincor, which I think is a trade name for 
steel coated with zinc. The zinc will protect the steel (iron) from oxidation. 
Because it is lower in the electrochemical table zinc oxide will protect the
iron. 
The steel is coated with a thickness of 2.5 to 5 microns (data from
manufacturers). 

The question is about a zincor chassis which we want to contact with Be Cu 
fingers. Do the fingers penetrate the zinc oxide in a reproducible and
consistent 
manner? 

When we install the fingers they penetrate because the radiated emissions 
of a fire-wire cable are reduced by about 10-15dB. But this is but a snapshot 
of the present situation. 

We do not know if the BeCu finger to Zincor chassis contact is 
reproducible and maintains good performance in a office environment 
over a life time of at least 1 year or more. 

I can imagine that EMC engineers have encountered similar problems before. 
Any experience, lessons learned or published literature to share?? 

Kind regards, 

Jan Vercammen 

RE: NRTL vs. NRTL, NCB vs. NCB

[owner-emc-p...@majordomo.ieee.org]

Peter, 

NOTE: THIS EMAIL DOES NOT REPRESENT THE POLICY OR OPINION OF MY EMPLOYER. 

Thanks for your thoughtful response. Based on the many responses that I have
received both on and off-line, it is evident that much of the compliance
engineering community is now faced with NCBs and NRTLs that are driven by the
"bottom line."

Because I respect, and have learned much from, working-level NCB and NRTL
engineers, that are mostly driven by product safety and sound engineering
principles, it can be assumed the problem is within the boardroom of these
organizations.

If "The Process" now promulgates policies designed to (only) increase revenue,
which do not necessarily ensure operator or end-user safety, then the process
is (yet) another tax on business and another trade restraint. Perhaps it is
time to press our company officers to put political pressure on the
bureaucracy that certifies these organizations.

Product Compliance is too important to be driven by revenue-production
schemes. 

luck to all of us, 
Brian 

-Original Message- 
From: Peter L. Tarver [ mailto:peter.tar...@sanmina-sci.com] 
Sent: Tuesday, April 13, 2004 1:09 PM 
To: emc-p...@majordomo.ieee.org 
Subject: RE: NRTL vs. NRTL, NCB vs. NCB 

Brian - 

You've heard much of what I might have otherwise said from 
others.  I will add: 

All NRTLs are not created equal.  I've reviewed reports from 
several of them and found minor inadequacies and 
inaccuracies here in there in them, which are of little 
consequence.  On the other hand, some NRTLs are consistent 
in misapplying requirements or not applying them where 
there's no evidence of engineering rationale to support that 
decision. 

There are, in fact no rules that require an NCB to accept a 
CB Scheme Certificate and Test Report that doesn't also 
allow an NCB to review the report and decide if additional 
testing or a more thorough retesting is necessary.  You can 
read more on this by downloading the IECEE 01 and IECEE 02 
documents that define operation and interoperation of NCBs 
under the CB Scheme.  In fact, retesting and factory 
surveillance are criteria explicitly identified in IECEE 02 
as an issue when an NCB considers acceptance of a CB Scheme 
Certificate and Test Report when applying for a national 
certification. 


Here's one to grab you:  I've recently been involved with an 
CBTL where three iterative updates were required to a CB 
Scheme report to which one previous amendment was made.  The 
CBTL had tested the product twice in the previous 18 months, 
one of which occurred in the previous 9 months (the original 
evaluation and the previous amendment).  Yet, the self-same 
CBTL stated they "needed" to retest on the next report 
amendment, on the basis that their "accreditation" required 
it.  No amount of rational discussion could sway them and no 
engineering rationale was forthcoming from them. 

In their favor, at least, that the next revision of the CB 
Scheme report would otherwise have been the fourth report 
amendment.  The practice of limiting the number of report 
amendments is documented in IECEE02.  However, neither IECEE 
01 nor IECEE 02 stipulate retesting is necessary at this 
stage. 

To make matters more interesting, the update would only have 
corrected an omission of detail in the safety critical 
components list, that was need to support a GS License. 

When I related this story to management, their first 
conclusion was that the NCB didn't trust their own test data 
or they were putting the squeeze on us to wring a few more 
bucks out of us.  It's hard to disagree. 


Regards, 

Peter L. Tarver, PE 
ptar...@ieee.org 

Re: laminated capacitor source

[owner-emc-p...@majordomo.ieee.org]

I read in !emc-pstc that Fred Townsend  wrote (in
<407c73c3.1080...@dctolight.net>) about 'laminated capacitor source' on
Tue, 13 Apr 2004:
>I don't understand.  Xc and ESR are not normally related to each other. Are
you 
>using modern math?

It's an example of Q = 10^-6.
-- 
Regards, John Woodgate, OOO - Own Opinions Only. 
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk 


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Re: laminated capacitor source

[owner-emc-p...@majordomo.ieee.org]

At 11:50 AM -0700 4/13/04, Fred Townsend wrote:
>John Woodgate wrote:
>
>>I read in !emc-pstc that Chris Maxwell 
>> wrote
>>(in 
>><39F706
a00b5e946b516261c077441c002a...@utexch1w.gnnettest.com>)
>>about 'laminated capacitor source' on Tue, 13 Apr 2004:
>>
>>>I think that they gave the product a name something like
>>>the "Micro Q" series.
>>>
>>
>>A definite marketroid name. Do we want our decoupling capacitors to have
>>extremely low Q?
>>
>Yes, John, you want the bypass circuitry to be low Q!  [...]
>
>Fred Townsend

And another GOTCHA if I may.

Lossy caps (or anything lossy in this business) will dissipate some 
heat.  If your power rail has high di/dt or RF currents, the cap will 
heat up.  The cap life may shorten insignificantly, or given the 
severe conditions end quickly and spectacularly.  Lossy caps may 
bring down your predicted MTBF, but depending on other failure 
contributors (such as stressed tantalum caps) it is probably a very 
acceptable trade to reduce emissions.

Eric Lifsey
http://www.relia.net/~elifsey/


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