Re: [PSES] rationale behind conducted immunity levels in EN 55035 / IEC 61000-4-6

[Jeff Keyzer]

Hello Ghery,

 

Thank you for clarifying the difference between the test methods in IEC 
61000-4-6 vs. the spec CISPR 35. 

My reason for mentioning IEC 61000-4-6 was because of the statement regarding 
AM modulation and the fact that similar voltage levels appear in this document 
as the others. I was curious if there was a significance to the choice of 1V, 
3V, 10V as reference/guide levels, because I’ve seen these test levels in other 
places. 

 

To be clear, I’m not claiming that the test levels are wrong, just trying to 
understand the rationale behind them.  

 

My questions are essentially:

 

*   Why 3V rms?  Why not 2V, or 5V?
*   Was this value chosen based on a specific scenario or measurement(s), 
or in response to a specific threat?  (Such as the AM radio telephone 
interference that Joe Randolph mentioned.)
*   Have there been studies to characterize the conducted interference 
levels that are present in various environments, such as residential?

 

Again, I am not arguing that the levels should be changed, just trying to 
understand them.

 

On the safety side, we have reports like IEC TR 62368-2 which provide 
explanatory information that gives some insight into how the safety standard 
was defined.  I was curious if there was anything similar for CISPR 35 or CISPR 
24.

 

Thank you again for your reply.

Jeff

 

 

From: n6...@comcast.net  
Sent: Thursday, March 25, 2021 5:30 PM
To: 'Jeff Keyzer' ; EMC-PSTC@LISTSERV.IEEE.ORG
Subject: RE: [PSES] rationale behind conducted immunity levels in EN 55035 / 
IEC 61000-4-6

 

Jeff,

 

I’m not sure what the technical rationale was back when CISPR 24 was originally 
published (yes, the 3 V limit dates back to then) but as I recall the idea was 
that above 80 MHz you could generate a uniform field and below 80 MHz this was 
far more difficult.  Why 80 MHz?  Because it was convenient (as best as I 
recall).  When we wrote CISPR 35 the thought was that 3 V/m resulted in a lower 
voltage than was tested to in CISPR 24, so the limit was lowered.

 

The test levels called out in IEC 61000-4-6 have no bearing on the levels 
actually called out in CISPR 35.  The same goes for radiated immunity above 80 
MHz.  The IEC 61000-4-x documents are called out as test methods, the test 
levels are called out in the product family standards, in this case CISPR 35.

 

If you (or the client) feel that the test levels are wrong I would suggest that 
you join the US CISPR I TAG and make your concerns known.  Contact me privately 
and I’ll be happy to provide you with the email address of the US Technical 
Expert who will (I’m sure) be happy to have you join the TAG.

 

I hope this helps.

 

Ghery S. Pettit

Chair, CISPR SC I

 

 

From: Jeff Keyzer mailto:j...@mightyohm.com> > 
Sent: Thursday, March 25, 2021 10:21 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG <mailto:EMC-PSTC@LISTSERV.IEEE.ORG> 
Subject: [PSES] rationale behind conducted immunity levels in EN 55035 / IEC 
61000-4-6

 

Hello all,

 

I am looking for background information on the rationale behind the conducted 
immunity test levels defined in EN 55035 / CISPR 35 and IEC 61000-4-6.

 

Specifically, in 55035:2016  table 2, clause 2.1 calls for a test level of 3V 
rms from 0.15 to 10MHz.  It also defines a slope that reduces the signal level 
above 10MHz.

 

What is the technical rationale behind 3V rms being the desired immunity level 
for ITE equipment?

 

Second, why does the voltage level taper above 10MHz in 55035, as opposed to 
55024, where the test remains constant from 150kHz - 80MHz?

 

IEC 61000-4-6 also calls for 1V, 3V, 10V rms test levels and calls for 80% AM 
modulation "to simulate actual threats".  Is the rationale behind this 
documented somewhere? What threats were considered?

 

I suspect this is a rabbit hole, but curiosity (and a concerned client) has 
gotten the best of me.

--

Jeff Keyzer

MightyOhm LLC
j...@mightyohm.com <mailto:j...@mightyohm.com> 

-


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Re: [PSES] rationale behind conducted immunity levels in EN 55035 / IEC 61000-4-6

[Ken Javor]

While I had nothing to do with any CISPR limit setting or test methods, it
seems intuitively appealing that the 80 MHz demarcation between conducted
and radiated immunity is based on the efficiency of the biconical antenna,
or any similarly sized antenna:




Ken Javor
Phone: (256) 650-5261


From: "Ghery S. Pettit" 
Reply-To: 
Date: Thu, 25 Mar 2021 17:29:40 -0700
To: 
Subject: Re: [PSES] rationale behind conducted immunity levels in EN 55035 /
IEC 61000-4-6

Jeff,
 
I¹m not sure what the technical rationale was back when CISPR 24 was
originally published (yes, the 3 V limit dates back to then) but as I recall
the idea was that above 80 MHz you could generate a uniform field and below
80 MHz this was far more difficult.  Why 80 MHz?  Because it was convenient
(as best as I recall).  When we wrote CISPR 35 the thought was that 3 V/m
resulted in a lower voltage than was tested to in CISPR 24, so the limit was
lowered.
 
The test levels called out in IEC 61000-4-6 have no bearing on the levels
actually called out in CISPR 35.  The same goes for radiated immunity above
80 MHz.  The IEC 61000-4-x documents are called out as test methods, the
test levels are called out in the product family standards, in this case
CISPR 35.
 
If you (or the client) feel that the test levels are wrong I would suggest
that you join the US CISPR I TAG and make your concerns known.  Contact me
privately and I¹ll be happy to provide you with the email address of the US
Technical Expert who will (I¹m sure) be happy to have you join the TAG.
 
I hope this helps.
 
Ghery S. Pettit
Chair, CISPR SC I
 
 

From: Jeff Keyzer 
Sent: Thursday, March 25, 2021 10:21 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] rationale behind conducted immunity levels in EN 55035 / IEC
61000-4-6
 

Hello all,

 

I am looking for background information on the rationale behind the
conducted immunity test levels defined in EN 55035 / CISPR 35 and IEC
61000-4-6.

 

Specifically, in 55035:2016  table 2, clause 2.1 calls for a test level of
3V rms from 0.15 to 10MHz.  It also defines a slope that reduces the signal
level above 10MHz.

 

What is the technical rationale behind 3V rms being the desired immunity
level for ITE equipment?

 

Second, why does the voltage level taper above 10MHz in 55035, as opposed to
55024, where the test remains constant from 150kHz - 80MHz?

 

IEC 61000-4-6 also calls for 1V, 3V, 10V rms test levels and calls for 80%
AM modulation "to simulate actual threats".  Is the rationale behind this
documented somewhere? What threats were considered?

 

I suspect this is a rabbit hole, but curiosity (and a concerned client) has
gotten the best of me.

--

Jeff Keyzer

MightyOhm LLC
j...@mightyohm.com
-

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Re: [PSES] rationale behind conducted immunity levels in EN 55035 / IEC 61000-4-6

[Ghery S. Pettit]

Jeff,

 

I’m not sure what the technical rationale was back when CISPR 24 was originally 
published (yes, the 3 V limit dates back to then) but as I recall the idea was 
that above 80 MHz you could generate a uniform field and below 80 MHz this was 
far more difficult.  Why 80 MHz?  Because it was convenient (as best as I 
recall).  When we wrote CISPR 35 the thought was that 3 V/m resulted in a lower 
voltage than was tested to in CISPR 24, so the limit was lowered.

 

The test levels called out in IEC 61000-4-6 have no bearing on the levels 
actually called out in CISPR 35.  The same goes for radiated immunity above 80 
MHz.  The IEC 61000-4-x documents are called out as test methods, the test 
levels are called out in the product family standards, in this case CISPR 35.

 

If you (or the client) feel that the test levels are wrong I would suggest that 
you join the US CISPR I TAG and make your concerns known.  Contact me privately 
and I’ll be happy to provide you with the email address of the US Technical 
Expert who will (I’m sure) be happy to have you join the TAG.

 

I hope this helps.

 

Ghery S. Pettit

Chair, CISPR SC I

 

 

From: Jeff Keyzer  
Sent: Thursday, March 25, 2021 10:21 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] rationale behind conducted immunity levels in EN 55035 / IEC 
61000-4-6

 

Hello all,

 

I am looking for background information on the rationale behind the conducted 
immunity test levels defined in EN 55035 / CISPR 35 and IEC 61000-4-6.

 

Specifically, in 55035:2016  table 2, clause 2.1 calls for a test level of 3V 
rms from 0.15 to 10MHz.  It also defines a slope that reduces the signal level 
above 10MHz.

 

What is the technical rationale behind 3V rms being the desired immunity level 
for ITE equipment?

 

Second, why does the voltage level taper above 10MHz in 55035, as opposed to 
55024, where the test remains constant from 150kHz - 80MHz?

 

IEC 61000-4-6 also calls for 1V, 3V, 10V rms test levels and calls for 80% AM 
modulation "to simulate actual threats".  Is the rationale behind this 
documented somewhere? What threats were considered?

 

I suspect this is a rabbit hole, but curiosity (and a concerned client) has 
gotten the best of me.

--

Jeff Keyzer

MightyOhm LLC
j...@mightyohm.com <mailto:j...@mightyohm.com> 

-


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Re: [PSES] rationale behind conducted immunity levels in EN 55035 / IEC 61000-4-6

[Ken Javor]

Not an answer, but one would expect some sort of correlation between the
61000-4-6 levels of 1, 3, and 10 V, and the 61000-4-3 levels of 1, 3, and 10
V/m.

But I have asked for and never seen the derivation.

Ken Javor
Phone: (256) 650-5261

 

Hello all,

 

I am looking for background information on the rationale behind the
conducted immunity test levels defined in EN 55035 / CISPR 35 and IEC
61000-4-6.

 

Specifically, in 55035:2016  table 2, clause 2.1 calls for a test level of
3V rms from 0.15 to 10MHz.  It also defines a slope that reduces the signal
level above 10MHz.

 

What is the technical rationale behind 3V rms being the desired immunity
level for ITE equipment?

 

Second, why does the voltage level taper above 10MHz in 55035, as opposed to
55024, where the test remains constant from 150kHz - 80MHz?

 

IEC 61000-4-6 also calls for 1V, 3V, 10V rms test levels and calls for 80%
AM modulation "to simulate actual threats".  Is the rationale behind this
documented somewhere? What threats were considered?

 

I suspect this is a rabbit hole, but curiosity (and a concerned client) has
gotten the best of me.

--

Jeff Keyzer

MightyOhm LLC
j...@mightyohm.com
-

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Re: [PSES] rationale behind conducted immunity levels in EN 55035 / IEC 61000-4-6

[Paasche, Dieter]

The reduction on the level on radiated emissions might come from the CISPR 20, 
As you might know CIPSR 35 is a combination of CISPR 24 and CISPR 20.


Sincerely,

Dieter Paasche
Senior Product Developer, Electrical
CHRISTIE
809 Wellington Street North
Kitchener, ON N2G 4Y7
Phone: 519-744-8005 ext.7211
www.christiedigital.com<http://www.christiedigital.com/>

This e-mail message (including attachments, if any) is confidential.  Any 
unauthorized use, distribution or disclosure is prohibited.  If you have 
received this e-mail message in error, please notify the sender by reply e-mail 
or telephone and delete it and any attachments from your computer system and 
records.

From: Joe Randolph 
Sent: Thursday, March 25, 2021 1:58 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] rationale behind conducted immunity levels in EN 55035 / 
IEC 61000-4-6

CAUTION:This email originated from outside of the organization. Do not click 
links or open attachments unless you recognize the sender and know the content 
is safe.

Hi Jeff:

Back in the days when people had ordinary telephones and AM radio stations were 
common, it was a "known thing" that cables near an AM radio transmitter could 
develop common mode voltages up to 3 Vrms.  If the phone did not have perfect 
earth balance at the AM frequency, there would be a common-mode-to-differential 
conversion that would create a differential RF signal on the phone line pair.

Any non-linearity in the phone circuit, such as a diode, would demodulate the 
differential AM RF signal, with the result that the AM radio music/voice could 
be clearly heard in the telephone handset.

I'm describing this to you because it is the only situation where I have 
personally seen a performance degradation due to common mode RF on a cable.  
Hearing AM radio broadcasts in ordinary phones was a common problem.

CISPR has extended this principle to a range of frequencies that is larger than 
the AM band, and to performance degradation that that includes digital 
malfunctions as well.

Presumably they had their reasons for this, but I do not know the rationale.  
All I can say is that I hope the real-world example I described above gives you 
some idea of what CISPR may be concerned about.


Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
j...@randolph-telecom.com<mailto:j...@randolph-telecom.com>
http://www.randolph-telecom.com<https://nam11.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.randolph-telecom.com%2F&data=04%7C01%7CDieter.Paasche%40christiedigital.com%7C30ad8bdd7e6542fbe4c808d8efb78292%7Cdf46f062ad2c407688e6c675c789a0d8%7C0%7C0%7C637522918751734875%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=Nd8efb9uM7GI1w3%2BvqBtCbUGSISn5ove3ekTU8SXaf4%3D&reserved=0>

From: Jeff Keyzer [mailto:j...@mightyohm.com]
Sent: Thursday, March 25, 2021 1:21 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG<mailto:EMC-PSTC@LISTSERV.IEEE.ORG>
Subject: [PSES] rationale behind conducted immunity levels in EN 55035 / IEC 
61000-4-6

Hello all,

I am looking for background information on the rationale behind the conducted 
immunity test levels defined in EN 55035 / CISPR 35 and IEC 61000-4-6.

Specifically, in 55035:2016  table 2, clause 2.1 calls for a test level of 3V 
rms from 0.15 to 10MHz.  It also defines a slope that reduces the signal level 
above 10MHz.

What is the technical rationale behind 3V rms being the desired immunity level 
for ITE equipment?

Second, why does the voltage level taper above 10MHz in 55035, as opposed to 
55024, where the test remains constant from 150kHz - 80MHz?

IEC 61000-4-6 also calls for 1V, 3V, 10V rms test levels and calls for 80% AM 
modulation "to simulate actual threats".  Is the rationale behind this 
documented somewhere? What threats were considered?

I suspect this is a rabbit hole, but curiosity (and a concerned client) has 
gotten the best of me.
--
Jeff Keyzer
MightyOhm LLC
j...@mightyohm.com<mailto:j...@mightyohm.com>
-


This message is from the IEEE Product Safety Engineering Society emc-pstc 
discussion list. To post a message to the list, send your e-mail to 
mailto:emc-p...@ieee.org>>

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Attachments are not permitted but the IEEE PSES Online Communities site at 
http://product-compl

Re: [PSES] rationale behind conducted immunity levels in EN 55035 / IEC 61000-4-6

[Joe Randolph]

Hi Jeff:

 

Back in the days when people had ordinary telephones and AM radio stations were 
common, it was a “known thing” that cables near an AM radio transmitter could 
develop common mode voltages up to 3 Vrms.  If the phone did not have perfect 
earth balance at the AM frequency, there would be a common-mode-to-differential 
conversion that would create a differential RF signal on the phone line pair.  

 

Any non-linearity in the phone circuit, such as a diode, would demodulate the 
differential AM RF signal, with the result that the AM radio music/voice could 
be clearly heard in the telephone handset.

 

I’m describing this to you because it is the only situation where I have 
personally seen a performance degradation due to common mode RF on a cable.  
Hearing AM radio broadcasts in ordinary phones was a common problem.

 

CISPR has extended this principle to a range of frequencies that is larger than 
the AM band, and to performance degradation that that includes digital 
malfunctions as well.

 

Presumably they had their reasons for this, but I do not know the rationale.  
All I can say is that I hope the real-world example I described above gives you 
some idea of what CISPR may be concerned about.

 

 

Joe Randolph

Telecom Design Consultant

Randolph Telecom, Inc.

781-721-2848 (USA)

 <mailto:j...@randolph-telecom.com> j...@randolph-telecom.com

 <http://www.randolph-telecom.com> http://www.randolph-telecom.com

 

From: Jeff Keyzer [mailto:j...@mightyohm.com] 
Sent: Thursday, March 25, 2021 1:21 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] rationale behind conducted immunity levels in EN 55035 / IEC 
61000-4-6

 

Hello all,

 

I am looking for background information on the rationale behind the conducted 
immunity test levels defined in EN 55035 / CISPR 35 and IEC 61000-4-6.

 

Specifically, in 55035:2016  table 2, clause 2.1 calls for a test level of 3V 
rms from 0.15 to 10MHz.  It also defines a slope that reduces the signal level 
above 10MHz.

 

What is the technical rationale behind 3V rms being the desired immunity level 
for ITE equipment?

 

Second, why does the voltage level taper above 10MHz in 55035, as opposed to 
55024, where the test remains constant from 150kHz - 80MHz?

 

IEC 61000-4-6 also calls for 1V, 3V, 10V rms test levels and calls for 80% AM 
modulation "to simulate actual threats".  Is the rationale behind this 
documented somewhere? What threats were considered?

 

I suspect this is a rabbit hole, but curiosity (and a concerned client) has 
gotten the best of me.

--

Jeff Keyzer

MightyOhm LLC
j...@mightyohm.com <mailto:j...@mightyohm.com> 

-


This message is from the IEEE Product Safety Engineering Society emc-pstc 
discussion list. To post a message to the list, send your e-mail to 
mailto:emc-p...@ieee.org> >

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http://www.ieee-pses.org/emc-pstc.html

Attachments are not permitted but the IEEE PSES Online Communities site at 
http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used 
formats), large files, etc.

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[PSES] rationale behind conducted immunity levels in EN 55035 / IEC 61000-4-6

[Jeff Keyzer]

Hello all,

I am looking for background information on the rationale behind the
conducted immunity test levels defined in EN 55035 / CISPR 35 and IEC
61000-4-6.

Specifically, in 55035:2016  table 2, clause 2.1 calls for a test level of
3V rms from 0.15 to 10MHz.  It also defines a slope that reduces the signal
level above 10MHz.

What is the technical rationale behind 3V rms being the desired immunity
level for ITE equipment?

Second, why does the voltage level taper above 10MHz in 55035, as opposed
to 55024, where the test remains constant from 150kHz - 80MHz?

IEC 61000-4-6 also calls for 1V, 3V, 10V rms test levels and calls for 80%
AM modulation "to simulate actual threats".  Is the rationale behind this
documented somewhere? What threats were considered?

I suspect this is a rabbit hole, but curiosity (and a concerned client) has
gotten the best of me.
--
Jeff Keyzer
MightyOhm LLC
j...@mightyohm.com

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