Re: [PSES] "For indoor use only" on External Power Supply

[Richard Nute]

 

 

 

 

If without the warning and symbol, are the users qualified to use the products 
outdoor?

 

Users are rarely qualified to use products outdoors (regardless of the warning 
and the symbol).  But products can be qualified for use outdoors.

 

Standards have additional requirements for outdoor use, usually half the 
accessible voltage and half the accessible current, for both normal and 
single-fault conditions.  The assumption is that the product will be used in a 
wet environment.  

 

 

Rich

 

 

 

 

From: Scott Xe [mailto:scott...@gmail.com] 
Sent: Monday, April 04, 2016 3:58 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] "For indoor use only" on External Power Supply

 

Thanks for your info.  If it comes with an end product, such as audio/video 
products, IT accessories, etc.  It will not comply with IEC 60335-2-29 and 
seldom see it on the product.  If without the warning and symbol, are the users 
qualified to use the products outdoor?

 

On 4 April 2016 at 23:25, Scott Aldous  > wrote:

Hi Scott,

 

Information on symbol 5957 of IEC 60417 here 
 . The link includes a list of 
IEC standards that reference the symbol by number, including IEC 60335-2-29, 
which is the safety standard for household and similar electrical appliances - 
particular requirements for battery chargers.

 

On Mon, Apr 4, 2016 at 8:16 AM, Scott Xe  > wrote:

I notice a warning “For indoor use only” and a its symbol on the EPS, but not a 
must on on portable units.  What does it mean and which standard does mandate 
it?

 

Thanks and regards,

 

Scott

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-- 

Scott Aldous

Compliance Engineer

Google

650-253-1994  

scottald...@google.com  

 

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Re: [PSES] "For indoor use only" on External Power Supply

[Scott Xe]

Thanks for your info.  If it comes with an end product, such as audio/video
products, IT accessories, etc.  It will not comply with IEC 60335-2-29 and
seldom see it on the product.  If without the warning and symbol, are the
users qualified to use the products outdoor?

On 4 April 2016 at 23:25, Scott Aldous  wrote:

> Hi Scott,
>
> Information on symbol 5957 of IEC 60417 here
> . The link includes a
> list of IEC standards that reference the symbol by number, including IEC
> 60335-2-29, which is the safety standard for household and similar
> electrical appliances - particular requirements for battery chargers.
>
> On Mon, Apr 4, 2016 at 8:16 AM, Scott Xe  wrote:
>
>> I notice a warning “For indoor use only” and a its symbol on the EPS, but
>> not a must on on portable units.  What does it mean and which standard does
>> mandate it?
>>
>>
>> Thanks and regards,
>>
>>
>> Scott
>> -
>> 
>>
>> 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 
>> emc-p...@ieee.org
>>
>> All emc-pstc postings are archived and searchable on the web at:
>> 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.
>>
>> Website: http://www.ieee-pses.org/
>> Instructions: http://www.ieee-pses.org/list.html (including how to
>> unsubscribe) 
>> List rules: http://www.ieee-pses.org/listrules.html
>>
>> For help, send mail to the list administrators:
>> Scott Douglas sdoug...@ieee.org
>> Mike Cantwell mcantw...@ieee.org
>>
>> For policy questions, send mail to:
>> Jim Bacher j.bac...@ieee.org
>> David Heald dhe...@gmail.com
>>
>
>
>
> --
> Scott Aldous
> Compliance Engineer
> Google
> 650-253-1994
> scottald...@google.com
>

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Re: [PSES] Common mode current vs. differential mode current and LISN

[Ken Javor]

The characterization of the effect of stray capacitance between a victim
radio and ground is only a theoretical construct.  In fact, all the
measurements were made in an electrically small unlined shielded chamber
with the radio sitting on the floor, which was sheet metal.  So the
capacitance, whatever it was, was higher than what would be encountered in
the real world, and the the fact remains that the radios were 20 dB more
sensitive to cm than to dm, and also the average value of the cm to which
they were sensitive was precisely 48 dBuV, the FCC Class B limit back in the
day.

Ken Javor
Phone: (256) 650-5261



From: Richard Marshall 
Reply-To: Richard Marshall 
Date: Mon, 4 Apr 2016 21:22:36 +0100
To: 
Subject: Re: [PSES] Common mode current vs. differential mode current and
LISN

Ken,
 
I do not see any disagreement on the conversion of DM to CM, only
differences about what happens AFTER the conversion has happened.
 
Then there are two possible views;
 
FIRST VIEW
This is the ³What is on the Circuit diagram² view that is only valid at low
frequencies .  if I understand it properly, that is your argument and from
that position I agree with everything that you say, but consider further the
implications of the last sentence, repeated below;
 
It is only when the signal is referenced to ground that the radio receiver
becomes sensitized to it, because it has no line-to-ground filter elements
(Y-caps).
 
SECOND VIEW
The high-frequency radio engineer¹s view takes account of the transmission
line properties of the phase-to-neutral pair,  and also of the capacitance
to ground of the of the victim (radio in your example).
 
I affirm that;
 
-   Once the DM interference has been partly converted to CM ­ as we
have all agreed ­ then  that CM will be reflected back along the
phase-to-neutral pair towards the source in common-mode. That is the phase &
neutral are effectively in parallel and ground is the return path.

Waves travelling along transmission lines are reflected at points of
mismatch.  This is how ³ Standing Waves² are produced and they are
well-known phenomena.  Since  CM current flow radiates ­ that was
unchallenged on the first day of this thread ­ the unbalanced mismatch at
the LISN will necessarily cause the radiation of interference FROM THE
INCOMING CABLE.  My original post did not mention LISNs.  I commented on the
real-world situation but it is much the same-or worse.

 

-   If we introduce to the scene a victim radio connected across the
phase-to-neutral pair, then the FIRST VIEW correctly says that the radio¹s
bulk cap does its job of filtering DM.  However, the radio sees the shift in
the reference level of the DM signal, because components of the radio have
some stray  capacitance to true ground.  The radio may be a very small box
on a wooden table, in which case that capacitance is only a few 10¹s of pF,
or it may be huge if the ³radio² is a Hi-Fi radio with connection to a
roof-top antenna and to several loudspeakers.  This stray capacitance allows
the radio  to sense CM on its mains cable.  A ³shift in the reference level
of the DM signal²  is another way of saying ³CM²  and so that now has the
capability of creating interference if the receiver design is inadequate.
There are many ways for stray currents to get into low-level analogue
circuitry.  I did not mention radios either: the analysis is valid across
the board. 

 

So it is the circuit components that are not on the equipment circuit or on
its cabling layout that matter at Radio Frequencies ­ and that is where EMC
gets seriously interesting.

 

Richard
 
Richard Marshall Laboratories,
30 Ox Lane, Harpenden, Herts.,AL5 4HE, UK
+44 (0)1582 460815 www.design-emc.co.uk 
Member of the EMC Industry Association
 

From: Ken Javor [mailto:ken.ja...@emccompliance.com]
Sent: 03 April 2016 17:48
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Common mode current vs. differential mode current and
LISN
 
I think there is a fundamental misunderstanding of the mechanism converting
dm into cm, both on the part of Michel Mardiguian back in the day and those
who repeat his criticism in this thread.

What people are saying, (if I understand it properly) is no different than
if I used two LISNs, one with a different inductor value than the other.  In
that case, at frequencies where at least one LISN did not look like 50 ohms,
the EMI port measurement for the dm part would be different on each LISN,
and that would make it look like a cm signal, and therefore we have a
problem.

But that is flatly incorrect. The issue is not the relative value of the dm
portion at each LISN, but rather the reference for the signal.  For dm,
regardless of ³balance² both dm LISN contributions sum and they are
referenced from phase-to-neutral, not conductor-to-ground.  As long as the
dm contributions are phase-to-neutral, 

Re: [PSES] Common mode current vs. differential mode current and LISN

[Richard Marshall]

Ken,

 

I do not see any disagreement on the conversion of DM to CM, only
differences about what happens AFTER the conversion has happened.  

 

Then there are two possible views;

 

FIRST VIEW

This is the "What is on the Circuit diagram" view that is only valid at low
frequencies .  if I understand it properly, that is your argument and from
that position I agree with everything that you say, but consider further the
implications of the last sentence, repeated below;

 

It is only when the signal is referenced to ground that the radio receiver
becomes sensitized to it, because it has no line-to-ground filter elements
(Y-caps).

 

SECOND VIEW

The high-frequency radio engineer's view takes account of the transmission
line properties of the phase-to-neutral pair,  and also of the capacitance
to ground of the of the victim (radio in your example).

 

I affirm that;

 

-   Once the DM interference has been partly converted to CM - as we
have all agreed - then  that CM will be reflected back along the
phase-to-neutral pair towards the source in common-mode. That is the phase &
neutral are effectively in parallel and ground is the return path. 

Waves travelling along transmission lines are reflected at points of
mismatch.  This is how " Standing Waves" are produced and they are
well-known phenomena.  Since  CM current flow radiates - that was
unchallenged on the first day of this thread - the unbalanced mismatch at
the LISN will necessarily cause the radiation of interference FROM THE
INCOMING CABLE.  My original post did not mention LISNs.  I commented on the
real-world situation but it is much the same-or worse.

 

-   If we introduce to the scene a victim radio connected across the
phase-to-neutral pair, then the FIRST VIEW correctly says that the radio's
bulk cap does its job of filtering DM.  However, the radio sees the shift in
the reference level of the DM signal, because components of the radio have
some stray  capacitance to true ground.  The radio may be a very small box
on a wooden table, in which case that capacitance is only a few 10's of pF,
or it may be huge if the "radio" is a Hi-Fi radio with connection to a
roof-top antenna and to several loudspeakers.  This stray capacitance allows
the radio  to sense CM on its mains cable.  A "shift in the reference level
of the DM signal"  is another way of saying "CM"  and so that now has the
capability of creating interference if the receiver design is inadequate.
There are many ways for stray currents to get into low-level analogue
circuitry.  I did not mention radios either: the analysis is valid across
the board. 

 

So it is the circuit components that are not on the equipment circuit or on
its cabling layout that matter at Radio Frequencies - and that is where EMC
gets seriously interesting.

 

Richard

 

Richard Marshall Laboratories,

30 Ox Lane, Harpenden, Herts.,AL5 4HE, UK 

+44 (0)1582 460815   www.design-emc.co.uk

Member of the EMC Industry Association

 

From: Ken Javor [mailto:ken.ja...@emccompliance.com] 
Sent: 03 April 2016 17:48
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Common mode current vs. differential mode current and
LISN

 

I think there is a fundamental misunderstanding of the mechanism converting
dm into cm, both on the part of Michel Mardiguian back in the day and those
who repeat his criticism in this thread.

What people are saying, (if I understand it properly) is no different than
if I used two LISNs, one with a different inductor value than the other.  In
that case, at frequencies where at least one LISN did not look like 50 ohms,
the EMI port measurement for the dm part would be different on each LISN,
and that would make it look like a cm signal, and therefore we have a
problem.

But that is flatly incorrect. The issue is not the relative value of the dm
portion at each LISN, but rather the reference for the signal.  For dm,
regardless of "balance" both dm LISN contributions sum and they are
referenced from phase-to-neutral, not conductor-to-ground.  As long as the
dm contributions are phase-to-neutral, the bulk cap in the victim radio
power supply does its job of filtering and doesn't care how much dm is
measured to ground at each LISN.  It is only when the signal is referenced
to ground that the radio receiver becomes sensitized to it, because it has
no line-to-ground filter elements (Y-caps).

This point was made abundantly clear in the report that was presented to
TC77 back in 1998 (or thereabouts).

Ken Javor
Phone: (256) 650-5261



  _  

From: Richard Marshall < 
richard.marshal...@btinternet.com>
Reply-To: Richard Marshall < 
richard.marshal...@btinternet.com>
Date: Sun, 3 Apr 2016 12:54:43 +0100
To: <  EMC-PSTC@LISTSERV.IEEE.ORG>
Subject: Re: [PSES] Commom mode current vs. differential mode current and
LISN

Rich
 
I'm 

[PSES] Job Opening at Panduit

[Lei Wang]

Compliance engineer job opening - The position will be located at Lockport, IL 
60441 (a suburb of Chicago).
Contact me at lei.w...@panduit.com if interested.

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Re: [PSES] Maximum Allowed Duty Cycle Correction Factor per FCC 15.35

[Cortland Richmond]

On 4/4/2016 11:13 AM, Grasso, Charles wrote:
If memory serves me this is buried in 15.35(b) as the peak emission 
maximum allowed over the average value when using DCCF.

(b) Unless otherwise specified, on any frequency or frequencies above 1000
   MHz,  the radiated emission limits are based on the use of measurement
   instrumentation employing an average detector function. Unless otherwise
   specified, measurements above 1000 MHz shall be performed using a 
minimum
   resolution bandwidth of 1 MHz. When average radiated emission 
measurements
   are specified in this part, including average emission measurements 
below

   1000 MHz, there also is a limit on the peak level of the radio frequency
   emissions.  Unless  otherwise  specified,  e.g., see § § 15.250, 15.252,
   15.253(d), 15.255, 15.256, and 15.509 through 15.519 of this part, 
the limit

   on peak radio frequency emissions is 20 dB above the maximum permitted
   average emission limit applicable to the equipment under test. This peak
   limit applies to the total peak emission level radiated by the 
device, e.g.,

   the total peak power level. Note that the use of a pulse desensitization
   correction factor may be needed to determine the total peak emission 
level.
   The instruction manual or application note for the measurement 
instrument

   should  be consulted for determining pulse desensitization factors, as
   necessary.
http://www.hallikainen.com/FccRules/2015/15/35/


Cortland Richmond

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Re: [PSES] Commom mode current vs. differential mode current and LISN

[Richard Nute]

 

 

Hi Richard:

 

 

The usual class Y value of 4,700pF presents an
impedance of only 1.13 ohms at 30MHz, so it
provides a very substantial unbalance to create CM
from a neighbour's DM

 

All of the products I have seen have two Y
capacitors, one from L to E, and one from N to E.
With these two capacitors, there should be no
significant unbalance caused by the Y capacitors.

 

 

Best regards,

Rich

 

 

 

 


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Re: [PSES] Maximum Allowed Duty Cycle Correction Factor per FCC 15.35

[dward]

Remember, these are in regards to the limit, NOT the measured values.

 

​

Dennis Ward

This communication and its attachements contain information from PCTEST 
Engineering Laboratory, Inc., and is intended for the exclusive use of the 
recipient(s) named above.  It may contain information that is confidential 
and/or legally privileged.  Any unauthorized use that may compromise that 
confidentiality via distribution or disclosure is prohibited.  Please notify 
the sender immediately if you receive this communication in error, and delete 
it from your computer system.  Usage of PCTEST email addresses for non-business 
related activities is strictly prohibited.  No warranty is made that the e-mail 
or attachments(s) are free from computer virus or other defect.  Thank you.

 

From: Grasso, Charles [mailto:charles.gra...@echostar.com] 
Sent: Monday, April 4, 2016 8:13 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Maximum Allowed Duty Cycle Correction Factor per FCC 15.35

 

Hello Grace – If memory serves me this is buried in 15.35(b) as the peak 
emission maximum allowed over the average value when using DCCF.

 

Best Regards

Charles Grasso

Compliance Engineer

Echostar Communications

(w) 303-706-5467

(c) 303-204-2974

(t) 3032042...@vtext.com  

(e) charles.gra...@echostar.com  

(e2) chasgra...@gmail.com  

 

From: Grace Lin [mailto:graceli...@gmail.com] 
Sent: Friday, April 01, 2016 2:32 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG  
Subject: [PSES] Maximum Allowed Duty Cycle Correction Factor per FCC 15.35

 

Dear Members,

 

Could  you please advise the standard which specified the maximum allowed duty 
cycle correction factor of 20 dB?

 

I remember seeing the requirement from a standard.  With a quick look at the 
FCC 15.35, ANSI C63.4-2014, and ANSI C63.10-2013, I couldn't locate the 20 dB 
maximum requirement.

 

Thank you very much for your time and I look forward to hearing from you.

 

Best regards,

Grace Lin 

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Re: [PSES] "For indoor use only" on External Power Supply

[Brian O'Connell]

Off the top of my pointy head - CSA No 223, UL1310, UL1741 are examples where 
this marking phrase could be required. There are no known Klingon national 
versions of any standards with this warning statement. The meaning is literal, 
but 'indoor' is typically defined via the IP rating that would be provided by 
the environment.

Brian

From: Scott Xe [mailto:scott...@gmail.com] 
Sent: Monday, April 04, 2016 8:17 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] "For indoor use only" on External Power Supply

I notice a warning “For indoor use only” and a its symbol on the EPS, but not a 
must on on portable units.  What does it mean and which standard does mandate 
it?

Thanks and regards,

Scott

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Re: [PSES] "For indoor use only" on External Power Supply

[Scott Aldous]

Hi Scott,

Information on symbol 5957 of IEC 60417 here
. The link includes a list
of IEC standards that reference the symbol by number, including IEC
60335-2-29, which is the safety standard for household and similar
electrical appliances - particular requirements for battery chargers.

On Mon, Apr 4, 2016 at 8:16 AM, Scott Xe  wrote:

> I notice a warning “For indoor use only” and a its symbol on the EPS, but
> not a must on on portable units.  What does it mean and which standard does
> mandate it?
>
>
> Thanks and regards,
>
>
> Scott
> -
> 
>
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-- 
Scott Aldous
Compliance Engineer
Google
650-253-1994
scottald...@google.com

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[PSES] "For indoor use only" on External Power Supply

[Scott Xe]

I notice a warning “For indoor use only” and a its symbol on the EPS, but
not a must on on portable units.  What does it mean and which standard does
mandate it?


Thanks and regards,


Scott

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Re: [PSES] Maximum Allowed Duty Cycle Correction Factor per FCC 15.35

[Grasso, Charles]

Hello Grace – If memory serves me this is buried in 15.35(b) as the peak 
emission maximum allowed over the average value when using DCCF.

Best Regards
Charles Grasso
Compliance Engineer
Echostar Communications
(w) 303-706-5467
(c) 303-204-2974
(t) 3032042...@vtext.com
(e) charles.gra...@echostar.com
(e2) chasgra...@gmail.com

From: Grace Lin [mailto:graceli...@gmail.com]
Sent: Friday, April 01, 2016 2:32 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] Maximum Allowed Duty Cycle Correction Factor per FCC 15.35

Dear Members,

Could  you please advise the standard which specified the maximum allowed duty 
cycle correction factor of 20 dB?

I remember seeing the requirement from a standard.  With a quick look at the 
FCC 15.35, ANSI C63.4-2014, and ANSI C63.10-2013, I couldn't locate the 20 dB 
maximum requirement.

Thank you very much for your time and I look forward to hearing from you.

Best regards,
Grace Lin
-


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>

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Re: [PSES] Commom mode current vs. differential mode current and LISN

[Grasso, Charles]

Ok - Got it. Thanks!

Best Regards
Charles Grasso
Compliance Engineer
Echostar Communications
(w) 303-706-5467
(c) 303-204-2974
(t) 3032042...@vtext.com
(e) charles.gra...@echostar.com
(e2) chasgra...@gmail.com


-Original Message-
From: Cortland Richmond [mailto:k...@earthlink.net] 
Sent: Thursday, March 31, 2016 4:30 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Commom mode current vs. differential mode current and LISN

On 3/31/2016 4:47 PM, Grasso, Charles wrote:
> Why are you looking at the "noise" in the time domain?
> What spec are you trying to comply with?

It was already non-compliant and I had to find out how to fix it.

I do this kind of probing to find out where [stuff] comes from and where it 
goes, in THIS case, where the highest E and H field FS was **on the PWB**.  A 
"nude" 'scope probe with suitable insulation slipped over it works for close-in 
E-field, and miniature coax with a loop on the end (~ 2mm diameter) for 
sniffing the H field -- plus one can rotate it to find traces carrying 
switching noise around on the board; it long ago ceased to surprise me to find 
the relevant bypass capacitors some distance away from the SMPS

That's AFTER the first items are sent to a test lab and fail, usually.  
When I was at Alcatel USA (formerly DSC) I asked for got read-only privileges 
on all schematics and PWB's in the CAD shop when I was hired, and could stop 
that [rude word] before it got built. Heh.


Cortland Richmond

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Re: [PSES] Maximum Allowed Duty Cycle Correction Factor per FCC 15.35

[Michael Derby]

Hi Grace,

 

I think this is a mistake.   I think there is not a maximum allowed duty cycle 
of 20 dB.

 

I think this mistake comes from the fact that there is a peak limit which 
exists at 20 dB higher than the average limit.  




This is not the same as a difference in levels!   This is a difference in 
limits.

 

So, the limits say that you measure the peak; then you calculate the average 
based on the duty cycle.

And the Peak ‘limit’ is 20 dB above the average ‘limit’.

 

Some people seem to read this that the peak ‘value’ must be no more than 20 dB 
above the average ‘value’, but that is not correct.

 

The average ‘value’ must be below the average ‘limit’.

The peak ‘value’ must be below the peak ‘limit’.

The peak ‘limit’ is 20 dB higher than the average ‘limit’.

 

For example, let’s say you have a remote control at 315 MHz, FCC 15.231, such 
as a keyfob.   The average limit is 75.6 dBμV/m.

Therefore, there also exists a peak limit, of 95.6 dBμV/m.

 

Let’s say that you take the keyfob to the lab and measure it on a test site.   
You measure 90.0 dBμV/m, peak.

 

You calculate the duty cycle and find that it transmits for only 6 ms in the 
100 ms period.   Duty cycle factor is therefore:  20 log (6/100)  =  -24.4 dB.

 

So now you know your average value is:   

Peak value - duty cycle = Average

90.0 – 24.4  =  65.6 dBμV/m.

 

Peak Limit  =  95.6 dBμV/m

Peak Level  =  90.0 dBμV/m

Average Limit  =  75.6 dBμV/m

Average Level  =  65.6 dBμV/m

 

…..everyone’s happy.

 

Well, everyone except the person who thought that the average value could not 
be more than 20 dB less than the peak value.   :)

 

 

Thanks,

 

 

Michael.

 

 

 

 

From: Grace Lin [mailto:graceli...@gmail.com] 
Sent: 01 April 2016 21:32
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] Maximum Allowed Duty Cycle Correction Factor per FCC 15.35

 

Dear Members,

 

Could  you please advise the standard which specified the maximum allowed duty 
cycle correction factor of 20 dB?

 

I remember seeing the requirement from a standard.  With a quick look at the 
FCC 15.35, ANSI C63.4-2014, and ANSI C63.10-2013, I couldn't locate the 20 dB 
maximum requirement.

 

Thank you very much for your time and I look forward to hearing from you.

 

Best regards,

Grace Lin 

-


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