Re: [PSES] Clarifications for Functional Earthing

[Nyffenegger, Dave]

Hi Rich/all,

OK, I think this helps answer my original questions but opens up some others.  
So you are saying DIN GRN/YEL rail terminal block indicates bonding conductor 
and it's OK to use this to connect functional earth to chassis even if there 
are no other bonding conductors needed and connected to the DIN GRN/YEL 
terminal block? 

60417-5018 is defined as "Noiseless (clean) earth (ground): To identify a 
noiseless (clean) earth (ground) terminal, e.g. of a specially designed 
earthing (grounding) system to avoid causing malfunction of the equipment."  So 
functional earth connections to the DIN GRN/YEL terminal block  as described 
above should be shown using the 5018 symbol right (yes, the chassis does have a 
dedicated PE stud)?  And since by definition this ground is earth no need to 
show a line between 5018 and 5019 (or 5017) on a schematic right?  Or is the 
line sometimes shown on schematics even though it's redundant?

You stated usually there is usually only one PE/5019 mark per machine.  I am 
working with machinery subject to IEC/EN 60950-1 and comprised of several 
interconnected modules/machine sections.  The modules are large and different 
combinations of modules are used for different machines.  Power (and protective 
earth conductor) is connected into a single main electrical box in one module 
and is distributed throughout.  Each module has an internal power cord (with 
bonding conductor) that connects into a downstream module or into the main 
electrical box.  Should only the connection for the protective earthing 
conductor in the main electrical box that is connected to the building 
protective earth should be marked as 5019/PE?

We have been using 5019/PE for the bonding conductor of each machine module 
where the bonding conductor comes into that module from the main electrical box 
or another module.  Is this wrong?  We have done this based on the definition 
"to identify any terminal which is intended for connection to an external 
conductor" considering the bonding conductor for each module as an external 
conductor to that module even though it's contained within the machine 
boundary, not connected directly to building earth.  Should 60417-5017 be used 
for ALL bonding connections within the machine/modules with 5019 reserved for 
only a single use within the machine where the connection is made to the 
building protective earth?  

60417-5017 is defined "To identify an earth (ground) terminal in cases where 
neither the symbol 5018 nor 5019 is explicitly stated.", does that mean that 
all "bonding" connections should be shown using 5017 leaving only the single " 
earthing" conductor to be shown using 5019?
 
Thanks
-Dave

-Original Message-
From: Richard Nute [mailto:ri...@ieee.org] 
Sent: Sunday, January 05, 2014 9:29 PM
To: Nyffenegger, Dave; EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Clarifications for Functional Earthing



Hi David:


Let me start my reply with some definitions:

Symbol 5019 means protective earth (ground).  Its purpose is "to identify any 
terminal which is intended for connection to an external conductor for 
protection against electric shock
in case of a fault..."   See IEC 60417.  Usually, this is the
terminal to which the power cord earthing/grounding wire is connected.

Usually, there is only one such terminal (and it follows that there is only one 
such mark).

GRN/YEL insulation color is reserved for the protective earthing conductor and 
the equipment protective bonding conductors.  Any other color can be used for 
functional earthing conductors.

The protective earthing conductor connects the protective earth terminal of the 
equipment to the protective earthing circuit of the building.

The protective bonding conductor connect various parts of the equipment 
(required to be grounded for safety) to the equipment protective grounding 
terminal.

The standards allow connection of functional earth conductors to the protective 
earth terminal (marked with the 5019 symbol).

Symbol 5017 means earth (ground).  Its purpose is "to identify an earth 
(ground) terminal in cases where neither the symbol 5018 nor 5019 is explicitly 
required."  While permitted by IEC 60417, IEC/EN 60950-1 specifically prohibits 
the use of this symbol for a functional earth terminal.

The DIN GRN/YEL rail terminal block is a bonding conductor.
If the conductor connected to the terminal block has GRN/YEL insulation, it is 
a bonding conductor.  If the conductor has another color, it is a functional 
earth conductor.

The chassis should have a PE terminal with the 5019 symbol.
This would connect the bonding conductors and the functional earth conductors 
to the chassis (and to the PE) through the DIN terminal block.

The 5017 symbol is only true (meaningful) if the PE is connected to earth.  If 
the equipment is subject to IEC/EN 60950-1, you cannot use the 5017 symbol 
(except on the terminal as you have quoted).

The construction you describe is, in my o

Re: [PSES] question about overheated/swollen UPS batteries

[Nyffenegger, Dave]

Doug,

I've experienced this for many years specifically using APC UPSs with 12V 7ah 
batteries and I've used lots of different battery brands.  Don't have any 
experience with non-APC UPSs.  Yes, when the batteries start to fail they swell 
up and sometimes need to be pried out of the UPS.  (I only use APC UPS with 
metal battery housing.) Just last week I noticed the battery fail LED on one of 
my UPS (it wasn't singing, only the fail LED was on) and when I pulled the 
battery I saw it had started leaking at the terminal.  This was the first time 
I've ever experienced an actual leak and I'd say I've replaced these failed UPS 
batteries at least 100 times.  (I have a lot of these UPSs between home and 
work.)  And I've only had to resort to prying out the batteries a handful of 
times although I see at least some swelling in probably half the failed 
batteries.  So I guess I won't worry too much about leaks anyway.  I think 
these UPSs can go for quite a while with the battery fail LED on wi!
 thout sounding alarm most likely cooking the battery until the battery is so 
far gone that the UPS will either shut down or will not come up after power 
cycle.

These batteries typically only last about two years in an APC UPS and the best 
battery warranty on the 12V 7ah I've seen is also two years.  Best thing is to 
keep an eye on the battery fail LED.  I'm not sure if the UPS charges the 
battery when it's switched off, so may be best to unplug the UPS when you're 
not using it.

-Dave

-Original Message-
From: Douglas Smith [mailto:d...@emcesd.com] 
Sent: Sunday, January 05, 2014 10:44 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] question about overheated/swollen UPS batteries

Hi Everyone,

I seem to have a continuing experience with UPS equipment overheating the 
batteries. Most all of my UPSs have done this at one time or another. Here is 
an example:

At the office, I was to be away for a week and if the power went out, some of 
my UPSs sound an alarm which can annoy people in hotel rooms directly above the 
office. So I turned that UPS off. Light out, output off. No sign of life so I 
thought it was really off. A few weeks later I tried to turn on that UPS (we 
don't use that computer every day) and it immediately switched off with a bad 
battery alarm. A coincidence I thought that would happen just then when it 
worked fine last time. I went to pull the UPS out from under the desk and found 
it very warm, even though it was off. The battery was red hot, so hot I could 
not hold it and it was beginning to swell up, but I was able to remove it. The 
interesting thing was that APC had replaced this unit a few years ago when the 
original one swelled the battery so much it would not come out! 
I was able to replace the battery and the unit works OK now. I replaced the 
battery on a second identical unit just in case.

How can this happen when I turned the unit off by the button on the front and 
the unit seemed off, no indication any power was on at all? 
And why do I keep having these problems. I spent two hours taking apart another 
APC unit (this one had a metal case, which I like) to remover a very swollen 
battery with a cracked case due to the swelling. I have another of the same 
model which has the same problem. Not sure I want to spend two hours again on 
that one.

All my units are APC, and I like them for their features and reliability 
(except for battery problems) and will likely buy APC in the future. I suspect 
this problem may occur on other brands as well, a general industry problem.
I could probably avoid problems by replacing batteries every year, but I still 
think the failure mode should be more friendly. Seems like there is a safety 
problem here both from overheating, spilling of the battery contents from a hot 
cracked case, and lack of performance suddenly when not expected.

Any thoughts? Has anyone else experienced this?

Doug

--
--
  ___  _Doug Smith
   \  / )   P.O. Box 60941
=   Boulder City, NV 89006-0941
 _ / \ / \ _TEL/FAX: 702-570-6108/570-6013
   /  /\  \ ] /  /\  \  Mobile:  408-858-4528
  |  q-( )  |  o  | Email:   d...@dsmith.org
   \ _ /]\ _ /  Web: http://www.dsmith.org
--

-

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 


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/
Inst

[PSES] question about overheated/swollen UPS batteries

[Douglas Smith]

Hi Everyone,

I seem to have a continuing experience with UPS equipment overheating 
the batteries. Most all of my UPSs have done this at one time or 
another. Here is an example:


At the office, I was to be away for a week and if the power went out, 
some of my UPSs sound an alarm which can annoy people in hotel rooms 
directly above the office. So I turned that UPS off. Light out, output 
off. No sign of life so I thought it was really off. A few weeks later I 
tried to turn on that UPS (we don't use that computer every day) and it 
immediately switched off with a bad battery alarm. A coincidence I 
thought that would happen just then when it worked fine last time. I 
went to pull the UPS out from under the desk and found it very warm, 
even though it was off. The battery was red hot, so hot I could not hold 
it and it was beginning to swell up, but I was able to remove it. The 
interesting thing was that APC had replaced this unit a few years ago 
when the original one swelled the battery so much it would not come out! 
I was able to replace the battery and the unit works OK now. I replaced 
the battery on a second identical unit just in case.


How can this happen when I turned the unit off by the button on the 
front and the unit seemed off, no indication any power was on at all? 
And why do I keep having these problems. I spent two hours taking apart 
another APC unit (this one had a metal case, which I like) to remover a 
very swollen battery with a cracked case due to the swelling. I have 
another of the same model which has the same problem. Not sure I want to 
spend two hours again on that one.


All my units are APC, and I like them for their features and reliability 
(except for battery problems) and will likely buy APC in the future. I 
suspect this problem may occur on other brands as well, a general 
industry problem.
I could probably avoid problems by replacing batteries every year, but I 
still think the failure mode should be more friendly. Seems like there 
is a safety problem here both from overheating, spilling of the battery 
contents from a hot cracked case, and lack of performance suddenly when 
not expected.


Any thoughts? Has anyone else experienced this?

Doug

--
--
 ___  _Doug Smith
  \  / )   P.O. Box 60941
   =   Boulder City, NV 89006-0941
_ / \ / \ _TEL/FAX: 702-570-6108/570-6013
  /  /\  \ ] /  /\  \  Mobile:  408-858-4528
 |  q-( )  |  o  | Email:   d...@dsmith.org
  \ _ /]\ _ /  Web: http://www.dsmith.org
--

-

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 

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 
Mike Cantwell 

For policy questions, send mail to:
Jim Bacher:  
David Heald: 

Re: [PSES] Clarifications for Functional Earthing

[Richard Nute]

Hi David:


Let me start my reply with some definitions:

Symbol 5019 means protective earth (ground).  Its purpose is
"to identify any terminal which is intended for connection to
an external conductor for protection against electric shock
in case of a fault..."   See IEC 60417.  Usually, this is the
terminal to which the power cord earthing/grounding wire is
connected.

Usually, there is only one such terminal (and it follows that
there is only one such mark).

GRN/YEL insulation color is reserved for the protective
earthing conductor and the equipment protective bonding
conductors.  Any other color can be used for functional
earthing conductors.

The protective earthing conductor connects the protective
earth terminal of the equipment to the protective earthing
circuit of the building.

The protective bonding conductor connect various parts of
the equipment (required to be grounded for safety) to the
equipment protective grounding terminal.

The standards allow connection of functional earth conductors
to the protective earth terminal (marked with the 5019 symbol).

Symbol 5017 means earth (ground).  Its purpose is "to
identify an earth (ground) terminal in cases where neither
the symbol 5018 nor 5019 is explicitly required."  While
permitted by IEC 60417, IEC/EN 60950-1 specifically prohibits
the use of this symbol for a functional earth terminal.

The DIN GRN/YEL rail terminal block is a bonding conductor.
If the conductor connected to the terminal block has GRN/YEL
insulation, it is a bonding conductor.  If the conductor has
another color, it is a functional earth conductor.

The chassis should have a PE terminal with the 5019 symbol.
This would connect the bonding conductors and the functional
earth conductors to the chassis (and to the PE) through the
DIN terminal block.

The 5017 symbol is only true (meaningful) if the PE is
connected to earth.  If the equipment is subject to IEC/EN
60950-1, you cannot use the 5017 symbol (except on the
terminal as you have quoted).

The construction you describe is, in my opinion, acceptable
(assuming you have a PE terminal on the chassis and it is
marked with the 5019 symbol).

Symbol 5020 means chassis.  You may find this useful.  You
can also show a line connecting 5020 to 5019 to show that the
chassis is connected to the PE terminal.


Best wishes for the New Year,
Rich



On 1/3/2014 10:10 PM, Nyffenegger, Dave wrote:

Hi Folks,

Background- EN60950-1:2006 1.2.13.9 “FUNCTIONAL EARTHING earthing of a point in 
equipment or in a system, which is necessary for a purpose other than safety”.

"2.6.2 Functional earthing
− it is permitted to connect the FUNCTIONAL EARTHING circuit to a protective 
earth terminal or
to a PROTECTIVE BONDING CONDUCTOR;and
− wiring terminals to be used only for FUNCTIONAL EARTHING shall not be marked 
by the
symbol (60417-IEC-5017) or by the symbol (60417-IEC-5019), except that, where a
wiring terminal is provided on a component (for example, a terminal block) or
subassembly, the symbol is permitted; and
− for internal FUNCTIONAL EARTHING conductors, the colour combination 
green-and-yellow
shall not be used except in multipurpose preassembled components"

Therefore am I correct in interpreting it is permitted to connect a functional 
earth conductor (not identified with GRN/YEL insulation) to a DIN rail mounted 
GRN/YEL PE terminal block?

GRN/YEL DIN rail terminal blocks are typically self-bonding to chassis ground.  
i.e. no need to add a separate conductor to tie the terminal blocks to PE 
assuming chassis has another PE connection for example a separate dedicated 
stud for main earth connection.  If I want to connect several functional earth 
conductors (for example cable shields) to a bank of GRN/YEL terminal blocks but 
that bank of GRN/YEL terminal blocks have NO PE connections (other than the 
mechanical connection to the DIN rail) is this permitted?  In this example, PE 
conductors are connected to a separate bank of  GRN/YEL terminal blocks.  The 
banks are separated in order to put the terminal blocks closer to where the 
connections need to be made to simplify the wiring in the enclosure.

EN 60204-1:2006 4.4.2 Electromagnetic compatibility states

"- connection of sensitive electrical circuits to the chassis. Such 
terminations should be
marked or labelled with the symbol IEC 60417-5020"
"– connection of sensitive electrical equipment or circuits directly to the PE 
circuit or to a
functional earthing conductor (FE), to minimize common mode disturbance.
This latter terminal should be marked or labelled by the symbol IEC 60417-5018"

My interpretation of this is that a functional earth connection to the chassis 
that is not specifically designated as PE (i.e. a stud not identified as PE, or 
a shield connected to a conductive back shell mounted to the chassis) should be 
shown schematically using the 5020 rake symbol.  A functional earth connection 
to a designated PE (for example GRN/YEL terminal blocks mentioned above s

[PSES] Analog Designer's Notebook - Part 2 Technical Tidbit plus more

[Doug Smith]

  
  
Hi Everyone,

I posted my latest Technical Tidbit a few days ago. Although about
analog op amps there is a definite slant towards SI and EMC. You
would not think a low frequency op amp needs to be bypassed on the
power as it if were a high speed digital IC, but the need is there.
--

Technical
Tidbit - January 2014
Analog Designer's Notebook Part 2 - The Importance of Good Power
Bypassing

  
This
  month's Technical Tidbit describes the importance of good
  power bypassing for op amps, even low frequency ones.
  
  



Abstract: Power bypassing is
  more important than one would think for analog ICs like op amps.
  Even low frequency op amps need
  high quality power bypassing to prevent the op amp from breaking
  into oscillation at a much higher frequency than the unity gain
  bandwidth of the device. The reason for this and recommendations
  are
  presented.
--

The link to the article is http://www.emcesd.com/tt2014/tt010114.htm

However, I have been adding new features to the site. Take a look
around the http://emcesd.com above the list of articles.

Doug
-- 
--
 ___  _Doug Smith
  \  / )   P.O. Box 60941
   =   Boulder City, NV 89006-0941
_ / \ / \ _TEL/FAX: 702-570-6108/570-6013
  /  /\  \ ] /  /\  \  Mobile:  408-858-4528
 |  q-( )  |  o  | Email:   d...@dsmith.org
  \ _ /]\ _ /  Web: http://www.dsmith.org
--

  

-

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 

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 
Mike Cantwell 

For policy questions, send mail to:
Jim Bacher  
David Heald