Re: [PSES] Questions on RCB, RCCB and ELCBs and GFCI protection devices

[Scott Aldous]

Thanks, Pete, for the detail!

On Thu, Feb 16, 2017 at 1:22 PM, Pete Perkins  wrote:

> Vincent et al,
>
>
>
>There have been several really good responses to your
> question on this listserv; it’s great to see everyone chime in and provide
> their info.
>
>
>
>I’d like to add a bit of background and detail to all of
> this.
>
>
>
>Scott pointed out the time vs current curve in the ABB
> paper.  This curve is from the original version of IEC 60479-1 ‘Effects of
> electric current  on humans …’ and has been slightly updated in the current
> version of the standard.  The small changes do not however affect the
> overall argument nor the application of this base data to the problem at
> hand.
>
>
>
>There are 3 electric shock levels stated in 60479-1.
> Perception of electric current is highly variable among persons and extends
> well into the low microamp range.  In 60479-1, the lowest level, the
> startle-reaction level (‘a’ line) is at 0.5mArms level; the next level, the
> letgo-immobilization level (‘b’ line) is 5mArms for times above one ac
> cycle (which provides protection for all individuals – men, women and
> children); the third level, the Ventricular Fibrillation level (‘c1, c2 and
> c3’ lines) is intended to illustrate a statistical distribution for VF and
> the lowest, ‘c1’ line is 30mArms for times above one ac cycle.
>
>The selection of 5mArms for the GFCI units is chosen to
> prevent immobilization if the earth/ground current goes above that value.
> These units are widely used in  North America especially in homes but also
> in commercial buildings anywhere there is ground present – bathrooms,
> kitchens, laundries, garage and outdoor outlets.
>
>The RCD units have been used in Europe for some time for
> industrial use intended to prevent serious hazard to workers.  The choice
> of the 30mArms limit has been considered adequate for that application.
>
>There is some question about the adequacy of the 30mArms
> limit in that the ‘c1’ line is not an absolute limit for persons.  It is a
> statistical limit, having been considered a 5% line in the past (but some
> folks today like to call it a 1% line).  In either case it is clear that
> there are humans who lie to the left of this line and will be subject to VF
> at lower currents. [When considered a 5% line it means that there are about
> 350 Million persons on planet earth to the left of the curve.]
>
>The US will introduce a higher current device for use in
> industrial and other high power uses (such as electric car chargers).  It
> looks like the devices will be 15mArms or 25mArms (and the limit prescribed
> for various installations).
>
>A further issue is that mains electronic switching devices
> are no longer sinusoidal and the circuits on which they work are subject to
> impulses which will push the current levels in the circuit being protected
> above the desired level (whether 5mArms, 15mArms, 25mArms or 30mArms).  The
> impulses are invading the space of the next higher protection level since
> it is the peak value of the impulse which causes the harm.  These impulse
> currents can be harmful to humans when accessible.
>
>Today there are issues using electronic switching units
> connected to GFCI and RCD units.  The feedback signals from the equipment
> will, in some cases, either falsely trip the protection device or not
> properly trip when the current exceeds the protection value.
>
>
>
>Obviously coordinated levels for outgoing emissions and
> incoming susceptibility  between equipments need to be fully worked out.
>
>
>
>Hopefully this further explanation is helpful to you and
> other on this network.
>
>
>
> :>) br,  Pete
>
>
>
> Peter E Perkins, PE
>
> Principal Product Safety & Regulatory Affairs Consultant
>
> PO Box 23427
>
> Tigard, ORe  97281-3427
>
>
>
> 503/452-1201 <(503)%20452-1201>
>
>
>
> p.perk...@ieee.org
>
>
>
> *From:* Scott Aldous [mailto:0220f70c299a-dmarc-requ...@ieee.org]
> *Sent:* Thursday, February 16, 2017 8:29 AM
> *To:* EMC-PSTC@LISTSERV.IEEE.ORG
> *Subject:* Re: [PSES] Questions on RCB, RCCB and ELCBs
>
>
>
> Hi Vincent,
>
>
>
> Here
> <https://library.e.abb.com/public/c4e584f06cc6c4fbc1257ad800496193/2CSC420004B0201_RCDs%20EN.pdf>
> is a technical guide from ABB that you may find helpful. With regard to the
> 30mA trip level for an RCD, the paper refers to IEC 60479-1 and reproduces
> a Figure from that standard on page 2 rela

Re: [PSES] Questions on RCB, RCCB and ELCBs and GFCI protection devices

[Pete Perkins]

Vincent et al,

 

   There have been several really good responses to your question 
on this listserv; it’s great to see everyone chime in and provide their info.  

 

   I’d like to add a bit of background and detail to all of this.  

 

   Scott pointed out the time vs current curve in the ABB paper.  
This curve is from the original version of IEC 60479-1 ‘Effects of electric 
current  on humans …’ and has been slightly updated in the current version of 
the standard.  The small changes do not however affect the overall argument nor 
the application of this base data to the problem at hand.  

 

   There are 3 electric shock levels stated in 60479-1.  Perception 
of electric current is highly variable among persons and extends well into the 
low microamp range.  In 60479-1, the lowest level, the startle-reaction level 
(‘a’ line) is at 0.5mArms level; the next level, the letgo-immobilization level 
(‘b’ line) is 5mArms for times above one ac cycle (which provides protection 
for all individuals – men, women and children); the third level, the 
Ventricular Fibrillation level (‘c1, c2 and c3’ lines) is intended to 
illustrate a statistical distribution for VF and the lowest, ‘c1’ line is 
30mArms for times above one ac cycle.   

   The selection of 5mArms for the GFCI units is chosen to prevent 
immobilization if the earth/ground current goes above that value.  These units 
are widely used in  North America especially in homes but also in commercial 
buildings anywhere there is ground present – bathrooms, kitchens, laundries, 
garage and outdoor outlets.  

   The RCD units have been used in Europe for some time for 
industrial use intended to prevent serious hazard to workers.  The choice of 
the 30mArms limit has been considered adequate for that application.  

   There is some question about the adequacy of the 30mArms limit 
in that the ‘c1’ line is not an absolute limit for persons.  It is a 
statistical limit, having been considered a 5% line in the past (but some folks 
today like to call it a 1% line).  In either case it is clear that there are 
humans who lie to the left of this line and will be subject to VF at lower 
currents. [When considered a 5% line it means that there are about 350 Million 
persons on planet earth to the left of the curve.]

   The US will introduce a higher current device for use in 
industrial and other high power uses (such as electric car chargers).  It looks 
like the devices will be 15mArms or 25mArms (and the limit prescribed for 
various installations).  

   A further issue is that mains electronic switching devices are 
no longer sinusoidal and the circuits on which they work are subject to 
impulses which will push the current levels in the circuit being protected 
above the desired level (whether 5mArms, 15mArms, 25mArms or 30mArms).  The 
impulses are invading the space of the next higher protection level since it is 
the peak value of the impulse which causes the harm.  These impulse currents 
can be harmful to humans when accessible.  

   Today there are issues using electronic switching units 
connected to GFCI and RCD units.  The feedback signals from the equipment will, 
in some cases, either falsely trip the protection device or not properly trip 
when the current exceeds the protection value.  

 

   Obviously coordinated levels for outgoing emissions and incoming 
susceptibility  between equipments need to be fully worked out.  

 

   Hopefully this further explanation is helpful to you and other 
on this network.  

 

:>) br,  Pete

 

Peter E Perkins, PE

Principal Product Safety & Regulatory Affairs Consultant

PO Box 23427

Tigard, ORe  97281-3427

 

503/452-1201

 

 <mailto:p.perk...@ieee.org> p.perk...@ieee.org

 

From: Scott Aldous [mailto:0220f70c299a-dmarc-requ...@ieee.org] 
Sent: Thursday, February 16, 2017 8:29 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Questions on RCB, RCCB and ELCBs

 

Hi Vincent,

 

Here 
<https://library.e.abb.com/public/c4e584f06cc6c4fbc1257ad800496193/2CSC420004B0201_RCDs%20EN.pdf>
  is a technical guide from ABB that you may find helpful. With regard to the 
30mA trip level for an RCD, the paper refers to IEC 60479-1 and reproduces a 
Figure from that standard on page 2 relating effects on the body from exposure 
to ac currents (15 Hz to 100 Hz) with different durations. I don't believe the 
paper explains this, but this graph is specific to a left hand to feet current 
path through the body. The version of the standard that I have actually has a 
figure that is slightly different from the ABB paper, FYI.

 

The paper seems to indicate that the 30mA level was chosen since it marks the 
delineation between regions made by the c1 curve. Referring to the table on the 
next page (the table from the standard has mor

Re: [PSES] Questions on RCB, RCCB and ELCBs

[Scott Aldous]

Hi Vincent,

Here

is a technical guide from ABB that you may find helpful. With regard to the
30mA trip level for an RCD, the paper refers to IEC 60479-1 and reproduces
a Figure from that standard on page 2 relating effects on the body from
exposure to ac currents (15 Hz to 100 Hz) with different durations. I don't
believe the paper explains this, but this graph is specific to a left hand
to feet current path through the body. The version of the standard that I
have actually has a figure that is slightly different from the ABB paper,
FYI.

The paper seems to indicate that the 30mA level was chosen since it marks
the delineation between regions made by the c1 curve. Referring to the
table on the next page (the table from the standard has more information),
although below that current level let-go can occur it does not mention
danger of ventricular fibrillation. If the assumption regarding the reason
for this choice is correct, it appears that the IEC chose ventricular
fibrillation as the major consideration, likely also considering that 30mA
is still within zone 2 (AC-2 in the standard) for durations up to about
200ms and that people will generally react to move away from contact. As
John mentions, likelihood of nuisance tripping was also surely taken into
account when choosing this level. It appears that the UL standard focused
on prevention of effects at a less severe level. Note that 5mA is always
within zone 2 (AC-2) regardless of duration.

That being said, I am not familiar with the history of the development of
the relevant standards. If there are folks on this forum who are, I would
love to see a more accurate or more detailed explanation.

On Thu, Feb 16, 2017 at 12:49 AM, John Woodgate 
wrote:

> 1. That's a really big question and the really big answer is too big for a
> mailing list. Search on the web for descriptions and/or comparisons.
>
>
>
> 2. The IEC standard is an international agreement. I suppose the GFCI is a
> US-only (or NA-only) specification. Fault currents are obviously half with
> 120 V supplies versus 230 V supplies. At 230 V, 5 mA would cause nuisance
> tripping and problems with protective conductor currents due to capacitance
> from L to PEC.
>
>
>
> 3. ELCBs required a PEC connection, so if the PEC is broken, the
> protection does not work. RCCBs detect the difference between L and N
> currents and do not use a PEC connection.
>
>
>
> With best wishes DESIGN IT IN! OOO – Own Opinions Only
>
> www.jmwa.demon.co.uk J M Woodgate and Associates Rayleigh England
>
>
>
> Sylvae in aeternum manent.
>
>
>
> *From:* Vincent Lee [mailto:08e6c8d35910-dmarc-requ...@ieee.org]
> *Sent:* Thursday, February 16, 2017 3:04 AM
> *To:* EMC-PSTC@LISTSERV.IEEE.ORG
> *Subject:* [PSES] Questions on RCB, RCCB and ELCBs
>
>
>
>
>
> Hi all,
>
>
>
> I am Vincent, newbies in Product Safety. Hence, I sincerely hope to seek
> your professional answers to my following questions,
>
>
>
> 1) What are the major differences between RCB, RCCB, GFCI and GFEP ?
>
>
>
> 2) If the human-let-go-current-threshold is about 10mA, why does IEC 61008
> RCCBs used in Household being specified at 30mA trip current while GFCI
> used in Household are specified at 5mA (+/- 1mA) ?
>
>
>
> 3) I heard that Residual Current Circuit Breaker are replacing Electrical
> Leakage Circuit Breaker, in what ways are RCCB better than ELCB for
> electrical safety protection that causes ELCB being replaced?
>
>
>
> Regards,
>
> Vincent
>
> -
> 
>
> 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>
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>
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> Mike Cantwell 
>
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> David Heald 
> -
> 
>
> 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)

Re: [PSES] Questions on RCB, RCCB and ELCBs

[John Woodgate]

1. That's a really big question and the really big answer is too big for a 
mailing list. Search on the web for descriptions and/or comparisons.
 
2. The IEC standard is an international agreement. I suppose the GFCI is a 
US-only (or NA-only) specification. Fault currents are obviously half with 120 
V supplies versus 230 V supplies. At 230 V, 5 mA would cause nuisance tripping 
and problems with protective conductor currents due to capacitance from L to 
PEC.
 
3. ELCBs required a PEC connection, so if the PEC is broken, the protection 
does not work. RCCBs detect the difference between L and N currents and do not 
use a PEC connection.
 
With best wishes DESIGN IT IN! OOO – Own Opinions Only
  www.jmwa.demon.co.uk J M Woodgate and 
Associates Rayleigh England
 
Sylvae in aeternum manent.
 
From: Vincent Lee [mailto:08e6c8d35910-dmarc-requ...@ieee.org] 
Sent: Thursday, February 16, 2017 3:04 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] Questions on RCB, RCCB and ELCBs
 
 
Hi all,
 
I am Vincent, newbies in Product Safety. Hence, I sincerely hope to seek your 
professional answers to my following questions,
 
1) What are the major differences between RCB, RCCB, GFCI and GFEP ?
 
2) If the human-let-go-current-threshold is about 10mA, why does IEC 61008 
RCCBs used in Household being specified at 30mA trip current while GFCI used in 
Household are specified at 5mA (+/- 1mA) ? 
 
3) I heard that Residual Current Circuit Breaker are replacing Electrical 
Leakage Circuit Breaker, in what ways are RCCB better than ELCB for electrical 
safety protection that causes ELCB being replaced?
 
Regards, 
Vincent
-

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.
Website: http://www.ieee-pses.org/
Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) 
 
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-

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:
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Attachments are not permitted but the IEEE PSES Online Communities site at 
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