Re: [PSES] MOV requirements

[Mick Maytum]

Ralph,
The answer to your question is in the US arm of your 
own company. Drop a line to James Moellmann, who has 
recently been to the IEC meetings in China and IEEE meetings 
in Florida all concerned with yet more standards on 
MOV-protected devices and equipment.


Regards
Mick

On 14/11/2011 19:30, ralph.mcdiar...@schneider-electric.com 
wrote:


Does the industry really need another standard, I wonder?
_
*
Ralph McDiarmid*  | *Schneider Electric **  |  Renewable 
Energies Business*  | *CANADA*  | *Regulatory Compliance 
Engineering*




From:   John Woodgate j...@jmwa.demon.co.uk
To: EMC-PSTC@LISTSERV.IEEE.ORG
Date:   11/11/2011 06:48 AM
Subject:Re: [PSES] MOV requirements






In message 4ebd2d05.5050...@ieee.org, dated Fri, 11 Nov 
2011, Mick

Maytum m.j.may...@ieee.org writes:

MOV, Varistor, VDR; Metal-Oxide Varistor are all names for a
voltage-limiting component using a particular technology.

I think this 'particular technology' is an important 
point. As I
understand it, devices like Transorbs (TM?) are quite 
different from
MOVs, being avalanche diodes with a very high thermal 
capacity. They
seem to be rarely used (cost?) but have desirable 
characteristics (like

not exploding!). Are there relevant standards?
--
OOO - Own Opinions Only. Try www.jmwa.demon.co.ukand 
www.isce.org.uk

John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK
Some people who are peeling the finch of the financial 
crisis are thinking of

biting a rook.

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[PSES] SPC component properties

[Mick Maytum]

Brian,
I appreciate for your purposes the SPC component of 
choice is the MOV. Quite right too, if you are considering 
cost and device safety standards like UL 1449. SPC 
standards, which tend to be for component electrical and 
environmental performance, can only overlap the requirements 
of an Equipment/Device safety standard.


Your perception of other protection technologies needs 
revision.


True, PN junction zener breakdown diodes have a very soft 
clamping characteristic. NB The zener breakdown effect only 
occurs below about 7 V.
To counter the poor zener clamping characteristic a 
multi-junction silicon semiconductor component using the 
punch-through effect can be used. This type of technology 
provides a sharp clamping characteristic from a few volts 
upwards. Punch-through voltage limiters can be found in 
Ethernet ports. These SPCs protect the Ethernet PHY chip 
against damaging overvoltages (even though 5-volts may not 
sound like an overvoltage)


Above 7 V a different breakdown effect comes in -- the 
avalanche effect.
Avalanche breakdown diodes have a good sharp clamping 
characteristic. You may see them referred to as SADs, 
Silicon Avalanche Diodes. The three-letter acronym powers 
that be in the IEC said they didn't want a sad component and 
so the ABD, Avalanche Breakdown Diode, acronym came into 
being. Unfortunately, many people, who don't know the 
difference between zener and avalanche breakdown, call ABDs 
zeners, which is totally wrong.
All PN junction semiconductors have relatively low thermal 
capacity and energy absorption capability. These 
deficiencies can be countered by using series and parallel 
combinations of ABDs. There are several companies in the US 
making AC Power SPDs using this approach -- costly, but 
these have a better clamping performance than an MOV.


The GDT uses gaseous discharge and the switching time from 
sparkover to the low-voltage arc can be in the tens of 
nanoseconds. The problem is that the sparkover voltage is 
dependent on the rate of voltage rise. This overshoot of 
surge sparkover to AC sparkover can be something like 2:1. 
This is not a firm ratio but dependent on the AC/DC 
sparkover voltage. An 80 V GDT will have a higher surge 
sparkover voltage than the sweet spot 250 V GDT.
An interesting trend I've noticed is for GDT MOV series 
combinations where PLC is being used. Put MOV protection 
(read capacitance) on the AC supply and PLC reach and 
environmental pollution are reduced. Protect using a low 
capacitance GDT MOV series combination and PLC reach and 
environmental pollution are maximised.


Regards
Mick


On 14/11/2011 21:04, Brian Oconnell wrote:

o further abuse a meme - moar standards! [insert troll-face here]

Another member has previously commented that there a several type of
components used to arrest a surge. For the purpose of my OP, was focused on
a MOV-type SPD as defined under UL CCNs VZCA2 and VZCA8, where the effective
standards are UL1449 and CSA C233.1, and various CSA TILs. And of course,
the wondrous IEC61051-2. This is another case where EMC requirements
(61000-4-5,6) can affect product safety. Last year's update to the 2d ed of
60950-1 for my component power supplies was, for some models, quite an
adventure.

A problem NOT ADDRESSED by TC108 is the increased energy AFTER a surge, or
during a SFC, due to the 120% rating requirement. Perhaps this was a
principal intent of UL1449 3d ed - verify that the high E and I do not make
the MOV puke it guts and start a fire. There are many sources of increased
energy - my two problem children are the effects of an inductive kick to the
circuit being 'protected' by the SPD*after*  the current interrupt device
has opened; and the higher voltage (CV^2), during a surge, at which the SPD
will start conducting.

As for GDTs - they take longer to get to low Z. And zener-type arrestors do
not have a sharp knee at the conduction level. The ZnO MOV seems to be the
best chance of survival, assuming the other  circuit components can handle
much higher coulombs running around before clamping.


Moar standards! Moar unintended effects! Moarrr

Brian

-Original Message-
From:emc-p...@ieee.org  [mailto:emc-p...@ieee.org]On Behalf Of
ralph.mcdiar...@schneider-electric.com
Sent: Monday, November 14, 2011 11:31 AM
To:EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] MOV requirements

Does the industry really need another standard, I wonder?

Ralph McDiarmid  |   Schneider Electric   |  Renewable Energies Business  |
CANADA  |   Regulatory Compliance Engineering


From: John Woodgatej...@jmwa.demon.co.uk
To:EMC-PSTC@LISTSERV.IEEE.ORG
Date: 11/11/2011 06:48 AM
Subject: Re: [PSES] MOV requirements

In message4ebd2d05.5050...@ieee.org, dated Fri, 11 Nov 2011, Mick
Maytumm.j.may...@ieee.org  writes:


MOV, Varistor, VDR; Metal-Oxide Varistor are all names for a
voltage-limiting component using a particular technology.

I think this 'particular technology' is an 

Re: [PSES] AC Powering or not to AC power that is the test option

[Mick Maytum]

Brian,
I find portions of our discussion has been transcribed 
to the entire IEC TC 108 group. Thus I feel I should respond 
to your TC 108 comments



A problem NOT ADDRESSED by TC108 is the increased energy AFTER a surge, or
during a SFC, due to the 120% rating requirement. Perhaps this was a
principal intent of UL1449 3d ed - verify that the high E and I do not make
the MOV puke it guts and start a fire.
I don't think TC 108 is deficient in missing out AC 
powering when surging. I'm not in love with some other stuff 
they do, but that's another discussion.


My reasoning is, if the surge damages the MOV, then all 
the applied AC does is provide a power source to cause a 
component power loss and temperature rise that might lead to 
thermal runaway and component destruction.
Without the application of AC power, there are 
measurement techniques available to tell if the component 
has been damaged. At the component level, measuring the MOV 
nominal voltage at 1 mA DC is a common approach. If this 
voltage changes by more than a given amount then the MOV has 
degraded due to surge.


I've spent a deal of time studying UL 1449 recently 
and, as I understand it, in the most stressful surge test UL 
doesn't apply AC power (like TC 108).


Type 2 SPDs have a Nominal discharge current test (As 
the MOV isn't a GDT with a gaseous filling, you can't have a 
discharge current in it, so the correct term is the more 
mundane nominal surge current).
Preferred current values are 3 kA, 5 kA, 10 kA and 
20 kA. These are currents in the SPD, not short-circuit 
ones, produced by an 8/20 current generator. No AC power is 
applied.


 Type 3 SPDs have an operating duty cycle test with AC 
power applied. The surge generator is a 1.2/50-8/20 
combination wave generator set for 6 kV open-circuit and 3 
kA short-circuit. Once you included the coupling/decoupling 
network and the component, it is only a quasi-8/20 current 
of a smaller amplitude than the short-circuit value in the MOV .


UL measure pre and post test limiting voltage - this is 
a very crude validation assessment method. A lot has gone 
wrong to cause a significant change in limiting voltage. On 
the bright side, because UL throws a lot of extra tests in, 
there is a leakage current test, which performs a similar 
appraisal as the component 1 mA nominal voltage test.


Regards
Mick

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Re: [PSES] Steady State Conditions - née thermal equilibrium

[Mick Maytum]

The IEC offers several definitions of thermal equilibrium in 
its Glossary.


thermal equilibrium conditions
stable temperature conditions indicated by temperature 
changes of no more than 3 K (5 °F) or 1 % of the absolute 
operating temperature, whichever is higher between two 
readings 15 min apart

IEC 62282-2, ed. 1.0 (2004-07)

thermal equilibrium
variation of less than 1 K between any two out of three 
consecutive measurements made at an interval of 5 min

IEC 61810-7, ed. 2.0 (2006-03)

thermal equilibrium
state reached when the observed temperature rise of any part 
of the welding equipment does not exceed 2 K/h

IEC 62135-1, ed. 1.0 (2008-07)

thermal equilibrium
the state reached when the temperature rises of the several 
parts of the machine do not vary by more than a gradient of 
2 K per hour
NOTE Thermal equilibrium may be determined from the 
time-temperature rise plot when the straight lines between 
points at the beginning and end of two successive reasonable 
intervals each have a gradient of less than 2 K per hour.

IEC 60034-1, ed. 12.0 (2010-02)

Nice to see a harmonised approach from the various IEC TCs

Regards
Mick




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Re: [PSES] Steady State Conditions - née thermal equilibrium

[Mick Maytum]

TC 1 controls the IEC IEV. There you find in the fundamental 
definitions


Area Electrical and magnetic devices / Operating 
conditions and testing

IEV ref 151-16-33
thermal equilibrium
 state reached when the temperature of the parts of 
a component or equipment operating in a given environment no 
longer varies faster than a specified limit


I remember when thermally testing CRT colour TVs that it 
took about 3 hours before the temperature stabilised. In 
this case, a fair bit of the power loss was power switching, 
which increased with the microclimate temperature. In part, 
it was more like a test for thermal runaway, with some of 
the TO-3 packaged transistors stabilising at about 130 
degree C case temperature in a 40 degree C room ambient 
(Athens Valley in the summer I was told).


I was involved with a variant of the TC 1 data base. You had 
to enter the data as HTML expressions in an Excel 
spreadsheet - a frustrating exercise if you were not 
proficient in HTML.


Mick


On 12/01/2012 11:24, John Woodgate wrote:
In message 4f0eba2a.8070...@ieee.org, dated Thu, 12 Jan 
2012, Mick Maytum m.j.may...@ieee.org writes:



Nice to see a harmonised approach from the various IEC TCs


The 60034 definition might be taken as more 'horizontal' 
(i.e. a reference definition that other committees should 
adopt) than the others.


May years ago, someone I know proposed to IEC that 
standard definitions and other widely-used wording should 
be held in a database from which product committees should 
select what they want. It wasn't progressed - it was 
probably a bit before its time, but it is quite 
practicable now.


Might take 100 years to agree on all the definitions, 
though. Can't be left to TC1 in isolation.


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Re: [PSES] Is this common knowledge - Electrical Ratings

[Mick Maytum]

Dans experience reminded me of a guy who bought a 120 V 
coffee maker as a present for someone in (old) England. 
Having some knowledge of AC supplies he bought a 240 V to 
120 V travel adaptor so the coffee maker could operate on UK 
240 V mains. Unfortunately the adaptor consisted of a series 
rectifier diode to apply half cycles of the AC. Had the 
coffee maker been electro-mechanical he might have got away 
with it. But the maker had sophisticated electronic 
controls. When powered up for the first and only time the 
result was spectacular.


Mick
On 27/01/2012 16:26, Dan Roman wrote:

Marked 120/240V would not necessarily mean a switch needs to be flipped or a 
selector moved, it could still be auto-ranging.  But something marked 120/240V 
would not be expected to operate at say 150V but something rated 120-240V 
should.

I would expect something marked 120/240V to operate in two ranges, at least 
108-127 and 216-254 but not necessarily in-between.

I think most consumers that purchased something locally expect to be able to 
plug in a device without fiddling with a switch or selector.  Probably the most 
common appliance that has a voltage selector switch paid attention to is a hair 
dryer during international travel after blowing up the first one!

Dan

-Original Message-
From: John Cotman [mailto:john.cot...@conformance.co.uk]
Sent: Friday, January 27, 2012 10:35 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Is this common knowledge - Electrical Ratings

Presumably:

Something marked 120-240V should run at any voltage in that range, and you'd
just need to plug it into a suitable supply (one would hope that it is also
rated to cover both 50Hz and 60Hz supplies).

A 120/240V making is an either one or the other indication, so there might
well be a selector switch.  If there is, the manufacturer would be well
advised not to be cryptic unless he likes product returns.

John C.

-Original Message-
From: Kevin Robinson [mailto:kevinrobinso...@gmail.com]
Sent: 27 January 2012 15:20
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] Is this common knowledge - Electrical Ratings

Happy Friday everyone

I am asking a question that I already know the answer to, but I am
trying to determine if it is common knowledge or if it was something
that I picked up along the way and have always accepted as being true.

If you were to see a product with a marked electrical rating of
120/240 V and another product with a marked rating of 120-240V, what
would be the difference between these two products?  Would a user or
operator need to do anything special with one or both of these
products to use it at 120V or 240V?

Thanks,

Kevin Robinson
OSHA

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Re: [PSES] Hipot with in-circuit voltage limiting devices IEC 61010-1 3rd Ed.

[Mick Maytum]

Clamping voltage is the MOV voltage under specified surge 
conditions. Typically that will be an 8/20 impulse.


IEC 61643-331, ed. 1.0 (2003-05)
clamping voltage VC
peak voltage across the MOV measured under conditions of a 
specified peak pulse current (IP) and specified waveform


Your 1 mA voltage is called the nominal voltage (not 
clamping voltage) when the MOV draws a specified low-level 
current.


IEC 61643-331, ed. 1.0 (2003-05)
nominal varistor voltage VN
voltage across the MOV measured at a specified pulsed 
current (IN), of specific duration
NOTE The MOV manufacturer specifies the current. Otherwise, 
1 mA is normally used. The pulse duration should be less 
than 40 ms, unless otherwise specified. In general, nominal 
value ±10 % is specified by the manufacturer.


Regards
Mick
On 10/05/2012 00:27, Doug Powell wrote:
A change was made in 3rd Ed. for routine mains hipot tests 
while clamping devices are still in the circuit; 
specifically clause F.3.2 (Ed. 3).


The standard states the test can be carried out at 0.9 
times the clamping voltage of the device and not less 
than twice the working voltage.  Edition 2 said not less 
than that of the working voltage.


My application is 230Vac and I initially selected 275Vrms 
MOVs.  Plugging in the F.3.2 equations, I get a hipot 
failure.


These devices have a very soft voltage knee and as a 
result of the dynamic resistance, the knee very time 
dependent.  The MOV supplier states the maximum clamping 
voltage using the 8/20 mS surge  is 710V and the DC 
clamping voltage with a 1 mA current source is 473V.  I 
would assume the 473V is very similar to the peak of the 
275 Vrms 50/60 Hz waveform, plus some headroom for 
component tolerance (~18%).


If you try running the numbers to re-select 
a different MOV value, it is very possible to get all tied 
up in knots.  So, which clamping voltage are we to use? 
 My thought is to use 2 x 230 = 460V and select the next 
higher MOV from the catalog.


Opinions, rulings, decrees from on high?



--
Thanks, -doug

Douglas E Powell
doug...@gmail.com mailto:doug...@gmail.com
http://www.linkedin.com/in/dougp01


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Re: [PSES] Hipot with in-circuit voltage limiting devices IEC 61010-1 3rd Ed.

[Mick Maytum]

Doug,
My previous message gave the IEC rulings - terms 
clamping voltage and nominal varistor voltage  - for two 
specific points on the MOV clamping (clipping) characteristic.


For completeness  IEC 61010-1, ed. 3.0 (2010-06) defines the 
following:

*working voltage *
highest r.m.s. value of the a.c. or d.c. voltage across any 
particular insulation which can occur when the equipment is 
supplied at rated voltage
NOTE 1 Transients and voltage fluctuations are not 
considered to be part of the working voltage.
NOTE 2 Both open-circuit conditions and normal operating 
conditions are taken into account.


I'm now giving an opinion.

Your (nominal) AC supply is 230V rms. The phase not less 
than twice the working voltage. means the hipot test is 
done with an AC value of at least 460 V rms or 650 V pk.


The hipot test voltage of 0.9 times the clamping voltage of 
the MOV is clearly crazy, as from your figures of 710 V  
clamping voltage and 473 V nominal varistor voltage, testing 
at 0.9x710 = 630 V would cause substantial current in the MOV.


 One could skate round this and say that the 1 mA nominal 
varistor voltage is the clamping/threshold/ voltage - a new 
term - and use an MOV or combination of MOVs to have a 
nominal voltage of 650/0.9 = 720 V.


Sounds like a letter to the Chair and Secretary of TC 66 is 
needed to resolve this matter.


Regards
Mick

On 10/05/2012 00:27, Doug Powell wrote:
A change was made in 3rd Ed. for routine mains hipot tests 
while clamping devices are still in the circuit; 
specifically clause F.3.2 (Ed. 3).


The standard states the test can be carried out at 0.9 
times the clamping voltage of the device and not less 
than twice the working voltage.  Edition 2 said not less 
than that of the working voltage.


My application is 230Vac and I initially selected 275Vrms 
MOVs.  Plugging in the F.3.2 equations, I get a hipot 
failure.


These devices have a very soft voltage knee and as a 
result of the dynamic resistance, the knee very time 
dependent.  The MOV supplier states the maximum clamping 
voltage using the 8/20 mS surge  is 710V and the DC 
clamping voltage with a 1 mA current source is 473V.  I 
would assume the 473V is very similar to the peak of the 
275 Vrms 50/60 Hz waveform, plus some headroom for 
component tolerance (~18%).


If you try running the numbers to re-select 
a different MOV value, it is very possible to get all tied 
up in knots.  So, which clamping voltage are we to use? 
 My thought is to use 2 x 230 = 460V and select the next 
higher MOV from the catalog.


Opinions, rulings, decrees from on high?



--
Thanks, -doug

Douglas E Powell
doug...@gmail.com mailto:doug...@gmail.com
http://www.linkedin.com/in/dougp01


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Re: [PSES] Hipot with in-circuit voltage limiting devices IEC 61010-1 3rd Ed.

[Mick Maytum]

Doug,
I wouldn't credit the TC 66 has having MOV component 
knowledge, just perceptions.


Since my last message I have sent messages to the Chair 
and Secretary of TC 66 wearing my IEC SC 37B chair hat.
I was restrained for a change, merely stating they were 
breaking the laws of physics for MOVs rather than crazy! I 
suggested that if the 0.9 factor was to work it should be 
applied to the nominal voltage not the clamping voltage.


   I'll keep you informed of developments if any.

Regards
Mick

On 10/05/2012 15:15, Doug Powell wrote:

Mick,

Sorry I didn't review this email before I just sent my 
last.  Clearly you see the same problem as I.  I have to 
wonder if the committee in reviewing this clause only 
used data sheets and did not validate in the lab.  Or is 
it possibly the committee members just missed this?


I would like to suggest the Vclamp we should use this the 
8 mS / 10 mS rating.  That's mS, not uS.



--
Thanks, -doug

Douglas E Powell
doug...@gmail.com mailto:doug...@gmail.com
http://www.linkedin.com/in/dougp01




On Thu, May 10, 2012 at 6:58 AM, Mick Maytum 
m.j.may...@ieee.org mailto:m.j.may...@ieee.org wrote:


Doug,
My previous message gave the IEC rulings - terms
clamping voltage and nominal varistor voltage  - for
two specific points on the MOV clamping (clipping)
characteristic.

For completeness  IEC 61010-1, ed. 3.0 (2010-06)
defines the following:
*working voltage *
highest r.m.s. value of the a.c. or d.c. voltage
across any particular insulation which can occur when
the equipment is supplied at rated voltage
NOTE 1 Transients and voltage fluctuations are not
considered to be part of the working voltage.
NOTE 2 Both open-circuit conditions and normal
operating conditions are taken into account.

I'm now giving an opinion.

Your (nominal) AC supply is 230V rms. The phase not
less than twice the working voltage. means the hipot
test is done with an AC value of at least 460 V rms or
650 V pk.

The hipot test voltage of 0.9 times the clamping
voltage of the MOV is clearly crazy, as from your
figures of 710 V  clamping voltage and 473 V nominal
varistor voltage, testing at 0.9x710 = 630 V would
cause substantial current in the MOV.

 One could skate round this and say that the 1 mA
nominal varistor voltage is the clamping/threshold/
voltage - a new term - and use an MOV or combination
of MOVs to have a nominal voltage of 650/0.9 = 720 V.

Sounds like a letter to the Chair and Secretary of TC
66 is needed to resolve this matter.

Regards
Mick




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Re: [PSES] 8/20 waveform

[Mick Maytum]

Kris,
If you pull a copy of Impulse generators for testing 
low voltage equipment from the IEEE PES Surge Protective 
Devices Committee (SPDC) Website.


http://pes-spdc.org/sites/default/files/Impulse_generatorsaddedrev2.pdf

Figure 12 of the document shows the typical 1.2/50-8/20 
combination wave generator output waveshape variation with 
external resistance for zero to 20 ohms.
As the resistance increases the peak current amplitude 
decreases and the 8/20 short-circuit waveshape moves towards 
1.2/50. Things get more complicated when the load is not a 
pure resistance.


Mick
On 03/05/2013 14:26, Carpentier Kristiaan wrote:


Hi group,

A combination wave surge generator gives a 1.2/50 voltage 
waveform and an 8/20 short-circuit current at the output 
of the generator with no CDN connected.


What happens with this current waveform when the output is 
not a real short-circuit but has a certain series 
resistance/impedance (5, 10, ...ohm): Will the waveform 
become longer in time or will only the current level 
decrease, or both?


Thanks,

Kris

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Re: [PSES] safety 60950 and surge suppression circuits - GDTs

[Mick Maytum]

John,
It is true that people used to worry about GDTs 
venting. In venting the GDT sparkover voltage greatly 
increased. In fact, there was a US trend to include a 
Back-Up (air) Gap (BUG) across the GDT component in case 
this happens. In fact, due to contamination, these BUGs were 
more unreliable than the GDTs they protected.
 UL came to the rescue and came up with a standard and 
expensive testing so that a BUG was unnecessary. Although 
the term is not much used today, these qualified components 
were known as Bugless GDTs.
I've worked with many major GDT manufacturers and the 
main life concern these days is voltage degradation with 
surging. The so-called fast GDTs do degrade in sparkover 
voltage a lot faster than (well made) standard GDTs. One 
service provider was replacing SPDs using fast GDTs every 
two years because of this problem.
Surge Protective Devices (SPDs) are complete assemblies 
made up from terminals, bases, housings and surge protective 
components (SPCs - GDTs, MOVs, ABDs etc.). I've notice that 
people wrongly use SPD when they are really talking about a 
surge protective component, SPC.


Regards
Mick


On 12/05/2013 20:39, John Woodgate wrote:
In message 518feba9.7000...@ieee.org, dated Sun, 12 May 
2013, Richard Nute ri...@ieee.org writes:


As for the requirement for the GDT to pass the hi-pot 
test...

???  I don't have any rationale for this.


If its seal was broken, letting the magic gas out, would 
it arc over at a lower voltage?


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Re: [PSES] safety 60950 and surge suppression circuits

[Mick Maytum]

Rich,
Given your rational that surge protective components 
(SPCs), such as MOVs or GDTs, can have a fault mode anywhere 
between a short-circuit and an open-circuit, looks like 
there is a disconnect in the test levels.
In the open-circuit situation, the SPC does not divert 
current and the full voltage is applied to the electrical 
insulation. That being the case and as TC 108 specifies MOVs 
are tested with a impulse generator voltage of 6 kV peak, 
why isn't the insulation tested with this 6 kV impulse?


Regards
Mick.
On 20/05/2013 22:50, Richard Nute wrote:

Hi Joe:


Very quickly...

SPDs are not considered reliable components or assemblies.
The safety standards anticipate a failure -- anywhere from
open-circuit to short-circuit.

In the event of an open-circuit, there is no indication of
such a failure.  And, of course, all transients then pass
through the open SPD.

Consequently, the equipment safety insulations will be
called upon to withstand the expected transient overvoltages.
So, the standards require performing the voltage withstand
test without the SPD in place.


Best regards,
Rich






On 5/20/2013 1:40 PM, Joe Randolph wrote:

Hi Rich:

I'm hoping that you can provide one of your 
straightforward Rich Nute Explanations for the apparent 
contradiction behind the rationale that allows a surge 
protection component to be placed across a required 
safety isolation barrier, and then removed for the 
purpose of performing the hipot test.


I have been involved with safety compliance for over 30 
years, and this concept is one that has never made 
complete sense to me.  On one level, I can just bump 
along and limit my attention to what the safety standard 
actually says, but I would like to understand what the 
thinking is behind that.


This allowance (removing surge protection components for 
the hipot test) appears in a variety of standards and 
clauses within those standards, such as EN 60950-1, 
clauses 5.2.2, 6.1.2, and 6.2.2.


If you could help clarify the thinking behind this 
allowance, I would greatly appreciate it.



Thanks,

Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
j...@randolph-telecom.com
http://www.randolph-telecom.com 
http://www.randolph-telecom.com/







Hi Bill:


SPDs, regardless of configuration, are notorious for being
prone to failure, either short-circuit or open-circuit or
any value of resistance between those two extremes.  (One
cannot predict the energy the SPD will be required to
dissipate.)

From a safety point of view, all such failures must be
accounted for such that the safety of the equipment is not
compromised by any failure of the SPD.

If the SPD should fail open-circuit, then expected
transients that are therefore not attenuated, must not
cause the insulation to fail.  Hence, the insulation must
pass the hi-pot test without the SPD in place.

As for the requirement for the GDT to pass the hi-pot 
test...

???  I don't have any rationale for this.


Best regards,
Rich





On 5/10/2013 10:11 AM, Bill Owsley wrote:
I'm running into a dilemma.   Not being a Safety 
Engineer myself, but rubbing elbows with them...
On a piece of ITE equipment, I need some surge 
suppression for worldwide markets with one annoying 
requirement for 4 kV, otherwise just 2 kV line to 
earth, and using either plugable cords or permanent 
connection, whichever is worse.
Now the Safety guys  tell me that MOV's alone cannot 
bridge the insulation (Basic or Functional, I forget.)  
between primary and earth, when using one of power 
cable options mentioned above.
But a proper qualified (GDT) gas discharge tube can do 
the bridging.  So we figured to use them in series.

On a quick and dirty bench test it works to 4 kV.
Then the Safety guys pull out the rest of the story and 
point out 5.2.2 which seems to indicate that the GDT is 
to meet the Hi-Pot test, 1500 vac.
Previously, section, 1.5.9.4 (?)  indicates that the 
surge protection devices can be removed during the 
Hi-Pot test.
But now I have a Surge suppression circuit that has to 
withstand the same Hi-Pot as the rest of the board.
Question is how does a surge protection circuit protect 
the board when it has to meet the same Hi-Pot test?
In other words, when a surge comes along, which is 
going to break over first?

The surge protection or the board?
Is the purpose of surge suppression is to keep the 
clamped voltage below a problem level?

What am I missing in this?

Thanks...
- Bill

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Re: [PSES] safety 60950 and surge suppression circuits - 13A plugs

[Mick Maytum]

Joe,
My memories of the early 13 A plugs in the UK is their 
consistency rather than inconsistency. I was in TV design at 
that time. Traditionally the early TV power supplies used a 
half-wave rectifier, so the chassis was either L or N. When 
the 13 A plug became widely used the chassis was inevitably 
poled as N. Good is some respects, but bad for the 
electricity supply as only current was drawn during the 
positive a.c. cycle. With all the 13 A plug TVs drawing a 
d.c. component from the a.c. mains that really upset the 
power distribution transformers. It was therefore decreed 
that half-wave rectification was banned and only full-wave 
rectifiers could be used in the TV power supplies.


Mick
On 05/06/2013 23:08, Joe Randolph wrote:

Hi Rich:

/SNIP

/CLAUSE 6.1.2

Clause 6.1.2 is the one that addresses the problem of 
hazards within the equipment getting onto the phone line 
and injuring a telephone service person who is working on 
the network.  I think the origin of this requirement comes 
from the old UK standard BS 6301, and was based on the 
possibility that a mis-wired mains plug could result in 
the equipment ground wire being connected to a live mains 
wire (this fault mechanism is more common in the UK than 
in most other countries due to the way consumers deal with 
conflicting plug configurations).  So, in this case, an 
equipment chassis that is supposed to be grounded becomes 
hot.

SNIP



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Re: [PSES] Crossed-out wheeled bin symbol

[Mick Maytum]

Each Annex is terminated by a short horizontal line. The 
thin line is meant to be there, but it is not part of the 
symbol.

Mick
On 24/09/2014 20:31, Brian Oconnell wrote:

Am confused over this. Cannot determine if thin line is a PDF 'artifact', or if 
that is the new image for the EEE mark. The HTML files for the directive links 
to a blank image:

http://eur-lex.europa.eu/resource.html?uri=CELEX:32012L0019.ENG.xhtml.L_2012197EN.01006602.tif.jpg

Anyone have a better source?

Brian

From: Monrad Monsen [mailto:monrad.mon...@oracle.com]
Sent: Wednesday, September 24, 2014 10:55 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Crossed-out wheeled bin symbol

Hi Scott,
If you look at the Recast WEEE directive 2012/19/EU annex IX, you will see that 
the crossed-out wheeled bin symbol does not have a black bar below the symbol.
http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2012:197:0038:0071:EN:PDF

Note:  If you look at the WEEE directive in a PDF provided by Europa, you will 
see that they put a small thin horizontal line at the end of the main directive 
and at the end of each annex.   For annex IX, the crossed-out wheeled bin 
symbol is at the end of the annex, but the symbol uses bold lines.  The later 
small thin horizontal line marking the end of the annex should not be confused 
as being a part of the crossed-out wheeled bin symbol.

Monrad

Note:  The statements and opinions expressed here are my own and do not 
necessarily represent those of any company I work for.
   
On 9/12/2014 9:52 AM, Scott Xe wrote:

Dear All,

I have learnt that in near future, the black bar below the crossed-out wheeled 
bin symbol will be removed similar to the one used in battery directive.  Have 
anyone heard the same?

Thanks and regards,

Scott

On 12 Sep, 2014, at 10:56 pm, Denis Ryskamp denis_rysk...@trimble.com wrote:


Gary:
  
Needed:

1)  A unique identification of the producer (Brand name, registration 
number,...)
2)  The crossed-out wheeled bin in accordance with Directive
3)  Put on market after 13 august 2005 shall be identified by at least one 
of the following:
a)  Date of manufacture/put on market, in uncoded text per ISO 8601 or 
other coded text, for which the code shall be made available for treatment 
facilities.
b)  Additional mark used in conjunction with the crossed-out wheeled bin 
(underline) The directive has the dimensional proportions. Height of the bin 
itself is 4mm minimum.
  
The crossed out wheeled bin symbol to be displayed in a visible, legible and indelible form on the product itself, near Producer ID, except for in exceptional cases where this is not possible because of the size or function of the product. If the symbol cannot be applied to the product due to product size or function, then the marking shall be printed on the packaging, in the instructions for use, and in the warranty.

  The directive has the dimensional proportions. Height of the bin itself is 
4mm minimum.
  
From: Gary McInturff [mailto:gary.mcintu...@esterline.com]

Sent: Friday, September 12, 2014 10:30 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] Visible - legible
  
Does anyone have a standards definition of visible - legible? In this particular instance it's for the WEEE symbol for an ITE product. I don't see a reference to the definition here. Anybody else? Is it a fixed height say 4mm, or is there some reference to readable from 1 meter (another non-definition because readable isn't defined),
  
Gary McInturff

Reliability/Compliance Engineer
  
  
  
Esterline Interface Technologies

Featuring
ADVANCED INPUT, GAMESMAN,
and LRE MEDICAL  products
600 W. Wilbur Avenue
Coeur d'Alene, ID  83815-9496
Toll Free: 800-444-5923 X1XXX
Tel:  (208) 635-8
Fax: (208) 635-8
  
www.esterline.com/interfacetechnologies
  
Technology, Innovation, Performance.
  
Information in or attached to this e-mail message may be subject to export control restrictions of the International Traffic in Arms Regulations (ITAR) (22 CFR pts. 120-130) or the Export Administration Regulations (EAR) (15 CFR pts. 730-774).  Before exporting this information outside the United States or releasing it to a foreign person in the United States, you need to determine whether a license under the EAR or the ITAR is required to do so.  If you have any questions about this obligation, please contact me.
  
  
  
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Re: [PSES] Graphic Symbols for Electrical and Electronics Diagrams

[Mick Maytum]

David,
I am familiar with IEEE Std 315, IEEE Std 315A 
(supplement) and the IEC 60617 database.
The 315 was created in 1975 and the 315A in 1986. These 
documents show some symbols with an over and under lined 
IEC label. At the time of creation the IEC reference was 
to the symbols in IEC publication 117. At the beginning of 
the 1980s IEC Publication  117:  Recommended  graphical   
symbols was replaced by Publication 617. Another ten years 
on and Publication 617 was replaced by IEC 60617.
 Many of the 315 and 315A document symbols no longer 
match what is in the current IEC 60617 database. For example 
the IEEE Std shows two IEC options for a resistor; a 
zig-zag line or a rectangle. Look in IEC 60617 and you find 
the zig zag resistor symbol (ref. S01355) was made obsolete 
in 1996-06 being replaced by the rectangle symbol (ref. 
S00555). There are many other symbol instances where the 
315/315A are out of date compared to IEC 60617.
The frustration with both the IEEE and IEC documents is 
that all the symbols are bit maps meaning you have to create 
your own vector versions or buy vector versions elsewhere. A 
years subscription to the IEC 60617 is expensive if you just 
want to check what is available. An alternative is to Google 
commercial libraries for CAD software as these will often 
have thumbnails of the symbols available. Just because a 
well-known vendor offers a set of IEC 60617 symbols doesn't 
mean they are drawn correctly either. The Autodesk Knowledge 
network does give you (fuzzy) previews of various symbol 
sets. You could have a stab in the dark and Google something 
like IEC60617 Symbols.pdf in the hope of getting a PDF file 
listing the symbols.


Regards
Mick


On 13/01/2015 19:06, Nyffenegger, Dave wrote:

Hi folks,

Anyone familiar with in IEC 60617-DB:2001 and IEEE 315/315A?  Perhaps the older 
IEEE standards are just a subset of the newer IEC standard?

-Dave

-Original Message-
From: Nyffenegger, Dave [mailto:dave.nyffeneg...@bhemail.com]
Sent: Saturday, January 10, 2015 12:05 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] Graphic Symbols for Electrical and Electronics Diagrams

Hi Folks,

EN 60204-1 section 17.6 says  Any graphical symbol not shown in IEC 
60617-DB:2001 shall be separately shown and described on the diagrams or supporting
documents.   NFPA 79 is harmonizing to EN 60204 and 17.7.1 has similar 
language but refers to IEEE 315/315A.   I don't have either symbol standard yet and 
IEC 60717 is only available by subscription to online dB.   The IEEE standards have 
been around for quite a while.  I'm wondering how similar the symbols are between 
IEC 60617 and IEEE 315, anybody know?  I can buy a copy of IEEE 315 for a reasonable 
price and I'm wondering if there is any additional need for the IEC 60617.  One 
would hope that a common set of symbols would be acceptable in the US and Europe.

Also, does anyone know what the restrictions are on  the  IEEE standard PDF 
files?  i.e. on one end of the spectrum with only a watermark and the other end 
node locked to a single PC, can't print or can only print 1 copy ever, can't 
move to another PC when the original goes south without divine intervention, 
making the PDF pretty much useless etc?

Thanks
-Dave

David P. Nyffenegger, PMP, SM-IEEE
Product Development Manager
Bell and Howell

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Re: [PSES] Graphic Symbols for Electrical and Electronics Diagrams

[Mick Maytum]

Having worked in many US standards development 
organisations (SDOs) I would tend to describe their attitude 
as parochial. This is partly because the working groups are 
mainly made up of US people who have not been exposed to the 
international scene. On the face of it the 315/315A must be 
trustworthy as it is also ANSI Y32.2, CSA Z99 and references 
the IEC! I wonder if the IEEE Standards Coordinating 
Committee 11, Graphic Symbols, which created 315/315A, is 
even still functioning - it certainly hasn't filed a 
mandatory Polices and Procedures document at the IEEE AudCom 
site. I regard 315/315A as of historical interest to show 
where we started out from and not where we are today.
As to your second question, yes you can get IEC 60617 
compliant AutoCAD libraries. I have previously used AutoCAD, 
but it is expensive software with a steep learning curve. I 
think you have to use it extensively to justify the 
investment. It would be nice to find a lower cost drawing 
package with a correctly drawn symbol set. I can remember 
being disappointed with the Visio offering. Even at the 
fundamental level it was wrong with the resistor symbol 
rectangle having a side 2.5:1 ratio instead of the IEC 60617 
ratio of 3.0:1.


Regards
Mick
On 17/01/2015 22:57, Nyffenegger, Dave wrote:

Mick,

Care to guess why NFPA 79 2015 (not to mention ANSI Y14) still refers to the older IEEE standard while at 
the same time tries to harmonize with EN 60204-1 (Requirements align with IEC 60204-1)?
Perhaps a not invented here syndrome?  Although IEEE  USA.  Sounds like I should not 
bother with the IEEE standards.

Interestingly my next question (not necessarily to PSES) was/is if there are 
(correct) IEC 60617 symbol libraries for AutoCAD.  That would perhaps eliminate 
the need for the subscription since that's primarily what we need the symbols 
for anyway.

Thanks
-Dave

-Original Message-
From: Mick Maytum [mailto:mjmay...@gmail.com]
Sent: Saturday, January 17, 2015 5:26 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Cc: Nyffenegger, Dave
Subject: Re: [PSES] Graphic Symbols for Electrical and Electronics Diagrams

David,
  I am familiar with IEEE Std 315, IEEE Std 315A
(supplement) and the IEC 60617 database.
  The 315 was created in 1975 and the 315A in 1986. These documents show some symbols 
with an over and under lined IEC label. At the time of creation the IEC 
reference was to the symbols in IEC publication 117. At the beginning of
the 1980s IEC Publication  117:  Recommended  graphical
symbols was replaced by Publication 617. Another ten years on and Publication 
617 was replaced by IEC 60617.
   Many of the 315 and 315A document symbols no longer match what is in the current 
IEC 60617 database. For example the IEEE Std shows two IEC options for a 
resistor; a zig-zag line or a rectangle. Look in IEC 60617 and you find the zig zag 
resistor symbol (ref. S01355) was made obsolete in 1996-06 being replaced by the 
rectangle symbol (ref.
S00555). There are many other symbol instances where the 315/315A are out of 
date compared to IEC 60617.
  The frustration with both the IEEE and IEC documents is that all the 
symbols are bit maps meaning you have to create your own vector versions or buy 
vector versions elsewhere. A years subscription to the IEC 60617 is expensive 
if you just want to check what is available. An alternative is to Google 
commercial libraries for CAD software as these will often have thumbnails of 
the symbols available. Just because a well-known vendor offers a set of IEC 
60617 symbols doesn't mean they are drawn correctly either. The Autodesk 
Knowledge network does give you (fuzzy) previews of various symbol sets. You 
could have a stab in the dark and Google something like IEC60617 Symbols.pdf in 
the hope of getting a PDF file listing the symbols.

Regards
Mick


On 13/01/2015 19:06, Nyffenegger, Dave wrote:

Hi folks,

Anyone familiar with in IEC 60617-DB:2001 and IEEE 315/315A?  Perhaps the older 
IEEE standards are just a subset of the newer IEC standard?

-Dave

-Original Message-
From: Nyffenegger, Dave [mailto:dave.nyffeneg...@bhemail.com]
Sent: Saturday, January 10, 2015 12:05 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] Graphic Symbols for Electrical and Electronics
Diagrams

Hi Folks,

EN 60204-1 section 17.6 says  Any graphical symbol not shown in IEC 
60617-DB:2001 shall be separately shown and described on the diagrams or supporting
documents.   NFPA 79 is harmonizing to EN 60204 and 17.7.1 has similar 
language but refers to IEEE 315/315A.   I don't have either symbol standard yet and 
IEC 60717 is only available by subscription to online dB.   The IEEE standards have 
been around for quite a while.  I'm wondering how similar the symbols are between 
IEC 60617 and IEEE 315, anybody know?  I can buy a copy of IEEE 315 for a reasonable 
price and I'm wondering if there is any additional need for the IEC 60617.  One 
would hope that a common set

Re: [PSES] Different surge test equipment, different results

[Mick Maytum]

Peter,
The metrics we use to specify the more complex surge waveshapes are 
only a modest improvement over the answer a red one to the what car 
do you drive? question.
The ring and possibly 8/20 (part of the combination) waveshapes 
have current reversals, which complicates matters. Without details of 
what your different results were I can only make generalised comments.
IEC 62475 defines the stand alone 8/20 waveshape. There was 
considerable committee discussion on how you can't get a perfect 
8.00/20.0 waveshape with the simple RLC circuits that many standards 
show. For example they worked out for 20 µs ±20% the nominal 8 µs is 
constrained to 6.9 µs ±0.5 µs or ±7.2 % not the allowed ±20%. 
Under-swing or current reversal is allowed up to 30 %. It seemed to me 
that the people in the IEEE PES SPDC C62 formulation group where adamant 
that no under swing occurs. By enforcing this design constraint the 
resultant waveshape moves further away from the 8/20 goal.
In life testing, 8/20 current reversal is bad news for GDT surge 
protective components (SPCs) as it shortens the number of cycles that 
can be endured.
Several years ago at an ATIS PEG conference there where two 
interesting presentations that mentioned ring waves. The Telcordia one 
used a standard C62 generator to track down the part of the distributed 
system which was vulnerable to lighting. The HydroQuebec approach was to 
use a fast rising (1.4 µs) surge to shock excite the system to produce 
its natural ring wave (nothing like the C62 one of course).
As John correctly noted the generator is a network and its apparent 
reduction to a Thévenin source equivalent by quoting an effective or 
fictive source impedance of 2 ohm can form a mental trap.
These surge generators are then applied to further networks and 
EUTs that may have non-linear elements like MOV SPCs or rectifiers. All 
these things can exaggerate differences between generators.
On the theoretical side there was a recent ITU-T contribution on 
recommended Spice models for 1.2/50-8/20 combination generators. 
Surprisingly some of the models didn't fully meet the 1.2/50 and 8/20 
requirements.
We have to work with the tools we are given and expect variances 
because not everything is exactly the same.

Mick

On 21/08/2015 19:50, Peter Tarver wrote:

Good morning.

I'm wondering if others have experienced cases where different
manufacturers' surge test equipment  (ANSI/IEEE C62.41 ring and
combination waves) with nearly identical open-circuit voltage and
short-circuit current calibrations have led to very different results.  In
these cases, other than addressing the issue by using the surge generator
that produces the worst-case result, what were thought to be the causes
for the different results (ignoring the real possibility of a marginal
design).


Regards,

Peter L. Tarver

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Re: [PSES] EN 62368-1 query

[Mick Maytum]

On 26-Oct-15 6:29 PM, Scott Aldous wrote:

_Table 5 (Capacitor Energy)_

For the energy from a capacitor, the table takes into account 
capacitance and voltage, so both need to be taken into account since 
the equation for available energy from a capacitor includes both 
variables. This is similar to 2.1.1.5c)2) from 60950-1.


IEC 60479-2 provides a linearised treatment of a capacitive discharge to 
the body. The examples consider both capacitive discharge charge and 
energy. In TC108 safety documents IEC 60950-21 and the coming IEC 
62368-3 you will find voltage versus maximum capacitance figures. What 
is counter-intuitive is that these curves are set by the capacitor charge.
If you calculate the capacitor value from the maximum body energy value 
far greater values of capacitance result. Whoever calculated the figure 
capacitance values back in 2000 or so worked out that for Remote Feeding 
Telecommunication circuits the capacitive charge was the critical 
parameter, not energy, setting the maximum capacitance value.

Regards
Mick

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Re: [PSES] EU Certifications Required for Surge Protectors?

[Mick Maytum]

IEC SC 37A deals with surge protective devices, SPDs. Non-power SPDs 
(signal) are handled by SC 37A Working Group 4. WG 4 produced IEC 
61643-21 Low voltage surge protective devices – Part 21: Surge 
protective devices connected to
telecommunications and signalling networks – Performance requirements 
and testing methods. The corresponding CENELEC standard is EN 61643-21.
As I remember it these standards have just a series of tests at 
different levels with no real guidance of which ones to choose for 
certain applications such as POTS, antenna and Ethernet in your case.


The IEC/EN 61643-21 application Guide is IEC/EN 61643-22. These have 
Annex D (informative) Transmission characteristics related to IT 
systems, which covers Ethernet, DSL, POTS and cable TV (no antenna SPD 
transmission). Annex F (informative) Protection of Ethernet systems is 
more a tutorial than guidance.


Regards,
Mick Maytum


-- Original Message --
From: "Brian O'Connell" <oconne...@tamuracorp.com>
To: EMC-PSTC@listserv.ieee.org
Sent: 06/04/2017 22:00:35
Subject: Re: [PSES] EU Certifications Required for Surge PRotectors?

Dunno, as have just used the standards referenced in annex G of 
62368-1, or whatever component requirements that would be scoped per 
the various end-use equipment standards. Otherwise, perhaps materials 
and component and test requirements per EN62305-x or EN61643-x?


Brian


From: Scott Douglas [mailto:sdouglas...@gmail.com]
Sent: Thursday, April 06, 2017 1:30 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] EU Certifications Required for Surge PRotectors?

Hello All,

We have three products that we sell in USA. We are looking at getting 
these approved for sale in the EU. Our famous certification house says 
they do not create CB Reports for this kind of product. We are 
unfamiliar with any type of standards in the ROW for these products.


So, we are looking to find out what standards would apply, either 
EU-wide, or are there specific country requirements for these kinds of 
products?


Here is a brief explanation of the three products:

1.   POTS telephone surge protector.  The current model is a 
passive device with a pair of RJ-11 jacks for telephone in & out and a 
ground wire terminal.  Listed by UL to UL497A, Standard for Protectors 
for Communication Circuits.
2.   CATV/Antenna surge protector.  The current model is a passive 
device with a pair of F-connectors and a ground wire terminal. Listed 
by UL to UL497B, Standard for Protectors for Data Communications and 
Fire Alarm Circuits
3.   LAN / Ethernet surge protector.  The current model is a 
passive device with a pair of RJ-45 jacks for Ethernet (CAT5) in & out 
and a ground wire terminal.  Listed by UL to UL497B.

These are all passive devices, no power supply required.
We are in California and would appreciate any comments related to what 
EU standards would apply and what test houses might be a good choice to 
getting these approvals.

Your comments and advice will be well appreciated.
Thank you.
Scott

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Re: [PSES] Regulatory requirements for MOVs placed line-to-ground on AC mains ports?

[Mick Maytum]

For my sins I am currently editing a 40 page MOV application guide. As 
the guide was written by a Chinese expert I have the additional task of 
translating the Chinlish to English. However this forces understanding 
and I found the document contains many gems I did not appreciate. On 
degradation three areas are mentioned:


1.	Varistor voltage at 1mA has decreased by more than 10 % of the 
initial value.
2.	Surge limiting voltage at a specified impulse current has increased 
by more than 10 % of the initial value.

3.  Leakage current or watt-loss shows a steady increase.

Then the comment is made that generally if the Varistor voltage has 
decreased by 10 %, the limiting voltage will have only increased by 3 %. 
Thus the Annex Q limiting voltage change limit of 10 % would be better 
replaced by a Varistor voltage change.


On fuses I did some calculations and found an anti-surge fuse in the 4 A 
region was required to withstand the Annex Q MOV requirement of a 3 kA 
8/20 surge. It should be remembered that most fuses will not interrupt 
an 8/20 surge as the fuse link plasma carries on conducing the 8/20 
impulse current. Ted makes the excellent point that in the equipment 
additional series impedances will exist that reduce the peak the peak 
surge current from an 1.2/50-8/20 generator.
Tests are now appearing for thermally protected MOVs, which disconnect 
the MOV in the event of exceeding a pre-set body temperature limit. 
Thermal disconnect, rather than current disconnect, gets to the heart of 
the matter. But, as far as I'm aware, none of these tests apply a surge 
voltage to check for open thermal switch arc over.


Regards,

Mick Maytum
Safety and Telecom
Standards
mjmay...@gmail.com
https://ictsp-essays.info

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Re: [PSES] Regulatory requirements for MOVs placed line-to-ground on AC mains ports?

[Mick Maytum]

Joe,
I'm away from my data at present. I think IEC 62368-1 in clause 1 
states that where a consistent connection to PE/ground cannot be 
guaranteed, such as with pluggable equipment, protection from mains to 
the PE requires to be a GDT and varistor to be connected in series.





Regards,

Mick Maytum

Safety and Telecom
Standards

mjmay...@gmail.com

www.ictsp-essays.info


-- Original Message --
From: "Joe Randolph" <j...@randolph-telecom.com>
To: EMC-PSTC@listserv.ieee.org
Sent: 31/10/2017 02:09:14
Subject: [PSES] Regulatory requirements for MOVs placed line-to-ground 
on AC mains ports?



Hello All:



Aside from surge tolerance during normal type testing, are there any 
regulatory requirements regarding the placement of MOVs from line to 
ground on an AC mains input port?




I seem to recall that some countries or standards are concerned about 
potential hazards associated with MOVs developing high leakage current, 
over time, in response to repeated surge events.  I’ve seen circuits 
where a GDT was added in series with the MOV, and I believe this had 
something to do with concerns about MOV leakage current.




I’ve also seen MOVs offered for sale that are packaged in a way that 
physically couples them to a thermally-activated one-time fuse.  This 
implies a concern with the MOV becoming leaky over time and 
overheating.




While I am familiar with the potential failure mechanism of MOVs 
developing high leakage current over time, I cannot point to any 
published safety standard that imposes any construction requirements 
that attempt to protect against this failure mode.  I thought I 
remembered seeing something on this topic many years ago in a UK 
standard, but that was a long time ago, prior to harmonization of the 
IEC 60950 series.






Thanks,



Joe Randolph

Telecom Design Consultant

Randolph Telecom, Inc.

781-721-2848 (USA)

j...@randolph-telecom.com

http://www.randolph-telecom.com




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Re: [PSES] IEC 61000-4-5:2014/AMD1:2017 - Using the correct CDN for AC mains testing

[Mick Maytum]

As an aside, when you come to CDNs for DC systems, things can become 
more complicated and interesting.
The AMD1 came about after the US National Committee commented "“The 
method for testing DC products in the current revision of IEC61000-4-5 
is causing many field related problems for test labs and manufacturers. 
Many products will not power up through the power CDN in the standard 
and in some cases may be damaged by the

inductance that is necessary to apply the surge."
 It is easy to understand why. The large series inductance of the CDN 
presents a high pulse impedance, which prevents rapid changes of 
current, which is abnormal to the normal system configuration. 
Electronic loads like converters and inverters expect a reasonably low 
impedance supply to start and operate.


AMD1, in the body text, allows the use of a larger current-rated CDN 
with ratings ≤125 A and in Annex I (informative), Issues relating to 
powering EUT’s having DC-DC converters on their inputs, suggests a 
damping circuit for reducing possible oscillations.


Example CDN component values can be found by searching for papers like 
"Influence of Power-Line Coupling/Decoupling Network on Output 
Characteristics of the Combination Wave Generator" and "Coupling and 
decoupling network for surge immunity test on power lines"


In such a DC system using a CDN whose values force the majority of the 
surge stress on the EUT can result in unrealistic surge conditions. The 
ITU-T currently opts for a two way approach. Existing CDN arrangements 
are grandfathered while giving the test option of using a CDN with 
values that reflect the longest connecting cable thus implementing a 
system surge test rather than an individual equipment surge test. The 
ITU-T has devised an interesting test circuit that imposes a common-mode 
surge on both supply polarities. Any system polarity earthing and the 
presence of any voltage limiting functions condition the resultant surge 
on the system to be common-mode, differential mode or a mixture of both.





Regards,

Mick Maytum

Safety and Telecom
Standards

mjmay...@gmail.com

https://ict-surge-protection-essays.co.uk/


-- Original Message --
From: "David Schaefer" 
To: EMC-PSTC@listserv.ieee.org
Sent: 02/04/2019 20:40:24
Subject: Re: [PSES] IEC 61000-4-5:2014/AMD1:2017 - Using the correct CDN 
for AC mains testing


A higher current rated CDN can be used, but only if it meets the lower 
current CDN’s waveform requirements. From the quoted section:




“Any higher current rated CDN can be used if it meets the specification 
requirements in Table 4 for the relevant lower current rating of the 
EUT (for


example: a CDN rated 64 A can be used for testing an EUT rated at 5 A, 
if it meets the specification requirements of a 16 A rated CDN).”




The reason for this is higher current CDNs are allowed to have pulse 
widths significantly shorter than lower ratings. Check out Table 4 of 
the 2014 edition. A 16 amp CDN differential mode pulse width is 
required to be 50 us +/- 10 us. A 125 Amp CDN is 50 us +10 us/-30 us. 
So yes, a 64 amp CDN can be used with a 5 amp product, if it meets the 
50 us +/- 10 us requirement.




Thanks,



ELEMENT__15px.jpeg

David Schaefer
Department Manager, EMC
Element Materials Technology
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From: John Woodgate [mailto:j...@woodjohn.uk]
Sent: Tuesday, April 2, 2019 2:12 PM
To:EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] IEC 61000-4-5:2014/AMD1:2017 - Using the correct 
CDN for AC mains testing




I think you did (answer your own question). The text you quote seems 
surprisingly (and gratifyingly) lucid. Under 16 A use a 16 A CDN. Over 
16 A up to 32 A, use a 32 A CDN.


Best wishes
John Woodgate OOO-Own Opinions Only
J M Woodgate and Associates www.woodjohn.uk
Rayleigh, Essex UK
On 2019-04-02 19:14, Richard Georgerian wrote:


Greeting colleagues,



Hopefully, someone in the PSTC group can correct my rational below and 
enlighten me on the finer points of CDNs.




The discussion within our applications group is, shall the EUT current 
rating be correctly matched to the CDN current rating? For example, 
don’t use a CDN rated for 32 A for a EUT that is rated for 2 A, to 
ensure that the correct Surge waveform will be applied to the EUT. I 
cannot think of a good rational why a CDN rated for 32 A cannot be 
used for a EUT rated for 2 A. We do understand that for the different 
current ratings of CDNs, 16 A, 32 A, 63A and 125 A, the internal 
components must have different values to meet the Surge waveform, for 
Open circuit and Short circuit. However, testing Open c

Re: [PSES] classification of the output

[Mick Maytum]

Pete,
Glad to see your thoughts agree with mine. With large amplitude 
voltage pulses there must be some EMC considerations that come into play 
for equipment EMC compliance.


I really wish that some alternative abbreviation had been created 
instead of ES. Many engineers would be looking for a Joule parameter for 
an energy source, yet Joules don't get a direct mention in the IEC 
62368-1 body text description (Why no entry in definitions?). Expressing 
ES as a voltage, current and charged capacitance (no inductive current) 
makes it multi-option classification. Further when it comes to 
telecommunications TNV circuits, those are classified by DC working 
voltage alone.
Thus they are ES1 or ES2 DC working voltage circuits not simply ES1 or 
ES2 circuits as that would drag all the other ES factors in.





Regards,

Mick

Safety and Telecom
Standards

mjmay...@gmail.com

https://ict-surge-protection-essays.co.uk/


-- Original Message --
From: "Pete Perkins" 
To: "Mick Maytum" ; EMC-PSTC@listserv.ieee.org
Sent: 13/03/2019 06:11:38
Subject: RE: [PSES] classification of the output


Mick, Thanx for the reply given on this thread.



I am familiar with the 60479 clauses you describe.  My 
overall comment is that 60479 folks primary focus is on preventing VF 
(not killing people).  Much of what you quoted relates to such electric 
shock situations.  Because of the data spread there probably are a few 
folks who lie below the curves shown in the standard.  Tasers meet 
these requirements yet there are occasional deaths with their use; the 
‘almost perfect weapon’ in my opinion.




In the product standards the allowed electric shock 
level is always set much lower so that the VF region is not involved.  
The upper limit to electric shock from equipment is the 
Letgo-immobilization limit of 5mArms/7mApk under fault conditions.  The 
long time separation to allow the heart to reset doesn’t come into play 
for this effect so it is irrelevant.  The peak current is the major 
factor that needs to be controlled.




:>) br,  Pete



Peter E Perkins, PE

Principal Product Safety & Regulatory Affairs Consultant

PO Box 23427

Tigard, ORe  97281-3427



503/452-1201



IEEE Life Fellow

p.perk...@ieee.org



Entropy ain’t what it used to be



From: Mick Maytum 
Sent: Tuesday, March 12, 2019 1:03 PM
To:EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] classification of the output



Joe Randolph and I talked about “pulsed power” delivery at the 2019 
ATIS-PEG conference last week and how it should be treated.




A good starting point is the IEC 60479 series of documents on “Effects 
of current on human beings and livestock”. IEC 62368-1 mentions the 
time locked IEC TS 60479-1:2005, but the current version is IEC 
60479-1:2018. The IEC TS 60479-2:2017 variant is particularly 
interesting as clause 9 covers “Effects of current pulse bursts and 
random complex irregular waveforms”. For sequential pulses separated by 
> 300 ms there isn’t a cumulative effect on the heart and each pulse 
can be treated as single, non-repetitive pulse of current. For safety, 
I believe pulsed power systems will insert this separation time when 
any non-load currents are detected to delay any following power pulse.




Thus only the effects of a single power pulse need to be evaluated 
provided the safety separation is >0.3 s. Primarily IEC TS 60479-2:2017 
is seeking to establish a “no fibrillation” condition, which is higher 
stress level than you’d want for a safety standard.




A 2018 ATIS-PEG conference paper on IEC TS 60479-2:2017 gave an example 
evaluation using the quoted pulsed currents produced by a TASER® gun. 
Safety tip - if anyone is pointing a TASER® gun at you, yell out you 
have a pre-existing medical condition.





Image removed by sender.

Regards,

Mick

Safety and Telecom
Standards

mjmay...@gmail.com

https://ict-surge-protection-essays.co.uk/



-- Original Message --

From: "Joe Randolph" 

To: EMC-PSTC@listserv.ieee.org

Sent: 12/03/2019 17:54:36

Subject: Re: [PSES] classification of the output




Hi Pete:



This discussion reminds me of some things I have been hearing about 
“digital power” as a way to deliver large amounts of power while 
keeping the circuit classification to ES1 or ES2.  A company called 
Voltserver has been promoting (and deploying) this technology.




I know few details about the scheme, and I’m not familiar with how IEC 
62368-1 evaluates things such as touch current.




However, as I understand it, the “digital power” method uses a series 
of short pulses with off periods during which the power sourcing 
device attempts to detect a fault condition.  The power is immediately 
cut off if a fault condition is detected.  I have heard that the pulse 
frequency is in the range of 7 KHz, and the voltages can be up to 380 
V.  The key to making this scheme even plausible is that the s

Re: [PSES] classification of the output

[Mick Maytum]

Joe Randolph and I talked about “pulsed power” delivery at the 2019 
ATIS-PEG conference last week and how it should be treated.


A good starting point is the IEC 60479 series of documents on “Effects 
of current on human beings and livestock”. IEC 62368-1 mentions the time 
locked IEC TS 60479-1:2005, but the current version is IEC 60479-1:2018. 
The IEC TS 60479-2:2017 variant is particularly interesting as clause 9 
covers “Effects of current pulse bursts and random complex irregular 
waveforms”. For sequential pulses separated by > 300 ms there isn’t a 
cumulative effect on the heart and each pulse can be treated as single, 
non-repetitive pulse of current. For safety, I believe pulsed power 
systems will insert this separation time when any non-load currents are 
detected to delay any following power pulse.


Thus only the effects of a single power pulse need to be evaluated 
provided the safety separation is >0.3 s. Primarily IEC TS 60479-2:2017 
is seeking to establish a “no fibrillation” condition, which is higher 
stress level than you’d want for a safety standard.


A 2018 ATIS-PEG conference paper on IEC TS 60479-2:2017 gave an example 
evaluation using the quoted pulsed currents produced by a TASER® gun. 
Safety tip - if anyone is pointing a TASER® gun at you, yell out you 
have a pre-existing medical condition.




Regards,

Mick

Safety and Telecom
Standards

mjmay...@gmail.com

https://ict-surge-protection-essays.co.uk/


-- Original Message --
From: "Joe Randolph" 
To: EMC-PSTC@listserv.ieee.org
Sent: 12/03/2019 17:54:36
Subject: Re: [PSES] classification of the output


Hi Pete:



This discussion reminds me of some things I have been hearing about 
“digital power” as a way to deliver large amounts of power while 
keeping the circuit classification to ES1 or ES2.  A company called 
Voltserver has been promoting (and deploying) this technology.




I know few details about the scheme, and I’m not familiar with how IEC 
62368-1 evaluates things such as touch current.




However, as I understand it, the “digital power” method uses a series 
of short pulses with off periods during which the power sourcing device 
attempts to detect a fault condition.  The power is immediately cut off 
if a fault condition is detected.  I have heard that the pulse 
frequency is in the range of 7 KHz, and the voltages can be up to 380 
V.  The key to making this scheme even plausible is that the system 
must respond VERY quickly to a fault condition (such as a human 
touching a live conductor).




I’m interested in hearing your thoughts (and hopefully Rich Nute’s 
thoughts too) regarding how the touch current tests in IEC 62368-1 
might apply to such a system.  I don’t know whether such a system would 
pass or fail the IEC 62368-1 tests.




Regardless of whether such a system would pass or fail the existing 
tests in IEC-62368-1, I think the important thing is to go back to 
first principles and evaluate whether the proposed “digital power” can 
be made sufficiently safe to prevent harm to humans.






Thanks,



Joe Randolph

Telecom Design Consultant

Randolph Telecom, Inc.

781-721-2848 (USA)

j...@randolph-telecom.com

http://www.randolph-telecom.com







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Re: [PSES] Dated and undated references

[Mick Maytum]

John's comment "e.g. in the rare case where a dated reference standard 
is found to be seriously defective." reminded me of an IEC 62368-1:2018 
problem caused by a dated reference.


The current IEC 61643-331:2017 is wrong in that an earlier draft 
document, instead of the IEC Editors draft was sent for publication. 
Heads rolled in SC 37B as a result and SC 37B is working of a 
replacement IEC 61643-331. This mishap made the IEC 62368-1:2018 
reference "from 8.1.1 of IEC 61643-331, Figure 4." is a misdirection as 
8.1.1 doesn't exist in IEC 61643-331:2017.  The correct reference for 
IEC 61643-331:2017 is "from 8.2.2 of IEC 61643-331, Figure 4." Thinking 
about what John said, it seems to me the quickest way of fixing the IEC 
62368-1:2018 reference, without invoking TC 108, would be for SC 37B to 
issue a clause 8 corrigendum.


Regards
Mick Maytum.

-- Original Message --
From: "John Woodgate" 
To: EMC-PSTC@listserv.ieee.org
Sent: 20/04/2019 08:41:51
Subject: [PSES] Dated and undated references, was: Re: [PSES] Question 
re: Measuring a signal in a noisy environment


I changed the Subject,  because my comments on the extract below are 
much more general.


The heading of Clause 2 (usually the Normative references clause in the 
past and now always so) in IEC/EN standards has changed over the years. 
and since I see IEC standards being cited without the 60 000 addition 
to the number that took place in 1998,  I guess that the changes 
haven't registered with some people.


This list isn't exhaustive but it illustrates the subject.

Long ago:  Mostly undated references with an invitation to 'explore the 
use of the latest edition'.


A few years ago: IEC restricted the use of dated references to cases 
where a particular clause was cited in the text. Although other dated 
references were allowed, IEC editors discouraged that.


Latest: As a result of a legal ruling in Europe, the Commission 
requires all references in ENs that are to be notified in the OJ under 
a Directive or Regulation to be dated, and IEC committees are mostly 
accepting that, as they want their standards to be adopted by CENELEC.


There always has been a lot of misunderstanding on this subject.

Undated references: The essential assumption is that all future 
editions will be as equally applicable as the current edition is. There 
can be NO guarantee of that, so the committee responsible for the 
standard that includes the reference should (but hardly ever does) 
review each new edition of undated standards to check that they are 
still applicable.


Dated references: In this case, the user of the referencing standard 
knows exactly which edition of the referred standard to apply, but can 
misguidedly assume that the latest edition should be applied. The 
committee responsible for the standard that includes the reference 
should (but hardly ever does) review each new edition of dated 
standards to check that they are still applicable, and if so, amend the 
referencing standard at the earliest reasonable opportunity. It's 
obviously unreasonable to issue an amendment when each new edition is 
published. Normal maintenance time-scales are sufficient, although 
there could be exceptions, e.g. in the rare case where a dated 
reference standard is found to be seriously defective.


Best wishes
John Woodgate OOO-Own Opinions Only
J M Woodgate and Associates www.woodjohn.uk
Rayleigh, Essex UK
On 2019-04-19 23:42, Ghery Pettit wrote:



We had a problem in the past where CISPR 24 (Edition 1) called out 
(dated reference) an older version of IEC 61000-4-4 than the latest 
version.  No problem except that the test setup for table top 
equipment was different.  I audited a lab to put them on the Intel 
approved EMC lab list and caught the error.  And they had IEC 
61000-4-4 on their Scope of Accreditation.  Got that problem (now not 
a problem with CISPR 24 Edition 2 or CISPR 35) fixed.



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This messa

Re: [PSES] High voltage versus High tension

[Mick Maytum]

The terms are international, not just EU.
If you look in the IEC Electropedia terms and definitions there is

en
high voltage
high tension
HV
voltage having a value above a conventionally adopted limit
Note – An example is the set of upper voltage values used in bulk power 
systems.

[SOURCE: 601-01-27 MOD]

fr
haute tension  f
HT  f
tension électrique de valeur supérieure à une limite adoptée par 
convention
Note – Un exemple est l'ensemble des tensions les plus élevées utilisées 
dans les réseaux de production-transport d'énergie électrique.

[SOURCE: 601-01-27 MOD]

In IEC English you can use high voltage or high tension, but in French 
there is only haute tension





Regards,

Mick

Safety and Telecom
Standards

mjmay...@gmail.com

https://ict-surge-protection-essays.co.uk/


-- Original Message --
From: "Regan Arndt" 
To: EMC-PSTC@listserv.ieee.org
Sent: 04/08/2020 00:35:01
Subject: [PSES] High voltage versus High tension



Hi folks,

I never encountered this before but am curious if anyone had any 
problems in using the European verbiage ‘High Tension’ in lieu of ‘High 
voltage’ during their 61010 assessment on their labels and 
documentation.


Unless I am mistaken on the Group & National differences, IEC 61010-1 
does not mention anything specific on allowing this alternative 
language.


I also want to know if ‘High tension’ would be a problem in the USA and 
Canada during a Field evaluation or NRTL certification? (I only ask to 
avoid having 2 labels/wording on a global product)


Thanks for sharing any experiences you had.


Regan Arndt

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