Dear Bostjan:
One of the uses of current rating on equipment is to determine that the
equipment, with all of the other equipment, would not overload the mains
circuit. If the actual current exceeds the marked current, then the equipment,
with all of the other equipment, can overload the
Subject: Re: [PSES] UL 60950-1 clause 2.2.3
In message f6d1e59f218e.540c8...@bendbroadband.com, dated Sun, 7
Sep 2014, Rich Nute ri...@bendbroadband.com writes:
I believe the authors of 60950-22 expected that user-accessible
parts
would comprise SELV circuits rather than grounded parts
Hi John:
I believe the authors of 60950-22 expected that user-accessible parts would
comprise SELV circuits rather than grounded parts. See 2.1.1 and 2.2 in
60950-1.
Grounded parts would be subject to 5.1 in 60950-1.
Best regards,
Rich
- Original Message -
From: John Cochran
Back in the old days -- say mid-50's
or earlier, broadcast transmitters were
required to be monitored full-time by
a qualified engineer. High-power AM
transmitters bombarded these guys with
all kinds of stuff.
Many of these old-timers reported
effects on the brain, but I can't
remember the
Hi Brian:
1. What is the status of IEC62368 and the associated and
infamous IEC62441 ? Ultimately, when are 60950-1 and 60065
projected to be replaced by 62368 ?
CDV2 will be issued to National Committees for voting
this or next month. (You can get a copy from your National
Hi Scott:
So, I went to the web sites you cited. Then, I went to
the citations. For one of the citations, the abstract
says:
Levels of DNA single-strand break were assayed in brain cells from rats
acutely exposed to low-intensity 2450 MHz microwaves using an alkaline
microgel
Is there a good document (in English) on
CCC processes? How to do it?
Are there any agents in England who can
assist or get CCC?
Thanks for your help,
Richard Nute
San Diego
-
This message is from the IEEE Product Safety Engineering Society
emc-pstc discussion list.Website:
Six Parisian libraries have already been the subject of a campaign of
measurements of electromagnetic waves, showing that electric
fields were
80 to 400 times below the regulatory limit. The city is aware of
concerns and wants to remain vigilant, said Anne Hidalgo, the first
deputy
Hi Jim:
I don't understand why electromechanical devices cannot be
proven to have reliable cycle life. There are
electromechanical devices tested for 6,000 cycles and 100,000
cycles commonly available, and there may be other classes
with even higher cycle life.
For a circuit-breaker,
Since May 16, worldwide spam messages have been sent
containing links to the Spiegel web site. One of those
messages found its way to emc-pstc.
The spam uses a variant of the mass-mailing worm Sober.
This worm taps into inboxes and then sends out infected
mail to everyone listed.
If
With thanks to Jim Eichner, the virus is confirmed.
Delete the message from RPICKARD.
For a complete description of the virus, see:
http://vil.nai.com/vil/content/v_127423.htm
Note that it spoofs the sender.
Also note that the virus was discovered today,
August 9. Perhaps that is why
Please treat the attachments to Ron Pickard's
message as a virus.
At the moment, we cannot confirm whether the
attachment contains a virus. The file passed
through the IEEE virus filters, which are
*VERY* good. Also, at least one subscriber
checked the files with Norton and did not
to post messages to emc-pstc.
I'm sure you've noticed in recent postings that the
IEEE provides effective virus protection. This will
continue.
Best regards,
Rich Nute, emc-pstc co-administrator
Jim Bacher, emc-pstc co-administrator
Hi Vic:
I have a Class 1 product. It has a double insulation barrier between
Primary
and earthed SELV, and basic between primary and the metal enclosure.
How can I perform an electrical strength test across the primary/SELV
barrier?
The construction you describe has two
Hi Josh:
This standard has been adopted by China and Japan. Japan has added a
source impedance for the test setup, but it implies to me that this is a
world-wide issue.
The question I was attempting to answer was
John's question if 61000-3-2 is not an EMC
standard, then what kind of a
Hi John:
Some have questioned whether 61000-3-2 is even an EMC standard!
If not, what do you think it is?
I fall into the group that question whether 61000-3-2
is an EMC -- Electo-Magnetic Compatibility -- standard.
The objective is to prevent reduction of peak voltage
on the
Hi Peter:
The body shape and dimensions, the pin sizes shapes,
dimensions and orientations where they interface with an
appliance coupler I know are defined. I don't have copies
of all of the IEC60320 documents and am unaware that the
product interior side of the appliance
Hi Peter and Raymond:
To verify the veracity of my memory, I went to my lab and
took two manufacturer's C14 appliance inlets and applied
5kVac from both poles to the earthing terminal for 7 mins.
each, with the instrument sensitivity adjusted to its
maximum (eg, minimum
Hi Peter and Raymond:
In the sake of fairness, it should be noted that both of my
EUTs had solder loops and were not intended for surface or
through-hole mounting to a PWB. For the sake of our mutual
edification, it would be interesting to see how the
appliance inlet in
Hello Chengwee:
Whether customer can accept his adaptor with only 1500Vac hipot tested
where
other power supplies can withstand 3000Vac?
This is an interesting question as it implies
that the higher the withstand voltage the better
the unit. The statement may even imply that a
Hi Peter:
I have and continue to advocate (in IEC TC 108)
that such classes should apply to CIRCUITS, not
to products.
If this is endemic in IEC (as your statement implies), it
may require a elephantine effort. Good luck.
Yes. And thank you.
The IEC Class I and
Hi Chengwee:
In my years working in power supply industry, I have never done the ground
continuity test between Earth terminal to the DC output for adaptor.
Normally I wouldn't trust the PE path with anything less than 18AWG or
equivalent.
There are two kinds of tests that I
Hi Peter:
No where does the standard state that by simply providing a
Functional Earth, even through an appliance inlet (implying
use of a power supply cord), the equipment is not considered
Class II. One is simply limited to not marking with the
aforementioned symbol.
Hi John:
I do have one question for the group just for my own knowledge...back in my
TUV days I worked almost exclusively with IEC60950 and seem to remember
that
a class II product can have a functional earth connection provided Primary
and other hazardous voltages are insulated
Hi Raymond:
If the dc output is connected to the PE terminal,
then the dc output could become live in the event
of a fault in the basic insulation between mains
and the PE terminal.
I think it may not be the case in practice. Even the dc output is
connected to the
Hi Raymond:
1. Earth continuity test
As the class 1 is due to the additional earthing plate, how can I ignore
the earth continuity test?
Class I is due to the adapter having an appliance
coupler with a PE terminal.
Without this earthing plate, the unit is in fact a class 2
Hi Chengwee Lai:
2. Earth Continuity or ground bond testing with 25A or higher is not
applicable with plastic case and not applicable at the DC output side. It
was meant to check the earth protection continuity of a metal chassis.
Protective earthing is required for any conductive
Hi Raymond:
Any product with a PE (ground) connection is, by
definition, a Class I product. The common adapters
you describe, despite being encased in plastic, are
Class I products.
1. Function of the grounding plate
The primary and the secondary is reinforced insulation and
Hi Brian:
Does a cap rate Y2 IAW EN132400 and IEC 60384-14 meet all requirements for
the UL CCN for EMI filters (FOKY2, UL1414)?
Only if the Y-cap bears the UL mark. Look
for the mark on the cap.
Is the UL CCN FOKY2 based on UL1283?
UL 1414 applies to capacitors which can be
Hi Bryan:
I have a request from the design community to implement a routine impulse
test in lieu of a Hi-Pot test. This product is evaluated to 61010-1 and the
reason for the request is that a measuring circuit connected to the
affected
output circuit contains a resistor string
Hi Sam:
Correct me if I'm wrong, but the point of the type-level hipot test is not
to simulate a real-life condition (like surge protection), but to simulate
years of insulation degradation, which happens with or without surge
protection.
I disagree.
Primary circuits are subject
Hi Chris:
During safety testing at the lab, the unit passes HiPot
testing. However, the unit is broken by the testing.
Rigorously, the unit passes its type testing because
it doesn't become unsafe by the Hipot. However, it isn't
functional after the test; and it
Hi Peter:
Is anyone aware of any CTL decisions for
IEC60950:2000 or -1, where operator accessible
fuse replacement marking requirements may be
waived, based on the fuse not being required for
safety reasons (did not open during any test
under any conditions of test) and where of the
Hi Dave:
I need a sheet of plastic that goes between a PCB
and a metal enclosure. This is to make a creepage
spec. What plastics are good for this? Will
polycarbonate be suitable and have a 94V-0 rating?
With respect to IEC 60950...
A plastic material used as an electrical
Hi Peter:
Out of curiosity, I wrote NARTE directly regarding the
below, to see what benefit they believe NARTE certification
would offer someone who already has experience in product
safety and a PE Registration. It's been a week and they
have not responded. Perhaps that's
Hi John:
If the breakers are 230 V/16 A and 120 V/15 A, then
the power distributed at 230 V is roughly twice that
at 120 V.
But your '120 V' is also '240 V' for some equipment. Besides, I think I
was being 'generous'; electrical energy consumption per head in USA is
Hi John:
For 3% voltage drop at maximum rated load, the
source resistance is about 0.2 ohm. So the
maximum rms current would be system nominal
voltage divided by 0.2 ohm, or 600 amps for 120
V and 1150 amps for 230 V.
For 230V, there are two modifications. One is
Hi Richard:
You mention a few times the 25 Amp test. The designs I have seen that try
and use this approach (and I don't ever recall seeing a design I was happy
with) were all switch mode power supplies where there was an input fuse of
about 2A, meaning that the test would be
Hi David:
In regards to your suggestions below, would it not be wise to take into
consideration the future plans of the LVD?
The original question was specific to the LVD.
My response was specific to the LVD.
You raise a new question with regard to a future
EU directive, the
Hi John and Richard:
The transformer screen/shield between primary
and secondary windings is intended to carry
the fault current in the event of a failure
of basic insulation between the primary and
the screen/shield.
The screen/shield must be capable of carrying
the full fault current and
Hi David:
It is being suggested that this product does not need safety testing and
does not need to include the reference to EN 60950 and the LVD in the CE
DoC, since it is SELV circuits only.
The LVD applies to products with voltage ratings
between 50 and 1000 V ac and between
Hi Doug:
The question is, how do I independently validate the material used, since a
vendor could theoretically choose whatever they want and stamp it as V-0?
I interpret your question as to how to determine
whether or not a PCB is counterfeit or not.
A UL-certified PCB would have
Hi Dan:
Thank you for giving us straight answers and helping us
to overcome the conventional wisdom about fuses.
Several years ago, I put together an article addressing
fuses, their operation, and how to select the fuse rating.
See:
http://www.ewh.ieee.org/soc/emcs/pstc/psn/
Then,
Hi Richard:
is the below information true
for both the AC and DC hipot methods?
Some companies have contractors,subcontractors,
incoming and final hipot...
so it does and can occur at least 4 times,
before its shipped to a customer.
The theory says that the onset of the
Hi John:
There is a justification for a high-current test **where it won't cause
any new damage**. The justification is that it will find bad joints in
the PEC path, and stranded PEC and bond wires that have only one or two
strands still intact.
The high-current test will NOT
Hi John:
I don't think you can draw universal conclusions from just one
experiment. In addition, the rate of increase of voltage is limited in
the test procedures. In your experiment, there was only one increase of
voltage, whereas in repeated testing, there are many. At best, we
Hi John:
My last (3) employers have required all repaired or modified units to
be
hi-potted. If a unit has been repaired, then the cover was removed,
and
the unit is no longer controlled by the oroginal production hi-pot.
I think this is too stringent.
Hi Gregg and Barry:
Australia has an actual standard which lists the tests and procedures for
the regular testing of equipment in use, and equipment that has been
So has the UK. it was called (something like) The Electricity at Work
Act generally a good thing put a dangerously
Hi Ilan:
I was looking for a viable comparison between glow wire and the UL94
flammability rating. The point of this little comparison is to bypass the
glow wire test for materials, which are properly rated for UL94.
There is no comparison between the glow-wire test and
the flame
Hi Alexandru:
1. Is the combination of Basic Insulation + FuseTransorb(15V) equivalent
to
Reinforced Insulation?
No.
The scheme of protection against electric shock relies on
passive devices, not active devices.
As a general rule, active devices, e.g., transorb, are not
allowed as
Strange behavior of the list-server. Although I got some out-of-office
replies, neither I or my fellows in the office (members of the list) have
received the message posted 24 h ago. I'll try again...
We are still experiencing delivery problems from
the listserver. The IEEE gurus
Hi Gordon:
Does anyone know from where the values for creepage and clearances given in
EN61010-1 (safety requirements for electrical equipment for measurement,
control and laboratory use - part 1 general requirements) are derived i.e.
are there other standards below 61010 in this
Hi Pete:
This usually means developing a focus group and getting them to pick it out
of a group of symbols when asked to identify the symbol for 'XXX'.
I take this to mean that the group is given the
definition and then asked to identify the symbol
that matches the definition.
Hi Richard:
Products should be designed so that no safety symbols/words are required
(at least for the user/operator).
A very laudable viewpoint and one that is easily achievable in the examples
you provided. However, with certain products there has to be a residual
Hi Richard:
You said We in the product safety industry must be very careful that we
use
symbols in strict accordance with their definitions. No issue with you
there. However, the paper states that some of these misuses were
perpetrated by people not even connected with
Hi Richard:
As you say, this web site provides a discussion on the exclamation symbol.
However, the discussion is slanted in one direction that not everyone in
the
safety fraternity would necessarily subscribe to. For instance, I have
seen
the 'high voltage flash' sign used as a
For a history and discussion of this symbol, see:
http://www.triodyne.com/SAFETY~1/sb_v17n2.pdf
Best regards,
Rich
This message is from the IEEE EMC Society Product Safety
Technical Committee emc-pstc discussion list.
Visit our web site at:
Hi Enci:
Only this morning have I just tested a competitive product from a
manufacturer in Germany, which failed miserably (+40dB) on conducted
emissions testing and earth leakage, to be fair only 2mA, but the standard
clearly states 1mA!.
What standard specifies 1 mA?
The
Hi Enci:
How about as a consumer, buying a PC, then 6 months later (with no
modifications) finds it is non-compliant (highly likeyl!!).. Can the
consumer return it/demand correction/!?!?
The consumer can always attempt to return a
product or demand correction of a non-compliant
The recent string with the subject OK, what's going on?
alleges that a named manufacturer's product does not
comply with a requirement.
We feel that, in the case of a negative or derogatory
comment or allegation (in this case non-compliance), the
manufacturer (or individual) should NOT be
Hi Gary:
Your comment triggers another comment: Leadership.
Typically, we tend to let the inspector be the
leader for the duration of the inspection.
The host can be the leader.
The host can set the agenda (in advance, although
the inspector need not be notified). First, is to
decide
Hi Rick:
On the surface it seemed like a simple exercise of putting a DC current
meter in series with each of the outputs. Given that the current demand
for each of these outputs is dynamic, corresponding with the processing
activity, does it make sense to measure this output
Hi Alice:
Scenario : Component A with rating mentioned in the UL's product report as
90-135/180-265 Vac, however in the phyical unit is written as 115/230 V .
Q1 : Is this a non conformity ? Should a VN be raised ?
Yes, this is a non-conformity.
In this case, the report should be
Hi Peter:
I am trying to find the rationale why production-line ratyhing tests
in North America are usually done with a simple ohmmeter and without
passing a current of say 25 A through the circuit. There must be some
rationale of doing it this way somewhere.
I can't answer that
Hi Peter:
Anyone knows of ANSI or other North American production-line test
procedures/requirements for electrical/electronic equipment? Some UL
and CSA standards specify the procedures for roduction-line tests, but
what I am looking for is the source of these procedures/requirements.
A message was posted that defamed another
subscriber.
That subscriber has been un-subscribed and
notified as to the reason.
Richard Nute
Administrator, IEEE emc-pstc listserver
This message is from the IEEE EMC Society Product Safety
Technical Committee emc-pstc discussion list.
A message was posted by the EMC Compliance
Management Group that was a blatant violation
of our rules against advertising.
The subscriber has been un-subscribed and
notified as to the reason.
Richard Nute
Administrator, IEEE emc-pstc listserver
This message is from the IEEE EMC
Hi Peter:
My comments were based on the proposed requirement to
test the PE path with the circuit prospective current
transient, e.g. 200 amps from a 10,000-amp source for
the period of time required to operate the overcurrent
device -- say less than a second or so.
(The 200 amps is a
Hi Neil:
All I get on visiting the site is 404 Page not found error on their
home page. Access to all other pages seems to be ok. Using their search
engine facility does not seem to find anything with respect to
application notes or harmonics. Anyone else have this problem?
Hi Peter:
Not quite. I^2·t will tell you the let through current of
the copper trace, but will not necessarily tell you if the
construction will be compliant. The compliance criteria for
this test include:
* no damage to the trace (no lifting, probably no
Hi Chris:
It seems funny to me that most equipment has been historically made with
18AWG protective ground pigtail wires; and 25A ground fault tests have been
used for years.
Now that PC traces are being used for protective ground; we want to test
with 200A or greater impulse
Hi John:
Is it not permitted to express a personal preference on this group? I
*prefer, personally*, not to use printed board traces as parts of the
PEC. I'm not suggesting that should be in IEC 60950 or any other
standard.
Of course we express personal preferences in
this
This message has been converted via the evaluation version of
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your Software Evaluation Agreement is prohibited. Please contact
Transend Corporation at (650) 324-5370 or sales.i...@transend.com
to obtain a license suitable for use in a
Hi John:
Thank you for that and the rest of the information, which could prove to
be very helpful indeed. I would like to use it in my continuing efforts
to defuse the arguments between the former TC74 experts in TC108 and the
SC77A/WG1 people. May I say that the information came
Hi John:
Yes, delta-wye distribution transformer overheating
does occur due to the circulation and dissipation of
the triplen harmonics in the primary (delta) winding.
Thank you for that and the rest of the information, which could prove to
be very helpful indeed. I
Hi John:
The Bad: some FETs fail very violently, and can actually be a fire hazard
and/or shock hazard in open-frame switchers;
Really? There doesn't seem to be enough combustible material to cause a
fire hazard, and an open-frame switcher always has to be in some sort of
While s-c and o-c at device terminals do not simulate true
fault conditions within components, testing must be
practical. If we are to begin considering simulation of
true fault conditions within components, there may be no end
to the number of tests.
We can easily put bounds
Hi John:
Aren't you in the USA? If so, you must have imagined the peak-
flattening. I am assured by the US experts on SC77A/WG1 that this
phenomenon is unknown in USA, and the only effect of IEC/EN 61000-3-2 is
that it increases the prices of PCs dramatically and keeps US
Hi Brian:
The environment being considered is a switching power supply. The technique
that safety agencies use to simulate a SFC on a power FET does not seem,
IMHO, to simulate the actual failure mode of the device. To wit: when the
mosfet fails short, it blows itself open; so
Hi John:
The only other problem that I know of is distribution
transformer overheating. But, I believe such
transformers are very much larger than 3 kVA, so 3 kVA
of non-linear loads would have very little effect.
I mean *concentrations* of loads, individually below 3
Hi John:
In the USA, this has largely been fixed by a change in
the USA National Electrical Code.
There must be quite a number of installations that are not yet upgraded.
Where a problem existed, it was fixed by pulling
another neutral.
Are there any other problems
Hi Peter:
For safety, it is not clear from the standards whether
the main branch circuit breaker tripping during fault
conditions is an acceptable result.
I see no reason why this should not be acceptable. What
is your view? Some third party labs find it acceptable
Hi John:
No, this is not much of an issue for the U.S. (unless your facility
is
actually affecting the utility);
... or frying the neutral conductors with third-harmonic current.
In the USA, this has largely been fixed by a change in
the USA National Electrical Code.
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Please do not post messages with attachments.
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Hi John:
The electrical safety legislation seems to be a bit more complicated in
U.S.
compared to EU.
A very great deal more complicated, because the practical requirements
are not centralized but delegated down though the local government
chain, and in some cases
Hi Gregg:
I argue with some of your statements. :-)
Dave's question - Does this apply to in-house test equipment?
Hi Dave - Good question (Please see attached). I'm sorry about the file
size but I took it from the Department of Labor web site several years ago
when this
Hi Gary:
Rich Nute (I think) wrote and excellent article or e-mail on this not
too
long ago and should be in the archives. Its pretty concise and clear but goes
into some pretty good specifics and the state laws and how they very and you
will find it very helpful.
Unfortunately
Hi Dave:
Does this apply to in-house test equipment? That is, equipment that is
built
in-house and remains on site? In the past I have designed in-house
equipment
to meet the safety standards but did not send the equipment out for testing
and certification.
Yes.
If you check
Hi Joe:
As has been discussed in previous threads, NRTL Listing is not a
requirement to sell electronic products in the U.S. However, there are
cities, counties, etc. within the U.S. that do require NRTL Listing.
These include Los Angeles and Chicago. Does anyone have a
Hi Richard:
Does anyone know of web sites or other sources that describe feasible
alternatives to bominated fire retardants in plastics?
There are a number of alternatives to brominated
fire retardants:
Phosphorus
Mineral
Phosphorus is probably the most-used.
There are some
Hi Gary:
As a result of searching for my copy of the
indoor use only symbol, I discovered that
I have a reference to the standard where the
symbol is published:
DIN 30 600 Reg. No. 02808-3
If one of our subscribers has a copy of this
standard, perhaps he could verify the
reference.
Hi John:
It is not an ISO or IEC symbol.
It is either in IEC60417 already or will be in the future.
It is not currently in IEC 60417.
(I have no visibility as to future
adoption of this symbol into IEC
60417.)
Since one of our members could not
decipher the symbol, I question
Hi Luke:
This won't work. If you want to look at how badly online forums work,
look at the IEE website.
Unfortunately, this requires a membership and a
login.
I really would like to know more about the
success of web-based forums.
Best regards,
Rich
Thank you for all the comments on the listserver-
based service versus the web-based service.
The IEEE listserver WILL continue.
I apologize for not being clear on this point.
We started with listserver service. However, the
listserver does not satisfy all of the needs of
our
Hi Jim:
Thanks for your message.
The EMC Laboratory that I work for (Acme Testing Company in Acme,
Washington) has the quietest open-field Emissions Sites (OATS) within a
1000
mile radius. We planned it that way. The village of Acme has a total
population of under 100 people.
Hi Charles:
a) Does anyone one know the genesis
of the requirement to lift the Neutral
AND the Ground simultaneously
during a leakage current test??
(I am referring to UL6500)
While I am not familiar with UL 6500 per se,
I believe I can comment on the lift of the
neutral.
Some fire tests use a methenamine timed burning
tablet.
This tablet is specified in USA government
standards for furniture flammablity testing.
(See 16 CFR Part 1630.4 or CPSC standard FF 1-70.)
It is also specified in ASTM D2859. I have also
seen it used to test fire enclosures
in
Regarding postings, here is a re-statement of our
guidelines that were sent to you when you
subscribed:
1. No attachments (because many of our subscribers
use dial-up modems for which message size
determines the download time).
If an attachment is appropriate or necessary to
docopocoss
This word was unknown to me. I checked an
American dictionary and could not find it.
Then, I called up the Google search engine
and entered the word, hoping to find an
English dictionary.
Google immediately came back with the
definition.
Rich
Hi Chris:
OSHA rules apply to employers.
OSHA electrical rules require employers (1) to
use only electrical products that have been
certified by an NRTL, or (2) in the case of
custom products, to test the product in place.
If you sell a non-NRTL-certified custom product
to an employer
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