insulation”.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
<mailto:j...@randolph-telecom.com> j...@randolph-telecom.com
<http://www.randolph-telecom.com> http://www.randolph-telecom.com
From: John Woodgate [mailto:j...@woodjohn.uk]
Sent: Mond
eries also has VDE
approval to IEC 61051-2.
I hope this helps.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
<mailto:j...@randolph-telecom.com> j...@randolph-telecom.com
<http://www.randolph-telecom.com> http://www.randolph-telecom.com
ed
for Surge Protection on AC Mains Ports (randolph-telecom.com)
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
<mailto:j...@randolph-telecom.com> j...@randolph-telecom.com
<http://www.randolph-telecom.com/> http://www.randolph-telecom.c
additional safeguards are not particularly difficult of expensive to provide.
If you still have questions after reading the article, feel free to contact me.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
<mailto:j...@randolph-telecom.com
that understand the
rationale behind any requirement that is giving you trouble. Once you know the
rationale, you will better understand whether the requirement should apply to
your specific application.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA
point is that the AC mains transformer is not required to have
any isolation barrier whatsoever, if the secondary circuits have acceptable
isolation from ordinary users (such as a plastic enclosure with no
accessible ports).
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
78
in 60950-1 to refer to this
distinction.
I'm short on time today, but I'll try to elaborate further later.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
<mailto:j...@randolph-telecom.com> j...@randolph-telecom.com
<http://www.ra
le if the user is instructed to use a tool to
access the area, such as a battery compartment.
I don't know the details of the removable part on the product in question,
but perhaps the above considerations will help you evaluate the available
options.
Joe Randolph
Telecom Design Consulta
on between the primary
and secondary. Most of the ones I have seen are for comparatively low-power
applications.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
<mailto:j...@randolph-telecom.com> j...@randolph-telecom.com
<http://www.randolp
ormer? In this
case, wouldn't the entire contents of the enclosure would be treated as
though they are 230 Vrms AC mains.
I realize that this might seem like an unlikely type of product, but I have
seen such configurations used in the past, it seemed okay to me.
Joe Randolph
Telec
ges_IN-1300.pdf
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
j...@randolph-telecom.com
http://www.randolph-telecom.com
-Original Message-
From: Peter Tarver [mailto:ptar...@ieee.org]
Sent: Friday, July 9, 2021 1:13 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
equires
that the earth connection must be "reliable" as defined elsewhere in the
standard.
Note that different standards have different internal definitions for what
constitutes a "reliable" earthing connection. So, it's important to use the
internal definition that appears
of what CISPR may be concerned about.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
<mailto:j...@randolph-telecom.com> j...@randolph-telecom.com
<http://www.randolph-telecom.com> http://www.randolph-telecom.com
From: Jeff Keyz
signal passes through the transition region
on the input. Logic gates that are intentionally designed to operate correctly
with slow rise/fall times will be described as having a “Schmitt trigger” input
stage.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721
le requirements appear in AS/NZS 3100.
Thanks again for helping me to get oriented in my search.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
<mailto:j...@randolph-telecom.com> j...@randolph-telecom.com
<http://www.randolph-telecom.
inks to standards that are not relevant.
What I'm trying to determine is what safety standards (if any) a
manufacturer of such devices must have their product comply with. And, what
is the traceability path from the product label to the standard that the
product complies with.
Thank
electrical safety covered by 60335-1.
Does this sound like a correct summary of the situation?
Thanks,
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
<mailto:j...@randolph-telecom.com> j...@randolph-telecom.com
<http://www.randolph-te
Does anyone know whether such a standard is in the developmental stages
within the IEC?
In the meantime, the closest existing IEC standard that might be used for
electrical safety of E-cigarettes appears to be IEC 60335 for "Household and
Similar Electrical Appliances - Safety.&quo
earlier edition.
However, they are not obligated to do so.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
<mailto:j...@randolph-telecom.com> j...@randolph-telecom.com
<http://www.randolph-telecom.com/> http://www.randolph-telecom.com
the USA are not, by themselves, legally binding.
However, many UL standards are called out by law by OSHA and in state
electrical codes (which typically call out NFPA 70).
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
<mailto:j...@rando
hope is that some testing next week will show that the non-SELV circuit
meets the criteria for a limited-current circuit. In that case, I would not
have to deal with double insulation at all.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
<mailto:j.
to rely on
just a fault analysis. Class 2 specifically states that "double insulation"
be provided to prevent electric shock. At present, I do not see a way
around this if the 60V circuit is indeed classified as hazardous.
Joe Randolph
Telecom Design Consultant
Randolph Telecom
and creepage/clearance requirements would seem to apply
between the 60V circuit and the USB port.
Is there a compliance path through the standard that would not require
double insulation between the 60V circuit and the USB port? So far I have
not found such a path.
Joe Randolph
Telecom
capacitor, I have never
personally sensed a shock from such configurations, so what I am describing may
not be the cause of the electric shock problem you describe.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
<mailto:j...@randolph-telecom.com
uot;protective impedance." Based on just a review of the circuit diagram, I
think it has a 50/50 chance of meeting the requirement for protective
impedance.
If it does meet the requirement for protective impedance, do you think that
the approach described in Item 3 above would be accepta
eceived here have identified some
useful approaches for trying to demonstrate compliance as a Class 2
appliance per 60335-1, and I plan to think carefully about those approaches.
Right now, the main sticking point is the apparent requirement to provide
double insulation, with its attendant creepage and
s
in IEC 62368-1 for ITE and Audio/Video products. It would be helpful to
know whether any relevant changes are in the pipeline. I'm aware that a
2016 edition of IEC 60335-1 has been published, but it's my impression that
the touch current requirements are the same as those in the 2009 editio
October 2018 issue
of InCompliance Magazine.
I agree that for new approvals of ITE products, IEC 62368-1 is the appropriate
choice for most countries.
Thanks,
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
<mailto:j...@randolph-telecom.com
pecific to ITE equipment used in
a factory environment, or are IEC 60950-1 and IEC 62368-1 the most
appropriate safety standards use for this type of product?
Thanks,
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
j...@randolph-telecom.com <mailto:
Just some food for thought.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
<mailto:j...@randolph-telecom.com> j...@randolph-telecom.com
<http://www.randolph-telecom.com> http://www.randolph-telecom.com
From: Larry K. Sti
Hi Ian:
I have a vague recollection that the lower voltage limit either has been, or
will be, withdrawn in the EU. The change may be specifically related to the
use of EN 62368-1, but I can't recall where I saw it.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
78
unlikely to demodulate RF, you can
get some indication of whether the headset in question is the source of the
demodulation.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
<mailto:j...@randolph-telecom.com> j...@randolph-telecom.com
<http://www
standards as a condition for purchasing the
product. It is common for all of the major USA carriers (Verizon, AT&T,
Centurylink, etc.) to require some degree of Telcordia compliance for any
products they use in their networks.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
Thanks Charlie.
It looks like the scope language for the new LVD/EMCD is sufficient to pick
up wireline telephones without needing the previously explicit references in
the RTTE.
Thanks,
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
<mailt
in the RTTE
directive.
I'm just looking for the specific regulatory framework that now applies to
wireline phones.
Thanks,
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
j...@randolph-telecom.com <mailto:j...@randolph-telecom.com
, this would not provide much protection against overheating of the
MOV unless the MOV failed at an effective resistance of less than 12 ohms.
Anything higher than that would just keep producing heat.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA
ion level less than 240 W cannot cause
ignition of nearby materials, then a 1A fuse would appear to provide the
"adequate breaking capacity" called for in 60950-1.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
j...@randolph-telecom.com
http://www.r
ses overheating of the MOV, rather than a fuse that responds only to current.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
j...@randolph-telecom.com
http://www.randolph-telecom.com
-Original Message-
From: Mick Maytum [mailto:mjmay...@gmai
added elements, considerable testing would be required to determine
whether a proposed MOV circuit would pass the tests in G.8.
Hopefully someone with more knowledge on this topic can tell me whether I am
misinterpreting Annex G.8 in 62638-1.
Thanks,
Joe Randolph
Telecom Design
that I know how to implement solutions that comply with either
standard. For the short-term, though, it appears that 60950-1 is the best
option for this particular project.
Thanks,
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
<mailto:j...@rando
under 0.5 mA, there is no practical way to achieve this. The
same fuse must also be able to survive the anticipated surge currents for which
the MOV was installed.
So, the authors of clause 1.5.9.2 must have had some other definition in mind
for the term, "adequate surge protection."
T
a question about whether clause 1.5.9.2 in 60950-1 means that
there must be fuses in each of the Line conductors when two MOVs are installed
line-to-ground on the AC mains input. It sure looks that way when I read the
requirement.
Joe Randolph
Telecom Design Consultant
Randolph Teleco
of series fuses, although
fuses are not explicitly required in order to pass the tests.
I would appreciate any additional input that might help me determine whether
the above interpretations are correct.
Thanks,
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781
hed 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,
Jo
t is not that difficult to design an AC mains isolation barrier that
can withstand 15 kV.
If you are not familiar with lightning surge testing and the various
protection schemes that can be used, I can provide some suggested reference
material or some off-line email support.
Joe Randolph
y
probably have to be classified as TNV-1 anyway. If they are only routed
within the building, you have the option to classify them as SELV. For a
SELV classification, it would be best to stay under 60 VDC maximum.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721
you still have questions on this topic, I would be happy to try and
answer them.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
<mailto:j...@randolph-telecom.com> j...@randolph-telecom.com
<http://www.randolph-telecom.com> http://www.ra
Germany has historically been 60V, and I believe they still are.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
<mailto:j...@randolph-telecom.com> j...@randolph-telecom.com
<http://www.randolph-telecom.com> http://www.randolph-telecom.
barrier between an Ethernet cable and the corresponding
Ethernet PHY chip on the other side of the isolation transformer.
I can provide more details on this if you are interested.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
<mailto:j...@rando
many years. Technically, the
ringing signals on an ordinary phone line are not classified as “hazardous.”
Rather, they are classified as “TNV-3.” Perhaps this has something to do with
the way ordinary phone cables are regulated.
Joe Randolph
Telecom Design Consultant
Randolph Telecom
are likely to have less difficulty applying it than IEC
62368-1.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
<mailto:j...@randolph-telecom.com> j...@randolph-telecom.com
<http://www.randolph-telecom.com> http://www.randolph-telecom.
that do not immediately come to mind because they
have harmonized their requirements with the EU and it's basically no additional
work if the product already meets the EU requirements.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
j...@randolph-telecom.com
ames I
have seen, but a little google searching will likely turn them up.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
<mailto:j...@randolph-telecom.com> j...@randolph-telecom.com
<http://www.randolph-telecom.com> http://www.r
specific
individual doing the inspection (the AHJ) has wide latitude to pick and choose
from both editions, but this may be a mistaken impression. It certainly would
create a lot of uncertainly for a company that is trying to deploy a single
product throughout the USA.
Joe Randolph
take steps to ensure that in the area where the
solder resist is being used for safety compliance does not contain any
openings in the solder resist.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
<mailto:j...@randolph-telecom.com> j...@ra
ut I believe there is no
change in the notion that creepage distances do not apply on the inner
layers of a printed circuit board.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
<mailto:j...@randolph-telecom.com> j...@randolph-telecom.com
<http:
requirements in GR-1089
are generally the most stringent lightning requirements worldwide.
In the end, though, whether NEBS compliance is required, or what subset of
the NEBS requirements will be required, gets down to a negotiation between
the manufacturer and the carrier.
Joe Randolph
ng do not indicate that it caused
personal injury, but my guess is that any laboratory equipment designed to try
and create ball lightning would be highly hazardous. My suggestion is the
proverbial, "Don't try this at home."
Joe Randolph
Telecom Design Consultant
Randolph Teleco
there are any obvious implementation errors.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
<mailto:j...@randolph-telecom.com> j...@randolph-telecom.com
<http://www.randolph-telecom.com> http://www.randolph-telecom.com
From: ce-tes
derations
that I described regarding the current telecom industry. When field
failures are expensive, attention to reliability goes up. If field failures
are not expensive (in terms of cost or company reputation), attention to
reliability goes down.
Joe Randolph
Telecom Design Consultant
Ran
will perform
its intended function. As a co-worker once pointed out, "a block of wood
will pass FCC Part 68." I suspect this same concept can be extended to the
full suite of EMC requirements in the EU or in GR-1089.
So, we probably need to keep some perspective on the limitations
applicable regulatory
standards will guarantee reliable performance in the field.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
<mailto:j...@randolph-telecom.com> j...@randolph-telecom.com
<http://www.randolph-telecom.com> http://www.randolph
air gap.
However, the way the question was posed, I think this effect should already
have been accounted for. The question was why two barriers in series sometimes
have a lower breakdown voltage than the sum of the two barriers tested
separately.
Joe Randolph
Telecom Design Consultant
ilure would only become evident during a
sustained hipot test, as opposed to a 1.2/50 uS lightning surge.
In any event, Rich Nute is one of our resident experts on the failure of
insulation, so hopefully he will chime in here.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
, it’s not just a
few jurisdictions like Los Angeles that require an NRTL listing. In effect,
this requirement exists in any jurisdiction that has adopted the relevant
clause from the NEC (which probably accounts for 99% of the USA).
Joe Randolph
Telecom Design Consultant
Randolph
of devices, is an NRTL
listing now required throughout the USA by the NEC?
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
j...@randolph-telecom.com <mailto:j...@randolph-telecom.com&g
idate MIL specs as well.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
j...@randolph-telecom.com
http://www.randolph-telecom.com
-Original Message-
From: Pete Perkins [mailto:0061f3f32d0c-dmarc-requ...@ieee.org]
Sent: Monday, November 24, 2014 4:37
g detection. I think you will find the requirements to be
easy to meet.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
j...@randolph-telecom.com
http://www.randolph-telecom.com
-Original Message-
From: Larry K. Stillings [mailto:la...@complianceworld
As I recall, touch current is effectively measured with the ground pin lifted.
The rationale is that there should be no hazard even if the safety ground is
left floating.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
<mailto:j...@randolph-telecom.
requirements for creepage, clearance, or distance through
solid insulation.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
<mailto:j...@randolph-telecom.com> j...@randolph-telecom.com
<http://www.randolph-telecom.com> http://www.randolph
citly designed for high
primary-to-secondary isolation (5000 VRMS) is the Bourns SM51589PEL. The
external primary-to-secondary creepage distance of the package is
approximately 10 mm.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
<mailto:j...@
not
related to any attempt to directly protect users from
transients.
I have added some more blue text in-line to
try and clarify my conclusions about how this relates to the SPD
allowances in 60950.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
j...@randolph
s to
rest on the assumption of having a reliable ground. Do you agree
with this interpretation?No. The OPERATION of an SPD
requires a ground. If the
ground is not there, then the SPD will not work. This is
okay from a safety point of view. We do (or should) not
require the SPD to work, only that it no
to ground on an AC mains port is based on the *assumption* that
the ground is reliable, I can accept that. However, I don't think
that same rationale was carried forward into clause 6 when the isolation
requirements for telecom were written. I have never been able to
make sense out of the SPD a
ts. So,
under the standard it is possible to include SPDs across the barrier
without ensuring that the SPDs will direct overvoltage surge currents to
earth.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
j...@randolph-telecom.com
http://www.randolph-telecom.com
port as a
simple AC mains port unless I could find evidence that other approaches
have been widely accepted at the international level.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
j...@randolph-telecom.com
http://www.randolph-telecom.com
Thanks Chet and
goes straight back to the central office and is not shared among
neighbors.
Another consideration is that the impedance and loss characteristics of
twisted-pair telecom cables are quite different from AC mains
wiring.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (U
e analysis Rich provided
is a good example of the sort of thinking that would have to go into
method 3b. I'm traveling this week but I can probably find
the article for you when I get back to the office.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
http
I have described is a "by the book"
interpretation of how the tests should be applied. Some test labs
take short cuts, such as simply testing the modem in the on-hook and
off-hook states, without actually setting up data calls.
If you have further questions about how to do these tests, fee
lace some requirements on how the system is installed
and bonded to earth ground.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
j...@randolph-telecom.com
http://www.randolph-telecom.com
What are the safety
considerations using gas tubes on the AC mains? Do you
lications use an MOV in series
with the gas tube. The MOV would block the follow-on current, while
the gas tube would set the turn-on voltage.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
j...@randolph-telecom.com
http://www.randolph-telecom.com
The First G
ube across a barrier that breaks
down at 6 KV to 10 KV invites surge currents that otherwise would not
occur.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
j...@randolph-telecom.com
http://www.randolph-telecom.com
An air gap is a gas tube without
the tube
A
opper layout will be
damaged by the very first surge that breaks down over the spark gap, and
the board may need to be replaced anyway.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
j...@randolph-telecom.com
http://www.randolph-telecom.com
Our engineers are wo
that exceed the rating of the
insulation. If the size of the air gap is coordinated properly with
a good insulation barrier, the gap could be expected to trigger very
rarely (if ever) in the product's lifetime.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-28
trigger voltage was very high (say, 9
KV), the device could be expected to trigger very rarely, if ever, in
actual use.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
j...@randolph-telecom.com
http://www.randolph-telecom.com
Brian,
I am personally opposed t
on the
second edition of 60950 was an effort to address some of these concerns,
but I'm not sure it fully resolved the matter. I suppose that part
of the answer depends on the details of the specific type of product you
are trying to analyze.
Joe Randolph
Telecom Design Consultant
Randolph T
as TNV-1. A T1/E1 line is typically classified as
TNV-1.
If the lines are used only within a building and do not carry AC power
ringing, they can often be classified as SELV. However, no
"ordinary" phone line that comes from a central office can be
classified as SELV.
Joe Randolph
Tele
e the higher voltages are usually coupled with higher source
resistance in the feed circuit, so that the short-circuit feed current
remains below 100 mA in most cases. For safety compliance, I
believe that all of the standard battery voltages now used in Europe
qualify for classification as TNV
, and Luxembourg as using 60 VDC
batteries.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
j...@randolph-telecom.com
http://www.randolph-telecom.com
Hello All,
Google has not been helpful. Perhaps someone here has more information
than the Interwebs.
Has anyone seen a
on based on your experience of
living in the UK. It does appear, though, that the authors of EN
41003 felt they had to address the possibility of a mis-wired AC mains
plug.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
j...@randolph-telecom.com
http://www.rand
ld make it okay to have them in place? The problem
I see is that clause 6.2 does not require that the SPD be connected to a
reliable earth. The SPD can simply bridge the required 1000 VRMS
barrier, which effectively defeats the barrier during normal
use.
Joe Randolph
Telecom Design Consultant
Randol
barrier is if the SPD is connected to a
reliable earth. That explanation makes sense to me and seems
defensible. However, in the absence of this constraint , allowing
an SPD to be connected across an isolation barrier does not seem to make
any sense at all.
Joe Randolph
Telecom Design Consult
frequently)
there is no explicit requirement that the SPD be connected to a reliable
ground. Rather, it is simply allowed to bridge the isolation
barrier. Based on quick read of clause 5.2.2, the situation would
appear to be similar there as well.
Joe Randolph
Telecom Design Consultant
Randolph
appear in clauses 5.2.2, 6.1.2, and
6.2. It also appears in TIA-968 for equipment connected to the
telecom network.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
j...@randolph-telecom.com
http://www.randolph-telecom.com
Hi Joe:
Very quickly...
SPDs are not
y appreciate it.
Thanks,
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
j...@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 valu
think to accomplish that is to
provide the non-safety person with a list of all the countries that are
members of the CB scheme, showing which ones have national deviations and
which ones do not. It may also be necessary to provide some
explanation of what the CB scheme is and how it works.
up in these nuances unless Ian tells us these countries are important for
his particular product, *and* that he thinks he has to classify his
Ethernet interface as TNV-1.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
j...@randolph-telecom.com
http://www.randolph-telecom.c
makes the entire device a SELV circuit (unless there
are other ports on the device that are not SELV).
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
j...@randolph-telecom.com
http://www.randolph-telecom.com
Dear colleagues
We are developing a hand held
rtain applications where MOVs are the best
match for the application.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
j...@randolph-telecom.com
http://www.randolph-telecom.com
-
This message is from the IEEE Pr
this broad definition, devices such as zener
diodes, MOVs, sidactors, and even gas tubes could be legitimately
characterized as TVS devices.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
j...@randolph-telecom.com
http://www.randolph-telecom.com
Gentlemen:
My he
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