Hi Richard,
I am afraid I led you astray a little for NZ. This type of power supply
does NOT require any form of approval presently in NZ.
A little history
These types of devices have not been required to be approved in NZ in the
past. NZ is presently completely revamping their electrical
Hi Chris:
In other words: don't test if you know already the result before the test
is made.
A good safety engineer can predict the result
(not pass-fail but the measured value) of each
and every safety test.
For example, a good safety engineer can predict
leakage current to
Another possibility is that the US equipment may have been designed for a
three phase Y input with a neutral and was used on a European three phase
delta circuit. Someone could have then tied the neutral terminal to ground
creating a serious hazard as well as a voltage imbalance.
Just a
He's right. Tying neutral directly to the chassis is just WRONG, even if
you could be sure it would always be neutral (not guaranteed at all).
Sounds like somebody got neutral and the safety ground mixed up. I'd send
the unit back to the manufacturer with a nasty note. I would also question
Dave,
It is my understanding, as you state, that earth ground and neutral should
not be tied together in a piece of equipment except to ground reference the
output of a transformer that is part of the equipment, although I can not
quote chapter and verse from the NEC or 1950 on this. I suspect
Hi Richard and Dave:
In answer to Richard's comment:
The neutral is never to be tied to the chassis of equipment. It is not
allowed by any safety standard nor the National Electrical Code. The neutral
is to be tied to earth at one and only one point and that is that the
service
THANKS TO ALL FOR THE REPLIES - THANKS, NED, FOR THE EXACT ANSWER !!
-Original Message-
From: Ned Devine [mailto:ndev...@entela.com]
Sent: Tuesday, October 10, 2000 10:01 AM
To: emc-p...@majordomo.ieee.org
Subject: RE: Label Rub test per IEC60950
Hi,
The requirement is for The
The neutral is never to be tied to the chassis of equipment. It is not
allowed by any safety standard nor the National Electrical Code. The neutral
is to be tied to earth at one and only one point and that is that the
service entrance or the electrical box fed by an on-premises transformer. I
Let me see if I understand. The board without the resist coating has a UL
certified temperature rating. We don't know the temperature rating of the
coating; but if it does ignite, at least we know the certified burn rate.
Well, perhaps the ignition temperature is high enough so that we don't have
Ooops I meant to say I can't guarantee you that NOT I won't provide you
with
Maybe I should stop using my cell phone so much... :-)
Jeff
-Original Message-
From: Bailey, Jeff [mailto:jbai...@mysst.com]
Sent: Wednesday, October 11, 2000 12:35 PM
To: 'emc-pstc'
Subject: RE: DoC TCF
The company that I work for in the U.K has recentlyreceived from the USA an
item of test equipment, provided to us under contract, in which, we
discovered, the 240v neutral line was connected to earth/unit chassis. This
became apparent when the unit was plugged into a U.K 120-0-120 supply and
In the instance of EN 61000-3-2 and EN 61000-3-3, we MUST look to regulatory
authorities to make the decision.
I think the basis of the whole argument is this:
For many products covered by these standards, the essential requirements
as listed by many competent EMC engineers would not include
Richard -
Then the answer is no. The MOT, as Pete Perkins pointed out, establishes
the test points for thermal conditioning, but solder resists are then tested
in conjunction with the PWB only for flammability classification.
Regards,
Peter L. Tarver, PE
ptar...@nortelnetworks.com
Hello Group,
I have a good idea (first hand knowledge) of what UL looks for with respect
to dc supply circuitry /= 60 Vdc (e.g. telecom equip supply). UL considers
(with caveats on the supply) that it is SELV secondary with operational
insulation requiring 500 Vac/707 Vdc dielectric withstand
You are correct. I used the wrong term. I should have said the solder resist
coating. Is this coating included in the temperature ratings?
Richard Woods
--
From: mike harris [SMTP:tecco...@i-cafe.net]
Sent: Wednesday, October 11, 2000 11:25 AM
To:
Hi Richard,
AB uses the TCF route quite frequently and they list their DoC's online.
Try going to http://www.ab.com/certification/ce/docs/index.html and look at
a couple of DoC's through
the links found there. It won't provide you with the rules for wording are
adhered to
or not but it may give
Hi Richard Peter,
Richard, I wonder if you are calling the solder resist coating as conformal
coating?
If so, I expect that the resist coating is ignored for any PWB ratings and
insulation properties.
My understanding is that conformal coating is a completely other issue from
resist
I'd like to throw my two cents worth in here.
First, compliance with a national/international standard or regulatory
regime does not guarantee adequate product performance or safety. That is
the responsibility of the manufacturer. The standard(s) gives guidance to
achieve that acceptable level
You're welcome, Richard.
MOTs are developed for a copper clad industrial laminate and verified by
certain tests on a finished PWB. Conformal coatings are not a normal part
of this process, though I suppose a board house could ask for such
considerations to be made for a selection of coatings.
Richard,
DoC is the same except that instead of a list of harmonised standards, you
list the name and address of the Competent Body, and the serial number and
date of the Certificate they issued to you.
Regards,
Jon Griver
VP Quality Assurance
Medson Ltd.
I have seen several Declarations
Hello Massimo,
The scope of EN475 is as follows:
specifies the characteristics of electrically-generated signals intended for
use with medical devices, either individually or as part of a centralized
system. This standard applies only if a particular device standard makes
reference to it.
I
I have seen several Declarations of Compliance when harmonized standards are
used, but I don't recall seeing one where the TCF route was followed for one
or more essential requirements. What wording is used on DoC to note that a
Competent/Notified Body rendered an opinion that a product complies
Pete thanks for your reply. I have noticed that the conformal coating on
some boards begins to discolor when subjected to continuous high
temperatures. In some samples, the coating begins to darken, bubble and
delaminate from the surface. Is the conformal coating considered when
setting the rated
Sorry folks,
It seems you cannot go straight to the results screen :-(
Try
http://astimage.daps.dla.mil/quicksearch/
and insert 1686 in the Document Number box.
regards,
Geoff Lister
Senior Engineer
Motion Media Technology Ltd.
http://www.motion-media.com
-Original Message-
From:
Hi Richard,
It's certainly mandatory for Australia, but was not mandatory for NZ last time
I looked.
The standard should be AS/NZS 3108, or for IT equipment you may use AS/NZS 3260.
Let me know if you need further assistance.
Regards
Barry Esmore
AUS-TICK
(The Australian Compliance
Michael,
I could not find revision B of the spec, but
revision C is available as a free download
from the following address.
Regards,
Geoff Lister
Senior Engineer
Motion Media Technology Ltd.
http://www.motion-media.com
http://assist.daps.mil/eAccess/index.cfm?ident_number=37095
PSNet,
PWB's are one form of plastic insulating materials. They must endure for a
long time without giving up the properties that make them good insulators or
enclosures for insulators. In the long term the volatiles evaporate away
and the molecular structure breaks down giving way to
I don't know if this is what you are after:
MIL-STD-1686B rates ESD sensitivity of class 3 parts, assemblies or equipment
at sensitivity levels ranging from 4000 to 15999 volts. I don't see a subclass
rating (i.e., 3a)
Appendix C of this standard requires testing at 2000 volts for assemblies
Hi Richard:
When a PCB is rated 105C or 130C or whatever, what does that really mean?
Can I really operate a 130C rated board at a maximum surface temperature of
130C for years without being concerned about reliability or safety? Is there
a relationship between de-rating and
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