Dear Friends,
Thanks very much to the input regarding CB Tripping During Fault Testing.
There were many thoughts on the subject and I am sure that next time the wall
CB trips during fault tests at your third part certification laboratory, you
have something to talk about - make sure they do not
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
This thread has been largely theoretical. Let's look at
some empirical test results for a product I just completed
testing.
The product has a redundant power configuration and nearly
identical current paths for each of two power supplies,
though one has about 2 in. longer traces on one side of
From: Rich Nute
Sent: Wednesday, February 05, 2003 12:20 PM
Hi Peter:
Hi, Rich.
This test implies a near 0-ohm fault to the
PE, where the PE circuit includes a PE trace
on the PWB.
That's a reasonable assumption and is convenient for the
purposes of testing. It is unlikely to be the
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
. Tarver; emc-p...@majordomo.ieee.org
Subject: Re: EN60950 protective conductor test (was Re: Circuit Breaker
Tripping Dring Fault Tests)
Why not provide a fuse to prevent deterioration of the PE trace on a PCB?
Joking of course, but now that I have your attention, I would like to see
]
Sent: Tuesday, February 04, 2003 11:36 AM
To: Peter L. Tarver; emc-p...@majordomo.ieee.org
Subject: Re: EN60950 protective conductor test (was Re: Circuit Breaker
Tripping Dring Fault Tests)
Why not provide a fuse to prevent deterioration of the PE trace on a PCB?
Joking of course
Chris,
Douglas Brooks wrote an article about Preese's and Onderdonk's equations
for fusing currents of wires, which was published in Printed Circuit
Magazine. It can be downloaded from UltraCAD's web site at
http://www.ultracad.com/fusing.pdf
Appendix F of the book that I am writing for
I read in !emc-pstc that Chris Maxwell chris.maxw...@nettest.com wrote
(in 83d652574e7af740873674f9fc12dbaaf7e...@utexh1w2.gnnettest.com)
about 'EN60950 protective conductor test (was Re: Circuit Breaker
Tripping Dring Fault Tests)' on Tue, 4 Feb 2003:
This would make heat dissipation different
(was Re: Circuit Breaker
Tripping Dring Fault Tests)
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
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
discoloration)
* no damage to
Message-
From: drcuthbert [SMTP:drcuthb...@micron.com]
Sent: Monday, February 03, 2003 7:50 PM
To: 'John Woodgate'; emc-p...@majordomo.ieee.org
Subject: RE: EN60950 protective conductor test (was Re: Circuit Breaker
Tripping Dring Fault Tests)
What is needed is the I squared t
I read in !emc-pstc that cnew...@xycom.com wrote (in 85256CC2.005F2DA4.
0...@notes.fw.xycom.com) about 'EN60950 protective conductor test (was
Re: Circuit Breaker Tripping Dring Fault Tests)' on Mon, 3 Feb
2003:
My UL guy tells me that I should expect the typical service type CB to be
rated
I've had extensive discussion with UL regarding the
performance of this test. Below are my comments, taken from
these discussions.
-Original Message-
From: Carl Newton
Sent: Monday, February 03, 2003 9:20 AM
1. Three samples are tested;
Intended to demonstrate repeatability of
: Circuit Breaker
Tripping Dring Fault Tests)
Carl, If the primary supply circuitry and components provide double or
reinforced insulation, nothing can become live in the event of a single
fault, the test becomes unnecessary, and I would argue that fact.
If the design does not provide double
, February 03, 2003 11:19 AM
Subject: RE: EN60950 protective conductor test (was Re: Circuit Breaker
Tripping Dring Fault Tests)
A slight divergence from the EN specifically, but I thought that the
following would be helpful to this thread:
I am presently working this issue with a UL engineer
This thread has been interesting. I am, at this moment, considering a design
where I am almost forced to use a PC (printed circuit) trace for Earth ground.
It seems funny to me that most equipment has been historically made with 18AWG
protective ground pigtail wires; and 25A ground fault tests
I read in !emc-pstc that Nick Williams nick.willi...@conformance.co.uk
wrote (in p05200f03ba60957364e4@[192.168.1.28]) about 'EN60950
protective conductor test (was Re: Circuit Breaker Tripping Dring Fault
Tests)' on Fri, 31 Jan 2003:
At 12:22 + 31/1/03, John Woodgate wrote
the sender by reply e-mail and destroy all copies of the original
message.
From: Peter L. Tarver [mailto:peter.tar...@sanmina-sci.com]
Sent: Friday, January 31, 2003 9:23 AM
To: John Woodgate; emc-p...@majordomo.ieee.org
Subject: RE: Circuit Breaker Tripping Dring Fault Tests
John -
This proposal
At 12:22 + 31/1/03, John Woodgate wrote:
There is a proposed amendment to IEC/EN 60950-1 requiring a test of the
protective conductor network at *prospective short-circuit current* for
the time it takes for the mains circuit protective device to operate.
The details are controversial at
John -
This proposal is based on a North American D1 Deviation to
IEC60950, Subclause 2.6.3.3, and is derived from CSA 22.2 No
0.4. I have a product in my lab that this applies to and
two more products coming in to which it will also apply.
Regards,
Peter L. Tarver, PE
Product Safety Manager
I read in !emc-pstc that Peter L. Tarver peter.tar...@sanmina-sci.com
wrote (in nebbkemlgllmjofmoplekehbedaa.peter.tar...@sanmina-sci.com)
about 'Circuit Breaker Tripping Dring Fault Tests' on Thu, 30 Jan 2003:
John -
That impedance value is suprisingly high,
It applies to 230 V 50 Hz
John -
That impedance value is suprisingly high, but tends to
support the contention that the fault current at an outlet
will be much lower than was suggested (65kA, which, to me,
appeared more like a peak surge current than a fault
current).
For those interested, below are what the IEC Web
I read in !emc-pstc that Peter L. Tarver peter.tar...@sanmina-sci.com
wrote (in nebbkemlgllmjofmoplegegaedaa.peter.tar...@sanmina-sci.com)
about 'Circuit Breaker Tripping Dring Fault Tests' on Wed, 29 Jan 2003:
In a typical household operating at 120V, it's unlikely
that a fault current available
From: Gregg Kervill
Sent: Tuesday, January 28, 2003 3:21 PM
Like most regulatory issues the answer is YES and NO.
Therefore it is dangerous and extremely misleading (to
many
lurkers) to apply a general answer to all conditions:
Generally the equipment is expected to protect itself with
To: Rich Nute
Cc: emc-p...@majordomo.ieee.org
Subject: Re: Circuit Breaker Tripping Dring Fault Tests
Rich and group,
Just one interesting point continuing the thought of fuse sizes for
branch circuit protection. Awhile back, I was conducting a series of UL tests
on a household food mixer
Peter -
I agree that this is an acceptable result in the US and
Canada. There are, however, additional considerations:
For Pluggable Equipment Type A (to borrow a term from the
60950 standards), the largest branch circuit protection is
assumed during testing (20A) and there is no further
[mailto:ai...@gulftel.com]
Sent: Tuesday, January 28, 2003 11:00 PM
To: peter merguerian; emc-p...@majordomo.ieee.org
Subject: Re: Circuit Breaker Tripping Dring Fault Tests
Here is what I think the requirements are:
If the product remains safe, within the meaning of the standard, and the
branch
Two points:
To assure the safety of your product consider not whether it is safe if the
breaker trips, but what is the failure mode of your product if the breaker
(which you do not provide) does not trip. If you rely on the breaker, you
need to properly specify it.
In the US, there have been
...@majordomo.ieee.org
Subject: RE: Circuit Breaker Tripping Dring Fault Tests
I've been trying to solve this one myself. I work with one pair of standards
(UL458 / CSA107.1) where they specifically say that opening the branch circuit
protection is acceptable during component fault testing, but NOT during short
, January 28, 2003 2:54 PM
To: emc-p...@majordomo.ieee.org
Subject: Circuit Breaker Tripping Dring Fault Tests
Dear All,
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
-emc-p...@majordomo.ieee.org
01/28/2003 07:23 PM
Please respond to Rich Nute
To:pmerguerian2...@yahoo.com
cc:emc-p...@majordomo.ieee.org
Subject:Re: Circuit Breaker Tripping Dring Fault Tests
Hi Peter:
For safety
-
From: peter merguerian mailto:pmerguerian2...@yahoo.com
To: emc-p...@majordomo.ieee.org
Sent: Tuesday, January 28, 2003 1:54 PM
Subject: Circuit Breaker Tripping Dring Fault Tests
Dear All,
For safety, it is not clear from the standards whether the main branch circuit
breaker tripping
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
.
Best regards
Gregg
From: owner-emc-p...@majordomo.ieee.org
[mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of peter merguerian
Sent: Tuesday, January 28, 2003 2:54 PM
To: emc-p...@majordomo.ieee.org
Subject: Circuit Breaker Tripping Dring Fault Tests
Dear All,
For safety
...@majordomo.ieee.org
Subject: Circuit Breaker Tripping Dring Fault Tests
Dear All,
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
Dear All,
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 and others do not.
Anyone can
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