Hi Folks
As promised in my email of 8 Dec 2004 (as below), I have taken all the
comments that I already had, or were sent to me recently via the forum, and
collated them according to the clause numbers of the standard, with due
attributions.
Some of the comments are pretty definitive, and some are opinions without
final outcomes.
I hope that I have correctly transposed the comments and attributions, and
that some of the omissions will be excused on the basis of duplications
(sometimes several times). Please excuse any errors where I have missed
something (but let me know).
It will be interesting to see the extent to which these issues are resolved in
the next edition of the standard. Therefore I will now take a look at some
related documents which have come my way - courtesy of various sources (who
know who they are, but probably best not to mention names at this point!) -
and see how these issues appear to be being addressed.
Regards
John Allen
ERA Technology
Here is the text (from WORD version rejected by the L-Soft Server)
GENERAL INTRODUCTION
As promised in my email of 08 Dec 2004, I have taken all the comments that I
already had , or were sent to me recently via the forum, and collated them
according to the clause numbers of the standard, with due attributions.
Some of the comments are pretty definitive, and some are opinions without
final outcomes.
I hope that I have correctly transposed the comments and attributions, and
that some of the omissions will be excused on the basis of duplications
(sometimes several times).
It will be interesting to see the extent to which these issues are resolved in
the next edition of the standard.
John Allen
ERA Technology
16 Jan 2005
6.7.3.1
(Ralph McDiarmid, AscT, Compliance Engineering Group, Xantrex Technology Inc
Section 6.7.3.1 para b) provides guidance on when to use the awkward clearance
calculation in 6.7.3.2
For example, I would classify the working voltage between a mains and a
secondary circuit as a mixed voltage or a voltage derived from more that one
circuit, thereby requiring the use of 6.7.3.2 to determine clearance.
However, I would use Table 5 for determining clearance from a secondary (mains
derived) circuit to a grounded, metal enclosure.
The determination about whether the clearance is for basic or for reinforced
insulation requires information about accessibility and protective bonding
6.7.3.2
"6.7.3.2 CLEARANCE values where table 5 does not apply and for circuits
in measurement category I
(Ralph McDiarmid, AscT, Compliance Engineering Group, Xantrex Technology Inc
Specifically, section 6.7.3.2 contains two errors which I have verified with
CSA here in Canada.
1) page 93 should read,"...for a voltage of 1.6 times the maximum voltage,
Um" ( not "1.6x actual working voltage)
2) calculation for variable "F" in para a) on page 93 shows 0.347. I make it
0.297
Circuits derived from Mains would include, in my interpretation, any circuit
which derives energy from the mains but which is galvanically isolated from it
and often given the term "secondary circuits".
6.8.4 "Voltage tests" & Table 9 "Test voltages for BASIC INSULATION" (Page 52).
(John Allen, ERA Technology, to the IEC Committee Chairman)
We are reasonably sure that there is a misprint in Column 1 "Clearance" of
Table 9 , as follows: The line entry between "1.0" and "2.0" is "1.4" but it
should be "1.5" (mm).
We believe that this is obvious from Table 8 "Clearance for measurement
categories II, III and IV" where "1.5" (mm) is mentioned in numerous places
but "1.4" is not mentioned at all.
Apart from anything else, 1.5mm is the category II minimum value for nominal
line voltages of >150V<=300V - which will be the mimimum value for a very
large amount of equipment.
Therefore the majority of users of the standard will have to start out by
interpolating in Table 9 - and may result in many mistakes in test voltages -
in fact interpolating from the existing values may result directly in test
errors.
Nevertheless, even if we are wrong about the need for the "1.4" entry, we
think that the test voltages for 1.5mm should be given as well.
Also. assuming that we are correct we do need the correct values for 1.5mm,
please could you find a way of making this information available in advance of
the long process of issuing an amendment to the standards
We also recommend that a critical review be made of all the values stated in
Table 9 as the existance of the above probable error brings in to doubt the
rest.
Subject: RE: IEC/EN 61010-1, 2001 'Circuits derived from Mains Circuits'
(Gail Birdsall, Hach Co.)
Most recent version of UL 61010-1 (July 2004) - they have added a deviation to
table 9 of the IEC 61010-1 standard. It states:
Table 9 D2 Modification
Add the following new row of values for a clearance of "1.5 mm."
1.5mm 2560V-pk (impulse) 1390V-rms 1970V-pk
Note that the voltages have been adjusted up from the Table 9 values stated
for 1.4 mm clearance, which states:
1.4mm 2440V-pk (impulse) 1330V-rms 1880V-pk
6.8.4 - Table 9 - Multiplication Factors for Test Voltage for Reinforced
Insulation (Various Opinions - solutions not fully defined)
Subject: RE: IEC/EN 61010-1, 2001 'Circuits derived from Mains Circuits'
(Ralph McDiarmid, AscT, Compliance Engineering Group, Xantrex Technology Inc
To follow on this discussion about the problems with 61010-1:2001, I take
exception with section 6.8.4 where in the 5th paragraph it states 1.6x the
values in Table 9 for Reinforced Insulation.
Surely, if the clearance is already dimensioned for reinforced (usually 2x
distance for BI) then you would test the voltage tabulated in Table 9 for
that clearance.
If on the other hand, you dimensioned a clearance for BI where one for RI is
called, then you would use the 1.6x the voltage for that clearance value. You
in fact would end up with the same test voltage (or sufficiently close to it).
For example, if you needed a clearance for a RI of 5.0mm, the test voltage in
Table 9 calls out 3110Vac. If that boundary was dimensioned for only BI or
2.5mm, then the test voltage for the RI requirement would need to be 1.6x
voltage for 2.5mm (BI) or 1.6x1960=3136Vac. (excellent agreement)
That approach would align with that of 664-1 section 3.1.5 {Dimensioning of
clearances for basic, supplementary and reinforced insulation}.
To look up a test voltage for a clearance dimensioned for RI and then
multiply that by 1.6 provides an overstress dielectric test as I see it.
Subject: UL61010A-1 Voltage Tests levels for DB
(Chris Wells, [email protected])
As some of you know from my other email strings, I have been digging into the
new 2nd edition UL61010A-1.
I need to determine the test voltages (AC high pot) for each circuit and need
your help understanding the approach.
UL61010A-1 is different in a number of ways - particularly the tables out of
annex D are gone and the rational pushed into mostly section 6.
As an example I am trying to determine the High pot requirements for my power
supply input circuit.
I have given up on the single basic approach for now.
Using table 4 for mains the single basic C&C is 3mm.
Double that for Reinforced and I get 6mm.
The Voltage test section has a table 9 which shows the spacing of single basic
versus test voltage.
A very important sentence says that one takes the single basic test voltage
and multiplies it X 1.6.
There are two ways one could interpret this statement:
1) Take the basic barrier value of 3mm - find corresponding test
voltage and multiply it times
1.6. From memory I think this is 2210 X 1.6 = 3536. This makes sense to me
in that one would have excess C&C as a safety margin and the values are
similar to those found in annex D of the first edition.
2) Take the basic barrier value of 6mm - find the corresponding test
voltage and multiply it times 1.6. I do not have the exact values in memory
but this pushes the test voltage > 5K. This does not make sense in that the
C&C limit is too tight to support the test voltage and does not follow the
first edition limits.
Hopefully approach 1 is correct and I can sleep better.
If not then I do not understand the rational for the high test voltages.
Approach number 2 appears to be double jeopardy - first doubling the C&C and
then adding extra test voltage on top of that.
Also If one has a grounded chassis but trying to support double basic
isolation to the power supply secondary does this push the design to have
double basic isolation relative to the chassis too? The standard says that
the chassis C&C only needs to be single Basic but I suspect I must design to
my weakest link and make all of it 6mm? Same question for Y caps. Would this
push me from Y2 to Y1? The Y caps are grounded to the PCB ground plain which
is bonded well to the chassis.
I have asked these questions of our UL representative but the answer is slow
in coming.
Ultimately they will be my ultimate answer but I would appreciate any insight
in the meantime.
8.1.2 and Figure 4 (Page 63)
(John Allen, ERA Technology, to the IEC Committee Chairman)
According to Clause 8.1.2, Figure 4 consists of two drawings called "Figure 4"
and "Figure 4a)" - but neither is actually labelled in the Figure to show
which is which!
Clause 9
3) Clause 9 and Figure 5 (Page 66)
(John Allen, ERA Technology, to the IEC Committee Chairman)
There are several misprints in Fig 5 "Flow chart to explain the requirements
for protection against the spread of fire".
On the right hand side of the diagram there appear to be arrows missing
between the boxes for:
i) "Construction requirements for components 9.2.1 a)" and "ENCLOSURE
requirements 9.2.1 b)"
and
(ii) between "ENCLOSURE requirements 9.2.1 b)" and "Requirements for flammable
liquids 9.4 c), d) or e)".
Additionally, the Flow chart symbols in this diagram do not appear to conform
to some generally accepted principles, i.e. should there not be "decision
("OR")" box symbols where alternative routes are available (e.g. as in Fig
10).
4) Clause 9.3 and Tables 13 & 14 (Page 69)
(John Allen, ERA Technology, to the IEC Committee Chairman)
In 9.3 b) 2) the reference should be to Table 14 rather than Table 13.
5) Clause 10.5.3 and Figure 8 (Page 75)
(John Allen, ERA Technology, to the IEC Committee Chairman)
The Ball Pressure Test equipment is illustrated and referred to, but all the
dimensions for the equipment have been omitted.
Either these dimensions shall be placed on the diagram, or reference shall be
made to the appropriate IEC/ISO test standard (as is done for the Vicat test)."
From: John Allen [mailto:[email protected]]
Sent: 08 December 2004 09:29
To: - EMC PSTC Posts (E-mail)
Subject: RE: IEC/EN 61010-1 Edition 2
Hi Folks
For the mutual benefit (and certainly for my own!) I am going to try to put
together a collated set of the comments on the above, from what we already
knew and what people have sent me in the last few days.
I will also include anything I can find publically on IEC and CENELEC CTL
decisions, etc.
I will then make it available to anyone who wants it - warts and all, and
obviously with no guarrantees as I am not "on the inside"!
I aim to do this within before Xmas.
So, if anyone has anything else to add/points to query, then please let me
know before that.
PS: I note that UL have issued Practical Application Guidelines (PAG) for
60950 - have they done that for 61010, and if so does anyone have access to
them as that could be useful?
John Allen,
Technical Consultant
EMC and Safety Engineering
ERA Technology Ltd.
Cleeve Road
Leatherhead
Surrey KT22 7SA
UK
Tel: +44-1372-367025 (Direct)
+44-1372-367000 (Switchboard)
Fax: +44-1372-367102
Please take a minute to visit my recently updated (Sept 04) web pages at
http://www.era.co.uk/services/rcm.asp
and the main ERA Website at http://www.era.co.uk
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Copyright ERA Technology Ltd. 2005. (www.era.co.uk). All rights reserved. The
information supplied in this Commercial Communication should be treated in
confidence.
No liability whatsoever is accepted for any loss or damage
suffered as a result of accessing this message or any attachments.
**********************************************************************
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