Re: [PSES] requirement for spacings

[John Woodgate]

In message <002401d0eca7$2cb83e30$8628ba90$@cs.com>, dated Fri, 11 Sep 
2015, Pete Perkins <0061f3f32d0c-dmarc-requ...@ieee.org> writes:



You are going where no man has gone before - to repeat a familiar
saying.


Let's hope it's not a five-year mission, though. It could easily be.
--
OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk
When I turn my back on the sun, it's to look for a rainbow
John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK

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Re: [PSES] requirement for spacings

[Pete Perkins]

Bostjan et al,

The original ideas that led to insulation coordination were
conceived in the early days of electricity when it was clear that failures
in the system should be forced into the smaller, cheaper components and not
the larger expensive components.  Best not to have to replace the generator
due to a failure.  

The long term experience in all of this was captured in IEC 60664 -
Insulation Coordination - requirements and was based upon the experience
with the extensive power grid in place worldwide.  

Now a goodly portion of this power grid is being replaced with local
sources - such as the windmill or solar panel sources being installed.
There are now many more players (such as the ones that you are dealing with)
in this business.  Not many of them have the same level of experience  as
the traditional suppliers and, as such, aren't watching all of the same
issues in getting into this market.  

The safety standards for products have been built upon the
traditional network practices and should be acceptable in this new
electro-space but difficult to apply, as you have found.  

There will be a lot of pushing and shoving to get the correct set of
requirements smoothly running here.  

From your description the extreme voltage is not an external
transient but an expected startup condition of the generator.  If it cannot
be kept from the dc/dc smps you are designing then you must consider
accommodating it.  Or, alternatively, since the difference is relatively
small between the max tolerance and the occasional peak, you may consider
ignoring it and put up with the difficulty it may cause occasionally.  

None of this provides direct standards guidance but should give you
a place to start discussions with the customer and the test house folks.  

You are going where no man has gone before - to repeat a familiar
saying.  

:>) br, Pete
 
Peter E Perkins, PE
Principal Product Safety Engineer
PO Box 23427
Tigard, ORe  97281-3427
 
503/452-1201 fone/fax
p.perk...@ieee.org
 
_ _ _ _ _

Hello Rich,

I understand your point.

Unit is DC/DC converter supplied from generator or windmill. There is a 3
phase rectifier in front of the unit. Wind mild has rated phase voltage 230V
tolerances of -15%/+30% (e.g. 195,5-299V). For short period (at start)
output voltage can achieve 343V~ (up to 1 min). When you rectify this values
you get rated voltage 563Vdc and with considered ac tolerances 480-730Vdc.

If you check IEC 60950-1 standard, it says you need to consider for dc mains
tolerances of -15%/+20% unless otherwise specified by the manufacturer. For
clearances and creepage distances you only need to consider rated voltage
(not tolerances) of the product (only 560VDC will be marked on the unit). In
this particular case manufacturer specified a bit higher tolerances. There
is nothing mention about value of tolerances.


I know many products have rated voltage 220-240V and operational voltage
range 180-276V. For clearances and creepage distances only 240V was
considered.

Therefore I am a bit confused what should we consider for determination of
working voltage. Is it rated voltage (marked on the unit) or we need to
consider also tolerances or even short-term voltage?

Best regards,
Bostjan



-Original Message-
From: Richard Nute [mailto:ri...@ieee.org]
Sent: Thursday, September 10, 2015 12:28 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] requirement for spacings

> I can't understand how a 'rated voltage' can be
560 V
> +30%/-15%. It must
> mean something other than what is normally understood as 'rated 
> voltage'
> in safety standards.
 
In the IEC, rated voltage is a value assigned by the manufacturer.  

For years, standards committees have attempted to specify one or more
formats for the voltage rating.  Each standard is different, and sometimes
each edition is different.  

The problem is when a manufacturer uses a single, nominal value.  We know
that line voltages vary, so standards committees choose, say, +6%, -10%.

We have commonly seen wide-ranging power supplies rated 90-250 volts.  But,
we cannot fault a manufacturer for rating his wide-ranging product as 150
volts, +166%, -60%.  With your i-Phone, you can easily calculate whether the
equipment will operate on your power line!

In this case, the manufacturer has rated his product to operate from 470 to
728 volts.  What is wrong?


Best regards,
Rich

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Re: [PSES] requirement for spacings

[John Woodgate]

In message , 
dated Thu, 10 Sep 2015, =?iso-8859-2?Q?Bo=B9tjan_Glavi=E8?= 
 writes:


Therefore I am a bit confused what should we consider for determination 
of working voltage. Is it rated voltage (marked on the unit) or we need 
to consider also tolerances or even short-term voltage?


Rated voltage range should not be indicated as percentages, but as '470 
V - 728 V' in accordance with IEC/EN 61293. Then it's easier to see that 
the working voltage for determination of clearance and creepage is at 
least 728 V, but may be higher, depending on how over-voltages, if they 
occur, are treated in the relevant safety standard.

--
OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk
When I turn my back on the sun, it's to look for a rainbow
John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK

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Re: [PSES] requirement for spacings

[John Woodgate]

In message <002901d0eb4e$c4f177c0$4ed46740$@ieee.org>, dated Wed, 9 Sep 
2015, Richard Nute  writes:



In the IEC, rated voltage is a value assigned by the manufacturer.


Agreed; I introduced that simplified definition.


For years, standards committees have attempted to specify one or more 
formats for the voltage rating.  Each standard is different, and 
sometimes each edition is different.


Supply voltage rating is a special case, since indeed it may be 
multi-valued, but few other 'rated values' are multi-valued. IEC 61293 
(also EN 61293) (formerly a TC16 document, now TC3) specifies how supply 
voltage data shall be indicated. This was taken over from an original 
incentive of TC84.


The problem is when a manufacturer uses a single, nominal value.  We 
know that line voltages vary, so standards committees choose, say, +6%, 
-10%.


I'm not sure that's relevant to how the manufacturer *indicates* the 
rated supply voltage.


We have commonly seen wide-ranging power supplies rated 90-250 volts. 
But, we cannot fault a manufacturer for rating his wide-ranging product 
as 150 volts, +166%, -60%.


Not in accordance with IEC 61293. In any case, we do not know that the 
560 V is a supply voltage.


With your i-Phone, you can easily calculate whether the equipment will 
operate on your power line!


In this case, the manufacturer has rated his product to operate from 
470 to 728 volts.  What is wrong?


According to IEC 61293, that is indicated by '470 V - 728 V'.
--
OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk
When I turn my back on the sun, it's to look for a rainbow
John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK

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Re: [PSES] requirement for spacings

[Boštjan Glavič]

Hello Rich,

I understand your point.

Unit is DC/DC converter supplied from generator or windmill. There is a 3 phase 
rectifier in front of the unit. Wind mild has rated phase voltage 230V 
tolerances of -15%/+30% (e.g. 195,5-299V). For short period (at start) output 
voltage can achieve 343V~ (up to 1 min). When you rectify this values you get 
rated voltage 563Vdc and with considered ac tolerances 480-730Vdc.

If you check IEC 60950-1 standard, it says you need to consider for dc mains 
tolerances of -15%/+20% unless otherwise specified by the manufacturer. For 
clearances and creepage distances you only need to consider rated voltage (not 
tolerances) of the product (only 560VDC will be marked on the unit). In this 
particular case manufacturer specified a bit higher tolerances. There is 
nothing mention about value of tolerances.


I know many products have rated voltage 220-240V and operational voltage range 
180-276V. For clearances and creepage distances only 240V was considered.

Therefore I am a bit confused what should we consider for determination of 
working voltage. Is it rated voltage (marked on the unit) or we need to 
consider also tolerances or even short-term voltage?

Best regards,
Bostjan



-Original Message-
From: Richard Nute [mailto:ri...@ieee.org] 
Sent: Thursday, September 10, 2015 12:28 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] requirement for spacings

> I can't understand how a 'rated voltage' can be
560 V
> +30%/-15%. It must
> mean something other than what is normally understood as 'rated 
> voltage'
> in safety standards.
 
In the IEC, rated voltage is a value assigned by the manufacturer.  

For years, standards committees have attempted to specify one or more formats 
for the voltage rating.  Each standard is different, and sometimes each edition 
is different.  

The problem is when a manufacturer uses a single, nominal value.  We know that 
line voltages vary, so standards committees choose, say, +6%, -10%.

We have commonly seen wide-ranging power supplies rated 90-250 volts.  But, we 
cannot fault a manufacturer for rating his wide-ranging product as 150 volts, 
+166%, -60%.  With your i-Phone, you can easily calculate whether the equipment 
will operate on your power line!

In this case, the manufacturer has rated his product to operate from 470 to 728 
volts.  What is wrong?


Best regards,
Rich

-

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discussion list. To post a message to the list, send your e-mail to 


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Re: [PSES] requirement for spacings

[Richard Nute]

> I can't understand how a 'rated voltage' can be
560 V
> +30%/-15%. It must
> mean something other than what is normally
> understood as 'rated voltage'
> in safety standards.
 
In the IEC, rated voltage is a value assigned by
the manufacturer.  

For years, standards committees have attempted to
specify one or more formats for the voltage
rating.  Each standard is different, and sometimes
each edition is different.  

The problem is when a manufacturer uses a single,
nominal value.  We know that line voltages vary,
so standards committees choose, say, +6%, -10%.

We have commonly seen wide-ranging power supplies
rated 90-250 volts.  But, we cannot fault a
manufacturer for rating his wide-ranging product
as 150 volts, +166%, -60%.  With your i-Phone, you
can easily calculate whether the equipment will
operate on your power line!

In this case, the manufacturer has rated his
product to operate from 470 to 728 volts.  What is
wrong?


Best regards,
Rich

-

This message is from the IEEE Product Safety Engineering Society emc-pstc 
discussion list. To post a message to the list, send your e-mail to 


All emc-pstc postings are archived and searchable on the web at:
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Re: [PSES] requirement for spacings

[John Woodgate]

In message , 
dated Wed, 9 Sep 2015, =?iso-8859-2?Q?Bo=B9tjan_Glavi=E8?= 
 writes:


Manufacturer specified rated voltage of his product as 560VDC +30%/-15% 
but input voltage can temporarily reach 840VDC (max 1 min).


I can't understand how a 'rated voltage' can be 560 V +30%/-15%. It must 
mean something other than what is normally understood as 'rated voltage' 
in safety standards.

--
OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk
When I turn my back on the sun, it's to look for a rainbow
John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK

-

This message is from the IEEE Product Safety Engineering Society emc-pstc discussion 
list. To post a message to the list, send your e-mail to 

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Re: [PSES] requirement for spacings

[Brian O'Connell]

bmail rev 3.13 smptlib 2.7.10

UL508 points to UL840 as alternate for spacing at terminals and internal 
crp/clr. UL508 wants you to be min OV cat III for use of UL840. Also UL840 
addresses 'recurring peak voltages' for PCB spacings.

Brian


From: McDiarmid, Ralph [mailto:ralph.mcdiar...@schneider-electric.com] 
Sent: Wednesday, September 09, 2015 10:20 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] requirement for spacings

Clause 5.2.3 in EN50178 (Decisive Voltage) should help clarify.  It writes 
about "occurs continuously" and "worst operating condition". 

I don't think UL508 will be much help, unless it allows use of UL840 
(insulation coordination) as an alternate approach to spacings.
___ 

Ralph McDiarmid  |   Schneider Electric   |  Solar Business  |   CANADA  |   
Regulatory Compliance Engineering 


From: 
Boštjan Glavič  
To: 
EMC-PSTC@LISTSERV.IEEE.ORG, 
Date: 
09/09/2015 09:47 AM 
Subject: 
Re: [PSES] requirement for spacings




Dear Scot, Douglas,

Thank you.

Unit is investigated to UL 508, IEC 62477-1 and EN 50178. I have experiences 
with IEC 60950-1 which requires to determine required distances based on rated 
voltage - tolerances not considered. 840 VDC might appear on the input during 
start up of the generator.
However I need to agree with you that 30% tolerances seem to be very high and 
not consider that might be wrong.

Best regards,
Bostjan


On 9. sep. 2015, at 17.41, Douglas Powell 
mailto:doug...@gmail.com>> wrote:

Bostjan,

As Scott mentioned, it is very important to know which end standard is being 
applied to this product. In addition there are many other factors such as 
environmental conditions, application, location, etc.

If this is truly DC powered, it is entirely possible your spacings will be for 
secondary circuits and somewhat reduced. Nevertheless wiring, ‎connections, 
fuses and the like will have to be rated and certified/listed for that voltage.

If you can provide a little more information about the application and end use, 
we may be able to provide better assistance.

‎All the best, Doug


From: Scott Aldous
Sent: Wednesday, September 9, 2015 9:15 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG<mailto:EMC-PSTC@LISTSERV.IEEE.ORG>
Reply To: Scott Aldous
Subject: Re: [PSES] requirement for spacings


Hi Bostjan,

It's difficult to give detailed guidance without knowing what end standards are 
being applied, but the general guidance in IEC 60664-1 should be helpful.

In general, +30% tolerance on input voltage is outside the assumptions of most 
(if not all) safety standards. An electrical rating of 560Vdc +30%/-15% doesn't 
seem to be appropriate and should be expressed as a range instead. The range 
here is from 476 - 728 Vdc! For example, 600V rated wire would seem to be an 
acceptable choice for external wiring for the input of a device marked with a 
560V input rating, but in this case the input voltage may be able to be 
significantly higher than 600V for extended periods. A marked rating of 560Vdc 
would be misleading.

If your end standard allows the clearances to be determined based on assumed 
transient levels, then the nominal input voltage (or voltages) becomes less 
important for clearances as long as you are able to make an accurate assumption 
about the transients. The 840Vdc level potentially could be taken as a 
temporary overvoltage for the purposes of calculation of clearance, again 
depending on the end product standard. At least one end product standard that I 
know of, IEC 62109-1, takes both transient overvoltages and temporary 
overvoltages into account for calculation of clearances.

For creepage, at a minimum, I think you would want to base creepage distance 
requirements on the 728Vdc high end of the input voltage (560Vdc + 30%). 
Whether or not you should use the 840Vdc level instead may depend on the 
specifics of the case, such as how frequently this can happen, what controls 
are in place to ensure that this is reliably the case, etc. Again, the 
requirements of the end product standard need to be taken into account and will 
certainly influence your decision.

On Wed, Sep 9, 2015 at 4:03 AM, Boštjan Glavič 
mailto:bostjan.gla...@siq.si>> wrote:
Dear Experts,

Manufacturer specified rated voltage of his product as 560VDC +30%/-15% but 
input voltage can temporarily reach 840VDC (max 1 min).

Do we need to consider 840VDC for determination of required distances? Usually 
standard requires to consider rated voltage only what is in this case 560VDC 
(marked on the label).

Thank you for your support.
Best regards,
Bostjan


Boštjan Glavič
Laboratory of Electronic Engineering
Head of Laboratory
SIQ Ljubljana, Tržaška cesta 2
SI-1000 Ljubljana, Slovenia
T: + 386 (0)1 47 78 265
F: + 386 (0)1 47 78

Re: [PSES] requirement for spacings

[McDiarmid, Ralph]

Clause 5.2.3 in EN50178 (Decisive Voltage) should help clarify.  It writes 
about "occurs continuously" and "worst operating condition".

I don't think UL508 will be much help, unless it allows use of UL840 
(insulation coordination) as an alternate approach to spacings.
___ 


Ralph McDiarmid  |   Schneider Electric   |  Solar Business  |   CANADA  | 
  Regulatory Compliance Engineering 




From:
Boštjan Glavič 
To:
EMC-PSTC@LISTSERV.IEEE.ORG, 
Date:
09/09/2015 09:47 AM
Subject:
Re: [PSES] requirement for spacings



Dear Scot, Douglas,

Thank you.

Unit is investigated to UL 508, IEC 62477-1 and EN 50178. I have 
experiences with IEC 60950-1 which requires to determine required 
distances based on rated voltage - tolerances not considered. 840 VDC 
might appear on the input during start up of the generator.
However I need to agree with you that 30% tolerances seem to be very high 
and not consider that might be wrong.

Best regards,
Bostjan



On 9. sep. 2015, at 17.41, Douglas Powell mailto:doug...@gmail.com>> wrote:

Bostjan,

As Scott mentioned, it is very important to know which end standard is 
being applied to this product. In addition there are many other factors 
such as environmental conditions, application, location, etc.

If this is truly DC powered, it is entirely possible your spacings will be 
for secondary circuits and somewhat reduced. Nevertheless wiring, 
‎connections, fuses and the like will have to be rated and 
certified/listed for that voltage.

If you can provide a little more information about the application and end 
use, we may be able to provide better assistance.

‎All the best, Doug



From: Scott Aldous
Sent: Wednesday, September 9, 2015 9:15 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG<mailto:EMC-PSTC@LISTSERV.IEEE.ORG>
Reply To: Scott Aldous
Subject: Re: [PSES] requirement for spacings


Hi Bostjan,

It's difficult to give detailed guidance without knowing what end 
standards are being applied, but the general guidance in IEC 60664-1 
should be helpful.

In general, +30% tolerance on input voltage is outside the assumptions of 
most (if not all) safety standards. An electrical rating of 560Vdc 
+30%/-15% doesn't seem to be appropriate and should be expressed as a 
range instead. The range here is from 476 - 728 Vdc! For example, 600V 
rated wire would seem to be an acceptable choice for external wiring for 
the input of a device marked with a 560V input rating, but in this case 
the input voltage may be able to be significantly higher than 600V for 
extended periods. A marked rating of 560Vdc would be misleading.

If your end standard allows the clearances to be determined based on 
assumed transient levels, then the nominal input voltage (or voltages) 
becomes less important for clearances as long as you are able to make an 
accurate assumption about the transients. The 840Vdc level potentially 
could be taken as a temporary overvoltage for the purposes of calculation 
of clearance, again depending on the end product standard. At least one 
end product standard that I know of, IEC 62109-1, takes both transient 
overvoltages and temporary overvoltages into account for calculation of 
clearances.

For creepage, at a minimum, I think you would want to base creepage 
distance requirements on the 728Vdc high end of the input voltage (560Vdc 
+ 30%). Whether or not you should use the 840Vdc level instead may depend 
on the specifics of the case, such as how frequently this can happen, what 
controls are in place to ensure that this is reliably the case, etc. 
Again, the requirements of the end product standard need to be taken into 
account and will certainly influence your decision.

On Wed, Sep 9, 2015 at 4:03 AM, Boštjan Glavič mailto:bostjan.gla...@siq.si>> wrote:
Dear Experts,

Manufacturer specified rated voltage of his product as 560VDC +30%/-15% 
but input voltage can temporarily reach 840VDC (max 1 min).

Do we need to consider 840VDC for determination of required distances? 
Usually standard requires to consider rated voltage only what is in this 
case 560VDC (marked on the label).

Thank you for your support.
Best regards,
Bostjan



Boštjan Glavič
Laboratory of Electronic Engineering
Head of Laboratory
SIQ Ljubljana, Tržaška cesta 2
SI-1000 Ljubljana, Slovenia
T: + 386 (0)1 47 78 265
F: + 386 (0)1 47 78 444
E-Mail: bostjan.gla...@siq.si<mailto:bostjan.gla...@siq.si>



-

This message is from the IEEE Product Safety Engineering Society emc-pstc 
discussion list. To post a message to the list, send your e-mail to 
mailto:emc-p...@ieee.org>>

All emc-pstc postings are archived and searchable on the web at:
http://www.ieee-pses.org/emc-pstc.html

Attachments are not permitted but the IEEE PSES Online Communities site at 
http://product-compliance.oc.ieee.org/ can be used

Re: [PSES] requirement for spacings

[Boštjan Glavič]

Dear Scot, Douglas,

Thank you.

Unit is investigated to UL 508, IEC 62477-1 and EN 50178. I have experiences 
with IEC 60950-1 which requires to determine required distances based on rated 
voltage - tolerances not considered. 840 VDC might appear on the input during 
start up of the generator.
However I need to agree with you that 30% tolerances seem to be very high and 
not consider that might be wrong.

Best regards,
Bostjan



On 9. sep. 2015, at 17.41, Douglas Powell 
mailto:doug...@gmail.com>> wrote:

Bostjan,

As Scott mentioned, it is very important to know which end standard is being 
applied to this product. In addition there are many other factors such as 
environmental conditions, application, location, etc.

If this is truly DC powered, it is entirely possible your spacings will be for 
secondary circuits and somewhat reduced. Nevertheless wiring, ‎connections, 
fuses and the like will have to be rated and certified/listed for that voltage.

If you can provide a little more information about the application and end use, 
we may be able to provide better assistance.

‎All the best, Doug



From: Scott Aldous
Sent: Wednesday, September 9, 2015 9:15 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG<mailto:EMC-PSTC@LISTSERV.IEEE.ORG>
Reply To: Scott Aldous
Subject: Re: [PSES] requirement for spacings


Hi Bostjan,

It's difficult to give detailed guidance without knowing what end standards are 
being applied, but the general guidance in IEC 60664-1 should be helpful.

In general, +30% tolerance on input voltage is outside the assumptions of most 
(if not all) safety standards. An electrical rating of 560Vdc +30%/-15% doesn't 
seem to be appropriate and should be expressed as a range instead. The range 
here is from 476 - 728 Vdc! For example, 600V rated wire would seem to be an 
acceptable choice for external wiring for the input of a device marked with a 
560V input rating, but in this case the input voltage may be able to be 
significantly higher than 600V for extended periods. A marked rating of 560Vdc 
would be misleading.

If your end standard allows the clearances to be determined based on assumed 
transient levels, then the nominal input voltage (or voltages) becomes less 
important for clearances as long as you are able to make an accurate assumption 
about the transients. The 840Vdc level potentially could be taken as a 
temporary overvoltage for the purposes of calculation of clearance, again 
depending on the end product standard. At least one end product standard that I 
know of, IEC 62109-1, takes both transient overvoltages and temporary 
overvoltages into account for calculation of clearances.

For creepage, at a minimum, I think you would want to base creepage distance 
requirements on the 728Vdc high end of the input voltage (560Vdc + 30%). 
Whether or not you should use the 840Vdc level instead may depend on the 
specifics of the case, such as how frequently this can happen, what controls 
are in place to ensure that this is reliably the case, etc. Again, the 
requirements of the end product standard need to be taken into account and will 
certainly influence your decision.

On Wed, Sep 9, 2015 at 4:03 AM, Boštjan Glavič 
mailto:bostjan.gla...@siq.si>> wrote:
Dear Experts,

Manufacturer specified rated voltage of his product as 560VDC +30%/-15% but 
input voltage can temporarily reach 840VDC (max 1 min).

Do we need to consider 840VDC for determination of required distances? Usually 
standard requires to consider rated voltage only what is in this case 560VDC 
(marked on the label).

Thank you for your support.
Best regards,
Bostjan



Boštjan Glavič
Laboratory of Electronic Engineering
Head of Laboratory
SIQ Ljubljana, Tržaška cesta 2
SI-1000 Ljubljana, Slovenia
T: + 386 (0)1 47 78 265
F: + 386 (0)1 47 78 444
E-Mail: bostjan.gla...@siq.si<mailto:bostjan.gla...@siq.si>



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discussion list. To post a message to the list, send your e-mail to 
mailto:emc-p...@ieee.org>>

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Attachments are not permitted but the IEEE PSES Online Communities site at 
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--
Scott Aldous
Compliance Engineer
Google
650-253-1994
scottald...@google.com<mailto:scottald...@google.com>
-
---

Re: [PSES] requirement for spacings

[Douglas Powell]

  Bostjan,As Scott mentioned, it is very important to know which end standard is being applied to this product. In addition there are many other factors such as environmental conditions, application, location, etc.If this is truly DC powered, it is entirely possible your spacings will be for secondary circuits and somewhat reduced. Nevertheless wiring, ‎connections, fuses and the like will have to be rated and certified/listed for that voltage.  If you can provide a little more information about the application and end use, we may be able to provide better assistance.   ‎All the best, DougFrom: Scott AldousSent: Wednesday, September 9, 2015 9:15 AMTo: EMC-PSTC@LISTSERV.IEEE.ORGReply To: Scott AldousSubject: Re: [PSES] requirement for spacingsHi Bostjan,It's difficult to give detailed guidance without knowing what end standards are being applied, but the general guidance in IEC 60664-1 should be helpful.In general, +30% tolerance on input voltage is outside the assumptions of most (if not all) safety standards. An electrical rating of 560Vdc +30%/-15% doesn't seem to be appropriate and should be expressed as a range instead. The range here is from 476 - 728 Vdc! For example, 600V rated wire would seem to be an acceptable choice for external wiring for the input of a device marked with a 560V input rating, but in this case the input voltage may be able to be significantly higher than 600V for extended periods. A marked rating of 560Vdc would be misleading.If your end standard allows the clearances to be determined based on assumed transient levels, then the nominal input voltage (or voltages) becomes less important for clearances as long as you are able to make an accurate assumption about the transients. The 840Vdc level potentially could be taken as a temporary overvoltage for the purposes of calculation of clearance, again depending on the end product standard. At least one end product standard that I know of, IEC 62109-1, takes both transient overvoltages and temporary overvoltages into account for calculation of clearances.For creepage, at a minimum, I think you would want to base creepage distance requirements on the 728Vdc high end of the input voltage (560Vdc + 30%). Whether or not you should use the 840Vdc level instead may depend on the specifics of the case, such as how frequently this can happen, what controls are in place to ensure that this is reliably the case, etc. Again, the requirements of the end product standard need to be taken into account and will certainly influence your decision.On Wed, Sep 9, 2015 at 4:03 AM, Boštjan Glavič  wrote:Dear Experts,

Manufacturer specified rated voltage of his product as 560VDC +30%/-15% but input voltage can temporarily reach 840VDC (max 1 min).

Do we need to consider 840VDC for determination of required distances? Usually standard requires to consider rated voltage only what is in this case 560VDC (marked on the label).

Thank you for your support.
Best regards,
Bostjan



Boštjan Glavič
Laboratory of Electronic Engineering
Head of Laboratory
SIQ Ljubljana, Tržaška cesta 2
SI-1000 Ljubljana, Slovenia
T: + 386 (0)1 47 78 265
F: + 386 (0)1 47 78 444
E-Mail: bostjan.gla...@siq.si

 

-

This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to 

All emc-pstc postings are archived and searchable on the web at:
http://www.ieee-pses.org/emc-pstc.html

Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc.

Website:  http://www.ieee-pses.org/
Instructions:  http://www.ieee-pses.org/list.html (including how to unsubscribe)
List rules: http://www.ieee-pses.org/listrules.html

For help, send mail to the list administrators:
Scott Douglas 
Mike Cantwell 

For policy questions, send mail to:
Jim Bacher:  
David Heald: 
-- Scott AldousCompliance EngineerGoogle650-253-1994scottald...@google.com

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This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to t

Re: [PSES] requirement for spacings

[Scott Aldous]

Hi Bostjan,

It's difficult to give detailed guidance without knowing what end standards
are being applied, but the general guidance in IEC 60664-1 should be
helpful.

In general, +30% tolerance on input voltage is outside the assumptions of
most (if not all) safety standards. An electrical rating of 560Vdc
+30%/-15% doesn't seem to be appropriate and should be expressed as a range
instead. The range here is from 476 - 728 Vdc! For example, 600V rated wire
would seem to be an acceptable choice for external wiring for the input of
a device marked with a 560V input rating, but in this case the input
voltage may be able to be significantly higher than 600V for extended
periods. A marked rating of 560Vdc would be misleading.

If your end standard allows the clearances to be determined based on
assumed transient levels, then the nominal input voltage (or voltages)
becomes less important for clearances as long as you are able to make an
accurate assumption about the transients. The 840Vdc level potentially
could be taken as a temporary overvoltage for the purposes of calculation
of clearance, again depending on the end product standard. At least one end
product standard that I know of, IEC 62109-1, takes both transient
overvoltages and temporary overvoltages into account for calculation of
clearances.

For creepage, at a minimum, I think you would want to base creepage
distance requirements on the 728Vdc high end of the input voltage (560Vdc +
30%). Whether or not you should use the 840Vdc level instead may depend on
the specifics of the case, such as how frequently this can happen, what
controls are in place to ensure that this is reliably the case, etc. Again,
the requirements of the end product standard need to be taken into account
and will certainly influence your decision.

On Wed, Sep 9, 2015 at 4:03 AM, Boštjan Glavič 
wrote:

> Dear Experts,
>
> Manufacturer specified rated voltage of his product as 560VDC +30%/-15%
> but input voltage can temporarily reach 840VDC (max 1 min).
>
> Do we need to consider 840VDC for determination of required distances?
> Usually standard requires to consider rated voltage only what is in this
> case 560VDC (marked on the label).
>
> Thank you for your support.
> Best regards,
> Bostjan
>
>
>
> Boštjan Glavič
> Laboratory of Electronic Engineering
> Head of Laboratory
> SIQ Ljubljana, Tržaška cesta 2
> SI-1000 Ljubljana, Slovenia
> T: + 386 (0)1 47 78 265
> F: + 386 (0)1 47 78 444
> E-Mail: bostjan.gla...@siq.si
>
>
>
> -
> 
> This message is from the IEEE Product Safety Engineering Society emc-pstc
> discussion list. To post a message to the list, send your e-mail to <
> emc-p...@ieee.org>
>
> All emc-pstc postings are archived and searchable on the web at:
> http://www.ieee-pses.org/emc-pstc.html
>
> Attachments are not permitted but the IEEE PSES Online Communities site at
> http://product-compliance.oc.ieee.org/ can be used for graphics (in
> well-used formats), large files, etc.
>
> Website:  http://www.ieee-pses.org/
> Instructions:  http://www.ieee-pses.org/list.html (including how to
> unsubscribe)
> List rules: http://www.ieee-pses.org/listrules.html
>
> For help, send mail to the list administrators:
> Scott Douglas 
> Mike Cantwell 
>
> For policy questions, send mail to:
> Jim Bacher:  
> David Heald: 
>



-- 
Scott Aldous
Compliance Engineer
Google
650-253-1994
scottald...@google.com

-

This message is from the IEEE Product Safety Engineering Society emc-pstc 
discussion list. To post a message to the list, send your e-mail to 


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Attachments are not permitted but the IEEE PSES Online Communities site at 
http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used 
formats), large files, etc.

Website:  http://www.ieee-pses.org/
Instructions:  http://www.ieee-pses.org/list.html (including how to unsubscribe)
List rules: http://www.ieee-pses.org/listrules.html

For help, send mail to the list administrators:
Scott Douglas 
Mike Cantwell 

For policy questions, send mail to:
Jim Bacher:  
David Heald: 

[PSES] requirement for spacings

[Boštjan Glavič]

Dear Experts,

Manufacturer specified rated voltage of his product as 560VDC +30%/-15% but 
input voltage can temporarily reach 840VDC (max 1 min).

Do we need to consider 840VDC for determination of required distances? Usually 
standard requires to consider rated voltage only what is in this case 560VDC 
(marked on the label).

Thank you for your support.
Best regards,
Bostjan



Boštjan Glavič
Laboratory of Electronic Engineering
Head of Laboratory
SIQ Ljubljana, Tržaška cesta 2
SI-1000 Ljubljana, Slovenia
T: + 386 (0)1 47 78 265
F: + 386 (0)1 47 78 444
E-Mail: bostjan.gla...@siq.si

 

-

This message is from the IEEE Product Safety Engineering Society emc-pstc 
discussion list. To post a message to the list, send your e-mail to 


All emc-pstc postings are archived and searchable on the web at:
http://www.ieee-pses.org/emc-pstc.html

Attachments are not permitted but the IEEE PSES Online Communities site at 
http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used 
formats), large files, etc.

Website:  http://www.ieee-pses.org/
Instructions:  http://www.ieee-pses.org/list.html (including how to unsubscribe)
List rules: http://www.ieee-pses.org/listrules.html

For help, send mail to the list administrators:
Scott Douglas 
Mike Cantwell 

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Jim Bacher:  
David Heald: