Re: [PSES] Couple of loosely related safety questions

[Richard Nute]

 

 

Hi Brian:

 

This does not answer your questions, but MAY give you an analysis tool:

 

CLEARANCE is standards name for AIR INSULATION.

 

CREEPAGE DISTANCE is standards name for DISTANCE ACROSS THE SURFACE OF SOLID
INSULATION.

 

Hope to meet you at the Symposium!

 

Best regards,

Rich

 

 

From: Brian Gregory [mailto:brian_greg...@netzero.net] 
Sent: Friday, April 26, 2024 4:12 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] Couple of loosely related safety questions

 

 

1.  Clearances for US Safety:  

 

I'd cite the relevant standards, but they are so alike (identical Clearance
tables), and so alike to UL 508, I'll defer.  Here's the question:

 

When citing clearance spacing from "uninsulated live components"  does one
measure from the edge of a PCB to the enclosure well, or only from the live
components, like a pad, or the bottom pin of a thru-hole cap?

1a.  what sort of passivation or RTV could make those live components not
"uninsulated"?

 

2.  Slots to increase creepage for high-voltage components

 

A FET that's rated for say 600V does not have to follow PCB-creepage rules
for 600V, is clearly stated places like UL 1741, §26.1.1 exception #8.  For
other components, like say 1000V caps in 0805 packages or FET driver chips
the requirements aren't as clear.  Is a slot needed to maintain creepage or
not if the component is properly rated?  It does appear from a TI support
page for dual-bridge converters, that slots are recommended in order to
prevent contamination that may compromise the components isolation
performance.

 

My gut says:  no, slots are not needed between component terminals on a PCB,
but could be recommended for sensitive parts, like FET drivers.

 

Thoughts? 

 

Colorado Brian 

 

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Re: [PSES] Couple of loosely related safety questions

[John Allen]

Thank you, Rich!

Over 240 have already registered for ISPCE 2024!  This is the place to be for 
all Product Safety and Certifications knowledge transfer and networking - 
https://2024.psessymposium.org/.

Best Regards and Be Safe,

John

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From: Richard Nute 
Sent: Friday, April 26, 2024 6:54 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Couple of loosely related safety questions


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Hi Brian:

You should attend the IEEE PSES Symposium in Chicago next week to get the 
answers to these questions from experts.  Lots of experts in clearance and 
creepage will be there and will be happy to provide you with answers!

Best regards,
Rich


From: Brian Gregory [mailto:brian_greg...@netzero.net]
Sent: Friday, April 26, 2024 4:12 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] Couple of loosely related safety questions


1.  Clearances for US Safety:

I'd cite the relevant standards, but they are so alike (identical Clearance 
tables), and so alike to UL 508, I'll defer.  Here's the question:

When citing clearance spacing from "uninsulated live components"  does one 
measure from the edge of a PCB to the enclosure well, or only from the live 
components, like a pad, or the bottom pin of a thru-hole cap?
1a.  what sort of passivation or RTV could make those live components not 
"uninsulated"?

2.  Slots to increase creepage for high-voltage components

A FET that's rated for say 600V does not have to follow PCB-creepage rules for 
600V, is clearly stated places like UL 1741, §26.1.1 exception #8.  For other 
components, like say 1000V caps in 0805 packages or FET driver chips the 
requirements aren't as clear.  Is a slot needed to maintain creepage or not if 
the component is properly rated?  It does appear from a TI support page for 
dual-bridge converters, that slots are recommended in order to prevent 
contamination that may compromise the components isolation performance.

My gut says:  no, slots are not needed between component terminals on a PCB, 
but could be recommended for sensitive parts, like FET drivers.

Thoughts?

Colorado Brian



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To 

Re: [PSES] Couple of loosely related safety questions

[Richard Nute]

 

Hi Brian:

 

You should attend the IEEE PSES Symposium in Chicago next week to get the
answers to these questions from experts.  Lots of experts in clearance and
creepage will be there and will be happy to provide you with answers!

 

Best regards,

Rich

 

 

From: Brian Gregory [mailto:brian_greg...@netzero.net] 
Sent: Friday, April 26, 2024 4:12 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] Couple of loosely related safety questions

 

 

1.  Clearances for US Safety:  

 

I'd cite the relevant standards, but they are so alike (identical Clearance
tables), and so alike to UL 508, I'll defer.  Here's the question:

 

When citing clearance spacing from "uninsulated live components"  does one
measure from the edge of a PCB to the enclosure well, or only from the live
components, like a pad, or the bottom pin of a thru-hole cap?

1a.  what sort of passivation or RTV could make those live components not
"uninsulated"?

 

2.  Slots to increase creepage for high-voltage components

 

A FET that's rated for say 600V does not have to follow PCB-creepage rules
for 600V, is clearly stated places like UL 1741, §26.1.1 exception #8.  For
other components, like say 1000V caps in 0805 packages or FET driver chips
the requirements aren't as clear.  Is a slot needed to maintain creepage or
not if the component is properly rated?  It does appear from a TI support
page for dual-bridge converters, that slots are recommended in order to
prevent contamination that may compromise the components isolation
performance.

 

My gut says:  no, slots are not needed between component terminals on a PCB,
but could be recommended for sensitive parts, like FET drivers.

 

Thoughts? 

 

Colorado Brian 

 


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[PSES] Couple of loosely related safety questions

[Brian Gregory]

 1.  Clearances for US Safety:   I'd cite the relevant standards, but they are 
so alike (identical Clearance tables), and so alike to UL 508, I'll defer.  
Here's the question: When citing clearance spacing from "uninsulated live 
components"  does one measure from the edge of a PCB to the enclosure well, or 
only from the live components, like a pad, or the bottom pin of a thru-hole 
cap?1a.  what sort of passivation or RTV could make those live components not 
"uninsulated"? 2.  Slots to increase creepage for high-voltage components A FET 
that's rated for say 600V does not have to follow PCB-creepage rules for 600V, 
is clearly stated places like UL 1741, §26.1.1 exception #8.  For other 
components, like say 1000V caps in 0805 packages or FET driver chips the 
requirements aren't as clear.  Is a slot needed to maintain creepage or not if 
the component is properly rated?  It does appear from a TI support page for 
dual-bridge converters, that slots are recommended in order to prevent 
contamination that may compromise the components isolation performance. My gut 
says:  no, slots are not needed between component terminals on a PCB, but could 
be recommended for sensitive parts, like FET drivers. Thoughts?  Colorado Brian

-

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Re: [PSES] DoC - reference to ROHS directive

[Matthew Wilson | GBE]

In our experience purchasers/compliance officers in large retail organisations 
expect to explicitly see the RoHS amendment listed in the DoC text as per Mike 
writes below, because this ticks their box that the product has addressed the 
additional four substances the amendment was concerned with.  They may also 
want it to say ‘RoHS 3’ in the DoC and supporting documentation (technical 
file) too.

Hence a triumph of commercial requirements/persons with clipboards(!) to use 
colloquial terms and extra words over the actual obligation.  I gave up arguing 
and just did what they wanted, path of least resistance and all that!

Have had some other run ins with some retailers on some other things too that 
weren’t relevant to the product in question, but they wanted it declared none 
the less.  I won that one though   A story for my book for whenever I get to 
retirement age (probably never because the UK will be broke by then but I 
digress!)

Matthew Wilson,
GB Electronics (UK) Ltd.


Matthew WilsonMIET
Technical Director
GB Electronics (UK) Ltd
matthew.wil...@gbelectronics.com
www.gbelectronics.com
+44 (0) 1903 244 500
Ascot House|Mulberry Close|Woods Way
Goring-by-Sea|West Sussex|BN12 4QY|UK
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From: Charlie Blackham 
Sent: Monday, April 22, 2024 7:26 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] DoC - reference to ROHS directive

I wouldn’t say that it was “wrong” to add the amendment, though I don’t 
recommend adding it, but since the amendment applies whether you like it or 
not, you don’t need to declare that you have applied it as it’s inherent in a 
declaration to 2011/65/EU.

The same goes for any exemptions you may have applied, or indeed have 
previously applied but have now expired.

Best regards
Charlie

Charlie Blackham
Sulis Consultants Ltd
Tel: +44 (0)7946 624317
Web: https://sulisconsultants.com/
Registered in England and Wales, number 05466247

From: MIKE SHERMAN mailto:msherma...@comcast.net>>
Sent: Monday, April 22, 2024 2:43 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] DoC - reference to ROHS directive

What I've seen is language like
"2011/65/EU RoHS directive with amendment 2015/863/EU"
or
"2011/65/EU RoHS directive as amended by 2015/863/EU"

The 2015 amendment adds four substances to the original six, so you should 
mention both it and the 2011 directive.

Mike Sherman
Sherman PSC LLC
On 04/21/2024 12:52 PM CDT Amund Westin 
mailto:am...@westin-emission.no>> wrote:


I have the last 10+ years made reference to ROHS directive 2011/65/EU in the 
DoC.
Now, I have been told to switch to 2015/863/EU? Is that correct?

>From what I see on the EU web site, 2015/863 is a Commission Delegated 
>Directive, amending Annex II to Directive 2011/65/EU
As I understand, 2011/65/EU is still in charge, and is the directive to be 
listed in the DoC.

Comments?

BR Amund




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