Re: [PSES] EN/IEC 61010-1 insulation question

2023-05-16 Thread Richard Nute 
 

 

Hi James:

 

On further consideration, the standard’s “NOTE” following 6.7.3.1 is incorrect. 
 When a hi-pot test is done on the primary (mains) circuit, the voltage 
(attenuated) will also appear (where it can) in secondary circuits due to the 
capacitance to the primary circuits.  In other words, the primary circuit 
hi-pot test tests all possible insulations, whether primary or secondary.  

 

Of course, the standard requires hi-pot tests of the secondary circuits 
regardless of my assertion.  

 

Best regards,

Rich

 

 

From: James Pawson (U3C)  
Sent: Tuesday, May 16, 2023 11:08 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG; Richard Nute 
Subject: Re: [PSES] EN/IEC 61010-1 insulation question

 

Thanks Richard! 



 Richard Nute wrote 

 

Hi James:

 

My answers to your questions:

 

1.  Does 6.7.3   apply for the clearance between the secondary 
winding and earth as indicated?

Yes.  

2.  If NO to 1) then what parts should this insulation be between? 
3.  If YES to 1) then:

a.  what is the safety hazard that is being addressed by applying Basic 
insulation values from Table 6 here?

The standard’s assumption is that transient voltages do appear in secondary 
circuits.  See NOTE following 6.7.3.1 <http://6.7.3.1> .  A transient voltage 
can cause a clearance or creepage to fail.  Solid insulation is required to 
have suitable electric strength to withstand the transient voltage. 

b.  Why isn’t this shown on Figure D.1e) as being required?

I assume that the figures are either insulation in general, including 
clearances (air insulation) or just for solid insulation.  

4.  If the working voltage between terminals X and Y in the sketch is less 
than the Hazardous Live thresholds in 6.3.1   then it is be 
permitted to be present on an Acccessible external terminal, correct?

Yes.

5.  Earthing either end of this winding will make 6.7.3   
redundant, correct?

I wouldn’t describe the requirement as “redundant.”  If one end of the winding 
is connected to earth, then clearly the clearance and creepage requirements do 
not apply to that one terminal.  However, the other terminal still must meet 
the clearance and creepage requirement.  

 

The standard seems not clear as to whether clearance (air insulation) is 
considered as insulation or a separate parameter.  

 

Note that the values for creepage distance are based on rated voltage, not 
transient voltage.  This is because failure of a creepage is caused by a 
long-term voltage.  However, physically, a creepage cannot be less than a 
clearance.   

 

Good luck,

Rich

 

 


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Re: [PSES] EN/IEC 61010-1 insulation question

2023-05-16 Thread James Pawson (U3C) 
Thanks Richard! 

 Richard Nute wrote 

> 
>
>Hi James:
>
> 
>
>My answers to your questions:
>
> 
>
>1. Does 6.7.3 apply for the clearance between the secondary winding and
>earth as indicated?
>
>Yes.  
>
>2. If NO to 1) then what parts should this insulation be between? 
>3. If YES to 1) then:
>
>a. what is the safety hazard that is being addressed by applying Basic
>insulation values from Table 6 here?
>
>The standard's assumption is that transient voltages do appear in secondary
>circuits.  See NOTE following 6.7.3.1.  A transient voltage can cause a
>clearance or creepage to fail.  Solid insulation is required to have
>suitable electric strength to withstand the transient voltage. 
>
>b. Why isn't this shown on Figure D.1e) as being required?
>
>I assume that the figures are either insulation in general, including
>clearances (air insulation) or just for solid insulation.  
>
>4. If the working voltage between terminals X and Y in the sketch is
>less than the Hazardous Live thresholds in 6.3.1 then it is be permitted to
>be present on an Acccessible external terminal, correct?
>
>Yes.
>
>5. Earthing either end of this winding will make 6.7.3 redundant,
>correct?
>
>I wouldn't describe the requirement as "redundant."  If one end of the
>winding is connected to earth, then clearly the clearance and creepage
>requirements do not apply to that one terminal.  However, the other terminal
>still must meet the clearance and creepage requirement.  
>
> 
>
>The standard seems not clear as to whether clearance (air insulation) is
>considered as insulation or a separate parameter.  
>
> 
>
>Note that the values for creepage distance are based on rated voltage, not
>transient voltage.  This is because failure of a creepage is caused by a
>long-term voltage.  However, physically, a creepage cannot be less than a
>clearance.   
>
> 
>
>Good luck,
>
>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:
>http://www.ieee-pses.org/emc-pstc.html
>
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>unsubscribe)
>List rules: http://www.ieee-pses.org/listrules.html
>
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>Mike Cantwell 
>
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>David Heald: 
>_
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Re: [PSES] EN/IEC 61010-1 insulation question

2023-05-15 Thread Richard Nute 
 

Hi James:

 

My answers to your questions:

 

1.  Does 6.7.3 apply for the clearance between the secondary winding and
earth as indicated?

Yes.  

2.  If NO to 1) then what parts should this insulation be between? 
3.  If YES to 1) then:

a.  what is the safety hazard that is being addressed by applying Basic
insulation values from Table 6 here?

The standard's assumption is that transient voltages do appear in secondary
circuits.  See NOTE following 6.7.3.1.  A transient voltage can cause a
clearance or creepage to fail.  Solid insulation is required to have
suitable electric strength to withstand the transient voltage. 

b.  Why isn't this shown on Figure D.1e) as being required?

I assume that the figures are either insulation in general, including
clearances (air insulation) or just for solid insulation.  

4.  If the working voltage between terminals X and Y in the sketch is
less than the Hazardous Live thresholds in 6.3.1 then it is be permitted to
be present on an Acccessible external terminal, correct?

Yes.

5.  Earthing either end of this winding will make 6.7.3 redundant,
correct?

I wouldn't describe the requirement as "redundant."  If one end of the
winding is connected to earth, then clearly the clearance and creepage
requirements do not apply to that one terminal.  However, the other terminal
still must meet the clearance and creepage requirement.  

 

The standard seems not clear as to whether clearance (air insulation) is
considered as insulation or a separate parameter.  

 

Note that the values for creepage distance are based on rated voltage, not
transient voltage.  This is because failure of a creepage is caused by a
long-term voltage.  However, physically, a creepage cannot be less than a
clearance.   

 

Good luck,

Rich

 

 


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Re: [PSES] EN/IEC 61010-1 insulation question

2023-05-12 Thread James Pawson (U3C) 
Hello all,

 

Thanks for the replies. 

 

I got to the bottom of my issue. All of clause 6.7 only applies to Hazardous
Live voltages. This voltage is not above the threshold so these requirements
for insulation do not apply.

 

Thanks and all the best

James

 

James Pawson

Managing Director & EMC Problem Solver

 

Unit 3 Compliance Ltd

EMC : Environmental & Vibration : Electrical Safety : CE & UKCA :
Consultancy

 

  www.unit3compliance.co.uk |
 ja...@unit3compliance.co.uk 

+44(0)1274 911747  |  +44(0)7811 139957

2 Wellington Business Park, New Lane, Bradford, BD4 8AL

Registered in England and Wales # 10574298

 

Office hours:

Every morning my full attention is on consultancy, testing, and
troubleshooting activities for our customers' projects. I'm contactable
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For inquiries, bookings, and testing updates please send us an email on
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01274 911747. Our lead times for testing and consultancy are typically 4-5
weeks.

 

 

 

 

From: James Pawson (U3C)  
Sent: Wednesday, May 10, 2023 5:42 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] EN/IEC 61010-1 insulation question

 

Hello experts, it's me again, with another safety question.

 

May I ask for your thoughts on a clause in EN 61010-1? This is about the
difference between 6.7.2 and 6.7.3. The attached sketch explains my
thinking.

 

The circuit is a 24Vdc secondary circuit derived from an AC/DC SMPS.

 

Questions:

1.  Does 6.7.3 apply for the clearance between the secondary winding and
earth as indicated?
2.  If NO to 1) then what parts should this insulation be between? 
3.  If YES to 1) then:

a.  what is the safety hazard that is being addressed by applying Basic
insulation values from Table 6 here?
b.  Why isn't this shown on Figure D.1e) as being required?

4.  If the working voltage between terminals X and Y in the sketch is
less than the Hazardous Live thresholds in 6.3.1 then it is be permitted to
be present on an Acccessible external terminal, correct?
5.  Earthing either end of this winding will make 6.7.3 redundant,
correct?

 

Thanks in advance.

 

All the best

James

 

James Pawson

Unit 3 Compliance Ltd

EMC : Environmental & Vibration : Electrical Safety : CE & UKCA :
Consultancy

 

  www.unit3compliance.co.uk |
 ja...@unit3compliance.co.uk 

+44(0)1274 911747  |  +44(0)7811 139957

2 Wellington Business Park, New Lane, Bradford, BD4 8AL

Registered in England and Wales # 10574298

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