Re: [PSES] Assess risk of electric shock from charged capacitors

2022-10-17 Thread Dan Roman 
Just charge them up with your DC hipot tester to peak voltage when in the
off state.if the circuit and your hipot tester allow.  May work in some
circumstances with simple front ends.

 

Dan

 

 

From: Ken Javor [mailto:ken.ja...@emccompliance.com] 
Sent: Monday, October 17, 2022 10:12 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Assess risk of electric shock from charged capacitors

 

I'm curious as to the rationale behind that. It should be obvious that the
power was turned off at the appropriate time. That would be demonstrated
using an o'scope, just as in the hit or miss method.

What's different?

Ken Javor
Phone: (256) 650-5261



  _  

From: "doug...@gmail.com" 
Reply-To: "doug...@gmail.com" 
Date: Mon, 17 Oct 2022 17:37:21 -0600
To: 
Subject: Re: [PSES] Assess risk of electric shock from charged capacitors

Ken,

Yes, but I have had certification engineers hesitate or disallow using any
home-brew solid state circuits to control safety testing.

-Doug


Douglas E Powell
Laporte, Colorado USA
doug...@gmail.com
LinkedIn  

(UTC -06:00) Mountain Time (US-MDT)




On Mon, Oct 17, 2022 at 1:18 PM Ken Javor 
wrote:

A simple circuit can provide disconnect at the peak of the ac waveform.

Ken Javor
Phone: (256) 650-5261




  _  


From: "doug...@gmail.com  " http://doug...@gmail.com> >
Reply-To: "doug...@gmail.com  " http://doug...@gmail.com> >
Date: Mon, 17 Oct 2022 13:08:17 -0600
To: http://EMC-PSTC@LISTSERV.IEEE.ORG> >
Subject: Re: [PSES] Assess risk of electric shock from charged capacitors

On the question of probe resistance, I always recommend 100:1 probes which
will have a negligible effect on overall timing.  Additionally, it may be
necessary to perform the test a number times to ensure the disconnect occurs
at the peak of the sine wave.  For me, experience has shown this may take up
to 10x attempts.

-Doug


Douglas E Powell
Laporte, Colorado USA
doug...@gmail.com  
LinkedIn  

(UTC -06:00) Mountain Time (US-MDT)




On Mon, Oct 17, 2022 at 11:32 AM Richard Nute http://ri...@ieee.org> > wrote:

 
 
Hi Scott:
 
Many dual channel scopes (whether digital or analog) include an "add"
function for the two channels.  One channel must be inverted to measure the
charged capacitance.
 
The resistance of the two probes must be accounted for in the capacitance
discharge time.  (The same - for only one probe -- is true for the scheme
using an isolating transformer.)
 
You should get the same results for both methods.
 
Best regards,
Rich 
IEEE Life Fellow
IEEE Medal for Environmental and Safety Technologies
 
 
 

From: Scott Xe http://scott...@gmail.com> > 
Sent: Monday, October 17, 2022 8:18 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG  
Subject: Re: [PSES] Assess risk of electric shock from charged capacitors
 

In order to judge if there is no risk of electric shock from charged
capacitors, it is required to measure the voltage across L and N of mains
plug after the removal of power input.  To avoid grounding loop between test
equipment and the unit under test, an isolating transformer is strongly
recommended.  I have learnt another way by using Add Function and two hot
probes of a dual channel DSO.  Can someone advise which way is more common
in safety conformity test.  Especially the latter one, I have not tried it
yet before and appreciate any notes I must take in the measurement.

 

Thanks and regards,

 

Scott
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Re: [PSES] Assess risk of electric shock from charged capacitors

2022-10-17 Thread Ken Javor 
I¹m curious as to the rationale behind that. It should be obvious that the
power was turned off at the appropriate time. That would be demonstrated
using an o¹scope, just as in the hit or miss method.

What¹s different?

Ken Javor
Phone: (256) 650-5261



From: "doug...@gmail.com" 
Reply-To: "doug...@gmail.com" 
Date: Mon, 17 Oct 2022 17:37:21 -0600
To: 
Subject: Re: [PSES] Assess risk of electric shock from charged capacitors

Ken,

Yes, but I have had certification engineers hesitate or disallow using any
home-brew solid state circuits to control safety testing.

-Doug


Douglas E Powell
Laporte, Colorado USA
doug...@gmail.com
LinkedIn 

(UTC -06:00) Mountain Time (US-MDT)




On Mon, Oct 17, 2022 at 1:18 PM Ken Javor 
wrote:
> A simple circuit can provide disconnect at the peak of the ac waveform.
> 
> Ken Javor
> Phone: (256) 650-5261
> 
> 
> 
> From: "doug...@gmail.com  "   >
> Reply-To: "doug...@gmail.com  "   >
> Date: Mon, 17 Oct 2022 13:08:17 -0600
> To: http://EMC-PSTC@LISTSERV.IEEE.ORG> >
> Subject: Re: [PSES] Assess risk of electric shock from charged capacitors
> 
> On the question of probe resistance, I always recommend 100:1 probes which
> will have a negligible effect on overall timing.  Additionally, it may be
> necessary to perform the test a number times to ensure the disconnect occurs
> at the peak of the sine wave.  For me, experience has shown this may take up
> to 10x attempts.
> 
> -Doug
> 
> 
> Douglas E Powell
> Laporte, Colorado USA
> doug...@gmail.com 
> LinkedIn 
> 
> (UTC -06:00) Mountain Time (US-MDT)
> 
> 
> 
> 
> On Mon, Oct 17, 2022 at 11:32 AM Richard Nute   > wrote:
>>  
>>  
>> Hi Scott:
>>  
>> Many dual channel scopes (whether digital or analog) include an ³add²
>> function for the two channels.  One channel must be inverted to measure the
>> charged capacitance.
>>  
>> The resistance of the two probes must be accounted for in the capacitance
>> discharge time.  (The same ­ for only one probe -- is true for the scheme
>> using an isolating transformer.)
>>  
>> You should get the same results for both methods.
>>  
>> Best regards,
>> Rich 
>> IEEE Life Fellow
>> IEEE Medal for Environmental and Safety Technologies
>>  
>>  
>>  
>> 
>> From: Scott Xe http://scott...@gmail.com> >
>> Sent: Monday, October 17, 2022 8:18 AM
>> To: EMC-PSTC@LISTSERV.IEEE.ORG 
>> Subject: Re: [PSES] Assess risk of electric shock from charged capacitors
>>  
>> 
>> In order to judge if there is no risk of electric shock from charged
>> capacitors, it is required to measure the voltage across L and N of mains
>> plug after the removal of power input.  To avoid grounding loop between test
>> equipment and the unit under test, an isolating transformer is strongly
>> recommended.  I have learnt another way by using Add Function and two hot
>> probes of a dual channel DSO.  Can someone advise which way is more common in
>> safety conformity test.  Especially the latter one, I have not tried it yet
>> before and appreciate any notes I must take in the measurement.
>> 
>>  
>> 
>> Thanks and regards,
>> 
>>  
>> 
>> Scott
>> -
>> 
>> 
>> 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:
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>> 
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>> unsubscribe) 
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> 
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Re: [PSES] Assess risk of electric shock from charged capacitors

2022-10-17 Thread Douglas E Powell 
Ken,

Yes, but I have had certification engineers hesitate or disallow using any
home-brew solid state circuits to control safety testing.

-Doug


Douglas E Powell
Laporte, Colorado USA
doug...@gmail.com
LinkedIn 

(UTC -06:00) Mountain Time (US-MDT)




On Mon, Oct 17, 2022 at 1:18 PM Ken Javor 
wrote:

> A simple circuit can provide disconnect at the peak of the ac waveform.
>
> Ken Javor
> Phone: (256) 650-5261
>
>
> --
> *From: *"doug...@gmail.com" 
> *Reply-To: *"doug...@gmail.com" 
> *Date: *Mon, 17 Oct 2022 13:08:17 -0600
> *To: *
> *Subject: *Re: [PSES] Assess risk of electric shock from charged
> capacitors
>
> On the question of probe resistance, I always recommend 100:1 probes which
> will have a negligible effect on overall timing.  Additionally, it may be
> necessary to perform the test a number times to ensure the disconnect
> occurs at the peak of the sine wave.  For me, experience has shown this may
> take up to 10x attempts.
>
> -Doug
>
>
> Douglas E Powell
> Laporte, Colorado USA
> doug...@gmail.com
> LinkedIn 
>
> (UTC -06:00) Mountain Time (US-MDT)
>
>
>
>
> On Mon, Oct 17, 2022 at 11:32 AM Richard Nute  wrote:
>
>
>
> Hi Scott:
>
> Many dual channel scopes (whether digital or analog) include an “add”
> function for the two channels.  One channel must be inverted to measure the
> charged capacitance.
>
> The resistance of the two probes must be accounted for in the capacitance
> discharge time.  (The same – for only one probe -- is true for the scheme
> using an isolating transformer.)
>
> You should get the same results for both methods.
>
> Best regards,
> Rich
> IEEE Life Fellow
> IEEE Medal for Environmental and Safety Technologies
>
>
>
>
> *From:* Scott Xe 
> *Sent:* Monday, October 17, 2022 8:18 AM
> *To:* EMC-PSTC@LISTSERV.IEEE.ORG
> *Subject:* Re: [PSES] Assess risk of electric shock from charged
> capacitors
>
>
> In order to judge if there is no risk of electric shock from charged
> capacitors, it is required to measure the voltage across L and N of mains
> plug after the removal of power input.  To avoid grounding loop between
> test equipment and the unit under test, an isolating transformer is
> strongly recommended.  I have learnt another way by using Add Function and
> two hot probes of a dual channel DSO.  Can someone advise which way is more
> common in safety conformity test.  Especially the latter one, I have not
> tried it yet before and appreciate any notes I must take in the measurement.
>
>
>
> Thanks and regards,
>
>
>
> Scott
> -
> 
>
> 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
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Re: [PSES] Assess risk of electric shock from charged capacitors

2022-10-17 Thread Ken Javor 
A simple circuit can provide disconnect at the peak of the ac waveform.

Ken Javor
Phone: (256) 650-5261



From: "doug...@gmail.com" 
Reply-To: "doug...@gmail.com" 
Date: Mon, 17 Oct 2022 13:08:17 -0600
To: 
Subject: Re: [PSES] Assess risk of electric shock from charged capacitors

On the question of probe resistance, I always recommend 100:1 probes which
will have a negligible effect on overall timing.  Additionally, it may be
necessary to perform the test a number times to ensure the disconnect occurs
at the peak of the sine wave.  For me, experience has shown this may take up
to 10x attempts.

-Doug


Douglas E Powell
Laporte, Colorado USA
doug...@gmail.com
LinkedIn 

(UTC -06:00) Mountain Time (US-MDT)




On Mon, Oct 17, 2022 at 11:32 AM Richard Nute  wrote:
>  
>  
> Hi Scott:
>  
> Many dual channel scopes (whether digital or analog) include an ³add² function
> for the two channels.  One channel must be inverted to measure the charged
> capacitance.
>  
> The resistance of the two probes must be accounted for in the capacitance
> discharge time.  (The same ­ for only one probe -- is true for the scheme
> using an isolating transformer.)
>  
> You should get the same results for both methods.
>  
> Best regards,
> Rich 
> IEEE Life Fellow
> IEEE Medal for Environmental and Safety Technologies
>  
>  
>  
> 
> From: Scott Xe 
> Sent: Monday, October 17, 2022 8:18 AM
> To: EMC-PSTC@LISTSERV.IEEE.ORG
> Subject: Re: [PSES] Assess risk of electric shock from charged capacitors
>  
> 
> In order to judge if there is no risk of electric shock from charged
> capacitors, it is required to measure the voltage across L and N of mains plug
> after the removal of power input.  To avoid grounding loop between test
> equipment and the unit under test, an isolating transformer is strongly
> recommended.  I have learnt another way by using Add Function and two hot
> probes of a dual channel DSO.  Can someone advise which way is more common in
> safety conformity test.  Especially the latter one, I have not tried it yet
> before and appreciate any notes I must take in the measurement.
> 
>  
> 
> Thanks and regards,
> 
>  
> 
> Scott
> -
> 
> 
> 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
> 
> 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:
> Mike Cantwell mcantw...@ieee.org
> 
> For policy questions, send mail to:
> Jim Bacher  j.bac...@ieee.org
> David Heald dhe...@gmail.com
> 
> 
>  To unsubscribe from the EMC-PSTC list, click the following link:
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Re: [PSES] Assess risk of electric shock from charged capacitors

2022-10-17 Thread Douglas E Powell 
On the question of probe resistance, I always recommend 100:1 probes which
will have a negligible effect on overall timing.  Additionally, it may be
necessary to perform the test a number times to ensure the disconnect
occurs at the peak of the sine wave.  For me, experience has shown this may
take up to 10x attempts.

-Doug


Douglas E Powell
Laporte, Colorado USA
doug...@gmail.com
LinkedIn 

(UTC -06:00) Mountain Time (US-MDT)




On Mon, Oct 17, 2022 at 11:32 AM Richard Nute  wrote:

>
>
>
>
> Hi Scott:
>
>
>
> Many dual channel scopes (whether digital or analog) include an “add”
> function for the two channels.  One channel must be inverted to measure the
> charged capacitance.
>
>
>
> The resistance of the two probes must be accounted for in the capacitance
> discharge time.  (The same – for only one probe -- is true for the scheme
> using an isolating transformer.)
>
>
>
> You should get the same results for both methods.
>
>
>
> Best regards,
>
> Rich
>
> IEEE Life Fellow
>
> IEEE Medal for Environmental and Safety Technologies
>
>
>
>
>
>
>
> *From:* Scott Xe 
> *Sent:* Monday, October 17, 2022 8:18 AM
> *To:* EMC-PSTC@LISTSERV.IEEE.ORG
> *Subject:* Re: [PSES] Assess risk of electric shock from charged
> capacitors
>
>
>
> In order to judge if there is no risk of electric shock from charged
> capacitors, it is required to measure the voltage across L and N of mains
> plug after the removal of power input.  To avoid grounding loop between
> test equipment and the unit under test, an isolating transformer is
> strongly recommended.  I have learnt another way by using Add Function and
> two hot probes of a dual channel DSO.  Can someone advise which way is more
> common in safety conformity test.  Especially the latter one, I have not
> tried it yet before and appreciate any notes I must take in the measurement.
>
>
>
> Thanks and regards,
>
>
>
> Scott
> -
> 
>
> 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
>
> Website: http://www.ieee-pses.org/
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> unsubscribe) 
> List rules: http://www.ieee-pses.org/listrules.html
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>
> For policy questions, send mail to:
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> David Heald dhe...@gmail.com
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Re: [PSES] Assess risk of electric shock from charged capacitors

2022-10-17 Thread Brian Kunde 
Another way to go is to buy a Capacitor Discharge Tester that is made to
perform the test you want.  Just plug it in and press a couple buttons.
There may be more on the market but the only one I know of is made by
Compliance West USA, model CDT-240.  We have the 15 amp version.  The nice
thing about this is you just plug it in, select the standard and test you
want to test to, then start.  Simple and safe.

On our products, we find that the load of the product itself discharges the
"X" caps very quickly. Worst case is when the power switch is OFF and the
RF Line Filter is still connected to the AC Mains. Most line filters have
adequate bleeder resistors to discharge the caps to a safe level within the
5 seconds (or whatever standard you are using).  But some of the larger
line filters used in industrial equipment (typically permanently mounted)
do not discharge their caps fast enough.  So this is always a good test to
run.

Hope this was helpful.
The Other Brian

On Mon, Oct 17, 2022 at 11:18 AM Scott Xe  wrote:

> In order to judge if there is no risk of electric shock from charged
> capacitors, it is required to measure the voltage across L and N of mains
> plug after the removal of power input.  To avoid grounding loop between
> test equipment and the unit under test, an isolating transformer is
> strongly recommended.  I have learnt another way by using Add Function and
> two hot probes of a dual channel DSO.  Can someone advise which way is more
> common in safety conformity test.  Especially the latter one, I have not
> tried it yet before and appreciate any notes I must take in the measurement.
>
> Thanks and regards,
>
> Scott
>
>> -
> 
>
> 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
>
> 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:
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>
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> --
>
> To unsubscribe from the EMC-PSTC list, click the following link:
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Re: [PSES] Assess risk of electric shock from charged capacitors

2022-10-17 Thread Richard Nute 
 

 

Hi Scott:

 

Many dual channel scopes (whether digital or analog) include an “add” function 
for the two channels.  One channel must be inverted to measure the charged 
capacitance.

 

The resistance of the two probes must be accounted for in the capacitance 
discharge time.  (The same – for only one probe -- is true for the scheme using 
an isolating transformer.)

 

You should get the same results for both methods.

 

Best regards,

Rich 

IEEE Life Fellow

IEEE Medal for Environmental and Safety Technologies

 

 

 

From: Scott Xe  
Sent: Monday, October 17, 2022 8:18 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Assess risk of electric shock from charged capacitors

 

In order to judge if there is no risk of electric shock from charged 
capacitors, it is required to measure the voltage across L and N of mains plug 
after the removal of power input.  To avoid grounding loop between test 
equipment and the unit under test, an isolating transformer is strongly 
recommended.  I have learnt another way by using Add Function and two hot 
probes of a dual channel DSO.  Can someone advise which way is more common in 
safety conformity test.  Especially the latter one, I have not tried it yet 
before and appreciate any notes I must take in the measurement.

 

Thanks and regards,

 

Scott


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Re: [PSES] Assess risk of electric shock from charged capacitors

2022-10-17 Thread Douglas E Powell 
Scott,

I very much prefer the two-channel o'scope dual-probe method using the A-B
function.  Alternatively a differential o'scope probe is an option,
although they tend to be rather pricey.  It is usually not necessary to get
high speed probes as this is only line frequency.

It is inadvisable to isolate the o'scope and use the grounding pin on
Neutral as any errors can cause the o'scope chassis to go live.  In that
case, even the set screws holding knobs on the controls would be a
potential shock hazard.

-Doug


Douglas E Powell
Laporte, Colorado USA
doug...@gmail.com
LinkedIn 

(UTC -06:00) Mountain Time (US-MDT)


On Mon, Oct 17, 2022 at 9:17 AM Scott Xe  wrote:

> In order to judge if there is no risk of electric shock from charged
> capacitors, it is required to measure the voltage across L and N of mains
> plug after the removal of power input.  To avoid grounding loop between
> test equipment and the unit under test, an isolating transformer is
> strongly recommended.  I have learnt another way by using Add Function and
> two hot probes of a dual channel DSO.  Can someone advise which way is more
> common in safety conformity test.  Especially the latter one, I have not
> tried it yet before and appreciate any notes I must take in the measurement.
>
> Thanks and regards,
>
> Scott
>
>> -
> 
>
> 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
>
> Website: http://www.ieee-pses.org/
> Instructions: http://www.ieee-pses.org/list.html (including how to
> unsubscribe) 
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>
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>
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Re: [PSES] Assess risk of electric shock from charged capacitors

2022-10-17 Thread Scott Xe 
In order to judge if there is no risk of electric shock from charged
capacitors, it is required to measure the voltage across L and N of mains
plug after the removal of power input.  To avoid grounding loop between
test equipment and the unit under test, an isolating transformer is
strongly recommended.  I have learnt another way by using Add Function and
two hot probes of a dual channel DSO.  Can someone advise which way is more
common in safety conformity test.  Especially the latter one, I have not
tried it yet before and appreciate any notes I must take in the measurement.

Thanks and regards,

Scott

>

-

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