Re: [PSES] [EXTERNAL] Re: [PSES] electric shock from capacitor discharge

[John Allen]

I believe most Standards that have a requirement regarding it, require bleed 
off within 60 seconds.

From: Pete Perkins <0061f3f32d0c-dmarc-requ...@listserv.ieee.org>
Sent: Wednesday, September 30, 2020 10:48 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] [EXTERNAL] Re: [PSES] electric shock from capacitor 
discharge

Rich et al,It’s been a while but, as I remember, servicing laser 
products used on industrial equipment required consideration of the stored cap 
charge that could be accessible to the technician.

:>) br,  Pete

Peter E Perkins, PE
Principal Product Safety & Regulatory Affairs Consultant
PO Box 1067
Albany, ORe  97321-0413

503/452-1201

IEEE Life Fellow
IEEE PSES 2020 Distinguished Lecturer
p.perk...@ieee.org<mailto:p.perk...@ieee.org>

Entropy ain’t what it used to be

From: MIKE SHERMAN mailto:msherma...@comcast.net>>
Sent: Wednesday, September 30, 2020 8:42 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG<mailto:EMC-PSTC@LISTSERV.IEEE.ORG>
Subject: Re: [PSES] [EXTERNAL] Re: [PSES] electric shock from capacitor 
discharge

I've seen some motor caps on industrial induction motors whose capacitance gave 
me pause. I think we specified a minimum bleed down time to allow before 
servicing.
Mike Sherman
Graco Inc.
On 09/29/2020 10:21 PM Ted Eckert 
<07cf6ebeab9d-dmarc-requ...@listserv.ieee.org<mailto:07cf6ebeab9d-dmarc-requ...@listserv.ieee.org>>
 wrote:


Hi Rich,

I can’t think of many cases of modern IT equipment with a significant risk of 
capacitance discharge through the plug. However, I could foresee motor-driven 
equipment where it could be an issue. The manufacturer might put a power factor 
correction capacitor across the line to compensate for the inductive load of 
the motor. The motor should bleed off the charge of the capacitor, but there 
may still be some residual charge when the user pulls the plug. You probably 
wouldn’t have that large of a capacitor on a plug-connected motor appliance, 
but it is possible.

It’s been more than a decade since I worked with large motor-drive appliances, 
so my memory of their workings isn’t great. I’m sure there is somebody on this 
list server who can correct any error I’ve made in my statements.

Ted Eckert
The opinions expressed are my own and do not necessarily reflect those of my 
employer.


From: MIKE SHERMAN mailto:msherma...@comcast.net>>
Sent: Tuesday, September 29, 2020 5:58 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG<mailto:EMC-PSTC@LISTSERV.IEEE.ORG>
Subject: [EXTERNAL] Re: [PSES] electric shock from capacitor discharge

Rich --

Are you including old CRTs as capacitors? I recall that, even with the early 
Macs, you had to be careful to discharge the tube if you were going to mess 
around inside.

Mike
On 09/29/2020 4:27 PM Richard Nute mailto:ri...@ieee.org>> 
wrote:




I am interested in knowing what constructions, situations, and products where a 
capacitive discharge into a body could take place.

I am aware of the X and Y capacitors discharge at the prongs of a power plug.  
I don’t immediately know of other situations or products that might discharge a 
capacitor into a body.

I would appreciate descriptions of such discharges into a body, not conjecture. 
 Preferably, normal conditions and some single-fault conditions.

Do we need to include capacitive discharge requirements in the safety standards?

Stay safe!

Rich

-


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Instructions: htt

Re: [PSES] [EXTERNAL] Re: [PSES] electric shock from capacitor discharge

[Pete Perkins]

Rich et al,It’s been a while but, as I remember, servicing laser 
products used on industrial equipment required consideration of the stored cap 
charge that could be accessible to the technician.  

 

:>) br,  Pete

 

Peter E Perkins, PE

Principal Product Safety & Regulatory Affairs Consultant

PO Box 1067

Albany, ORe  97321-0413

 

503/452-1201

 

IEEE Life Fellow

IEEE PSES 2020 Distinguished Lecturer

 <mailto:p.perk...@ieee.org> p.perk...@ieee.org

 

Entropy ain’t what it used to be

 

From: MIKE SHERMAN  
Sent: Wednesday, September 30, 2020 8:42 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] [EXTERNAL] Re: [PSES] electric shock from capacitor 
discharge

 

I've seen some motor caps on industrial induction motors whose capacitance gave 
me pause. I think we specified a minimum bleed down time to allow before 
servicing. 

Mike Sherman 

Graco Inc. 

On 09/29/2020 10:21 PM Ted Eckert 
<07cf6ebeab9d-dmarc-requ...@listserv.ieee.org 
<mailto:07cf6ebeab9d-dmarc-requ...@listserv.ieee.org> > wrote: 

 

 

Hi Rich,

 

I can’t think of many cases of modern IT equipment with a significant risk of 
capacitance discharge through the plug. However, I could foresee motor-driven 
equipment where it could be an issue. The manufacturer might put a power factor 
correction capacitor across the line to compensate for the inductive load of 
the motor. The motor should bleed off the charge of the capacitor, but there 
may still be some residual charge when the user pulls the plug. You probably 
wouldn’t have that large of a capacitor on a plug-connected motor appliance, 
but it is possible.

 

It’s been more than a decade since I worked with large motor-drive appliances, 
so my memory of their workings isn’t great. I’m sure there is somebody on this 
list server who can correct any error I’ve made in my statements.

 

Ted Eckert

The opinions expressed are my own and do not necessarily reflect those of my 
employer.

 

 

From: MIKE SHERMAN mailto:msherma...@comcast.net> > 
Sent: Tuesday, September 29, 2020 5:58 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG <mailto:EMC-PSTC@LISTSERV.IEEE.ORG> 
Subject: [EXTERNAL] Re: [PSES] electric shock from capacitor discharge

 

Rich -- 

 

Are you including old CRTs as capacitors? I recall that, even with the early 
Macs, you had to be careful to discharge the tube if you were going to mess 
around inside. 

 

Mike 

On 09/29/2020 4:27 PM Richard Nute mailto:ri...@ieee.org> > 
wrote:

 

 

 

I am interested in knowing what constructions, situations, and products where a 
capacitive discharge into a body could take place.

I am aware of the X and Y capacitors discharge at the prongs of a power plug.  
I don’t immediately know of other situations or products that might discharge a 
capacitor into a body.  

I would appreciate descriptions of such discharges into a body, not conjecture. 
 Preferably, normal conditions and some single-fault conditions. 

Do we need to include capacitive discharge requirements in the safety standards?

Stay safe!

Rich


- 


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Re: [PSES] [EXTERNAL] Re: [PSES] electric shock from capacitor discharge

[MIKE SHERMAN]

I've seen some motor caps on industrial induction motors whose capacitance gave 
me pause. I think we specified a minimum bleed down time to allow before 
servicing.
Mike Sherman
Graco Inc.

> On 09/29/2020 10:21 PM Ted Eckert 
> <07cf6ebeab9d-dmarc-requ...@listserv.ieee.org> wrote:
> 
> 
> 
> Hi Rich,
> 
> 
> I can’t think of many cases of modern IT equipment with a significant 
> risk of capacitance discharge through the plug. However, I could foresee 
> motor-driven equipment where it could be an issue. The manufacturer might put 
> a power factor correction capacitor across the line to compensate for the 
> inductive load of the motor. The motor should bleed off the charge of the 
> capacitor, but there may still be some residual charge when the user pulls 
> the plug. You probably wouldn’t have that large of a capacitor on a 
> plug-connected motor appliance, but it is possible.
> 
> 
> It’s been more than a decade since I worked with large motor-drive 
> appliances, so my memory of their workings isn’t great. I’m sure there is 
> somebody on this list server who can correct any error I’ve made in my 
> statements.
> 
> 
> Ted Eckert
> 
> The opinions expressed are my own and do not necessarily reflect those of 
> my employer.
> 
>  
> 
> 
> From: MIKE SHERMAN 
> Sent: Tuesday, September 29, 2020 5:58 PM
> To: EMC-PSTC@LISTSERV.IEEE.ORG
> Subject: [EXTERNAL] Re: [PSES] electric shock from capacitor discharge
> 
> 
> Rich --
> 
>  
> 
> Are you including old CRTs as capacitors? I recall that, even with the 
> early Macs, you had to be careful to discharge the tube if you were going to 
> mess around inside.
> 
>  
> 
> Mike
> 
> > > 
> > On 09/29/2020 4:27 PM Richard Nute  > mailto:ri...@ieee.org > wrote:
> > 
> > 
> > 
> > 
> > I am interested in knowing what constructions, situations, and 
> > products where a capacitive discharge into a body could take place.
> > 
> > I am aware of the X and Y capacitors discharge at the prongs of a 
> > power plug.  I don’t immediately know of other situations or products that 
> > might discharge a capacitor into a body. 
> > 
> > I would appreciate descriptions of such discharges into a body, not 
> > conjecture.  Preferably, normal conditions and some single-fault 
> > conditions. 
> > 
> > Do we need to include capacitive discharge requirements in the 
> > safety standards?
> > 
> > Stay safe!
> > 
> > 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 mailto:emc-p...@ieee.org >
> > 
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> > 
> > Attachments are not permitted but the IEEE PSES Online Communities 
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Re: [PSES] [EXTERNAL] Re: [PSES] electric shock from capacitor discharge

[Julia Curson]

I second Ted’s comment on motor drives. The capacitor charge risk post switch 
off is usually handled with a time delayed interlock on the housing cabinet, 
along with an acrylic sheet shield or such covering to protect against 
accidental contact if the cabinet is open. And of course ubiquitous signage as 
required by the standards.

On 30 Sep 2020, at 04:22, Ted Eckert 
<07cf6ebeab9d-dmarc-requ...@listserv.ieee.org> wrote:


Hi Rich,

I can’t think of many cases of modern IT equipment with a significant risk of 
capacitance discharge through the plug. However, I could foresee motor-driven 
equipment where it could be an issue. The manufacturer might put a power factor 
correction capacitor across the line to compensate for the inductive load of 
the motor. The motor should bleed off the charge of the capacitor, but there 
may still be some residual charge when the user pulls the plug. You probably 
wouldn’t have that large of a capacitor on a plug-connected motor appliance, 
but it is possible.

It’s been more than a decade since I worked with large motor-drive appliances, 
so my memory of their workings isn’t great. I’m sure there is somebody on this 
list server who can correct any error I’ve made in my statements.

Ted Eckert
The opinions expressed are my own and do not necessarily reflect those of my 
employer.


From: MIKE SHERMAN 
Sent: Tuesday, September 29, 2020 5:58 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [EXTERNAL] Re: [PSES] electric shock from capacitor discharge

Rich --

Are you including old CRTs as capacitors? I recall that, even with the early 
Macs, you had to be careful to discharge the tube if you were going to mess 
around inside.

Mike
On 09/29/2020 4:27 PM Richard Nute mailto:ri...@ieee.org>> 
wrote:




I am interested in knowing what constructions, situations, and products where a 
capacitive discharge into a body could take place.

I am aware of the X and Y capacitors discharge at the prongs of a power plug.  
I don’t immediately know of other situations or products that might discharge a 
capacitor into a body.

I would appreciate descriptions of such discharges into a body, not conjecture. 
 Preferably, normal conditions and some single-fault conditions.

Do we need to include capacitive discharge requirements in the safety standards?

Stay safe!

Rich

-


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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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http://product-compliance.oc.ieee.org/
 can be used for graphics (in well-used formats), large files, etc.

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

Re: [PSES] [EXTERNAL] Re: [PSES] electric shock from capacitor discharge

[Ted Eckert]

Hi Rich,

I can’t think of many cases of modern IT equipment with a significant risk of 
capacitance discharge through the plug. However, I could foresee motor-driven 
equipment where it could be an issue. The manufacturer might put a power factor 
correction capacitor across the line to compensate for the inductive load of 
the motor. The motor should bleed off the charge of the capacitor, but there 
may still be some residual charge when the user pulls the plug. You probably 
wouldn’t have that large of a capacitor on a plug-connected motor appliance, 
but it is possible.

It’s been more than a decade since I worked with large motor-drive appliances, 
so my memory of their workings isn’t great. I’m sure there is somebody on this 
list server who can correct any error I’ve made in my statements.

Ted Eckert
The opinions expressed are my own and do not necessarily reflect those of my 
employer.


From: MIKE SHERMAN 
Sent: Tuesday, September 29, 2020 5:58 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [EXTERNAL] Re: [PSES] electric shock from capacitor discharge

Rich --

Are you including old CRTs as capacitors? I recall that, even with the early 
Macs, you had to be careful to discharge the tube if you were going to mess 
around inside.

Mike
On 09/29/2020 4:27 PM Richard Nute mailto:ri...@ieee.org>> 
wrote:




I am interested in knowing what constructions, situations, and products where a 
capacitive discharge into a body could take place.

I am aware of the X and Y capacitors discharge at the prongs of a power plug.  
I don’t immediately know of other situations or products that might discharge a 
capacitor into a body.

I would appreciate descriptions of such discharges into a body, not conjecture. 
 Preferably, normal conditions and some single-fault conditions.

Do we need to include capacitive discharge requirements in the safety standards?

Stay safe!

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 
mailto:emc-p...@ieee.org>>

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 can be used for graphics (in well-used formats), large files, etc.

Website: 
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Mike Cantwell mailto:mcantw...@ieee.org>>

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Jim Bacher mailto:j.bac...@ieee.org>>
David Heald mailto:dhe...@gmail.com>>
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