Re: [PSES] Pickle

[Pete Perkins]

Resending after deleting Doug's image (which wasn't allowed
on the PSNet and  resulted in my message being returned, unsent).  

 

John,

 

   I'll chime in here, rather belatedly it appears.  

 

   A detailed risk assessment is in order here.  

   A useful method for evaluation of circuits, including for
safety functions, is to determine the effects of open or shorts for each
component.  

   UL does some of this in fault testing which is helpful.  

   A more comprehensive method is to do this by reviewing the
schematic and developing a spreadsheet which explains the expected effect of
opening and shorting each component.  

   The use of each of these techniques complements one another. 

 

   Hope this helps.   

 

:>) br,  Pete

 

Peter E Perkins, PE

Principal Product Safety & Regulatory Affairs Consultant

PO Box 23427

Tigard, ORe  97281-3427

 

503/452-1201

 

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

 

From: John Allen [mailto:jral...@productsafetyinc.com] 
Sent: Tuesday, November 28, 2017 1:02 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Pickle

 

Thanks everyone!

 

Either test or re-design is required.

 

I appreciate the input.

 

John

 

  _  

From: Doug Powell 
Sent: Tuesday, November 28, 2017 2:07 PM
To: John Allen
Cc: EMC-PSTC
Subject: Re: [PSES] Pickle 

 

John,

 

UL 991 is a test method for qualifying solid-state circuits for safety
function.  It is generally referenced by another standard and is not used as
a primary certification standard as such.  Additionally, semiconductors are
not certified individually to UL 991 as this is not a component standard.
It is very important that the circuits where the semiconductors are used be
evaluated.  If you are familiar with the EMC immunity testing of IEC/CISPR
standards, it is very much like this.  Radiated immunity, EFT, surge, ESD,
etc.

 

-Doug

 

 

Douglas E Powell

Laporte, Colorado USA

 <http://www.linkedin.com/in/dougp01> http://www.linkedin.com/in/dougp01



 <http://www.linkedin.com/in/dougp01> Doug Powell | Professional Profile |
LinkedIn

www.linkedin.com

View Doug Powell's professional profile on LinkedIn. LinkedIn is the world's
largest business network, helping professionals like Doug Powell discover
inside connections to recommended job candidates, industry experts, and
business partners.

 

 

On Tue, Nov 28, 2017 at 11:44 AM, John Allen mailto:jral...@productsafetyinc.com> > wrote:

Hi,

 

We have a pickle of a situation and wondering if anyone knows a simple
fix.

 

We have a moving wall that complies with the maximum force limits of UL962.

An IC measures the voltage of a resistor and if appropriate, allows the
correct current to be sent to a motor that moves the wall.

If too much current is allowed to the motor, the force created is greater
than the limit.

We have a fuse, but it won't open before the force is created.

 

A UL991 investigation on the IC and Resistor circuit is necessary.  I agree
with that.  That said - 

 

1.  I could not find any UL Recognized Component circuits that comply
with UL 991.  Is there such a category??  I searched UL's database for
anything UL 991 and came up with a few categories.  FSPC2 is a likely
candidate, but the few Listings that are in there are heavy duty motor
controllers or position sensing devices, etc.
2.  If we redesign to not use the IC, won't we still be subjected to UL
991?  If we use discrete components (resistors and capacitors vs ICs) does
that get us out of UL 991?

 

Any insight would be appreciated. 

 

Best Regards,

 

John

 

-


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

All emc-pstc postings are archived and searchable on the web at:
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well-used formats), large files, etc.

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

For help, send mail to the list administrators:
Scott Douglas <sdoug...@ieee.org <mailto:sdoug...@ieee.org> >
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For policy questions, send mail to:
Jim Bacher <j.bac...@ieee.org <mailto:j.bac...@ieee.org> >
David Heald <dhe...@gmail.com <mailto:dhe...@gmail.com> > 





 

-- 

 

Douglas E Powell

doug...@gmail.com <mailto

Re: [PSES] Pickle

[John Allen]

Not sure if it's a new category.  It says "Last Updated on 2017-09-15" at the 
bottom of the Guide Card.  Does that mean anything??



From: Brian O'Connell 
Sent: Thursday, November 30, 2017 12:53 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Pickle

Is 'QVGS2' a new CCN?

Brian


From: John Allen [mailto:jral...@productsafetyinc.com]
Sent: Thursday, November 30, 2017 8:51 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Pickle

Hi,

To pass along the learning that came out of this.

A fuse did not have a tight enough tolerance, but we found a UL R/C Protector - 
QVG2S - that will open before the hazard.  The NRTL agreed as long as we prove 
it opens before the hazard, UL 991 and 1998 are not required.

Thanks again for the input and help,

John


From: John Allen 
Sent: Tuesday, November 28, 2017 3:02 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Pickle

Thanks everyone!

Either test or re-design is required.

I appreciate the input.

John


From: Doug Powell 
Sent: Tuesday, November 28, 2017 2:07 PM
To: John Allen
Cc: EMC-PSTC
Subject: Re: [PSES] Pickle

John,

UL 991 is a test method for qualifying solid-state circuits for safety 
function.  It is generally referenced by another standard and is not used as a 
primary certification standard as such.  Additionally, semiconductors are not 
certified individually to UL 991 as this is not a component standard.  It is 
very important that the circuits where the semiconductors are used be 
evaluated.  If you are familiar with the EMC immunity testing of IEC/CISPR 
standards, it is very much like this.  Radiated immunity, EFT, surge, ESD,  etc.

-Doug


Douglas E Powell
Laporte, Colorado USA
http://www.linkedin.com/in/dougp01

Doug Powell | Professional Profile | LinkedIn
www.linkedin.com<http://www.linkedin.com>
View Doug Powell's professional profile on LinkedIn. LinkedIn is the world's 
largest business network, helping professionals like Doug Powell discover 
inside connections to recommended job candidates, industry experts, and 
business partners.


On Tue, Nov 28, 2017 at 11:44 AM, John Allen  
wrote:
Hi,

We have a pickle of a situation and wondering if anyone knows a simple 
fix.

We have a moving wall that complies with the maximum force limits of UL962.
An IC measures the voltage of a resistor and if appropriate, allows the correct 
current to be sent to a motor that moves the wall.
If too much current is allowed to the motor, the force created is greater than 
the limit.
We have a fuse, but it won't open before the force is created.

A UL991 investigation on the IC and Resistor circuit is necessary.  I agree 
with that.  That said -

1. I could not find any UL Recognized Component circuits that comply with UL 
991.  Is there such a category??  I searched UL's database for anything UL 991 
and came up with a few categories.  FSPC2 is a likely candidate, but the few 
Listings that are in there are heavy duty motor controllers or position sensing 
devices, etc.
2. If we redesign to not use the IC, won't we still be subjected to UL 991?  If 
we use discrete components (resistors and capacitors vs ICs) does that get us 
out of UL 991?

Any insight would be appreciated.

Best Regards,

John

-

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.
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List rules: http://www.ieee-pses.org/listrules.html
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Mike Cantwell <mcantw...@ieee.org>
For policy questions, send mail to:
Jim Bacher <j.bac...@ieee.org>
David Heald <dhe...@gmail.com>


Douglas E Powell

doug...@gmail.com
http://www.linkedin.com/in/dougp01

-

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.

Re: [PSES] Pickle

[Brian O'Connell]

Is 'QVGS2' a new CCN?

Brian


From: John Allen [mailto:jral...@productsafetyinc.com] 
Sent: Thursday, November 30, 2017 8:51 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Pickle

Hi,

To pass along the learning that came out of this.

A fuse did not have a tight enough tolerance, but we found a UL R/C Protector - 
QVG2S - that will open before the hazard.  The NRTL agreed as long as we prove 
it opens before the hazard, UL 991 and 1998 are not required.

Thanks again for the input and help,

John


From: John Allen 
Sent: Tuesday, November 28, 2017 3:02 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Pickle 
 
Thanks everyone!

Either test or re-design is required.

I appreciate the input.

John


From: Doug Powell 
Sent: Tuesday, November 28, 2017 2:07 PM
To: John Allen
Cc: EMC-PSTC
Subject: Re: [PSES] Pickle 
 
John,

UL 991 is a test method for qualifying solid-state circuits for safety 
function.  It is generally referenced by another standard and is not used as a 
primary certification standard as such.  Additionally, semiconductors are not 
certified individually to UL 991 as this is not a component standard.  It is 
very important that the circuits where the semiconductors are used be 
evaluated.  If you are familiar with the EMC immunity testing of IEC/CISPR 
standards, it is very much like this.  Radiated immunity, EFT, surge, ESD,  etc.

-Doug


Douglas E Powell
Laporte, Colorado USA
http://www.linkedin.com/in/dougp01

Doug Powell | Professional Profile | LinkedIn
www.linkedin.com
View Doug Powell's professional profile on LinkedIn. LinkedIn is the world's 
largest business network, helping professionals like Doug Powell discover 
inside connections to recommended job candidates, industry experts, and 
business partners.


On Tue, Nov 28, 2017 at 11:44 AM, John Allen  
wrote:
Hi,

We have a pickle of a situation and wondering if anyone knows a simple 
fix.

We have a moving wall that complies with the maximum force limits of UL962.
An IC measures the voltage of a resistor and if appropriate, allows the correct 
current to be sent to a motor that moves the wall.
If too much current is allowed to the motor, the force created is greater than 
the limit.
We have a fuse, but it won't open before the force is created.

A UL991 investigation on the IC and Resistor circuit is necessary.  I agree 
with that.  That said - 

1. I could not find any UL Recognized Component circuits that comply with UL 
991.  Is there such a category??  I searched UL's database for anything UL 991 
and came up with a few categories.  FSPC2 is a likely candidate, but the few 
Listings that are in there are heavy duty motor controllers or position sensing 
devices, etc.
2. If we redesign to not use the IC, won't we still be subjected to UL 991?  If 
we use discrete components (resistors and capacitors vs ICs) does that get us 
out of UL 991?

Any insight would be appreciated. 

Best Regards,

John

-

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 
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Scott Douglas <sdoug...@ieee.org>
Mike Cantwell <mcantw...@ieee.org> 
For policy questions, send mail to:
Jim Bacher <j.bac...@ieee.org>
David Heald <dhe...@gmail.com> 


Douglas E Powell

doug...@gmail.com
http://www.linkedin.com/in/dougp01

-

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/
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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: 

Re: [PSES] Pickle

[John Allen]

Hi,


To pass along the learning that came out of this.


A fuse did not have a tight enough tolerance, but we found a UL R/C Protector - 
QVG2S - that will open before the hazard.  The NRTL agreed as long as we prove 
it opens before the hazard, UL 991 and 1998 are not required.


Thanks again for the input and help,


John



From: John Allen 
Sent: Tuesday, November 28, 2017 3:02 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Pickle


Thanks everyone!


Either test or re-design is required.


I appreciate the input.


John



From: Doug Powell 
Sent: Tuesday, November 28, 2017 2:07 PM
To: John Allen
Cc: EMC-PSTC
Subject: Re: [PSES] Pickle

John,

UL 991 is a test method for qualifying solid-state circuits for safety 
function.  It is generally referenced by another standard and is not used as a 
primary certification standard as such.  Additionally, semiconductors are not 
certified individually to UL 991 as this is not a component standard.  It is 
very important that the circuits where the semiconductors are used be 
evaluated.  If you are familiar with the EMC immunity testing of IEC/CISPR 
standards, it is very much like this.  Radiated immunity, EFT, surge, ESD,  etc.

-Doug


Douglas E Powell
Laporte, Colorado USA
http://www.linkedin.com/in/dougp01
[https://media.licdn.com/mpr/mpr/shrinknp_200_200/AAEAAQ1hJDI5ODhkOGExLWExNGQtNDZmYi1hNjkyLTEwN2Y2M2VmZDcyZg.jpg]<http://www.linkedin.com/in/dougp01>

Doug Powell | Professional Profile | 
LinkedIn<http://www.linkedin.com/in/dougp01>
www.linkedin.com
View Doug Powell’s professional profile on LinkedIn. LinkedIn is the world's 
largest business network, helping professionals like Doug Powell discover 
inside connections to recommended job candidates, industry experts, and 
business partners.



On Tue, Nov 28, 2017 at 11:44 AM, John Allen 
mailto:jral...@productsafetyinc.com>> wrote:

Hi,


We have a pickle of a situation and wondering if anyone knows a simple 
fix.


We have a moving wall that complies with the maximum force limits of UL962.

An IC measures the voltage of a resistor and if appropriate, allows the correct 
current to be sent to a motor that moves the wall.

If too much current is allowed to the motor, the force created is greater than 
the limit.

We have a fuse, but it won't open before the force is created.


A UL991 investigation on the IC and Resistor circuit is necessary.  I agree 
with that.  That said -


  1.  I could not find any UL Recognized Component circuits that comply with UL 
991.  Is there such a category??  I searched UL's database for anything UL 991 
and came up with a few categories.  FSPC2 is a likely candidate, but the few 
Listings that are in there are heavy duty motor controllers or position sensing 
devices, etc.
  2.  If we redesign to not use the IC, won't we still be subjected to UL 991?  
If we use discrete components (resistors and capacitors vs ICs) does that get 
us out of UL 991?


Any insight would be appreciated.


Best Regards,


John


-


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<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 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 
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List rules: http://www.ieee-pses.org/listrules.html

For help, send mail to the list administrators:
Scott Douglas <sdoug...@ieee.org<mailto:sdoug...@ieee.org>>
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For policy questions, send mail to:
Jim Bacher <j.bac...@ieee.org<mailto:j.bac...@ieee.org>>
David Heald <dhe...@gmail.com<mailto:dhe...@gmail.com>>



--

Douglas E Powell

doug...@gmail.com<mailto:doug...@gmail.com>
http://www.linkedin.com/in/dougp01
-


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

Website: http://www.ieee-pses.org/
Instructions: http://www.ieee-pses.or

Re: [PSES] Pickle

[John Allen]

Thanks everyone!


Either test or re-design is required.


I appreciate the input.


John



From: Doug Powell 
Sent: Tuesday, November 28, 2017 2:07 PM
To: John Allen
Cc: EMC-PSTC
Subject: Re: [PSES] Pickle

John,

UL 991 is a test method for qualifying solid-state circuits for safety 
function.  It is generally referenced by another standard and is not used as a 
primary certification standard as such.  Additionally, semiconductors are not 
certified individually to UL 991 as this is not a component standard.  It is 
very important that the circuits where the semiconductors are used be 
evaluated.  If you are familiar with the EMC immunity testing of IEC/CISPR 
standards, it is very much like this.  Radiated immunity, EFT, surge, ESD,  etc.

-Doug


Douglas E Powell
Laporte, Colorado USA
http://www.linkedin.com/in/dougp01
[https://media.licdn.com/mpr/mpr/shrinknp_200_200/AAEAAQ1hJDI5ODhkOGExLWExNGQtNDZmYi1hNjkyLTEwN2Y2M2VmZDcyZg.jpg]<http://www.linkedin.com/in/dougp01>

Doug Powell | Professional Profile | 
LinkedIn<http://www.linkedin.com/in/dougp01>
www.linkedin.com
View Doug Powell’s professional profile on LinkedIn. LinkedIn is the world's 
largest business network, helping professionals like Doug Powell discover 
inside connections to recommended job candidates, industry experts, and 
business partners.



On Tue, Nov 28, 2017 at 11:44 AM, John Allen 
mailto:jral...@productsafetyinc.com>> wrote:

Hi,


We have a pickle of a situation and wondering if anyone knows a simple 
fix.


We have a moving wall that complies with the maximum force limits of UL962.

An IC measures the voltage of a resistor and if appropriate, allows the correct 
current to be sent to a motor that moves the wall.

If too much current is allowed to the motor, the force created is greater than 
the limit.

We have a fuse, but it won't open before the force is created.


A UL991 investigation on the IC and Resistor circuit is necessary.  I agree 
with that.  That said -


  1.  I could not find any UL Recognized Component circuits that comply with UL 
991.  Is there such a category??  I searched UL's database for anything UL 991 
and came up with a few categories.  FSPC2 is a likely candidate, but the few 
Listings that are in there are heavy duty motor controllers or position sensing 
devices, etc.
  2.  If we redesign to not use the IC, won't we still be subjected to UL 991?  
If we use discrete components (resistors and capacitors vs ICs) does that get 
us out of UL 991?


Any insight would be appreciated.


Best Regards,


John


-


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<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 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)<http://www.ieee-pses.org/list.html>
List rules: http://www.ieee-pses.org/listrules.html

For help, send mail to the list administrators:
Scott Douglas <sdoug...@ieee.org<mailto:sdoug...@ieee.org>>
Mike Cantwell <mcantw...@ieee.org<mailto:mcantw...@ieee.org>>

For policy questions, send mail to:
Jim Bacher <j.bac...@ieee.org<mailto:j.bac...@ieee.org>>
David Heald <dhe...@gmail.com<mailto:dhe...@gmail.com>>



--

Douglas E Powell

doug...@gmail.com<mailto:doug...@gmail.com>
http://www.linkedin.com/in/dougp01

-

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: 

Re: [PSES] Pickle

[Doug Powell]

John,

UL 991 is a test method for qualifying solid-state circuits for safety
function.  It is generally referenced by another standard and is not used
as a primary certification standard as such.  Additionally, semiconductors
are not certified individually to UL 991 as this is not a component
standard.  It is very important that the circuits where the semiconductors
are used be evaluated.  If you are familiar with the EMC immunity testing
of IEC/CISPR standards, it is very much like this.  Radiated immunity, EFT,
surge, ESD,  etc.

-Doug


Douglas E Powell
Laporte, Colorado USA
http://www.linkedin.com/in/dougp01

On Tue, Nov 28, 2017 at 11:44 AM, John Allen 
wrote:

> Hi,
>
>
> We have a pickle of a situation and wondering if anyone knows a simple
> fix.
>
>
> We have a moving wall that complies with the maximum force limits of UL962.
>
> An IC measures the voltage of a resistor and if appropriate, allows the
> correct current to be sent to a motor that moves the wall.
>
> If too much current is allowed to the motor, the force created is greater
> than the limit.
>
> We have a fuse, but it won't open before the force is created.
>
>
> A UL991 investigation on the IC and Resistor circuit is necessary.  I
> agree with that.  That said -
>
>
>
>1. I could not find any UL Recognized Component circuits that comply
>with UL 991.  Is there such a category??  I searched UL's database for
>anything UL 991 and came up with a few categories.  FSPC2 is a likely
>candidate, but the few Listings that are in there are heavy duty motor
>controllers or position sensing devices, etc.
>2. If we redesign to not use the IC, won't we still be subjected to UL
>991?  If we use discrete components (resistors and capacitors vs ICs) does
>that get us out of UL 991?
>
>
> Any insight would be appreciated.
>
>
> Best Regards,
>
>
> John
>
> -
> 
>
> 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/
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Douglas E Powell

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Re: [PSES] Pickle

[John Woodgate]

I don't know UL 991, but basic safety considerations indicate that a 
solution with discrete components would likely be less reliable, 
nowadays, than one using an IC. I wonder if a technique from regulated 
power supplies would work. This would be a 'watchdog' circuit that 
detects excessive current and shuts down the input to the IC. I can't 
give more details, in view of the limited input data.


John Woodgate OOO-Own Opinions Only
J M Woodgate and Associates www.woodjohn.uk
Rayleigh, Essex UK

On 2017-11-28 18:44, John Allen wrote:


Hi,


We have a pickle of a situation and wondering if anyone knows a simple 
fix.



We have a moving wall that complies with the maximum force limits of 
UL962.


An IC measures the voltage of a resistor and if appropriate, allows 
the correct current to be sent to a motor that moves the wall.


If too much current is allowed to the motor, the force created is 
greater than the limit.


We have a fuse, but it won't open before the force is created.


A UL991 investigation on the IC and Resistor circuit is necessary.  I 
agree with that. That said -



 1. I could not find any UL Recognized Component circuits that comply
with UL 991. Is there such a category??  I searched UL's database
for anything UL 991 and came up with a few categories.  FSPC2 is a
likely candidate, but the few Listings that are in there are heavy
duty motor controllers or position sensing devices, etc.
 2. If we redesign to not use the IC, won't we still be subjected to
UL 991?  If we use discrete components (resistors and capacitors
vs ICs) does that get us out of UL 991?


Any insight would be appreciated.


Best Regards,


John


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[PSES] Pickle

[John Allen]

Hi,


We have a pickle of a situation and wondering if anyone knows a simple 
fix.


We have a moving wall that complies with the maximum force limits of UL962.

An IC measures the voltage of a resistor and if appropriate, allows the correct 
current to be sent to a motor that moves the wall.

If too much current is allowed to the motor, the force created is greater than 
the limit.

We have a fuse, but it won't open before the force is created.


A UL991 investigation on the IC and Resistor circuit is necessary.  I agree 
with that.  That said -


  1.  I could not find any UL Recognized Component circuits that comply with UL 
991.  Is there such a category??  I searched UL's database for anything UL 991 
and came up with a few categories.  FSPC2 is a likely candidate, but the few 
Listings that are in there are heavy duty motor controllers or position sensing 
devices, etc.
  2.  If we redesign to not use the IC, won't we still be subjected to UL 991?  
If we use discrete components (resistors and capacitors vs ICs) does that get 
us out of UL 991?


Any insight would be appreciated.


Best Regards,


John


-

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