Re: [PSES] Using E-Stop in a Non-Emergency Task

[Douglas E Powell]

I would use caution.

I have looked into this in the past and possibly there have been recent
developments that would change what I learned.  My main concern is the
cycle life rating of the switch.  For what ever reason, many E-Stop
switches had a rating of only a few thousand cycles while your normal
on/off controls often have more than 100,000 cycle ratings.  I have
recommended to clients that on this alone, they should not be using an
E-Stop for routine on/off control.

That said, I have seen recent offerings of long life E-switches with
greater han 1 million cycle ratings. So I would say it pays to read the
ratings of the particular switch you are using and specicfically to learn
if the life cycle rating is controlled by the product certifications, or
not.

-Doug


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

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


On Tue, May 31, 2022 at 6:28 PM IBM Ken  wrote:

> From a practical standpoint, some designs use an EPO/EMO in series with a
> motor or other high current device potentially creating a hazard (laser,
> linear actuator, etc).  I can see why you would not want to use an EPO in
> this manner (breaking significant current on a regular basis could cause
> damage to the switch terminals).  However, if your EPO goes to a
> logic-level or low power control input to a relay, perhaps that is OK.  The
> standard I work with does not prohibit you from doing this.  You would need
> to show that the relay is designed appropriately to function as an on/off
> switch.  You might also want to consider the effect of 'training' users to
> use the EPO switch during service- that might lead to some learned behavior
> that is not appropriate for other pieces of equipment.
>
> -Ken A
>
> On Tue, May 31, 2022 at 9:20 AM Brian Kunde  wrote:
>
>> Greetings  to All!!
>>
>> I have an industrial machine with blades that has to be changed out by
>> the User/Operator.  The blade is behind a door with a positive mechanical
>> action switch that when opened puts the motor's VFD into a Safe Stop
>> Function Mode (this is a certified Safety Function).  In addition, power is
>> removed from the Start Button circuit so the motor cannot unexpectedly
>> start.
>>
>> When the E-Stop button is pressed, it does the same as the Door Switch
>> above, but in addition, it also opens the Motor Enable Relay which removes
>> the 3-phase power from the VFD.  Now the motor really really cannot
>> unexpectedly start.  I think this circuit arrangement is typical.
>>
>> We noticed that many of our Customers instruct their Employees
>> (Operators) to PRESS the E-STOP Button before changing out the Blade taking
>> advantage of the extra layers of protection.
>>
>> So here is my question.  Is it OK to instruct the Operator in OUR MANUALS
>> to Press the E-Stop when changing the blades?  We have always been told
>> that the E-Stop function should ONLY be used for Emergency and not for
>> routine tasks.  Is there any additional liability on  our company if we
>> give these instructions? In doing so, are we admitting that our product is
>> unsafe or not as safe and may unexpectedly start unless you press the
>> E-Stop?
>>
>> What is your opinion of this topic?
>>
>> Thanks to all.
>> The Other Brian
>>
>>
>> -
>> 
>>
>> 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
>>
>> For help, send mail to the list administrators:
>> 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
>>
> -
> 
>
> 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) 

Re: [PSES] Using E-Stop in a Non-Emergency Task

[IBM Ken]

>From a practical standpoint, some designs use an EPO/EMO in series with a
motor or other high current device potentially creating a hazard (laser,
linear actuator, etc).  I can see why you would not want to use an EPO in
this manner (breaking significant current on a regular basis could cause
damage to the switch terminals).  However, if your EPO goes to a
logic-level or low power control input to a relay, perhaps that is OK.  The
standard I work with does not prohibit you from doing this.  You would need
to show that the relay is designed appropriately to function as an on/off
switch.  You might also want to consider the effect of 'training' users to
use the EPO switch during service- that might lead to some learned behavior
that is not appropriate for other pieces of equipment.

-Ken A

On Tue, May 31, 2022 at 9:20 AM Brian Kunde  wrote:

> Greetings  to All!!
>
> I have an industrial machine with blades that has to be changed out by the
> User/Operator.  The blade is behind a door with a positive mechanical
> action switch that when opened puts the motor's VFD into a Safe Stop
> Function Mode (this is a certified Safety Function).  In addition, power is
> removed from the Start Button circuit so the motor cannot unexpectedly
> start.
>
> When the E-Stop button is pressed, it does the same as the Door Switch
> above, but in addition, it also opens the Motor Enable Relay which removes
> the 3-phase power from the VFD.  Now the motor really really cannot
> unexpectedly start.  I think this circuit arrangement is typical.
>
> We noticed that many of our Customers instruct their Employees (Operators)
> to PRESS the E-STOP Button before changing out the Blade taking advantage
> of the extra layers of protection.
>
> So here is my question.  Is it OK to instruct the Operator in OUR MANUALS
> to Press the E-Stop when changing the blades?  We have always been told
> that the E-Stop function should ONLY be used for Emergency and not for
> routine tasks.  Is there any additional liability on  our company if we
> give these instructions? In doing so, are we admitting that our product is
> unsafe or not as safe and may unexpectedly start unless you press the
> E-Stop?
>
> What is your opinion of this topic?
>
> Thanks to all.
> The Other Brian
>
>
> -
> 
>
> 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
>
> For help, send mail to the list administrators:
> 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
>

-

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: 

[PSES] Using E-Stop in a Non-Emergency Task

[Brian Kunde]

Greetings  to All!!

I have an industrial machine with blades that has to be changed out by the
User/Operator.  The blade is behind a door with a positive mechanical
action switch that when opened puts the motor's VFD into a Safe Stop
Function Mode (this is a certified Safety Function).  In addition, power is
removed from the Start Button circuit so the motor cannot unexpectedly
start.

When the E-Stop button is pressed, it does the same as the Door Switch
above, but in addition, it also opens the Motor Enable Relay which removes
the 3-phase power from the VFD.  Now the motor really really cannot
unexpectedly start.  I think this circuit arrangement is typical.

We noticed that many of our Customers instruct their Employees (Operators)
to PRESS the E-STOP Button before changing out the Blade taking advantage
of the extra layers of protection.

So here is my question.  Is it OK to instruct the Operator in OUR MANUALS
to Press the E-Stop when changing the blades?  We have always been told
that the E-Stop function should ONLY be used for Emergency and not for
routine tasks.  Is there any additional liability on  our company if we
give these instructions? In doing so, are we admitting that our product is
unsafe or not as safe and may unexpectedly start unless you press the
E-Stop?

What is your opinion of this topic?

Thanks to all.
The Other Brian

-

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: