Category 3 safety circuit requirements
Category 3 safety circuit requirements
(OP)
Is a RESET pushbutton required for Cat. 3, or is that just a "recommendation"? I see lots of examples of the RESET pushbutton in mfg. literature, but no reference to a requirement.
I do have the required redundancy, feedback aux. contacts, safety-rated interlock switch and E-Stop pushbutton, etc., but I wonder about the RESET.
Also, is there a thread or forum group here dedicated to electrical safety (motor control, hazardous machinery, etc.)circuit design?
Are you aware of any good training course on safety circuit design, other than the Pilz training in England?
Thanks.
I do have the required redundancy, feedback aux. contacts, safety-rated interlock switch and E-Stop pushbutton, etc., but I wonder about the RESET.
Also, is there a thread or forum group here dedicated to electrical safety (motor control, hazardous machinery, etc.)circuit design?
Are you aware of any good training course on safety circuit design, other than the Pilz training in England?
Thanks.





RE: Category 3 safety circuit requirements
RE: Category 3 safety circuit requirements
This sounds like a European SIL rating. Category 3 is pretty high.
steelerr,
ABB Eutech have done a lot of presentations in the Teesside area and probably further afield on the subject of SIL. Siemens also have published a lot literature - the rep dropped it in a while ago and I simply haven't had the time to go through it. If you want to trace it, the reference is 6ZB5 000-0AA02-0BA1
----------------------------------
Sometimes I only open my mouth to swap feet...
RE: Category 3 safety circuit requirements
it is a big download (12.1MB) so use broadband or better still, somebody elses.
RE: Category 3 safety circuit requirements
After a risk assessment is done, a manufacturer of industrial machinery determines whether Category B, 2, 3, or 4 (highest level) should be applied. Category 4 would be required if there were a possibility of death or very serious injury. Also into the consideration comes likelihood that the hazard would be present, how frequent the exposure (daily, constantly, for example).
Thanks for the feedback.
Bob Steele
www.gala-industries.com
RE: Category 3 safety circuit requirements
RE: Category 3 safety circuit requirements
RE: Category 3 safety circuit requirements
JRaef.com
"Engineers like to solve problems. If there are no problems handily available, they will create their own problems." Scott Adams
For the best use of Eng-Tips, please click here -> FAQ731-376
RE: Category 3 safety circuit requirements
<Category>
JRaef.com
"Engineers like to solve problems. If there are no problems handily available, they will create their own problems." Scott Adams
For the best use of Eng-Tips, please click here -> FAQ731-376
RE: Category 3 safety circuit requirements
I'll hit their website - thanks.
RE: Category 3 safety circuit requirements
Thanks for the link, sed2. The Siemens US web pages are hard to navigate, or at least used to be - I gave up. Maybe they have improved
RE: Category 3 safety circuit requirements
The European one hasn't.
Thanks for the link, sed2. I tried to find it and was defeated as normal. I have largely given up on the Siemens website because it is so difficult to find anything: the distributors know to send me a paper catalogue if they want any business. It's a shame because I actually like a lot of the Siemens products, but finding them is a nightmare!
----------------------------------
Sometimes I only open my mouth to swap feet...
RE: Category 3 safety circuit requirements
Maybe I'm biased or just used to it but I find the European website fairly easy to navigate:
http:/
The navigation tree on the left puts you into the right product group and then clicking on the "search documents for........" box will tend to home down on the right ones.
The North American internet does not have has much a range of info but I tend to find that they will have more detail that Europe tends to keep on intranet:
http://www2.sea.siemens.com/Support/
RE: Category 3 safety circuit requirements
RE: Category 3 safety circuit requirements
I'm glad to stumble across this thread here where I usually lurk, but I wish similarly useful discussion would be common on the "Codes, Standards, and Certifications" area of eng-tips. Without doing a cross post, I'll say that I have some interest in safety as a dominant part of machinery and motor control systems, yet I feel like I'm missing something.
I come from a background of the "NEC" where the distance between convenience receptacles is stipulated, but have yet to find a similarly specific and binding standard for the placement of E-Stops on machinery that can readily injure or kill it's users or operators. This strikes me as somewhat counterintuitive.
OSHA certainly doesn't handle such specifications or recommended engineering practices very well. I'm going to attempt to pore over the .pdf I got from the siemens link, but I'm skeptical about it's usefulness for prompting or enforcing better practices in dangerous applications. Are there any (other?) good forums or links dealing with this stuff?
RE: Category 3 safety circuit requirements
SILs come from IEC61508 family (61511 62061) of standards and the category's from EN 954-1. which I think has since been superseded but I can't remeber the new reference.
They both have similar uses but they are NOT interchangeable. SIL3 and Category 3 not the same.
The reliability category deals with the design of e-stop circuits etc. While the SIL is about the whole life cycle.
I think a forum on machine safety and standards would be a good idea.
RE: Category 3 safety circuit requirements
http://
Without actually purchasing the Standard, the second sentence under Note 3 of the A-B catalog refers to the RESET pushbutton I was asking about.
If the risk is rated high enough, you want to make sure that the system / machine doesn't suddenly restart as soon as you close the guard or reset the E-Stop or clear the error. Pressing the RESET pushbutton is a voluntary, intentional action, so no surprises occur if the controls are designed properly.
Many thanks to all who responded. I hope some sort of machine safety controls group eventually evolves in this forum. I'd be happy to participate.
Peace, Bob Steele
Eagle Rock, Virginia, USA
RE: Category 3 safety circuit requirements
Also the "Engineering Codes, Standards, and certifications section of eng-tips, has pretty low activity (at least compared to this forum), but a few items have been a bit informative to me.
I picked up the latest NFPA79, and am discouraged to find that it seems to be becoming the standard code for machinery controls/safety. I guess the other groups with published standards decided to just let the NFPA handle all that kind of stuff. I have some old IEEE published standards which were great at their time and as far as they went.
I have a LOT more regard for IEEE than the NFPA. IEEE has never had any publication which would be seen as the "National Exception Catalog" (N.E.C).