Re: The Importance Of "Interlocking"
Re: The Importance Of "Interlocking"
....No not really designer!
I'm sitting with a conundrum when I look at how these laws are interpreted world wide, how it is twisted by every manufacturer to get his product out there and to say it is legally save. It is not that easy when you end in a legal battle or if someone is dead. ■
Re: The Importance Of "Interlocking"
Well I don't know about South Africa, but reading the overview of
BS EN 62061:2005 Safety of machinery. Functional safety of safety-related electrical, electronic and programmable electronic control systems
the more I think it covers what you are talking about.
OK it's a European standard but doesn't SA have a similar standard? If you don't then I would have thought that 'due diligence' would have been satisfied working to another reputable standard i.e. this one. ■
Re: The Importance Of "Interlocking"
Well a simple example is https://forum.bulk-online.com/showth...380-The-Forums where things did not go a 100% as planned.
Yes! a lot is covered when we look at "standard's" set by government or the industry, but it is not always very clear in some of it's notes or recommendations.
How often do we look at how a plant evolve, what operating system is used to control a plant, what firmware version was used on the equipment when it was commissioned, are replacement parts loaded with the same firmware version, when should a plant be recommissioned? After a firmware update or PLC, controller etc. change! ■
Re: The Importance Of "Interlocking"
I'm afraid that's where 'due diligence' and 'best industry practice' come in, and applying these and making a decision can be part of an engineers lot.
Not applying these has caused disasters in the past (Flixborough and Buncefield come to mind) and sadly will cause disasters in the future. ■
Re: The Importance Of "Interlocking"
.....
....I think I'm going to end with a few more grey hairs in the near future.lol
Problems - assessors
In spite of the fact that IEC 61508 is one of the most detailed and useful standards in the functional safety
field, there are always issues of different interpretation between assessors. A significant number of
additional issues exist when using the IEC 61508 standard to certify standard products meant for multiple
applications. Some of the most significant of these issues include:
• the interpretation of which requirements apply to standard products versus bespoke systems,
• the interpretation of which requirements apply to complex logic solvers with multiple computer
communications networks versus a simple programmable device or simple electronic device without
any programming,
• the interpretation of which requirements apply to mechanical products (if the standard applies at all)
and
• the interpretation of which methods and solution combinations apply to which SIL level.
http://www.exida.com/articles/IEc%20...tification.pdf
Thanks for the input "designer".
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The Importance of "Interlocking"
Where do the engineering industry stand today when it comes to "Interlocking"?
Interlocking is a method of preventing undesired states in a state machine, which in a general sense can include any electrical, electronic, or mechanical device or system.
http://en.wikipedia.org/wiki/Interlock(engineering)
In most applications an interlock is a device used to help prevent a machine from harming its operator or damaging itself by stopping the machine when tripped.
We live today in a age where most processes are controlled in some way by a PLC or computerized program, what has it done to the safety of the human element involved in these operations.
How do these PLC's, variable speed-drives, controllers, etc, interface with the interlocks we use today on any plant, are they still safe and of value in the way they are written and integrated into todays plant operations?
How many of todays interlocks are still really "hardwired"?
"Refers to elements of a program or device that cannot be changed. Originally, the term was used to describe functionality that was built into the circuitry (i.e., the wires) of a device. Nowadays, however, the term is also used to describe constants built into software."
Can a lockout stop or a pull-wire in the field really stop that plant from operating in the way it is implemented in the circuit it is part of "is the operator or the plc in control"?
Today there are some alarming grey areas when it comes to this!
Your thoughts on how safe interlocks are today in the computer age!
Where do we go with lockout proceeder's in the future?
I feel there is a big gap in how these laws are interpreted today and how they are applied. ■