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Curvaceous Software Newsletter September 2002
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In this edition
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Revelutionary Alarm Rationalisation and Management
Forthcoming Events
Latest Papers



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Revolutionary Alarm Rationalisation and Management!
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How do you calculate the values at which to set your process alarm limits? There has never been a general scientific method to relate alarm limit values to either process operating conditions or to process control. The EEMUA Alarm Systems Guide says
"alarms on variables reflecting operating limits should be set on the boundary between the normal and upset states of the plant"

...but it says nothing about how to define or measure "Normal".

Curvaceous took a whole new look at alarms and the problems of alarm floods, false alarms and standing alarms. We concluded that the root of all the problems was the lack of any rational method for deciding the values at which alarm limits should be set to define the boundary of the "Normal state" of the plant. And we can do something to help!

Our methods for identifying the Best Operating Zone of a process, which are based on the past performance of the plant in achieving a particular business objective, automatically provides a multi-variable definition of "Normal". Using Curvaceous Visual Explorer (CVE)  we can quickly obtain much better values for fixed alarm limits (often known as high-high/low-low or emergency alarm limits) on each variable than we have ever had before. One does this with CVE in groups of several hundred variables at a time so it is very fast and all the new alarm limits are consistent with the same one objective and thus consistent with each other too.

There is a second time-saving in the subsequent review and HAZOP meetings. The systematic use of an easily-understandable and communicable methodology for finding new multivariable alarm limit values allays the doubts and concerns that previously fuelled the sometimes interminable discussion of possibilities that an individual alarm might be wrongly-set or indispensable in some circumstances. Time will also be saved in documenting alarms to achieve COMAH or OSHA compliance.

What about a method for finding high/low alarms (sometimes called warning alarms or alerts)? A large proportion of warning alarms are known to be false because operators have found from experience that ignoring them mostly has no discernable consequence! Being able to ignore many alarms is a very bad safety practice and devalues all alarms. The many false alarms contribute considerably to excessive alarm annunciation and to alarm floods.

Some plants have allowed operators to apply their own judgement and alter warning alarms to values more appropriate to the current process operation but this has created new problems, for example remembering to notify the next shift to reset the changed values when process conditions change again. There are software products offering to solve this subsequent set of problems too but much better, is to solve the basic underlying problem of finding better values for warning alarms instead.

Warning alarm values have been very difficult to establish because it hasnt been realised that the values at which they should be setare not constant but interact with each other, just as the values of the process variables interact. Warning alarm values in fact need to be changed continuously as the process changes its operating point. Curvaceous Process Modeller (CPM) automatically calculates the values of the Warning alarm levels from the position of the process operating point relative to the fixed Emergency alarm limits (so if you start by using CVE to define new Emergency Alarm Limits you wont have to alter them when you later want to improve Warning Alarms).

CPMs Alarm Advisory Algorithm gives advice on which manipulatable variables to move when an alarm occurs to return the process to "Normal".

Best of all for the Accountants is that the New Alarms help achieve the business objective that is the basis of the definition of "Normal" so as long as there is some business value in achieving "Normal" more often, the New Alarms and improved plant safety will pay for themselves!

What about IEC 61511 and 61508? Dont the same problems of having no method to calculate the values of alarm limits apply to Safety Alarms too? Yes they do and the 61508 and 61511 standards give no more guidance than the EEMUA Guide. 

Download copies of papers presented at NPRA and ERTC from our website for more information on the New Alarm Management or contact us directly to discuss and learn more about New Alarm Rationalisation. 

Curvaceous can help you solve many more of  your problems!
Take our Product Tour to see how Curvaceous can benefit you...

www.curvaceous.com/Marketing Lit/TourAugust02/Tour Bulk/Tourbulk.htm

The tour introduces you to our new and existing products including CPM and CRSV and gives comprehensive process examples throughout. Pass this link on to your colleagues or invite them to subscribe to our newsletter for more information.

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Forthcoming Events
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UMIST
October 17, 2002

AspenWorld 2002
October 27 - 31, 2002
Washington DC, USA
Robin Brooks will be presenting a paper jointly authored with Ineos Chlor entitled "First Experiences at Ineos Chlor with Geometric Process Control for Product Quality and Process Operation Improvement."
Visit www.aspentech.com

Honeywell European User Group
November 4 - 7, 2002
Nice, France.
Robin Brooks will be presenting  "A totally New Display Format for the Process Operator."
Visit http://honeywell.ugconference-emea.com

Supporting Control Room Operations
December 10 - 11, 2002
London, UK.
This is the thirteenth conference in the IBC Series on "Safe and Reliable Control Rooms"
Visit http://www.safetyevents.com

ACHEMA World Forum for the Process Industries
May 19 - 24, 2003
Frankfurt, Germany
Exhibition and Conference
Visit http://www.dechema.de

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Latest Papers
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Smart Fault Detection In Semiconductor Manufacturing
Part One: "Linking plasma process parameters to tool parameters and end-of-line results"

Ute Nehring and Andreas Steinbach, Infineon; and Robert McCafferty, Curvaceous Software.
First Published in Micro, May 2002
Part Two: "Taking RGAs and Metal Sputtering Where Theyve Never Been Before"

Ute Nehring and Andreas Steinbach, Infineon; and Robert McCafferty, Curvaceous Software.
First Published in Micro, July 2002 Copyright Canon Communications LLC, Used By Permission
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