EEMUA 191: engineers need to act on alarm KPI changes in Revision 3 13 March 2014

With EEMUA 191 Revision 3 changing requirements in terms of generating and representing KPIs (key performance indicators), engineers responsible for process plant control systems need to update their approaches.

EEMUA's (Engineering Equipment & Materials Users' Association) update went live on 11 September 2013, but Bruce Nicolson, senior control systems engineer at Intelligent Plant is concerned that some engineers are not aware of the implications for alarm visualisations.

Nicolson points, for example, to Section 6.5.1, which refers to 'two separate alarm situations that define the overall performance of the system: plant in steady state operation, or plant in abnormal/upset condition'.

"Mechanisms for improving performance in these two situations do differ and it is the abnormal situation that is the harder to address," he warns.

"It is sensible therefore to consider performance levels relating to the KPIs for each situation separately."

Steady state is measured by the mean average alarm rate per 10 minutes, and displayed in a simple diagram indicating the alarm system state, he advises.

Similarly, the upset state can be measured by taking the maximum 10-minute period per day and averaging it over the month.

"This KPI is usually displayed in the KPI table, but there is now context as to what it means and how much it needs to change," explains Nicolson.

System performance by state has also been changed – from a grid used to determine an alarm system's performance to state scatter charts.

"The same underlying alarm data is used for both pairs of grids. As well as an overall monthly average, daily values are plotted to give a feel for the range of behaviour that the system exhibits. Two charts are used instead of one to make the pattern of the daily values clearer," he says.

"Also, there are now four levels of behaviour, compared with the previous five, so for this data the classification goes from mostly robust to stable. This needs to be taken into account if comparing current performance with that documented in the past. It will only be meaningful if the past performance is measured in the same way."

"Engineers responsible for control systems on process plants should be aware of these changes and apply them as soon as possible to their systems," says Nicolson.

Brian Tinham

Related Companies
EEMUA
Intelligent Plant Ltd

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