Picture the control room at one of your power plants, then ask yourself the following:
- Do the operators acknowledge or silence the alarms without looking at or acting on them?
- Have you experienced any incidents or near-incidents because the operators did not detect or respond to alarms?
- Are some of the alarm horns turned off?
- Are some of the alarms disabled or suppressed for long periods without review?
Most of us with experience of power plant control rooms will answer Yes to one or more of those questions. What we may not know is the number of alarms that operators typically have to deal with in a shift. Nor, how many alarms the human brain can deal with at any one time.
How many alarms can the brain handle?
Research shows that the maximum number of alarms that the human mind can deal with is just seven, give or take two, in any 10-minute period.
Ideally, according to the ISA SP 18.2 guidelines, the maximum number of alarms an operator should face is no more than two in a 10-minute period. In reality, most process industry operators are subjected to a constant stream of alarms. In power generation alone, operators typically deal with 2,000 alarms per day and 350 in a 10-minute peak alarm period.
It is therefore unsurprising that operators become ambivalent to the constant drone of alarms, tending to ignore ‘nuisance’ alarms and run the plant on instinct. Clearly, operators cannot do their job effectively when critical alarms are intermixed with hundreds or even thousands of non-critical or nuisance alarms.
Standards and guidelines like EEMUA 191, ISA SP 18.2 and IEC 62682 have long recognized the need to reduce the number of alarms to match the operator’s cognitive capacity. And automation system vendors like ABB have long recognized the problem and developed advanced alarm management strategies and technologies for their customers.
1) Focus on the operator
The operators are among the plant’s most important assets. Their ability to make the correct decision at the right time has a huge impact on plant profitability, safety and reliability. Conversely, by taking the wrong decision at the wrong time the operator could harm others and the environment, and impact plant profitability.
At ABB, we’ve been working on the issue of operator effectiveness for many years, looking at how to empower the operators so that they can do their job more efficiently and make correct, informed and timely decisions. To remove the clutter and make it easier to develop a strategy, ABB has grouped its technology and best-practice solutions into four core disciplines known as the Four pillars of operator effectiveness. These are:
Plant system integration: Integrating plant operations into a single automation system that transforms raw data into actionable information in context;
High-performance HMI: Delivering a high-performance human machine interface that is designed to provide clear, intuitive process graphics, user-context navigation and simplified alarm management;
Operator competency: Improving operator knowledge and decision-making through training and process simulation; and
Human factors and ergonomics: Designing ergonomic control rooms to enhance operator performance and reduce stress and fatigue.
2) Develop a long-term alarm management strategy
Alarm management is not a product, set of features or a one-time implementation activity. It is part of a long-term plant strategy, established by management. It begins with an alarm philosophy that clearly defines the owner, procedures and the roles and responsibilities of all involved.
An advanced alarm management strategy should fulfill the following objectives:
- The purpose of an alarm system is to direct the operator's attention to plant conditions requiring timely assessment or action;
- Alarms should be presented at a rate that operators can deal with;
- Each alarm presented to the operator should be useful and relevant to the operator; and
- Each alarm should have a defined response.
High-performance HMIs like S+ Operations have advanced alarm handling and analysis tools that support implementation of alarm management strategies based on EEMUA 191 and ISA 18.2 requirements, thereby ensuring that each alarm generated will alert, inform and guide the operator to take the proper action.
What lies ahead in alarm management?
Alarm management is a process of continuous improvement - for the plant and for ABB.
As the world’s market-leading distributed control system in the power generation sector, Symphony Plus already has an advanced alarm management system and high-performance HMI that reduces unnecessary alarms and improves the effectiveness of operators.
Currently, we are developing new analytic models and graphics to enhance analysis of why specific alarms are generated, reduce the number of alarms and fine-tune their ranking by importance, to simplify the job of the operator.
These models and graphics include functionalities like:
- Deep de-chattering: is alarm D a chattering candidate to be removed from the operator’s view?
- Similar flood: Do alarms A, B and C occur in alarm flood episode E?
- Critical event: Is event A or action N before or after critical event C?
- Generic sequence: Is sequence P→Q→R responsible for alarm/event S?
- Parent-child: Does critical event C typically occur after alarm A?
- Hiding rules: Is alarm B or action M contained within the duration of alarm A?