In 1999, the Engineering Equipment and Materials Users’ Association (EEMUA) released its general guide to the design, management, and procurement of alarm systems for industrial plants. The guidance document (EEMUA 191), however, is vague about applications to specific facilities, such as electric power plants. This article specifies EEMUA 191 standards and practices applicable to the electric power industry and spells out specific variations in alarming practices that are tailored for today’s power plants.
Awareness of one area of power plant automation surpasses all others: alarm management. This heightened awareness can be attributed to a few key factors: risk reduction/mitigation, personnel safety, changes in the power plant chemical hazard profile, and a desire to improve/optimize plant automation systems’ alarm management.
In the past, alarm management was not a topic of grave concern, as it is today. In the 1960s and 1970s, it was not uncommon for there to be approximately 60 to 100 alarms configured per operator. Each was designed to be highly reliable and available; however, due to limitations in component design, these alarm components were also bulky, relatively costly, and highly proprietary in design. The end result was an overall alarm system that was manageable with respect to quantity of alarms; however, the system was not very flexible.
Today’s systems consist of a combination of some proprietary, but mostly standard, software components. These components enable us to create alarm systems that are flexible, small, and relatively inexpensive. However, this combination of flexibility and economy has resulted in one unintentional byproduct — alarm overload.
Instead of the previously manageable 60 to 100 alarms per operator, modern alarm systems are generating more than 1,000 alarms per operator. This overload effect can create several undesirable outcomes, including:
-
Causing a process disturbance to last longer than necessary.
-
Causing the original process disturbance to become worse than necessary.
-
Causing a catastrophic equipment, system and/or plant failure, as happened at the BP Texas City refinery explosion in 2005.
-
Creating increased stress for operators that can lead to poor judgment, decreased morale, and higher attrition rates.
In order to optimize plant operations, a centralized alarm system is recommended for logging plant alarms and presenting them to the operator in a unified and coordinated view. When developing a centralized system, a common basis of design must be applied to all control subsystems that constitute the overall plant automation system. At the end of the day, all of the control subsystems in the plant must follow the same design philosophies in order for the centralized alarm system view to be meaningful and useful.
Email
Comments
Print
Reuse
