Smarter alarm management can improve safety and profits

An effective alarm system is a key element for reliable power generation operations, but poorly configured and performing alarm systems in power plants can actually hinder the operator’s ability to effectively manage abnormal situations. This is a common problem throughout the power industry, and results in unplanned outages and decreased profitability.

Increasingly, we have found that alarm system failures are a contributing factor to several power generation incidents and accidents. This article covers the origin of the problem, its nature, and a proven seven-step methodology for significant alarm system improvement.

The Alarm Problem

The widespread use of modern Distributed Control Systems (DCSs) is the catalyst for today’s alarm system problems. Effective alarm system design best practices evolved after many of these systems were installed, resulting in inconsistent application and a near exponential growth in the number of configured alarms. The creation of alarms in modern control systems is performed through software configuration and has no incremental cost. Prior to this, adding an alarm involved installation of hardware and the costs associated with that. It is not unusual to see a single operator console with more than 3,500 configured alarms, which can result in hundreds to thousands of annunciated alarm occurrences per day. This overwhelms the operator making it impossible to acknowledge and respond to each one.

In the power industry, the alarm systems are often improperly configured by system integrators, without much involvement from the end user of the system. Poor initial alarm configurations can result from integrators reusing engineering from other projects or by applying rules of thumb that are not directly relevant to the specific operator’s needs. Alarms are not correctly prioritized, mixing trivial and important alarms in an inconsistent manner. Another problem is that data necessarily logged for predictive maintenance purposes is often mistakenly routed to the alarm system, distracting the operator from genuine alarms.

Many companies do not have proper alarm system management-of-change (MOC) policies. Some allow operators to change alarm settings at their individual preference, or to suppress their annunciation, without documentation or proper consideration of engineering design. Such practices cause an alarm system to change almost randomly over time and become even more inconsistent.

Some of the most prevalent alarm system problems include:

High continuous alarm rates - Alarm rates are often far above the ability of an operator to handle. Thousands of alarms must be ignored each week in such a system, with no guarantee that the right ones are always acted upon.

Alarm floods – An operator may experience hundreds of alarms within a few minutes of a minor upset, which may mask critical alarms and prevent timely corrective action.

Improperly suppressed alarms - Without records or notifications, improperly suppressed alarms can obscure the visibility of critical alarms.
Chattering and nuisance alarms – These contribute to operator fatigue and make detection of valid alarms more difficult.

Stale or long-standing alarms – These clutter the alarm system, also making detection of valid alarms difficult.

Seven Steps to Creating a Highly Effective Alarm System

Quick and accurate response to a well-designed alarm results in continued production and profitability. To achieve this goal, power generation facilities should implement an effective and comprehensive alarm management methodology. From our extensive experience in this field, PAS has developed a rigorous seven-step methodology for optimally managing alarm systems.

Performing these steps will help achieve alignment with the recently issued ISA 18.2 Standard on Alarm Management. This is an important document about alarm management and is in the process of being adopted as an international IEC standard.

Step 1: Create and Adopt an Alarm Philosophy
An Alarm Philosophy is a comprehensive document providing best practice guidelines for proper definition, design, implementation, and ongoing maintenance of a new or existing alarm system. It is a critical success factor for creating an effective alarm system and should be used in-house, as well as for contractors working on projects. Alarm philosophy development involves engineers, operators, and management.

Some basic principles for proper alarming that are generally not followed in the power industry include:
• Alarms must only be used for situations requiring operator action
• Alarms are not used to indicate normal status changes
• Alarm prioritization must be meaningful and consistent

Step 2: Alarm Performance Benchmarking
Existing alarm systems should be benchmarked against industry best practices to plan an improvement project. A benchmark establishes the current performance of the alarm system through a variety of analyses, including alarm rates, alarm flood periods, nuisance alarm counts, and alarm priority distribution. The benchmark will serve as the basis for measuring improvement. It also easily identifies the bad-actor alarms, which provides significant improvement opportunities with minimal effort.

Step 3: Bad-Actor Alarm Resolution
Nuisance or bad actor alarms are a common problem in most alarm systems and can render an alarm system virtually useless. Usually the top twenty most frequent alarms comprise anywhere from 25% to 95% of the entire alarm system load. Dealing with them successfully will result in major system improvement with comparatively minor effort.

Bad-actor alarms are resolved by applying appropriate alarm settings, such as deadbands, alarm on-delays and off-delays, process value filtering, and ensuring proper point ranging and measurement clamping.

Step 4: Alarm Documentation and Rationalization
Alarm Documentation and Rationalization (D&R) is a consistent methodology for rationalizing, prioritizing, documenting, and revising alarms. D&R involves a thorough re-examination of an existing alarm system to ensure it complies with the alarm philosophy.

During D&R, a team of knowledgeable people discuss each configured and possible alarm to verify it represents an abnormal situation requiring operator action. Alarms failing this test are de-configured. The remaining alarms are properly prioritized, and the alarm causes, consequences, proper operator responses, and any special alarm handling are documented.

Performing a D&R creates a Master Alarm Database, which is the collection of proper settings and information for each alarm. This document will be used in the rest of the process for state-based alarm management, flood suppression, audit and enforcement mechanisms, management of change, and operator information.

Step 5: Alarm System Audit and Enforcement
Proper Management of Change (MOC) is an essential practice. Without it, benefits achieved from alarm improvement efforts can be lost in a relatively short period. Alarm audit and enforcement is a software function which periodically and automatically checks for differences between the current alarm settings and the Master Alarm Database. It then reports any differences, and may optionally restore the system to the proper settings. This functionality helps manage the ongoing changes made by operators and others to ensure the alarm system remains in the proper configuration.

Step 6: Implement Real-Time Alarm Management
Power generation is a complex process subject to many abnormal situations, including equipment trips, unit trips, and post-outage restarts. Proper power generation alarming may involve sophisticated, real-time alarm management capabilities, which can be achieved by the following:

Alarm Shelving is the temporary suppression of alarms in a highly controlled manner. We recommend a software solution since paper-based procedures and tracking processes have historically been proven to be too cumbersome and unreliable.

State-Based Alarming is the adaptation of the alarm system to the current operating mode of the facility. This can include partial generation, load shedding, startup, or similar modes. State-based alarming dynamically modifies the alarm system settings in predetermined ways based on detecting changes in the process state.

Alarm Flood Suppression is the dynamic management of pre-defined groups of alarms based on triggering events, such as equipment trips. Alarm floods are the result of annunciating a large number of alarms in a short period of time, overwhelming the operator and rendering the alarm system unusable. The risks of having a major process upset or an accident are much higher during an alarm flood.

Step 7: Control and Maintain Alarm System Performance
Processes and sensors change over time, and alarm behavior will change with them. Alarms working correctly now may become nuisances or malfunction in the future. Therefore, alarm system Key Performance Indicators (KPIs) should be developed and routinely reported to appropriate personnel. Additionally, effective management of change methodologies, as well as an ongoing program of system analysis and correction of problems as they occur, is needed to maintain an effective alarm system. Modern alarm management software is an essential element to monitoring and maintaining alarm system performance.

Conclusion
Overloaded and malfunctioning alarm systems are common in power generation. They continue to negatively impact the profitability, safety, and environmental performance of such facilities worldwide. The good news is it is possible to achieve a highly effective alarm management system by following this rigorous seven step methodology.

Top 10 Most Frequent Recorded Alarms

Annunciated Alarms 

Randy Cole, PAS Director Technology Applications and Bill Hollifield, PAS Principal Alarm Management and HMI Consultant