Design of alarm systems

Abstract

This chapter relates to the design of control room alarm systems. Alarm systems are found on many user interfaces to large systems, e.g. in control rooms of power stations or chemical plants, in control centres for railway, road, air traffic or military systems, in aircraft cockpits, on bridges of ships, etc. Alarm systems are important because they are systems that provide stimulus typically an audible warning to make the operator aware of an operational problem. They should direct the operator's attention to an abnormal situation so that s/he can take preventative action. Modern processes and systems are often fitted with sophisticated protective systems to prevent hazard to people or major damage. However, action by operators is often very important to correct minor problems before they escalate into major disturbances and also to avoid unforeseen combinations of events where unprotected risks can arise. These major accidents provide obvious examples of alarm system failings. However, there is also strong evidence that large numbers of smaller and less obvious difficulties with alarm systems can have a very significant financial impact (Andow, 1998; Bransby and Jenkinson, 1998). This chapter provides an introduction on how to develop alarm systems to reduce these problems. It draws very heavily on an HSE Research Report on alarms (Bransby and Jenkinson, 1998) and the EEMUA Alarm Systems Guide (EEMUA, 1999). The latter document provides much more detailed and comprehensive guidance. In order to emphasise practical application, many of the ideas in the chapter are presented through industrial examples.