Safety-related system design in power system control and management

At this time of change in the UK Electricity Supply Industry (ESI) there are many new strategies and applications being developed to exploit the potential benefits of computer systems. Many computer based systems are used which may have serious safety implications. There are a number of definitions available for safety-related systems but the important aspect is the correlation between the system and the prevention of danger. A safety-related system contributes to the assurance of overall safety. It is intended to achieve, on its own or with other safety-related systems, the level of safety integrity necessary for the implementation of the required safety functions. A computer-based information system (CBIS) used in the control of a work activity must be assessed to check for any contribution it may make towards the safety functions of a safety-related system. With the increasing complexity of such systems, this task is very onerous. A safety case type of report which identifies safety issues and ways to address them could justify the system which is implemented in a clear risk based manner. A structured approach to the design, implementation and on-going operation of CBIS is essential. For this purpose, the methodology described, based on the safety lifecycle is strongly recommended.