The role of the operator in power plant incidents

Higher productivity is desired in a power plant to decrease operating costs. The key to higher productivity and lower operating costs is a carefully designed man-machine system. The interface between a process/machine and operator is the primary means for providing dialogue and introducing human judgment into the system. Thus operator, because of human limitations, is a major bottleneck in the overall system. In this paper two incidents, due to human error, in power plants A and B located in Iran will be discussed. The control system of power plant A is hard-wired modular electronic type and its man-machine interface (MMI) is desk and panel. A microprocessor based distributed control system (DCS) is provided to control power plant B and its MMI is CRT based. Follow up investigations to establish the cause of major faults or incidents arising from human errors are considered based on available manuscripts, log sheets, reports, printed records and interview with operators. Some cases are discussed in more detail to show the main factors affecting operator´s incorrect decisions. The outcome of the investigations, whether technical or disciplinary, eventually leads to safer and better system operation which may be brought about by recommended changes