Evaluating the reliability cost of computer system interruptions due to power system disturbances

The authors present a general modeling and simulation approach for estimating the cost of interruptions to a computer center caused by power system disturbances and outages. The major variables (e.g loss of revenue, equipment damage, renewal of lost records, costing data, user profiles, power system reliability characteristics, etc.) were included in the costing method. The simulation model was applied to the University of Alberta´s computer center, which does not have an uninterruptable power system. Actual historical databases (i.e. 11 years) were used in the case studies presented. The advantages and limitations of the reliability-costing methodology are discussed in some detail with reference to existing methods. It is concluded that estimating the cost of computer system interruptions is a complex and difficult task requiring large databases