CHAPTER ONE
INTRODUCTION
1.1 Background of Study
Electric power interruptions occur when system capacity, due to severe power outages, is insufficient to meet the system load levels. During these periods of inadequacy, outage costs will be borne by the utility, its customers and perhaps, by’ the entiresociety. The utility outage costs include loss of revenue, loss of future sales and increasedrepair expenditure and maintenance. These costs usually form only a smallpart of the total outages costs. The greater part is that borne by the consumers. Theoutage costs depend on many factors and situations, some of which are discussed inthe following sections. The problem of estimating outage costs is affected by the perceivedcosts of an electric outage and the point in time when a consumer would like tobuy electric energy but is unable to do so. Since there are different classes ofconsumers,each will tolerate loss of service differently. A residential consumer may suffer agreat deal of hardship if an outage occurs during a hot summer day or while he is engagingin domestic activities but it may be of little inconvenience to a commercialuser who is forced to close until power is restored. Also an outage may cause a greatloss to an industrial user if it occurs during the time of the production process. Therefore,consumers do not perceive service interruption to the same degree of hardship.The outage costs to a particular consumer depend also on the alternatives availableto that individual at the time of service interruption. If the outages are not expected,the consumer may have very limited alternatives and may incur a great loss.