ABSTRACT
The quality of service has three ingredients: voltage fluctuation, frequency variation and reliability. They are not entirely independent, since if demand exceeds generating capacity there is a choice between reducing frequency and voltage on the one hand and cutting off supplies on the other. The nature, causes and cures of poor quality of supply constitute an enormous technical subject. From the economic point of view, however, it is sufficient to note that the quality of supply can be improved at a cost. The problem is that a choice has to be made between selling electricity with a higher or lower quality of service at a higher or lower price. The reliability of a distribution network depends on the outage rates of its components, upon the time taken to restore supply and upon whether the components are in series or in parallel.
