Читать книгу System Reliability Theory - Marvin Rausand - Страница 43

Consider the electricity supply, which is supposed to be available at any time. The achieved average availability of the supply is quantified as

If we consider a period of one year, the total time is approximately 8760 hours. The downtime is the time, during the specified time period, the service is not available. The relationship between the average availability and the length of the downtime is illustrated in Table 1.1.

Table 1.1 Availability and downtime.

90	36.5 d
99	3.65 d
99.9	8.76 h
99.99	52 min
99.999	5 min