Availability is a quality criterion and/or a characteristic value of technical systems. It describes the possibility or the measure that technical systems fulfill certain requirements within an agreed period. Availability can be defined on the basis of eq. 1 and in the time when the technical systeme is available:
In this context, a distinction has to be made between planned and unplanned downtime. Since for availability calculation only the downtime in an agreed period is considered, a planned downtime (e.g. for performing servicing or maintenance tasks) lies outside the agreed period. Only an unplanned downtime is considered. If total availability was agreed on (e.g. 7 · 24 h) this means that there is no planned downtime. Each operation interruption is then considerede as downtime. If possible, maintenance tasks have to be performed during operation.
The characteristic value of “technical availability” is also well-known on the basis of eq. 2. It shows the holding time percentage for which the machine and/or equipment is available without technical interruption of production. Modern software with process data collection makes it possible to capture and visualize the technical availability (see Efficiency Control Cockpit, software module of Fill GmbH, Fig. 1 and Fig. 2).