DIN EN 61703:2017-08

This standard provides mathematical expressions for selected reliability, availability, maintainability and maintenance support measures defined in IEC 60050-191. The following classes of units are treated separately in this standard: - non-recoverable units; - recoverable units with a zero (or negligible) time to recovery; - recoverable units with a non-zero time to recovery. In order to keep the mathematical formulas as simple as possible, the following basic mathematical models are used to quantify the measures of reliability: - random variable (time to failure) for non-repairable units; - simple (ordinary) renewal processes for repairable units with zero time to recovery; - simple (ordinary) alternating renewal processes for repairable units with non-zero time to recovery. The application of each reliability measure is demonstrated by a simple example. This standard is mainly applicable to hardware dependability, but many terms and their definitions may be applied to items containing software. The responsible committee is DKE/K 132 "Zuverlässigkeit" ("Reliability") of the DKE (German Commission for Electrical, Electronic and Information Technologies) at DIN and VDE.