Definition:
Proven In Use (PIU), directly tied to route 2S, is an argument that a device’s reliable operating history can demonstrate its fitness for safety applications. The data would be manufacturer driven, and is driven by IEC 61508 §7.4.10.
Proven is use is the foundational concept of route 2S, and route 2S is essentially proven in use.
Note Prior use, proven in use, and routes are notoriously confusing in functional safety circles!
Key Points:
- Requires detailed records of failures and operating conditions.
- A valid pathway to achieve systematic capability level, although 1S is the more typical way.
- This would be associated with 2S.
Example:
An emergency shutdown relay with over 1 million hours of successful operation might qualify under Proven In Use. This analysis would be done by a CB and the CB would issue the SIL Certificate.
Cited Source:
- IEC 61508-2:2010, Clause 7.4.9.