CSLSs should be proof tested according to the specified proof test interval to ensure there are no dangerous faults present that are not being detected by continuous runtime diagnostics. A manual proof test for a CSLS is initiated from a DeltaV workstation and causes the CSLS card to go through reset and power-up testing. Proof testing of CSLS cards can also be done automatically.
Immediately following successful power-up testing there are no known dangerous faults present. Choose the proof test interval for a CSLS based on the associated SIF requiring the shortest proof test period to achieve the necessary probability of dangerous failure for its logic solver subsystem.
The CSLS proof test timer automatically counts the number of days since the last reset occurred. The CSLS Properties dialog in DeltaV Explorer has a Proof Testing tab for entering the proof testing interval and a reminder time value. The CSLS provides an alert when the number of days since the last reset exceeds the configured time. A reminder alert occurs a configured number of days before the "exceeds" alert to assist maintenance personnel in the planning of manual tests. There is an event record for the setting and clearing of proof test alerts. The proof test timer for a redundant CSLS indicates the number of days since the last reset of the Active card, which always occurs earlier than the last reset of the Standby card.