PSL tripped due to a trip of the 35W FE power watchdog; this trip was NOT due to a flow problem. The first attachment shows the output power of the lasers that make up the PSL (NPRO, 35W FE, HPO). It's somewhat hard to see in the picture, but the NPRO begins to lose power ~1 second before the FE and HPO lose power. The second attachment shows the NPRO output power compared to the relevant interlock signals for this trip. The NPRO loses power, causing a trip of the 35W FE power watchdog; this in turn causes the HPO to lose injection locking and ~6 seconds later a trip of the HPO power watchdog. The third attachment shows the NPRO power output compared to the output power from the NPRO pump diodes. Timeline of the trip at this point appears to be:
GPS time 1174069985: NPRO pump diodes lose power, causing a loss of the NPRO and by extension the 35W FE.
GPS time 1174069986: Loss of power in the 35W FE causes the power watchdog to trip, shutting down the FE laser (essentially just the pump diodes at this point). HPO injection locking breaks at this time.
GPS time 1174069992: HPO power watchdog trips as a result of the 35W FE shutdown, shutting down the HPO.
At this point it is unclear what caused the NPRO to lose power. This, on the surface at least, appears to be another occurrence of those rare PSL trips due to some glitch in the UPS the NPRO is plugged into (it has been some time since we've seen a trip like this); while I have no direct evidence of this, the behavior of this trip is identical to that of the previously linked trip from September 2016.
The system came back up without issue.
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jason.oberling@LIGO.ORG - 12:53, Monday 20 March 2017 (34951)
PSL tripped due to a trip of the 35W FE power watchdog; this trip was NOT due to a flow problem. The first attachment shows the output power of the lasers that make up the PSL (NPRO, 35W FE, HPO). It's somewhat hard to see in the picture, but the NPRO begins to lose power ~1 second before the FE and HPO lose power. The second attachment shows the NPRO output power compared to the relevant interlock signals for this trip. The NPRO loses power, causing a trip of the 35W FE power watchdog; this in turn causes the HPO to lose injection locking and ~6 seconds later a trip of the HPO power watchdog. The third attachment shows the NPRO power output compared to the output power from the NPRO pump diodes. Timeline of the trip at this point appears to be:
At this point it is unclear what caused the NPRO to lose power. This, on the surface at least, appears to be another occurrence of those rare PSL trips due to some glitch in the UPS the NPRO is plugged into (it has been some time since we've seen a trip like this); while I have no direct evidence of this, the behavior of this trip is identical to that of the previously linked trip from September 2016.
The system came back up without issue.
FRS 7665 was filed for this trip.