camilla.compton@LIGO.ORG - posted 15:48, Thursday 23 January 2020 - last comment - 15:00, Saturday 15 February 2020(54672)
Clearing OM1 and OM2 Saturations
Jenne, Sheila, Camilla
There has been a few cases of Operators having to manually clear OM1 and OM2 saturations (alogs 54597, 53454, 53460).
We have found that locklosses from ISC_LOCK state 102, 103, 104 (DRMI_LOCK_PREP_ASC, ENGAGE_DRMI_ASC, TURN_ON_BS_STAGE2) leave OM1 and OM2 Lock filter outputs with offsets that are not cleared in DOWN. These offsets should not effect locking as aren't used until after AQUIRE_DRMI_1F (where they are often successfully cleared), however sometimes this isn't the case, giving OMC verbal alarms and the GRD not continuing.
(e.g alog 53454 with attached image which shows lockloss from TURN_ON_BS_STAGE2 at -1830s, the Y offsets remain at 106 (M1_LOCK_Y_OUTPUT channels -4th and 6th plots), increasing to 109 during ENGAGE_DRMI_ASC, giving verbal OMC alarms, ending in a lockloss at -1190s).
In ISC_DRMI DOWN state these lock filters should be tuned off then cleared, to ensure this order is happening correctly I have added a wait 0.1s line in the GRD code.
Images attached to this report
Comments related to this report
We have now had 2 locklosses from TURN_ON_BS_STAGE2. In both, the OM1 and OM2 offsets have been cleared (see attached images) so this wait timer has helped.
Images attached to this comment
