Patrick, Kiwamu,
In this morning, Patrick found that the CO2Y was not outputting a laser power. In the end we could not figure out why it had shut off. The laser is now back on.
[Some more details]
I thought this was a return of the faulty behavior that we were trying to diagnose in the early October (30472). However, the combination of looking at the front panel of the laser controller and trending the warning/alarm states did not show us something conclusive. So no conclusion again.
When I went to the floor and checked the front panel, no red LED was found. The only unusual thing is the GATE LED which was found to be off. Pressing the red gate button then brought the GATE LED back in green as expected. This could be an indication of the IR sensor momentarily went to the fault state and came back normal leaving the laser shut off. In this scenario, the IR sensor does not latch any LEDs and for this reason I thought this could be it. Then looking at the trend at around the time the laser went off, I did not find any alarm flags raising at all. Even if it is a fast transient in the IR sensor, I would expect to see it in the trend. So these two observations together can't support the IR sensor scenario. Another plausible scenario would be somebody accidentally hitting the gate button resulting in no laser output.
I also went to the chiller and confirmed no error there - water level was mid-way (which I topped off), all seemed good.
That certainly sounds like the IR sensor. Unfortunately we don't currently have analogue readout from that channel, or a good error reporting system. We are already planning on fixing this with a new version of the controller that we should be getting ready for post O2 install.
Has there been a temperature change in the LVEA recently? And the Y-arm laser power is a bit highrer than before, but not as high as during your recent testing? I'm just wondering what else could be causing this sensor to be close to its tripping point.
Alastair, if this was due to the IR sensor, how do you exlain the fact that it didn't show up in ITMY_CO2_INTRLK_RTD_OR_IR_ALRM? Is it so fast that the digital system can not reacord the transient?
I don't understand that. Even if it doesn't latch the laser off, it should still show up on that channel. Is it possible that the chassis itself got a brief power glitch? If that was turned off/on momentarily then it would also put the laser into this state.
From trends the laser tripped off around 15:52 UTC this morning. This was well before the work on h1oaf took it down.
It's very possible that the Tuesday maint activity that involved IO chassis hardware work which may or may not have been involved in the dolphin network glitch -> Beckhoff issues (which lasted most of the day Tues), is what caused this particular TCS laser issue. It was compounded by the later h1oaf work that day which caused other chiller tripping. Cause of this full saga TBD...