Reports until 13:55, Saturday 28 February 2015
H1 ISC
alexan.staley@LIGO.ORG - posted 13:55, Saturday 28 February 2015 - last comment - 11:57, Monday 02 March 2015(16997)
MC at 5 W

Gabriele, Alexa

Gabriele had accidently unlocked the MC this morning, and had trouble relocking it. I know people had trouble with the MC yesterday morning, but there was no alog about this ... :(

The input power this morning was set to 5 W. When MC would try to acquire lock, the MC2 M3 LOCK L would reach the limit. I adjusted the input power to 2.8W and we locked immediatly. The IMC "DOWN" guardian adjusts the MC common mode board input gain depending on the input power (Power <4, 4 = 10); it's possible that the init and locked gain set for 5 W is not correct. This is something we new was not ideal, and we will correct. If you are having trouble locking the MC and the alignment looks good, I would suggest requesting the input power to 2.8 W and see if that works.  

Comments related to this report
eleanor.king@LIGO.ORG - 09:20, Monday 02 March 2015 (17014)
Link

On the bottom left of the LSC overview you can set the power scaling for the LSC (channel H1:PSL-POWER_SCALE_OFFSET).  I think in order for the MC to lock, this power scaling needs to match tyhe PSL power.  So an alternative to aleways locking the MC at 2.8W is to change this power scaling in the LSC screen.

alexan.staley@LIGO.ORG - 11:57, Monday 02 March 2015 (17020)
Link

I had confirmed that the power normalization in the LSC was the same as the input power, so it seems we had different problems.