Lakeshore 218 temperature controller #3 seems to have some problems, which cause its temperature readings to go haywire. This is the second occurrence this month.
This controller reads only Pt103 sensors, nothing directly related to the LH2 target loop. For future reference do not stop the beam in LH2 production mode for alarms on sensors from the dummy target ladder or the horizontal motion motor and brake. Please do page the target on-call, but do not stop the beam in this instance.
For reference I attach the Archiver plots of temperature readings from LS218#3 from 24 Jan and 16 Jan. On 16 Jan the LS218#3 controller actually "died" for almost 8 hours and then magically resurrected without (human) intervention. The controller does like to act up just past midnight.
Figure 1
Figure 2
