[Dsg-hallb_magnets] Hall B Torus - issue?

[Tyler Lemon]

Hi Ruben,


>From the PLC, the interlock limit is 65% for LL8120DP (PLC screenshot attached). The archiver shows that it briefly dropped below 65%, causing the interlock.


LL8120DP is now reading ~72%, so the interlock should be able to be cleared with the reset button on EPICS.


Best regards,

Tyler

________________________________
From: Dsg-hallb_magnets <dsg-hallb_magnets-bounces at jlab.org> on behalf of Tyler Lemon <tlemon at jlab.org>
Sent: Thursday, December 20, 2018 8:51:53 AM
To: Ruben Fair
Cc: dsg-hallb magnets; Denny Insley
Subject: Re: [Dsg-hallb_magnets] Hall B Torus - issue?


Hi Ruben,


Looking back at other ramps to zero, it doesn't seem that the LHe LL always decreases whenever the Torus is ramped down.


Also, from the archived data, the LL dropping to ~65% has happened previously with no interlock trip.


I'm still having PLC connectivity issues so I haven't been able to look at the PLC yet.


Best regards,

Tyler

________________________________
From: Ruben Fair
Sent: Thursday, December 20, 2018 8:31:07 AM
To: Tyler Lemon
Cc: Probir Ghoshal; Denny Insley
Subject: Re: Hall B Torus - issue?


Tyler,


Another thing to check is to see if the Helium level does this every time the magnet ramps up or down - which it might do as AC loss heating in the leads and splices boils off Helium in the reservoir.


Ruben


________________________________
From: Tyler Lemon
Sent: Thursday, December 20, 2018 8:16 AM
To: Ruben Fair; Nicholas Sandoval
Cc: Probir Ghoshal; Denny Insley; dsg-hallb magnets
Subject: Re: Hall B Torus - issue?


Hi Ruben,


I'm trying to look at it on the PLC but my computer is opening the program really slowly.


While I'm waiting, I looked at the archived signals (plot attached) for the interlock (blue signal), Torus current (yellow) and LL8120DP (pink, plot units are for LL8120DP).


It looks like the interlock first tripped when the Torus was at ~-200 A while it was ramping to 0 A.


At that time, LL8120DP dropped from ~71% to ~65% and has since returned to ~70%. It seems that the Helium screen is clear because the signal has probably gone back above its alarm limit.


I will verify this once the PLC program loads and I can connect to the PLC.


Best regards,

Tyler

________________________________
From: Ruben Fair
Sent: Thursday, December 20, 2018 7:56:29 AM
To: Nicholas Sandoval; Tyler Lemon
Cc: Probir Ghoshal; Denny Insley
Subject: Hall B Torus - issue?


Nick, Tyler,


Dan Carman has run both magnets down. However, when the Torus got to about 100 A, it went into a controlled ramp down. Examination of the interlocks suggests a cryogenic 'issue'.


See screen shot below. But examination of the Helium screen does not appear to show any anomaly. Could one of you have a look at this to see what this could be due to?


Regards


Ruben


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