[Dsg-hallb_magnets] Solenoid trip - comments/questions

[Amrit Yegneswaran]

hello pablo, 
very good questions and conjectures. 
i appreciate the fact that dsg is trying to understand the issue along with msg. 
with regards to your e-mail: my answers and comments are, in-line in blue. 

Have we heard anything about the lcw:92_Flow_Makeup signal? 
i guess it is not a state secret, so i can't understand that in the lab which is at the frontier of nuclear science , no one know what this signal about. 
i think that this signal as the name suggests, indicates flow makeup , i.e. if for some reason the flow is reduced, say for instance due to back pressure, flow is increased to maintain the steady state rate. 

Does anyone know what are the units for this signal? 
now this is embarrassing, really and truly. 
i am basically dead against plots with no units along the axes and no grid-lines, but i guess if one knows the units one could suppress it, to save cyber ink! 
bottom line, in a third world country like india, where i hail from, the school system would not let a third grader get away with this. 

It seems like during normal operation of the Solenoid at 2416 A, the recent pressure transducers installed on 11/12/2018, displayed a normal water return pressure (B_LCW_Level1_Ret) into 42-50 psi range, and water supply pressure (B_LCW_Level1_Sup) into 115 - 117 psi. When the Solenoid tripped B_LCW_Level1_Ret increased to ~ 60 psi, and B_LCW_Level1_Sup was mostly stable. (See attached myplot) 
very well observed. 
does an increase of 20% in the return pressure, trigger some unknown interlock or reduce the flow below threshold, that the trip occurs? 
i thought brian, you , et.al did some adjusting of the flow-meters fs1-fs4 (i think). 
i recall, i asked in a previous e-mail whether the flow was calibtrated, to which brian responded " no". 
so what if we are flowing a trickle and the back pressure increases and the flow stops? 
we should know how much we are flowing, isn't plant services the keeper of the books? 

Maybe this lcw:92_Flow_Makeup signal is showing the amount of water flow to make up and keep the supply water flow stable. 
Since the water return is greater than the max increment (~5 xxx units) of lcw:92_Flow_Makeup, this water flow compensation can only handle the enough supply water flow for ~ 10 min and then just give up. 
Could be some valve being opened (right at that time), which is part of the same Solenoid water return loop? 
excellent, see my earlier responses. 

now, dear dsg illuminati (brian, peter, amanda, tyler, pablo, george, marc) who are deeply involved in in assisting the magnet operations endeavor, i would very much like you to contact plant services, (yes, yet again and again and again), try and get a diagram/schematic of the lcw-92 sensor and location ( george/marc could do this); i was informed that doug tilles knew where such drawings were hoarded, so that we can have a reasonable discussion on wednesday! 

something about this saying "a blind man chasing a black cat, in a dark room" seems to reflect our current situation, but then again we can be the masters of our fate. 
yeah yeah ignorance is bliss and all that, but i hate it. 
we should get on this issue and figure it out, i know we can. 
memorare: morte prima di disonore 

goodnight and god bless 







From: "Pablo Campero" <campero at jlab.org> 
To: "dsg-hallb magnets" <dsg-hallb_magnets at jlab.org> 
Sent: Monday, November 26, 2018 5:22:31 PM 
Subject: [Dsg-hallb_magnets] Solenoid trip - comments/questions 

Hello, 

DSG has been discussing the last solenoid trip occurred on 11/25/2018. We have the following comments/questions: 

Have we heard anything about the lcw:92_Flow_Makeup signal? Does anyone know what are the units for this signal? 

It seems like during normal operation of the Solenoid at 2416 A, the recent pressure transducers installed on 11/12/2018, displayed a normal water return pressure (B_LCW_Level1_Ret) into 42-50 psi range, and water supply pressure (B_LCW_Level1_Sup) into 115 - 117 psi. When the Solenoid tripped B_LCW_Level1_Ret increased to ~ 60 psi, and B_LCW_Level1_Sup was mostly stable. (See attached myplot) 

Maybe this lcw:92_Flow_Makeup signal is showing the amount of water flow to make up and keep the supply water flow stable. 
Since the water return is greater than the max increment (~5 xxx units) of lcw:92_Flow_Makeup, this water flow compensation can only handle the enough supply water flow for ~ 10 min and then just give up. 
Could be some valve being opened (right at that time), which is part of the same Solenoid water return loop? 


Best Regards, 
Pablo 



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