[Dsg-hallb_magnets] Solenoid trip - comments/questions

[Ruben Fair]

Pablo

Denny and I were discussing this also this morning.

Yes the supply pressure ‘normally’ varies between 115 and 120 PSI while the return pressure varies between 43 and 47 PSI. This gives us a pressure differential between the supply and return of approximately 75 PSI or so. If you look closely at the supply pressure just before the makeup water kicks in, you will notice that the supply pressure variation seems to drop, then the makeup water gets a boost which tends to boost the supply pressure and the return pressure also increases but it increases to 60 PSI which now means that the pressure differential across the supply and return paths has reduced from 75 PSI to 60 PSI (or so). And a reduced pressure differential means a reduced flow. So the question is, could this drop of just 15 PSI be sufficient to trip the solenoid PSU interlock - perhaps if it eas already operating close to its limit. And why does it not seem to affect the Torus MPS - perhaps because all the pipes and hoses on the Torus are already 1” in diameter?

Now that the pipework (hoses) between the solenoid and the incoming manifold have been increased from 3/4” to 1”, we may not get such a huge drop in pressure differential.

Keep brainstorming though - good to have some fresh eyes on this.

Regards

Ruben

> On Nov 26, 2018, at 5:22 PM, Pablo Campero <campero at jlab.org> wrote:
> 
> 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
> 
> 
> <LCW and Solenoid signals plot.JPG>
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