[Dsg-hallb_magnets] Solenoid fast dump summary

[Pablo Campero]

Hello All, 



DSG has been analyzing the Solenoid fast dump events based on the logbook entries, data archived and analyzer tools. We generated a spreadsheet (See attached) that shows all Solenoid fast dump events summary from Sep 12th, 2017 to Feb 28th, 2018. 



Results indicates that there was a total of 12 fast dump during the mentioned period, from which, 11 were attributed to the QDs (Quench Detectors units used as a hardware interlock for the Voltage taps) and 1 due to the cryogenics interlock. 



During the commissioning period five fast dumps occurred due to the QD1/QD2, and one due cryogenics trips (Vapor cooled lead temp > 13.5 [K]). Over the engineering run five fast dumps generated as a result of QD1 and QD2 trips; finally over the physics run period we had one fast dump also due to QD1/QD2. 



Overall, we know that the main cause for the fast dumps were due to QD1 and QD2 which are covering the voltage taps in the coils (1-5) and splices, and the information/data reveals that VT18 (Voltage across splice - SJ9), which was originally part of the QD1 (Ch3 and Ch4) and QD2:Ch4 was the most conflicted voltage tap generating a total of 6 trips (See histogram attached). This evidence led to remove VT18 and VT17 from QD1:Ch4. Also voltage thresholds and time delay thresholds were increased in the QDs in order to prevent undesired fast dump events after the commissioning period (Sep, 2017). 



We noticed on three occasions: for 7th, 8th and 12th fast dumps, that even when the spike voltages generated on QD1:Ch3 and QD2:Ch4; especially the Sum values of VT's combinations where VT18 was involved, were under the set thresholds and still generated a fast dumps in the Solenoid. 





Best Regards, 

Pablo 
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