Nonconform opening of the Quench Interlock Loop Timestamp

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Non-conform opening of the Quench Interlock Loop Timestamp: 05/12/2015 12: 21: 36. 432 I.

Non-conform opening of the Quench Interlock Loop Timestamp: 05/12/2015 12: 21: 36. 432 I. Romera

Event sequence Timestamp Delta (s) 12: 21: 36. 434 Event Action PIC-CPLD detects opening

Event sequence Timestamp Delta (s) 12: 21: 36. 434 Event Action PIC-CPLD detects opening of the quench loop in AR 1 Beam dump triggered by PIC 1 12: 21: 37. 132 +0. 698 PIC-PLC detects opening of quench loop in AR 1 FPA and Global Protection activated in AR 1 12: 21: 37. 235 +0. 801 PIC-PLC detects opening of quench loop in AL 2 FPA and Global Protection activated in AL 2 12: 21: 39. 960 +3. 526 EE receives opening command in RR 17 Aperture of the EE in RR 17 12: 21: 40. 221 +3. 787 Aperture of the EE-switches in UA 23 Aperture of the EE in UA 23 12: 21: 45. 109 +8. 675 SIS sends redundant command None (EE switches already to open EE-switches opened) 2 1. In normal circumstances, CPLD and PLC should have detected the rupture of the loop at the same time (within 1 ms) 2. EE should have detected the rupture of the loop at the same time than PIC 2

Current and voltage on the Quench Interlock Loop PIC AR 1 detection Beam dump

Current and voltage on the Quench Interlock Loop PIC AR 1 detection Beam dump by PIC-CPLD EE trigger Oscillations in the quench loop current the moment of the dump PICat AL 2 detection 3

The Quench Interlock Loop Possible cause of the QPS trigger (Reiner): “Radiation induced problem

The Quench Interlock Loop Possible cause of the QPS trigger (Reiner): “Radiation induced problem on DQQBS board #3 of half cell B 10 L 2 causing oscillating, nonconform interlock signals. The problem affected only one of the redundant circuit boards, meaning that circuit protection was still fully assured. This is a particular effect of the ion run, where radiation losses around half-cell 10/11 are significantly higher than during normal operation. In conclusion there has been no protection issue, only a minor availability problem” 4

Quench loop detection thresholds FPA EE board: § Detection based on two redundant opto-couplers

Quench loop detection thresholds FPA EE board: § Detection based on two redundant opto-couplers § Current detection threshold set to 10 m. A (after August 2014 -> 100 Ω) § DQQLC and PIC: § Detection based on two redundant relays (Omron G 5 V-1) § Must release from 20 to 35% of the rated voltage (5 V) § Current detection threshold from 10 m. A up to 17 m. A § 5

Conclusions § 3 rd event this year provoked by radiation on m. BS boards:

Conclusions § 3 rd event this year provoked by radiation on m. BS boards: - 20/07/15 07: 25: 09. 301 (https: //issues. cern. ch/browse/TEMPECOMS-505 ) - 18/08/15 21: 16: 03. 984 (https: //issues. cern. ch/browse/TEMPECOMS-523 ) § SIS interlock to redundantly open the EE switches triggered correctly but EE FPA board was still faster to react § Mitigations: Set the same detection threshold on EE-FPA board and DQQLC 6