1. LHC ARC Commissioning report during LS1 Agenda: VRGPE documentation (former VRJGE) Active Penning modification By-Pass Valves modification LHC ARC commissioning report Nikolaos Chatzigeorgiou, FELL, November 2014

2. VRJGE documentation Investigation - documentation for VRGPE, ND100 ND100 wire identification VRGPE inside connections Overall architecture (Magnet, QRL, Beam lines) Generic VRJGE layout Connection schema VRJGE-PLC Nikolaos Chatzigeorgiou, FELL, November 2014

3. VRGPE investigation Investigation to overcome normal operation problems Signal integrity investigation (proposal of 4-20 mA) Behaviour understanding + schematics Influence between different gauges For the pennings, the major problems are divided in 4 categories: DC Common Mode voltage Analog Ground influence on the output voltage ON/OFF “oscillation” when Over Range AC noise captured by PVSS Nikolaos Chatzigeorgiou, FELL, November 2014

4. Active Penning modification The modification of the Penning grounding schematic targeted to overcome the DC common mode voltages appearing in the PLC input due to very long cable distances and current consumption. Thus forcing the PLC to ERROR state and affecting nearby gauges, as we can see in the above figure from ARC 34. Nikolaos Chatzigeorgiou, FELL, November 2014

5. DC Common Mode Voltage VGP ground was different from PLC input ground Solution: Extra parallel wires for all the penning power supply grounds. The goal is to keep CMV less than 1V on a 50mA consumption. Thus, less than 20Ω linear resistance for each penning ground. Results: All ARCs are cold by now and all the penning equipment is running OK. Nikolaos Chatzigeorgiou, FELL, November 2014 Penning Power Supply equivalent circuit, resistances for 800m ND100 cable (VRJGE.32Lx.Q)

6. Active Penning modification Nikolaos Chatzigeorgiou, FELL, November 2014

7. By-Pass Valves Installation - modification Modification PLC crates in RE28 and RE32. 7 crates are modified Installation MCA8 cable in VRGPE boxes. 7 cables in sector 23 Connect valves in sectors 23, 78, 81. Total 21 valves MCA8 cable modification in sector 23 due to different distance between RE32 and VRJGE ND100 wires modification for less drop for all LHC Nikolaos Chatzigeorgiou, FELL, November 2014

8. By-Pass Valves Installation - modification Worst case 11V arriving on the valve – long cables Valve can actuate with at least 13V (6 bar air) Cabling modified to increase voltage on the valve Nikolaos Chatzigeorgiou, FELL, November 2014

9. By-Pass Valves Installation - modification Nikolaos Chatzigeorgiou, FELL, November 2014

10. By-Pass Valves Installation - modification Nikolaos Chatzigeorgiou, FELL, November 2014 EquipmentTotal PairsPairs addedMin Voltage [V] Max Voltage [V] Mean Voltage [V] VVACH.11Rx.M6315.918.916.6 VVACH.19Rx.M4218.620.619.3 VVACH.27Rx.M4215.617.216.1 VVACH.33Rx.M6316.316.916.5 VVACH.27Lx.M4214.216.815.5 VVACH.19Lx.M421819.719.1 VVACH.11Lx.M631518.716.7

11. LS1 LHC ARC Commissioning Nikolaos Chatzigeorgiou, FELL, November 2014 Green Team: Henrik Vestergard, TE-VSC-ICM Nikolaos Chatzigeorgiou, TE-VSC-ICM Target: VPGFA & VPGFB By-Pass valves All active gauges in VRGPE (former VRJGE) CRYO sector interlocks

12. LS1 LHC Commissioning Nikolaos Chatzigeorgiou, FELL, November 2014 LSS+ARCs Check in VAC PVSS Verified by CRYO tem CRYO sector alarms Valve actuation Primary Pumps Turbo Pumps Remote Control VPGF Valve actuation Voltage drop Remote Control By-Pass 1 position simulator HV component test Remote Control Active VGP 3 positions simulator Calibration Active VGR 2 positions simulator Active VGM Modifications Terminal connections verification Alcove + Equipment Cabling

13. LS1 LHC ARC Commissioning VRGPE (active gauges) Nikolaos Chatzigeorgiou, FELL, November 2014 824 actives gauges from all LHC ARCs commissioned 74 active Pirani calibrated out of 328 (23%) 14 active Pirani Hirschman connectors badly installed (4%) 1 active Pirani changed the OP Amps 5 active gauge sensors not working (documented) 1 active Piezo connector badly installed (gauge side) 3 active Penning HV component low (2kV instead of 3kV) out of the 328 (1%) 1 active Penning IKR251 found dead and replaced

14. LS1 LHC ARC Commissioning CRYO sector interlocks Nikolaos Chatzigeorgiou, FELL, November 2014 All CRYO interlocks for the whole LHC tested and confirmed Interlocks are tested using local gauge simulators Tested using the VAC PVSS –Verified by CRYO teams 3 interlocks crossed in LSS1R (CRYO rack relocation in RB16) LSS12_01R1_VACM_NLOST crossed with LSS12_05R1_VACM_NLOST LSS12_04R1_VACM_NLOST crossed with LSS12_06R1_VACM_NLOST LSS12_0104_VACM_OK Crossed with LSS12_0506_VACM_OK 3 interlocks had software problem in VAC PLC and updated LSS56_secA_VACQ_NLOST LSS56_secA_VACQ_OK LSS56_secBA_VACQ_OK DSL line in P3, needs hardware and software revision Missing controller for Piezo - to be installed New software logic for the first 2 triplets – to be implemented

15. LS1 LHC ARC Commissioning By-Pass Valves Nikolaos Chatzigeorgiou, FELL, November 2014 56 By-Pass Valves from all LHC ARCs tested Tested using valve simulator which includes the same coil as the valves, for realistic voltage drop When pressure right & left was good, the real valve was tested 1 problem coming from the PLC in the Alcove, the +24V wire feeding the coil was not working good and replaced The VVACH.484.19R2.M had NO compressed air installed and repaired by Ludovic Mourier The VVACH.521.27L4.M valve, after modification, has a critical coil voltage of 14.2V - it may affect the actuation of the valve – action should be taken!

16. LS1 LHC ARC Commissioning Fixed Pumping Groups VPGFA & B Nikolaos Chatzigeorgiou, FELL, November 2014 96 Pumping Groups from all ARCs commissioned 3 Power Supplies changed 1 Turbo Pump changed – could be more but not documented 3 LOC_1VPG_RE changed (1 out of 3 the transistor was dead)

17. Conclusions and Future work The LHC ARC commissioning accomplished in schedule Many problems with the active Pirani cards, especially with the calibration procedure Until week 49, all the documents should be updated (final documents for VRJGE, commissioning reports, etc.) Discussion – Investigation - Prototyping to upgrade the active gauge electronics in the ARCs Design new Pirani PCB & Penning PCB with a better calibration procedure and more trustful pressure readout (based on the TPG300 model?) Design stage to convert the 0-10V to 4-20mA in order to have info in case of power cut and better signal integrity OR integrate stage for direct ADC and communication through PLC protocol (standard radiation tolerant electronics existing at CERN) Nikolaos Chatzigeorgiou, FELL, November 2014

18. Thank you very much Nikolaos Chatzigeorgiou TE-VSC-ICM Nikolaos.Chatzigeorgiou@cern.ch