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Transcript
AT-MEI-PE, R. Denz, CERN, CH-1211 Geneva 23 Hardware Commissioning of Sector 4/5 Quench Protection System R. Denz AT-MEI-PE 1 Prologue Compared to the 7/8 exercise significantly less problems time to introduce the QPS field team (the blue button on the war map …) Mathieu Favre: Installation, QPS local cabling and internal field-busses Vincent Froidbise: Digital quench detection systems AT-MEI-PE, R. Denz, CERN, CH-1211 Geneva 23 Joaquim Mourao: Main magnet protection, quench heater power supplies Grzegorz Seweryn: Installation, equipment preparation 2 600 A circuits Optimization of detector firmware lead to significant progress – 0.1 As-2 and 5 As-1 reached with RSD2.A45B2 (12 x MS, 0.4 H) – Inductance tables turned out to be very precise (Grazie Walter!) – Rather limited time for test & developments AT-MEI-PE, R. Denz, CERN, CH-1211 Geneva 23 Voltage “spikes” during 0 V crossing of 600 A power converter (see also talk given by Yves) – Triggered QPS very often • PC distortion: U_distortion x t_distortion = 2 V x 1 ms • QPS threshold: U_threshold x t_discrimination = 0.1 V x 20 ms – Special non-linear digital filter developed, implemented and successfully tested in lab No information yet on requirements for fast feedback – Fast feedback should have been tested in 4/5 – it will be a must for 5/6 3 Firing heaters without current in the magnet circuit Effect observed only in main dipoles after high current ramp – Not a spurious trigger or caused by EMC – recorded signals are consistent and real – Probably triggered by local heating of magnet causing a break-down of the persistent current AT-MEI-PE, R. Denz, CERN, CH-1211 Geneva 23 • One case observed after accidental firing of quench heaters – Order of magnitude corresponds to theoretical predictions ( N. Schwerg, S. Russenschuck) Main magnet quench detection systems have no information about current level – System reacts correctly by firing heaters – No safe work-around 4 Feedback from QPS teams Up to about 30% idling time noticed – even when working with “only” two fronts – Teams waiting for signatures, other experts, end of the RAT meeting … – Most critical times: 7h00 – 9h00 and 16h00 – 18h00 – Equipment / system downtime to be given more precisely AT-MEI-PE, R. Denz, CERN, CH-1211 Geneva 23 Limited flexibility of the sequencer application – More people should be able to change circuit parameters – Successfully performed hardware tests should not be repeated because of software issues Tests requiring presence of field teams in the tunnel shall be executed with high priority 5 Conclusions Hardware commissioning or 4/5 fully successful for QPS and EE – All circuits efficiently protected – no damage – All systems reached design parameters (or more …) – Number of accesses to LHC tunnel significantly reduced AT-MEI-PE, R. Denz, CERN, CH-1211 Geneva 23 – More trained QPS (hardware, firmware) experts available – Some very experienced QPS experts (including two team leaders) will leave during 1st half of 2008 • Four new experts for CCC operation required (4 front baseline) Preparation of QPS for LHC operation has started – QPS must become almost transparent to LHC operation – Macros, automatic re-arming after a PM event … See you soon in sector 5/6, 7/8, 8/1 … 6