MP3 List of main Issues during March 2010 MP3 - Team

Main issues on previous week CircuitProblemIntervention on field Remarks RB.A12 (22 March) Communication lost on one main dipole magnetYESRB circuit safe if I<2000A, but for higher energy, the heater power supplies must be charged. RU.L4 / RU.R4 (22,23,24 March) Many trips during controlled ramp down, even when using ‘correct’ di/dt NOWrong FGC parameters for slow abort and zero voltage crossing dI/dt (RU.L4) < 0.3A/s, dI/dt (RU.R4) < 0.08A/s RQTD/RQTF (23, 25 March) Tripped several times because of too fast trimming correction or wrong seqeunce when disabling the tune feedback. NO if I < 50A, U_res threshold = 2V if I > 50A, U_res threshold = 100mV RCO.A56B2 (22,24, 25,26) Tripped several times. Why?NO5th trip for RCO and 4th trip for RCD in 6 days. In all 5 events RCO goes first. RB.A23 (27 March) Discharging Heater Power supply on MB.B20R2YESFault on front-panel connector IT (27, 28 March) Inner triplet circuits trip frequently when being stopped with a Slow Power Abort NONeeds detailed analysis by EPC expert, probably related to not synchronized sequence of switching OFF nested converters ROF.A45B2 (28 March) Tripped during pre-cycle without apparent indication of a fault in the converter tbcFault is most likely related to the AC contactor state contact, might need EPC intervention, tbc RB.A45 (28 March) Blocked nQPS crate in B33R4 during beam injection NOReset of crate solved problem, but beam had to be dumped and sector switched off RQX.R2 (28 March) Trip of main triplet circuit at injection levelNONo apparent reason for trip (no signal above threshold), but ‘noisy’ Q2 signals, tbc by QPS expert MP3 Team

Main issues on previous week CircuitProblemIntervention on field Remarks RB.A12 (22 March) Communication lost on one main dipole magnetYESRB circuit safe if I<2000A, but for higher energy, the heater power supplies must be charged. RU.L4 / RU.R4 (22,23,24 March) Many trips during controlled ramp down, even when using ‘correct’ di/dt NOWrong FGC parameters for slow abort and zero voltage crossing dI/dt (RU.L4) < 0.3A/s, dI/dt (RU.R4) < 0.08A/s RQTD/RQTF (23, 25 March) Tripped several times because of too fast trimming correction or wrong sequence when disabling the tune feedback. NO if I < 50A, U_res threshold = 2V if I > 50A, U_res threshold = 100mV RCO.A56B2 (22,24, 25,26) Tripped several times. Why?NO5th trip for RCO and 4th trip for RCD in 6 days. In all 5 events RCO goes first. RB.A23 (27 March) Discharging Heater Power supply on MB.B20R2YESFault on front-panel connector IT (27, 28 March) Inner triplet circuits trip frequently when being stopped with a Slow Power Abort NONeeds detailed analysis by EPC expert, probably related to not synchronized sequence of switching OFF nested converters ROF.A45B2 (28 March) Tripped during pre-cycle without apparent indication of a fault in the converter tbcFault is most likely related to the AC contactor state contact, might need EPC intervention, tbc RB.A45 (28 March) Blocked nQPS crate in B33R4 during beam injection NOReset of crate solved problem, but beam had to be dumped and sector switched off RQX.R2 (28 March) 2 trips of main triplet circuit at injection levelNONo apparent reason for trip (no signal above threshold), but ‘noisy’ Q2 signals, tbc by QPS expert MP3 Team

RQX.R2 tripped twice while at injection current (450A) – No magnet quench at this low current – Heaters fired in both events (21:46 and 01:32), without clear indication as to the source of the (QPS) trigger – No apparent fault of the power converter RQX.R2 MP3 Team

RU.L4 still show frequent trips during controlled ramp downs – Problem related to incorrect ramp rate solved (now 0.3A/s) – Seems zero-voltage crossing problem, as QPS threshold will be raised when <50A, propose to align ramp rate with RU.R4, ie 0.08A/s to delay zero voltage crossing into <50A region RU.L4 MP3 Team

Resistance of 2 Ω in parallel on the circuit Note for operators : 600A detectors must be properly reset before re- starting the machine Frequent problems due to teething problems with tune feedback – Procedures and sequence fixed during the week RQTD/RQTF MP3 Team

RCO.A56B2 + ROF.A45B2 + IT MP3 Team ROF.A45B2 tripped with a fault which seems related to the AC contactor state contact -> might need an intervention to replace the power module (tbc by EPC) -> Currently not vital for beam operation RCO.A56B2 and RCD.A56B2: 5th trip for RCO and 4th trip for RCD in 6 days. In all 5 events RCO goes first, all events seem triggered by U_RES jumping to 250 mV in a step function (needs detailed analysis with EPC and QPS) -> Currently not vital for beam operation IT in general: Repetitive trips when switching them OFF or after Slow Power Aborts -> needs to be analysed by EPC, rather important as > pre-cycles