* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download From MARIC minutes of 22.11.2006
Survey
Document related concepts
Alternating current wikipedia , lookup
Multidimensional empirical mode decomposition wikipedia , lookup
Electronic engineering wikipedia , lookup
Electrical substation wikipedia , lookup
Sound level meter wikipedia , lookup
Fault tolerance wikipedia , lookup
Mains electricity wikipedia , lookup
Immunity-aware programming wikipedia , lookup
Transmission tower wikipedia , lookup
Opto-isolator wikipedia , lookup
Schmitt trigger wikipedia , lookup
Transcript
600A circuits: splices qualification W. Venturini Delsolaro for MPP Hardware Commissioning “Debriefing” Workshop 11 July 2007 Outline • • • • • Original motivation Procedure: PCS1, 2, 3, and 4 Procedure changes on the fly Findings and results What we have learned From MARIC minutes of 22.11.2006: PROBLEM OF BAD SPLICES IN LINE N of SEC. 7-8 Tests at Cryo-Lab R ~ 20 nΩ instead of expected 3 nΩ Calculations by M. Calvi + EEWG + MPP integration of new steps in the HCP (EDMS 519716) for 7-8 only, initially PCS steps • • • • “20 mV or as low as possible…” PCS1 tuning below 20 A: PCS2 programmed trip at 50 A PCS3 programmed trip at 100 A PCS4 splice verification at ± 200 A Indeed most powering details were defined during commissioning to cope with the 20mV threshold above 20 A. In some cases thresholds had to be raised to 40 mV (lattice sextupoles), for Q6 we used 50 mV RSD1.A78.B1; cycle ± 200 A V V Rs 2 I Noise in level in RSD.A7.B2 circuit URES=RS · I (resistive voltage computed by QPS) RSF1.A78.B1 from 0 to 200 A RCS.A78.B2 from 200A to 0A • • • • Resolution ~1μΩ, up to a few μΩ with noise. We can only measure the total R If consider 20 nΩ as “bad”, single bad splices are not detectable (this we knew) Tolerance from cryogenics 7 nΩ (LHC design report, vol. 1, p. 315) So, if we are strict, we cannot even say that cryogenics tolerances are met CIRCUIT MAGNET TYPE Number of magnets number of connections Sum of Connections Resistance if R=Rmax measured (20nOhm) [μOhm] Sum of Connections Resistance if R=R estimated in average in 7-8 (8nOhm) [μOhm] RQTxx MQT 8 90 1.80 0.72 RQTxx MQT 1 14 0.28 0.11 RQSxx MQS 2 42 0.84 0.34 RSxx MS 9 44 0.88 0.35 RSxx MS 10 46 0.92 0.37 RSxx MS 11 48 0.96 0.38 RSxx MS 12 50 1.00 0.40 RQTLxx MQTLI 1 10 0.20 0.08 RQTxx MQT 1 14 0.28 0.11 RQSxx MQS 2 42 0.84 0.34 RQSxx MQS 4 80 1.60 0.64 RSSxx MSS 4 68 1.36 0.54 RQTLxx MQTLI 1 10 0.20 0.08 RQTLxx MQTLI 2 6 0.12 0.05 RQ6 MQTLH 6 4 0.08 0.03 ROxx MO 8 68 1.36 0.54 ROxx MO 13 80 1.60 0.64 HWC RESULTS < 1 μΩ in almost all cases, 2.5 μΩ in RQS.L8.B1 Conclusions (1) • We had to learn how to power the 600A circuits circumventing the pitfalls of non linear inductances and parallel resistors (PCS1-3). This took the best part of the time (because of the low threshold). PCS4 was the easiest step • We verified the absence of “very bad” (>>1μΩ) splices for the “priority 1” short list of circuits • Tolerances from cryogenics (almost) OK • These tolerances are distinct from quench limits (local) • Time was very little: analysis was done “on the fly”, TIMBER data could not be used (filtering), as originally foreseen • For the future, access to “good” data would be an asset (METER on request for specified signals and time windows? Alternatively PM can be used, but it is more time consuming) • In other sectors the quality assurance of splices was reinforced, the likelihood of bad splices is much less (we could take the risk) Conclusions (2) • Goal for 7-8 was to avoid damage due to over voltages • There is still concern on the consequences of the thermal cycle, the same procedure (or a very similar) will be applied in 7-8, during 2nd run • After successful PCS4 the threshold can be brought to nominal • Concerning the “forbidden zone” between 20A and 200A we have no more reasons today than we had before to ignore it, apart from the lower likelihood of problems in other sectors • The same applies to the 20 mV threshold • MPP will issue a new standard procedure for Sect. 4-5