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PROTECTION FOR QXF

QXF protection meeting 28 th October 2013. PROTECTION FOR QXF. E. Todesco CERN, Geneva Switzerland. MARGIN VS COPPER. Estimate of the gain in time margin and temperature vs copper fraction Estimate of the gain in time margin and temperature vs operational gradient.

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PROTECTION FOR QXF

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  1. QXF protection meeting 28th October 2013 PROTECTION FOR QXF E. Todesco CERN, Geneva Switzerland

  2. MARGIN VS COPPER • Estimate of the gain in time margin and temperature vs copper fraction • Estimate of the gain in time margin and temperature vs operational gradient

  3. HQ RESULTS • 14-17 ms available to • See the quench (5 ms) • Validate (10 ms) • So we are justthere • I took the MIITsat 350 K PRELIMINARY Quench integral measured in HQ [G. Chlachidze]

  4. HQ RESULTS • 27-32 ms available to • See the quench (5 ms) • Validate (10 ms) • Heaterdelay (15 ms) • So we are justthere • I took the MIITsat 350 K • Quench back could have helped but itwill not PRELIMINARY Quench integral measured in HQ [G. Chlachidze]

  5. EXTRAPOLATION TO QXF • Hypothesis • Tmax set at 350 K: thisgives 33.2 MIITs • Scaling of the MIITsconsumedwith HQ results • So we gain 8 ms (previousestimates: in general QXF has 10 ms more margin w.r.t. HQ) • Pretty compatible withpreviousestimate (see first slidegiving 33 ms) • So we have to gain 10-15 additional ms

  6. CONCLUSIONS • HQ test show thatquench back induced by dump resistor in the machine willbenigligible • To have some gain for protection one wouldneed 8 circuits, not feasible • Goingfrom 2 to 4 power converterseems to addnegligiblemargin • Extrapolation to QXF shows thatwe have a margin of 35 ms, still 10-15 ms toosmall • Limited impact of increasingcopper • Lowering gradient by 7% wouldsolve the problem • Quench back will not play a role in protection • That’swhywe put the core … • It is the mostdifficultquantity to scale to QXF sowewouldneed to waituntil first test • I feel more confident to have a QPS relying on otherphenomenaratherthanquench back

  7. CONCLUSIONS • Untilnowwedid not address the issues related to 90% operation • But magnets must reach 90% • Wedid not address issues related to failure of one or more circuits • So eventhoughwe manage to have 50 ms time margin by lowering the operational gradient wewouldneedadditionalmargin • This is to beprovidedwith the otherstudiesoutlined in the working group

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