1. B. Auchmann, D. Rasmussen, A. Verweij
QPS thresholds for selected 600 A circuits update from MPE-TM
B. Auchmann, D. Rasmussen, A. Verweij
with kind help from J. Feuvrier, E. Garde, C. Gilloux, R. Denz, M. Karppinen, Q. King, Y. Thurel, G. Willering
MPE-TM meeting

2. Overview Recall recommendation Reiner’s proposal Busbar analysis
Magnet analysis
Special problems (wire between coils and splices)
Conclusions

3. Recommendation from TE-MPE-TM, 24. 01. 2013
The busbar protection defines the upper limit for QPS thresholds of all studied circuits: Uth ≤ 0.8 V, Δtdiscr ≤ 190 ms
Respecting these limits, set thresholds to the lowest practicable values.

4. Simple, radiation-hard QPS detection
Easiest detection via comparator on U_diff. I
U_trigger
U_diff
U_th

5. Threshold update proposal
Reiner Denz , discrimination time 20 ms, chosen to permit detection without inductive compensation.
CIRCUIT R_PAR L dIdt U_MAX U_TH (proposed)[V]
RSS.A78B
RSS.A78B
RQS.R7B
RQS.A78B
ROF.A78B1 Missing
ROF.A78B2 Missing
ROD.A78B1 Missing
ROD.A78B2 Missing
RQTL7.R7B
RQTL8.R7B
RQTL9.R7B
RQTL9.R7B
RQTL10.R7B
RQTL10.R7B
RQTL11.R7B
RQTL11.R7B
RQT12.R7B
RQT12.R7B
RQT13.R7B
RQT13.R7B

6. QP3 check of 1.2 V U_RES threshold
A. Verweij, QP3 calculation rules out 1.2 V threshold

7. Impact of new thresholds on magnets
Daniel simulated magnet quenches all relevant configurations. Temperature increases are acceptable.
circuit T_current T_porposed % T increase
RSS.A78B
RSS.A78B
RQS.R7B
RQS.A78B
ROF.A78B
ROF.A78B
ROD.A78B
ROD.A78B
RQTL7.R7B
RQTL8.R7B
RQTL9.R7B
RQTL9.R7B
RQTL10.R7B
RQTL10.R7B
RQTL11.R7B
RQTL11.R7B
RQT12.R7B
RQT12.R7B
RQT13.R7B
RQT13.R7B

8. Unstabilized wire between coils and splices
Problem 1: RQT wire btw. splice and R//
Problem solved by additional copper wire to bridge splice and R//.
Information by M. Karppinen.
600 A busbar
wire 3
R//
additional copper wire

9. Unstabilized wire between coils and splices
Problem 2: wire routing outside of coil
Longest routing: MQTLI, ~20 cm

10. Problem 2: QP3 + ROXIE estimate
MIITs for low-field region magnet quench: MA2s (RQTL7, MQTLI assemblies).
Add these MIITs to a QP3 simulation of adiabatic unidirectional quench propagation through 20-cm-long wire 3.
RRR=100. T_max=182 K.
Result: Safe for 0.8 V, 20 ms.
wire
magnet

11. Rainer’s proposal with safe limits
RR73/RR77
CIRCUIT R_PAR L dIdt U_MAX U_TH (proposed)[V]
RSS.A78B
RSS.A78B
RQS.R7B
RQS.A78B
ROF.A78B1 Missing
ROF.A78B2 Missing
ROD.A78B1 Missing
ROD.A78B2 Missing
RQTL7.R7B
RQTL8.R7B
RQTL9.R7B
RQTL9.R7B
RQTL10.R7B
RQTL10.R7B
RQTL11.R7B
RQTL11.R7B
RQT12.R7B
RQT12.R7B
RQT13.R7B
RQT13.R7B

12. Conclusion
New radiation-hard cards with compensation will be required!
No special tests without compensation during 2013 end-of-run powering tests.
Using an ADC already tested in power-converters would shorten development time, and require discrimination delays of ~50 ms with lower U_th than those studied.
Simulations have shown that this does not pose a problem for protection of busbars and magnets.

14. RCBXH/V – postponed Preliminary results:
threshold increase for faster ramp rates ok for magnet and wire between coils and splices (40 cm)
busbar protection needs additional studies. Large increase in thresholds unlikely due to lack of energy-extraction.