CSCM Type Test Powering & Cryogenic aspects

1. CSCM Type Test Powering & Cryogenic aspects B. Auchmann, K. Brodzinski, Z. Charifoulline, G. D’Angelo, K. Fuchsberger, A. Gorzawski, H. Pfeffer, I. Romera-Ramirez, V. Roger, S. Rowan, J. Steckert, H. Thiesen, A. Verweij, G. Willering, D. Wollmann, Cryo Operator. H. Thiesen TE-MPE-TM – 13 June 2013

2. CSCM Type Test • The CSCM type test have been realized in sector 23 beginning of April (from 08/04 to 23/04) • 6 power cycles (1, 2, 4, 6, 6 and 8 kA) have been realized with the RQF circuit and 8 (2, 4, 6, 7, 8, 6, 9 and 6 kA) with the RB circuit. TE-MPE-TM – CSCM type test - 13 June 2013 RQF.A23 (4 kA - 24 s) RB.A23 (6 kA - 50 s)

3. Objectives of CSCM the Type Test • The objectives of the CSCM type test were: • For the powering system (18 kV, PC, EE and PIC) • Validate the hardware and software modifications • Validate the special operating conditions (magnet at 20 K) • Validate the circuit models (discharge time in case of FastPA) • Control the current in the circuit specially during the diode transitions • For the cryogenic systems (DFBAs and Magnets) • Validate the special operation conditions • DFBAs operation at nominal condition (liquid He at 4.5 K – 1 bar) • Magnets at 20 K and 5 bar. • Validate the temperature stability in the magnets before the power cycles • Study the DT and DP during and after the power cycles • Study the recovery after the power cycles TE-MPE-TM – CSCM type test - 13 June 2013

4. Powering modifications • The powering circuits have been modified for the CSCM type test (EMDS#1278061) • The 2 thyristor bridges have been connected in series (normally in parallel) • The energy extraction switches have been short-circuited • The earth have been connected at the output of the RB power converter (normallyat the middle point of the EE system) • RB power converter has been used to power the RQF circuit TE-MPE-TM – CSCM type test - 13 June 2013

5. 18 kV power distribution network • The setting of the 18 kV MCB has been modified (EDMS#1275760) • Normal operating conditions of the RB power converter: 3MVA • CSCM operating conditions of the RB power converter: 6MVA • No hardware/software modification. 2 steps (125A and 135A) Tested at 9 kA Pb with existing parameters TE-MPE-TM – CSCM type test - 13 June 2013

6. ElQA • Before and after the CSCM type test, the 3 main circuits (RB, RQF and RQD) have been tested with success. • The conditions were: • BFBAs were at nominal conditions: Liquid helium at 4.5 K and 1 bar • Magnets were at 20 K and 4.5 bar • 600 V for the RB circuit and 400 V for the RQ circuits (do we need 600 V for RQ circuits?) • The results were: TE-MPE-TM – CSCM type test - 13 June 2013

7. ElQA • Before and after the CSCM type test, the 3 main circuits (RB, RQF and RQD) have been tested with success. • The conditions were: • BFBAs were at nominal conditions: Liquid helium at 4.5 K and 1 bar • Magnets were at 20 K and 4.5bar • 600 V for the RB circuit and 400 V for the RQ circuits (do we need 600 V for RQ circuits?) • The results were: TE-MPE-TM – CSCM type test - 13 June 2013

8. Power converter setting • One of the main challenges for the power converter was the management of the diode transitions: • Maximum voltage of the converter was limited at 400 V and the threshold of the diode at 20 K is about 2.8 V CSCM mathematic: 154 * 2.8 V = 431 V = 320 V 320 V 2.8 V TE-MPE-TM – CSCM type test - 13 June 2013

9. Power converter setting • One of the main challenges for the power converter was the management of the diode transitions: • If the diode transitions are too fast the control of the current is lost 1000 A 55 kA/s TE-MPE-TM – CSCM type test - 13 June 2013

10. Power converter setting • Solution has been found by reducing the standby current (< I_transition) and adding an intermediate current plateau before the CSCM cycle. V_out I_out Intermediate plateau at 200 A magnets 2.8 V transition diodes TE-MPE-TM – CSCM type test - 13 June 2013

11. Powering performance RQF.A23, 4 kA Maximum current error < 5A 3.2 A Ierr (mA) didt = 300 A/s tau = 18 s TE-MPE-TM – CSCM type test - 13 June 2013 Iref, Iout

12. Powering performance RB.A23, 6 kA Maximum current error < 5A 3.2 A Ierr (mA) didt = 483A/s TE-MPE-TM – CSCM type test - 13 June 2013 tau = 90 s Iref, Iout

13. Discharge time RQF.A23, 8 kA Iout • The time to ramp down the current at 8 kA is < 0.25 s for the RQ circuit • Do we need EE system? TE-MPE-TM – CSCM type test - 13 June 2013 230 ms

14. Powering performance Vout RB.A23, 9kA Iout • The time to ramp down the current at 8 kA is < 0.1 s for the RB circuit • Do we need EE system? TE-MPE-TM – CSCM type test - 13 June 2013 80 ms

15. Validation of the power converter at 12 kA and tau = 90 s • Three separated circuits to cool each SCR bridge • Power dissipated in the bridge is mainly linear with the current • Estimate temperature of semiconductor at 6.5 kA is about 70oC and maximum operating temperature for the thyrsitor is 125oC Half bridge + T_water_in = 28 oC Flow_water = 10 l/mn FWT Half bridge - Rhw = 5 oC/kW(1) or 8 oC/kW(2) Third Splice Review, 12 – 14 November 2012 The thermal characteristics of the water plates have to be identified and validated before to run at 12 kA.

16. Validation of the power converter at 12 kA and tau = 90 s 5 pipes of 10 mm Half bridge + 6 mm FWT Half bridge - 2 mm hole TE-MPE-TM – CSCM type test - 13 June 2013 4 pipes of 10 mm

17. CSCM Type Test – Cryogenic aspect DFBAs at 4.5 K and arc at 20 K Excellent temperature homogeneity: 20 K ± 2 K Q7 temperature: > 17 K 20 K TE-MPE-TM – CSCM type test - 13 June 2013 LSC – CSCM 1st results - 26 April 2013

18. CSCM Type Test – Cryogenic aspect Test of RB at 6 kA / 140 MJ (Emax # 300 MJ) 4.5 K 1 bar 10 hours TE-MPE-TM – CSCM type test - 13 June 2013

19. CSCM Type Test – Cryogenic aspect • Summary of operation: • DFBAs at 4.5 K at normal operation condition, • cold mass operation at ~20 K and 5 bar • Main conclusions: • 1. Good learning period with refrigeration stabilized, associated settings tested for above requirements, • 2. Stabilization of temperature over a sector could be provided with tolerance of +/- 2 K up to 4 kA of current cycles. Thermal effect from current 4 - 6 kA starts to introduce stronger thermal effect driving to bigger discrepancy for thermal homogeneity over a sector +/- 4 K. • 3. Recovery after the current cycling varies between ~3-5 hours depending on introduced current heat • Propagation of the test on other sectors: • The same cryogenic conditions can be provided for all LHC sectors, • The test planning should be proposed by LHC coordination (details of possible time window are to be discussed to adapt them with cryogenic installations availability) TE-MPE-TM – CSCM type test - 13 June 2013 Thanks to all persons involved for collaboration ! TE-CRG-OA_K.Brodzinski, 13.06.2013

20. CSCM test campaign at the end of LS1 • Simulation conditions for the CSCM campaign at the end of LS1: • CSCM campaign will be done in parallel with the survey campaign • Survey: 07H00 – 15H00 • CSCM: 15H00 – 23H00 • Planning by sector • 2 weeks for the preparation • 2 weeks for the tests of the 3 main circuits • 2 weeks for the recovery • Tests during the week (5 days) • Results: • No impact • First test in May 2014 • Last test in September 2014 TE-MPE-TM – CSCM type test - 13 June 2013

21. CSCM test campaign at the end of LS1 • Simulation condition for the CSCM campaign at the end of LS1: • CSCM campaign in parallel with the survey • Survey: 07H00 – 15H00 • CSCM: 15H00 – 23H00 • Planning by sector • 2 weeks for the preparation • 2 weeks for the tests of the 3 main circuits • 2 weeks for the recovery • Tests during the week (5 days) • Results: • No impact • First test in May 2014 • Last test in September 2014 TE-MPE-TM – CSCM type test - 13 June 2013

22. CSCM test campaign at the end of LS1 • 2 teams per CSCM activity • Could we do CSCM test in parallel with HWC ? • No other activities for the CSCM team during the powering tests TE-MPE-TM – CSCM type test - 13 June 2013