Powering the main linac implications Daniel Siemaszko, Serge Pittet OUTLINE : Cost impact of power converters, power consumption and powering strategy, power losses, heat load, needs in space allocation. TE EPC

Cost impact of converters (1/2) CONVERTER COST  POWER · MTBF · 1/MTTR · EFFICIENCY · PRECISION · REVERSABILITY · 1/VOLUME Radiations have an impact on: MTBF: Mean Time Between Failure must be as high as possible considering the large number of power converters needed in the main linac. MTTR: High spare quantity needed to compensate faulty module cool-down time. EFFICIENCY: Sensitive switch mode supplies needed for high efficiency. PRECISION: complex digital system needed in the 100ppm range. REVERSABILITY: increased number of switching and control devices. VOLUME: More sensitive active devices needed to reduce converter volume. 01/06/20102 TE EPC Daniel Siemaszko, Serge Pittet - EDMS

Cost impact of converters (2/2) MB and DB main converters: – POWER · MTBF · 1/MTTR · EFFICIENCY · PRECISION · REVERSABILITY · 1/VOLUME – Low radiation area needed. Correction dipoles: – POWER · MTBF · 1/MTTR · EFFICIENCY · PRECISION · REVERSABILITY · 1/VOLUME – Low radiation area needed. DB trims: – POWER · MTBF · 1/MTTR · EFFICIENCY · PRECISION · REVERSABILITY · 1/VOLUME – Radiation hard modules could be deployed. CriticalModerate impactReasonable 01/06/20103 TE EPC Daniel Siemaszko, Serge Pittet - EDMS

Radiations in the tunnel Most of the radiations come from the drive beam (90%). The expected average dose after four hours cooling reaches 100mSv/h. A technician coming down on a monthly basis will be walking 1.5h in the tunnel. The technicians will be exposed to a collective dose of 120mSv/year. 01/06/20104 TE EPC Daniel Siemaszko, Serge Pittet - EDMS

Power distribution High voltage cables (36kV) go through the tunnel to power each cavern. 36kV/400V transformers connect grid to distribution panels (Ref. C. Jach). 400V grid in the tunnel is impossible because of power dissipation and voltage drop. 01/06/20105 TE EPC Daniel Siemaszko, Serge Pittet - EDMS

Power consumption The consumption of the main linac is about MW per accelerating sector (considering losses). Need for a distribution transformer of about 2.5MVA for each accelerating sector. Total power consumption for the main linac: 80MW (100MVA). 01/06/2010Daniel Siemaszko, Serge Pittet - EDMS TE EPC Poweringfirst sectorlast sector DB decelerator420 kW MB converters500 kW200 kW Dipole correctors1.6 kW0.2 kW Transfer lines MB+DB (not yet specified)75 kW Turnarounds (possibly not through tunnel section)610 kW TOTAL (Load)1.6 MW1.3 MW TOTAL (Cable losses plus 85% converters efficiency)1.9 MW1.5 MW TOTAL (considering power factor cos  = 0.8)2.4 MVA1.9 MVA

EMI produced by cables 36kV grid produce 50Hz EMI on main beam transport. DC cables for powering magnets produce EMI on module. Magnetic field estimated for cables without shielding and arranged in compact pairs with very low distance between them. 01/06/20107 TE EPC EMI on MODULEPowering group of 60Powering group of 30Individual powering Main beam DC power 4.8  T9.5  T516  T Drive beam DC power 91  T182  T5409  T Trims/corr (MB and DB) 51  T50  T0.62  T TOTAL DC (Maximal value) 147  T241  T5926  T TOTAL AC (Maximal value)0.18  T EMI on TRANSPORTPowering group of 60Powering group of 30Individual powering Main beam DC power 0.14  T0.27  T15  T Drive beam DC power 2.6  T5.2  T155  T Trims/corr (MB and DB) 1.4  T2.9  T0.018  T TOTAL DC (Maximal value) 4.2  T8.5  T169  T TOTAL AC (Maximal value)6.6  T Daniel Siemaszko, Serge Pittet - EDMS

Space allocation in caverns 01/06/20108 TE EPC The required space allocation includes power converters of different sizes, distribution panel and the distribution transformer. Power converters stacked in standard racks. Small racks containing trimmers can be placed in the tunnel. Daniel Siemaszko, Serge Pittet - EDMS typeFirst sectorLast sector MB correctors5correctors/3U11 racks2 racks MB main converters4-7kW module164 racks22 racks DB trimmers5trimmers/3U26 racks DB main converters10kW module52 racks Transfer lines10kW module10 racks? Turn-arounds10-25kW module35 racks TOTAL272 racks + 26 trimmer racks121 racks + 26 trimmer racks

Cavern cross-section 01/06/20109 TE EPC Two stages of racks can be put in the middle of the cavern, leaving space for the cables and the technicians. 32m is needed for the converters in the first section cavern and 14m for the last. Another 4m is needed for the trimmers if they are not in the tunnel. Daniel Siemaszko, Serge Pittet - EDMS

Cavern cross-section 01/06/ TE EPC Daniel Siemaszko, Serge Pittet - EDMS

01/06/ Alternative trimmers control TE EPC Daniel Siemaszko, Serge Pittet - EDMS RAD-HARD Trimmers placed close to the magnets with limited precision to 1% (still insuring a current precision of 100ppm in the magnet). FEAS (CLIC Front End Acq. Sys.) ensures DA and AD conversion. Need for 4 analog and 4 digital floating signals per CLIC module with a 100Hz rate. Reference current managed by control unit, distribution references between mains and trimmers. (Consistent saving in cabling cost 25MCHF).

Correctors alternative control 01/06/201012Daniel Siemaszko, Serge Pittet - EDMS Correctors in the caverns using FEAS (CLIC Front End Acq. Sys.). Fast control loop in the corrector (10kHz/precision 1%). Slow control loop located over ground (1Hz), high precision (100ppm) allowed with temperature measurement and calibration parameters stored in database. Need for 1 analog input, 3 analog outputs and 2 digital signals for each corrector. FEAS with DA and AD converters and 100Hz read-out. TE EPC

Heat load in the caverns The converters in the caverns are water cooled but still, some heat dissipation to air is to be expected. The ventilation unit in the tunnel must sustain the whole heat load since the converters are in a confined space. The heat load is estimated with the following assumptions: Converters efficiency of 85%, water cooling efficiency of about 90% and dissipation to air of transformer is 1%. Heat load to air by transformer and converters: 52kW (down to 40kW). Heat load to water is about 260kW (down to 200kW), meaning a flow of 3.1l/s (11.2 m 3 /h) with  T=20° is considered, with a pressure of 6-9 bars. 01/06/ TE EPC Daniel Siemaszko, Serge Pittet - EDMS

Heat load in the tunnel Each trimmer dissipates from 1 to 50W. Total power dissipated by the trimmers in one section: 18kW Grouped in strings, each of them would dissipate 780W in the tunnel. Grouping in small racks and water cooling of trimmers is compulsory. One might expect some 40W of dissipation to air every 30-60m, depending on the amount of strings. Power dissipation in power cables is about 15W/m for the drive beam and 20W/m for the main beam assuming 30 magnets strings. The value of 35W/m is an absolute maximum. This value goes down to 20W/m in the last sector. 01/06/ TE EPC Daniel Siemaszko, Serge Pittet - EDMS

Needs in civil engineering Two types of caverns, one with an access lift (8 in total), one with access through tunnel only (40 in total). The length of the cavern should be enlarged. Dedicated shaft for cables have to be designed. Power converters in turnarounds would allow to save space in the caverns. However, we have good reasons to believe that radiation level will be too high because of neutron scattering. Radiation levels to be confirmed by simulations. 01/06/ TE EPC Daniel Siemaszko, Serge Pittet - EDMS