Powering the main linac implications Daniel Siemaszko, Serge Pittet 01.06.2010 OUTLINE : Cost impact of power converters, power consumption and powering

Powering the main linac implications

Daniel Siemaszko, Serge Pittet01.06.2010

OUTLINE : Cost impact of power converters, power consumption and powering strategy, power losses, heat load, needs in space allocation.

TE EPCTE 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.

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Daniel Siemaszko, Serge Pittet - EDMS 1075533

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.

Critical Moderate impact Reasonable

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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.

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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.

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400 kV Grid, Scc = 13 000 MVA

Main Substation- Central Campus

Local Loads

36 kV

400 kV

Surge Arrester

110 MVA400/36 kV

CircuitBreaker

Earthing Switch

IsolatingSwitch

400 V

36 kV

400 V

36 kV

Over ground

Underground

CircuitBreaker

Earthing Switch

IsolatingSwitch

Powering loops for redundancy


Power consumption

• The consumption of the main linac is about 1.5-1.9MW 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).

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Powering first sector last sectorDB decelerator 420 kW 420 kWMB converters 500 kW 200 kWDipole correctors 1.6 kW 0.2 kWTransfer lines MB+DB (not yet specified) 75 kW 75 kWTurnarounds (possibly not through tunnel section) 610 kW 610 kWTOTAL (Load) 1.6 MW 1.3 MWTOTAL (Cable losses plus 85% converters efficiency) 1.9 MW 1.5 MWTOTAL (considering power factor cos = 0.8) 2.4 MVA 1.9 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.

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AC Power

DC Power

DB

DB

MB

MB

0.5m0.5m

3m

Two-beam module

EMI on MODULE Powering group of 60 Powering group of 30 Individual poweringMain beam DC power 4.8 T 9.5 T 516 TDrive beam DC power 91 T 182 T 5409 TTrims/corr (MB and DB) 51 T 50 T 0.62 TTOTAL DC (Maximal value) 147 T 241 T 5926 TTOTAL AC (Maximal value) 0.18 T 0.18 T 0.18 T

EMI on TRANSPORT Powering group of 60 Powering group of 30 Individual poweringMain beam DC power 0.14 T 0.27 T 15 TDrive beam DC power 2.6 T 5.2 T 155 TTrims/corr (MB and DB) 1.4 T 2.9 T 0.018 TTOTAL DC (Maximal value) 4.2 T 8.5 T 169 TTOTAL AC (Maximal value) 6.6 T 6.6 T 6.6 T


Space allocation in caverns

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36/0.4 kV2000 kVA

DC/DC for magnets

Distribution panel

DC/DC for magnets

DC/DC for magnets

Rectifier

36kV

400V

48VDC

144 to 442 racks

Other devices

• 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.


3U3U3U3U3U3U

9U

9UPower

CTRL

Power Power

CTRL1

CTRL2

10-30kW 30-50kW10-30kW1-3kW

type First sector Last sectorMB correctors 5correctors/3U 11 racks 2 racksMB main converters 4-7kW module 164 racks 22 racksDB trimmers 5trimmers/3U 26 racks 26 racksDB main converters 10kW module 52 racks 52 racksTransfer lines 10kW module 10 racks? 10 racks?Turn-arounds 10-25kW module 35 racks 35 racksTOTAL 272 racks + 26 trimmer racks 121 racks + 26 trimmer racks

Cavern cross-section

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• 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.


Cavern cross-section

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Alternative trimmers controlTE EPCTE EPC


• 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

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• 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.

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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 m3/h) with T=20° is considered, with a pressure of 6-9 bars.

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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.

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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.

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Dedicated shaft for cables

Possible maintenance during operation

Dedicated shaft for cables

Strong protection from radiations plus access for technicians


Documents

Powering the main linac implications Daniel Siemaszko, Serge Pittet 01.06.2010 OUTLINE : Cost impact of power converters, power consumption and powering