Cooling down and acceptance tests - CEA/CEA · 2009. 4. 30. · CEA / DSM / Irfu / SACM Bertrand RENARD April 2009 2 1. Test Facility description OUTLINE 2. Coil Test procedure 3

Bertrand RENARD April 2009CEA / DSM / Irfu / SACM 1

Cooling down and acceptance tests

Saclay cryo-magnetic test facility for W7-X coils


1. Test Facility description

OUTLINE

2. Coil Test procedure

3. Cooling down

4. Improvements from the tests

Cryostat, Valve boxes and SatelliteLiquefier / refrigeratorPower SupplyData acquisition system


Cryostat, Valve boxes and Satellite

Test facility: one cryostat


Safety valves

CalibrationLeak

Wirings

Currentleads

Valves

Test facility: valve box


Test facility: inside the cryostat

NitrogenShield

Connectionsfor Coils


6

� Liquefier

Liquid helium tank: 5 000 liters

Production 70 l/h

use:Satellite tankCurrent leads

� Refrigerator

Power 200 W @ 4.5 K

Total mass flow rate46 g/s @ 300 K

15 g/s @ 5 K, 6 bars

Test facility: refrigerator / liquefier


� Power supply

cooled by water

Max current: 25 kA

Max voltage: +/-10 V

Ramp: 20 to 200 A/s

Scheme of the magnet safety system

Test facility: power supply and safety system

� Magnet Safety SystemNormal: slow discharge through the power supply.Quench: fast discharge through 20 mΩprotection resistor.

Bertrand RENARD April 2009CEA / DSM / Irfu / SACM 8Laurent GENINI Greifswald June 16-17, 2008CEA/DSM/IRFU/SACM

� 80 sensors for each coil:Temperatures, pressure, mass flow, strain gauges,

extensometers, voltage drops, current, vacuum…

� During cool down and warm up:All sensors: 0,025 Hz.

� During current test:� All sensors: 1 Hz.�In case of quench:

Cryogenic sensors: 100 Hz.Voltage drops and current: 5 kHz

Quench acquisition window: Pre trigger 2 s Post trigger 8 s

Test facility: data acquisition system



OUTLINE

2. Coil Test procedureCoil preparationRoom temperature testsCryogenic testsRecording and documentation

3. Cooling down



Unloading from transport lorry and transport frame

Visual checks

Coil installation under the support ring

Test procedure: coil preparation


Conductor bending

Junction boxes

Reinforcement structure

Cabling and tests• Temperature sensors, • Strain gauges, • Extensometers

Insulation of conductor

QD tests

DC test

Test procedure: coil preparation


Cryostat open:

QD test

DC test

Cryostat closed:

Vacuum pumping

Leak test

Cooling down

RRR measurement

Test procedure: cooling down


Nominal current

Temperature margin test

Fast discharge

Nominal temperature check

Interlayer resistance

Pressure drop

Test procedure: current test

Non-planar coil: 17.6 kAStored energy: 7.7 MJDischarge time: ~ 2.5 s

Planar coil: 16 kAStored energy: 1.2 MJDischarge time: 0.45 s


Leak measurement

AC test (interturn insulation)

DC test (ground insulation)

Impedance measurement

Warming up (electric heating + break vacuum with nitrogen)

Test procedure: warming up

Impedance measurement from Ehmler et al.


Cabling and tests• Temperature sensors, • Strain gauges, • Extensometers

QD tests

DC test

Junction boxes dismantling

Preparation for departure

Visual checks

Truck loading

Test procedure: coil departure preparation



OUTLINE

Description

2. Coil Test procedureRequirements

3. Cooling downDescription and limitations

4. Improvements from the testsNon-conformities and modifications


Coil cooling down: energy extracted

2.3 mCoil average diameter

Total mass

Case (ss)

Insulation (Epoxy resin)

Conductor total

Conductor total length

5300 kg

3640 kg

540 kg

870 kg

945 m

Non-planar coil inertia


AAB10, 11-20 July 2007, position 2A

The inlet temperature ramp reaches the limit of 2 K/h

Coil cooling down: ramp


∆T in-out reaches the limit of 40 K on the casing

Coil cooling down: maximum gradient


Total coil energy loss

Coil cooling down: total power

),(.)(. 2/ condradNPHmdt

dTTCpm outinHe

coilcoil

++∆=

∑


Coil cooling down: limitations

Helium inlet temperature limiting parameters:

� Maximum gradient in the coil: 40 K

� Maximum rate of inlet temperature decrease:2 K/h between 300 and 100 K

4 K/h between 100 and 50 K

10 K/h below 50 K

� Refrigerator power� Mass flow rate

� Nitrogen power



OUTLINE

2. Coil Test procedure

3. Cooling down


Test required values and non-conformitiesImprovements on the test facilityImprovements of the coils, retest…� a chance to learn!


All tests are recorded for legal liability and manufacturing warranty.

A complete paper and electronic documentationis produced.

(one engineer full time)

Improvements from tests: documentation

If the “Scope and Requirements” are not fulfuilled, a

non-conformity reportis issued

This NCR requires a decision about possible actions to modify the coils or the test facility


Liquefier / Refrigerator

Little ageing problems, big delays

� Leak on the body of a manual valve

delay roughly 3 months

� Deviation of a pressure sensor

delay roughly 3 weeks

� Actions:

Additional safety analysis of pollution in the He cycle

Maintenance

Replacement of the cycle compressor (last year)

Improvements from tests: liquefier maintenance


Leak on the junction boxes� Problem

After 3 years of tests, suddenly leaks appeared on the junction boxes…

Finding and avoiding leaks is time consuming

Improvements from tests: helium leak

� Possibilities:

Junction box surface

Rectangular gasket

� Actions:

Realization of boxes for a leak test outside of the cryostat

More caution and systematic testing


High electric resistance � Problem

High resistance between extra length busbars and the junction boxes… Impossibility to perform the current test at the nominal values.

Improvements from tests: junction resistance

� Actions performed:

Re gilding of copper surfaces

Increase in caution during connection of the bus

� Possibilities:

Oxidization of the gold

Parallelism between the copper plates and the junction boxes


DC test under vacuum to check the insulation of the coil

� Problem: cryostat alone DC test valid

with coils DC test hazardous

Not valid DC test

� For non planar coils:

9.1 kV at room T,10.4 kV at cryogenic T.

� Actions :

Vacuum test for the QD feedthroughevery other current tests

Addition of insulation rings between cryostat and QD feedthrough

Additional Paschen test planned for the coils

Improvements from tests: DC tests


- Coil testing is 90% accomplished (15/03/09)

- 84 current tests performed

(63 different coils + 7 coils twice + 7 coils three times)

- Yearly ratio has increased (projection)

Assessment of the tests

• Preparation of coils and coil sensors• Cooling and warming speed• Maintenance of cold box and Helium circuits• Helium liquefaction before cold tests

Maximum speed of testing is limited by:

0

5

10

15

20

25

30

0 1 2 3 4 5 6

Year (+2003)

Cur

rent

test

s


CONCLUSION

Cryogenic and current tests are a big effort

These tests demonstrate that coils work

Many improvements and techings gained from the tests

QD wires modified

Reworked insulation of double layer connections (coil types 4&5)

Leaks repaired on aluminium weldings and casing circuits

Team 5 Technicians and 3 Engineers + support other CEA services

Documents

Cooling down and acceptance tests - CEA/CEA · 2009. 4. 30. · CEA / DSM / Irfu / SACM Bertrand RENARD April 2009 2 1. Test Facility description OUTLINE 2. Coil Test procedure 3