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Winding and tooling tests

Insulation choice

F.Rondeaux

120-21 /01/2011 Dipole design review- II-8 Winding and tooling tests – insulation choice – F.Rondeaux

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Dipole design review- II-8 Winding and tooling tests – insulation choice – F.Rondeaux 2

Outline

• Tests :– First winding tests (March – April 2010)– Winding tests still to be done– Mechanical tests on stacks– Conductor behaviour during heat treatment

• Insulation– Specifications– Conductor insulation

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Dipole design review- II-8 Winding and tooling tests – insulation choice – F.Rondeaux

Tests

3

Coil design

Tests

Tooling design - Winding- Heat treatment- Impregnation

There is a list of questions we have to answer to be able to built the coil.The aim of the test program is to allow us to have these answers.

Validation of parameters- Materials parameters- Insulation thickness- …

Verify feasibility Winding tests

Geometry, dimensions of the moulds…?

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4Dipole design review- II-8 Winding and tooling tests – insulation choice – F.Rondeaux

First winding tests (March – April 2010) 1/4

• Q: how to wind the coil in the block design configuration(cf. II-4) with the design cable (cf.II-2)?

• Q: what geometry for the ends?

bending tests have been performed :

• bare copper cable • HFM dimensions • up to 10 turns.

• dedicated tooling with modularity • variable ramp angle • versatile HW-bend geometry • 3 options for the end

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5Dipole design review- II-8 Winding and tooling tests – insulation choice – F.Rondeaux

First winding tests – tooling 2/4

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First bending tests – results 3/4

• A tension of 30 daN has been considered as the best compromise in terms of cable behavior.

• The circular end (which shows simplest geometry and saves conductor in comparison with ellipse and superellipse end options) is retained.

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Close‐up on the hard‐way bend zone after several turns

Bending test tooling (final configuration)

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Dipole design review- II-8 Winding and tooling tests – insulation choice – F.Rondeaux

First winding tests – results 4/4

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• The flared configuration has been shown to be possible with the angle of 25° (considered as the largest reasonable value, and also the most critical in terms of bending radius): the cable is mechanically stable and a good quality winding has been achieved.

•Additional tests with other parameters (angle = 15°, opposite winding direction) have confirmed the result.

Profile obtained with the natural curvature of the cable (positions of the rolls)

R = 500 mm

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8Dipole design review- II-8 Winding and tooling tests – insulation choice – F.Rondeaux

Winding tests still to be done• Winding test with returned ends (dummy cable)

– Coil self supported– OK for the 2nd layer– Simplify the tooling – Avoid friction tape / rolls

• Validation of the winding options with the actual insulated cable.20-21 /01/2011

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Dipole design review- II-8 Winding and tooling tests – insulation choice – F.Rondeaux

Mechanical tests on stacks

• Q: validate the hypothesis on properties of the materials used for the model.

• Q: define the size to be imposed on the coil during the heat treatment and the impregnation.

• Avoid over stress during the manufacturing steps.• Dimensioning the sections of reaction mould / impregnation mould.• Dimensions used in modeling (at low temp. under stress) ↔ dimensions

required for tooling.

• Tests on stacks – Modularity of the test setup (≠ heights, …)– Compression at 300 K, at 4K– Thermal restraint

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Dipole design review- II-8 Winding and tooling tests – insulation choice – F.Rondeaux

Conductor behavior during heat treatment 1/2• Q : How to manage the behavior of the cable during the heat

treatment?

- Stress relief, increase of volume during the Nb3Sn formation, thermal expansion...

- Influence of manufacturing process, composition and structure of filaments and strands

Tests to be performed on the 2 types of conductor (PIT, IT)

• How can we observe / quantify the deformation?

– Structure of the mould? Ends fixed?– Compression on the cable?

Need to define the experimental protocol

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11Dipole design review- II-8 Winding and tooling tests – insulation choice – F.Rondeaux

Conductor behavior during heat treatment 2/2

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• Potential configurations for heat treatment tests on cable :– Length of cable free (1 m)– Length of cable in a mould with ≠ fixation points– Length of cable following the end geometry + half of the strait section– …?

– Final test : full scale mock-up with 5 insulated turns

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Dipole design review- II-8 Winding and tooling tests – insulation choice – F.Rondeaux

Insulation• Based on NED developments. • Mechanical requirements : support 150 MPa in compression.• Electrical requirements : maximum service voltage = 1000V

Dielectric tests on the chosen materials• Thermal properties and radiation resistance are not an issue for FRESCA II

coil.

• Specifications (conductor insulation):– Insulation thickness : 150-200 µm per conductor face

• Q: How to qualify/verify the thickness of tapes?– Insulation type : S-glass fiber + epoxy resin

• Need of– Insulation between layers

compatibility with impregnation process requirement– ground insulation

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13Dipole design review- II-8 Winding and tooling tests – insulation choice – F.Rondeaux

Conductor insulation• Insulation type : glass fiber + epoxy resin

– S2 glass tape desized• Tape (#416 from JPS) currently used for the SMC not completely

satisfactory.• Hiltex S2 tape used at CEA no more available.

Find new solution– Sleeve from Berkeley? – Braid S-glass tape directly on the conductor?

• RAL will check if it is possible– New tape (S2, Hiltex ALF boron free alumina-silica fiber tape …)?

– Vacuum impregnation • with epoxy resin (RAL, LARP …) ?

(baseline = RAL#71A , 100 p. DGEBA MY750 + 55p. POPDA HY5922, Hunstman)• with cyanate ester / epoxy blend (chosen by ITER for radiation hardness) ?

• Insulation and impregnation will be tested on an SMC.

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14Dipole design review- II-8 Winding and tooling tests – insulation choice – F.Rondeaux

Conclusion

• Good quality winding can be achieved in the design geometry.• Next steps:

- Winding test with returned ends (dummy cable + actual insulated cable): tooling under study.

- Mechanical tests on stacks : to be defined.− validate the parameters used for the design studies− dimension the moulds

- Management of the conductor behavior of the conductor during the heat treatment: study starting.

- Choice of the insulation : search of solution under way.

• The detailed program is under construction.

Thanks for your attention

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