The scaling of transport AC losses in Roebel cables with varying strand parameters

Jiang, Zhenan; Staines, M.P.; Long, N.J.; Badcock, Rodney A.; Bumby, Chris W.; Talantsev, E. F.; Hamilton, Kent; Buckley, R. G.; Amemiya, Naoyuki

doi:10.1088/0953-2048/27/7/075007

Cited by 23 publications

(12 citation statements)

References 35 publications

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“…This indicates that AC loss can be scaled by the overall threshold transport Ic measured at the 1 V criterion across the entire series connected coil assembly. This is again consistent with previous work [11], whilst similar scaling of AC loss by the overall cable Ic have also been observed in HTS Roebel cables [12,17]. Theoretical justification of this scaling is provided by Wolfbrandt and Magnuson [18], who derived from Brandt and Indenbom [16] an expression for total AC loss in a superconductor per cycle per length, which is valid in the case of field-independent Jc, with…”

Section: Fig 6 Heresupporting

confidence: 90%

AC Loss Measurements in a Hybrid REBCO/BSCCO Coil Assembly

Jiang

Staines

Long

et al. 2017

IEEE Trans. Appl. Supercond.

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Wire cost and AC loss are paramount issues for the future uptake of HTS AC machines. In particular, new approaches which reduce the total manufacturing cost of HTS coils are critical to the future commercial uptake of HTS technology. Here, we present the results of AC loss measurements s of a hybrid HTS coil assembly comprising end windings (EWs) wound with BSCCO wire and a central winding (CW) wound with REBCO wire. As a cost mitigation measure, we have chosen to use REBCO wire which possesses a relatively low self-field Ic at 77 K, equating to approximately half that of the BSCCO wire.Transport AC loss measurements were made on the total coil assembly at both 77 K and 65 K, using a recently developed lockin amplifier approach. We show the AC losses in the assembly at these temperatures scale with the overall transport critical current threshold of the hybrid coil assembly. The results are then compared with a reference coil assembly having similar geometrical dimensions, and in which both the EWs and CW were wound with identical BSCCO wire. Surprisingly we observe that the AC loss of the hybrid coil is lower than that of the BSCCO coil, despite the CW of the hybrid coil employing wire a lower overall average Ic. We attribute this effect to the lower AC loss of coated conductor REBCO wire under parallel field, which is the dominant field orientation in the CW region.Based on this observation we conclude that hybrid assembly design is a good design strategy for HTS coil assemblies, enabling both wire cost and AC loss to be balanced.

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Section: Fig 6 Heresupporting

confidence: 90%

AC Loss Measurements in a Hybrid REBCO/BSCCO Coil Assembly

Jiang

Staines

Long

et al. 2017

IEEE Trans. Appl. Supercond.

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Section: Fig 6 Heresupporting

confidence: 93%

AC Loss Measurements in a Hybrid REBCO/BSCCO Coil Assembly

Jiang¹,

Staines²,

Long³

et al. 2021

Preprint

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Wire cost and ac loss are paramount issues for the future uptake of high-temperature superconductor (HTS) ac machines. In particular, new approaches which reduce the total manufacturing cost of HTS coils are critical to the future commercial uptake of HTS technology. Here, we present the results of ac loss measurements of a hybrid HTS coil assembly comprising end windings (EWs) wound with BSCCO wire and a central winding (CW) wound with REBCO wire. As a cost mitigation measure, we have chosen to use REBCO wire which possesses a relatively low self-field Ic at 77 K, equating to approximately half that of the BSCCO wire. Transport ac loss measurements were made on the total coil assembly at both 77 K and 65 K, using a recently developed lockin amplifier approach. We show the ac losses in the assembly at these temperatures scale with the overall transport critical current threshold of the hybrid coil assembly. The results are then compared with a reference coil assembly having similar geometrical dimensions, and in which both the EWs and CW were wound with identical BSCCO wire. Surprisingly, we observe that the ac loss of the hybrid coil is lower than that of the BSCCO coil, despite the CW of the hybrid coil employing wire a lower overall average Ic. We attribute this effect to the lower ac loss of coated conductor REBCO wire under parallel field, which is the dominant field orientation in the CW region. Based on this observation, we conclude that the hybrid assembly design is a good design strategy for HTS coil assemblies, enabling both wire cost and ac loss to be balanced. © 2017 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.

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“…This implies AC loss in the assemblies can simply be scaled by the macroscopic coil Ic. Similarly, scaling AC loss by the overall wire/cable critical current has been reported in single wires and Roebel cables [24,26,29].…”

Section: Ac Loss In the Coil Assembliesmentioning

confidence: 54%

AC loss measurements in HTS coil assemblies with hybrid coil structures

Jiang

Long

Staines

et al. 2016

Supercond. Sci. Technol.

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Both AC loss and wire cost in coil windings are critical factors for HTS AC machinery applications. We present AC loss measurement results in three HTS coil assemblies at 77 K and 65 K which have hybrid coil structure comprising one central winding (CW) and two end windings (EWs) wound with ReBCO and BSCCO wires with different self-field Ic values at 77 K. All AC loss results in the coil assemblies are hysteretic and the normalized AC losses in the coil assemblies at different temperatures can be scaled with the Ic value of the coil assemblies. The normalised results show that AC loss in a coil assembly with BSCCO CW can be reduced by using EWs wound with high Ic ReBCO wires, whilst further AC loss reduction can be achieved by replacing the BSCCO CW with ReBCO CW. The results imply a flexible hybrid coil structure is possible which considers both AC loss and wire cost in coil assemblies.

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The scaling of transport AC losses in Roebel cables with varying strand parameters

Cited by 23 publications

References 35 publications

AC Loss Measurements in a Hybrid REBCO/BSCCO Coil Assembly

AC Loss Measurements in a Hybrid REBCO/BSCCO Coil Assembly

AC Loss Measurements in a Hybrid REBCO/BSCCO Coil Assembly

AC loss measurements in HTS coil assemblies with hybrid coil structures

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