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To minimise AC losses in power dense electrical machines, multistrand stator windings are routinely employed. However, the magnitude of AC losses can be highly sensitive to the strand transposition achieved in the as-manufactured winding, which can differ significantly from that assumed during design. This paper employs X-ray Computed Tomography (XCT) to verify the twisted strand transposition in a compressed aluminium coil, through the construction of 3D models for each of the strands within the coil. These models enable the strand transposition to be verified by qualitative and quantitative means, providing initial insight into the actual strand transposition achieved at the mid-point of the coil active length.

Compressed windings can substantively increase the power density of electrical machines. However, the compression of coils can lead to significant deformation of the conductor lay, cross-sections and insulation coating, impacting the longevity, loss and thermal performance of such windings. This paper presents the use of high resolution X-ray Computed Tomography (XCT), along with 2D and 3D image segmentation techniques, to perform an initial characterisation of a compressed aluminium winding. From the XCT derived data, significant localised conductor deformation and strand insulation thinning has been observed.