Project requirements · Mechanical
Torsion (wind turbine loop)
The cable in a wind turbine drip loop survives repeated twisting as the nacelle yaws.
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Constructions that meet it
- Fine-wire class 5 or 6 conductor: changes no layer: a property of the conductor. Fine-wire class 5 or 6 conductor with short lay, tapes and lubricated layers that let the elements slide (class 5/6 copper or aluminium). Drawbacks: Class 6 is larger for the same section.
- Rubber or PUR sheath and insulation: changes no layer: a property of the sheath compound. Rubber or TPE / PUR sheath and insulation (EPR, EM2, cross-linked polyolefin) (rubber / PUR). Drawbacks: Cost.
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Tests
- Maker torsion tests (classes as printed by Lapp; their origin standard not found): ± 150 °/m at 1 rpm. Pass: TW-0: 5000 cycles at ≥ +5 °C; TW-1: 2000 cycles at ≥ -20 °C; TW-2: 2000 cycles at ≥ -40 °C
- Nexans WINDLINK: ± 150 °/m (± 100 °/m for 400 mm²). Pass: 2000 cycles, no copper wire broken
- Helukabel tower test: ± 150 ° per 1 m. Pass: more than 16,000 cycles (WK 137)
How specifications state it
Named as '± 150 °/m, N cycles at T °C'; no single international standard found.
Where it is asked for
- wind turbines (loop between nacelle and tower)
- robots
Sources
- Lapp ÖLFLEX wind loop datasheet (valid from 06.02.2019): TW-0, TW-1, ± 150 °/m at 1 rpm (maker's catalogue)
- Lapp-based datasheet on RS (TW-2, 2000 cycles at ≥ -40 °C), via search results (quoted by others)
- Nexans WINDLINK low voltage cable product page (quoted by others)
- HELUWIND WK 137-Torsion FT4 product listing (more than 16,000 cycles) (quoted by others)