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Product

UL 2277 WTTC 1000V torsion wind cableUL 2277 WTTC 1000 V & UL 44 RHW-2CSA FT4 & IEC 60332-3-22±100°/m Torsion down to −40 °C

WK 137-Torsion FT4 Wind-Turbine Nacelle Drip-Loop Torsion Power CableUL 2277 WTTC 1000 V / RHW-2 / CSA FT4 (−40 to +90 °C) wind-turbine drip-loop torsion

Dual-certified North American and European wind-turbine nacelle-to-tower drip-loop torsion power cable (HELUWIND WK 137-Torsion FT4) approved to UL 2277 (WTTC 1000 V), UL 44 (RHW-2), CSA FT4 and IEC 60332-3-22, tested for ±100°/m bi-directional yaw.

Anti-torsion braid
Flame-retardant
Oil-resistant
Approved
Order designation
WK 137-Torsion FT4 1×240 mm² (500 kcmil)
Outer Ø ≈
31.8 mm
Copper weight
2,304 kg/km
Total weight ≈
2,710 kg/km
Ampacity (air)
670 A
All sizes (11)
Request a quoteDatasheetWhatsApp
Engineering reply in 2 business hoursCut-to-length export drumsEN 10204 3.1 certificate per drum
Rated voltage
1000 V (WTTC)
600 V (UL RHW-2) · 0.6/1 kV IEC
Yaw torsion
±100° / metre
tested over > 5,000–10,000 cycles
Temp. range
−40 to +90 °C
90 °C wet & dry (UL RHW-2/WTTC)
Flame rating
CSA FT4 / Cat A
UL 1685 FT4 vertical tray + IEC
Conductor
Class 5 / K Cu
torsion-optimised bare/tinned Cu
Min. bend R
4 × OD (fixed)
6 × OD dynamic nacelle loop

Typical values for this cable type, based on UL 2277 (WTTC 1000 V) / UL 44 (RHW-2) / CSA FT4 / IEC 60332-3-22 — confirmed in the datasheet and quotation for your order.

Application fit

Is WK 137-Torsion FT4 right for your machine?

Specifically engineered for the free-hanging nacelle-to-upper-tower drip loop and tower cable trays in onshore and offshore wind turbines exported to North America (UL/CSA) and global IEC markets.

Free-hanging vertical run

Suitable

Suspended in the 8–15 m free-hanging nacelle drip loop, absorbing ±3.5 full nacelle yaw rotations (±100°/m) down to −40 °C.

Fixed installation

Suitable

Dual-rated UL 44 RHW-2 / WTTC 1000 V and CSA FT4 for direct routing onto vertical tower ladders without a transition splice box.

Offshore platform & shipboard deck trays

Suitable

Cross-linked elastomeric jacket resists hydraulic pitch oil, gearbox synthetic ester lubricants, salt mist and condensation.

Typical machinesOnshore & Offshore Wind Turbine Nacelle Drip LoopsNorth American (UL/CSA) & Global Wind Generator TowersDFIG & Full-Converter Stator/Rotor Power DropsYaw-Drive & Pitch-Control Power Distribution

Construction

Layer by layer

Shown: WK 137-Torsion FT4 1×240 mm² (500 kcmil) 1000 V WTTC / RHW-2 with torsion-lay Class 5 bare copper conductor, non-woven separator tape, heavy-wall cross-linked EPR/HEPR (RHW-2) insulation and black FT4 flame/oil-resistant cross-linked elastomer outer sheath.

1234
Schematic, not to scale — generated from the layer data
#LayerMaterial & reference
1Torsion-compensated fine-stranded copper (Class 5 /IEC 60228 Class 5 / ASTM Class K annealed bare (or tinned) copper with long-pitchAbsorbs ±100°/m axial twist without strand birdcaging or work-hardening at −40 °C
2Low-friction torsion slip separator tapeSynthetic polyester/non-woven sliding tape over conductorAllows the conductor bundle to rotate microscopically inside the insulation during yaw cycles
3Cross-linked EPR / HEPR dielectric (UL RHW-2)90 °C wet/dry thermoset Ethylene-Propylene Rubber compoundMaintains elastic modulus at −40 °C and withstands VFD/converter voltage spikes up to 1000 V
4Cross-linked CPE / Polychloroprene FT4 torsion jacketHeavy-duty thermoset elastomer compound (Black, UV-stabilised, Oil Res I & II)Passes CSA FT4 / IEEE 1202 vertical tray flame test and resists turbine gearbox oils

WK 137-Torsion FT4 Single-Core (16–500 mm² / 6 AWG–1000 kcmil)

Main generator-to-transformer tower drop cables bundled in trefoil or spacer clamps

WK 137-Torsion FT4 Multi-Core (3G–5G / Control)

Auxiliary nacelle power, yaw motor and pitch power feeders

Technical data

Ratings & operating limits

Typical values: Typical values for this cable type, based on UL 2277 (WTTC 1000 V) / UL 44 (RHW-2) / CSA FT4 / IEC 60332-3-22. Values for your order are confirmed in the datasheet and quotation.

Electrical

Rated voltage
1,000 V (UL 2277 WTTC / CSA) · 600 V (UL 44 RHW-2) · 0.6/1 kV (IEC 60502-1)
Factory AC dielectric withstand test
3.5 kV AC rms for 5 minutes

Thermal

Operating temperature range
−40 °C to +90 °C (torsion & fixed, wet or dry) · +250 °C short-circuit
Thermal cycling & overload stability
Verified thermal ageing and short-circuit withstand per standard

Mechanical

Torsion angle & endurance qualification
±100°/m (up to ±150°/m short-loop) over > 5,000 cycles down to −40 °C
Minimum bending radius
4 × OD (static tower ladder) · 6 × OD (dynamic nacelle drip loop)

Resistance

Vertical tray flame retardance
CSA C22.2 No. 0.3 FT4, UL 1685 FT4 / IEEE 1202 & IEC 60332-3-22 Cat A
Oil, UV & cold-impact resistance
UL Oil Res I & II (+60/+75 °C), 720 h Sunlight Resistant & −40 °C Cold

Reference standards

Dual North American & European approvals
cURus / cULus UL 2277 WTTC 1000V, UL 44 RHW-2, CSA FT4, CE & RoHS
Factory QA & material compliance
EN 10204 3.1 routine test certificate · RoHS 2 & REACH compliant

Identification

Dual metric & AWG/kcmil sizing
Marked with both metric (mm²) and North American (AWG / kcmil) sizes
Customs tariff (HS)
8544.49

Sizes

11 standard WK 137-Torsion FT4 1000 V wind-turbine cable sizes

Single-core (35–300 mm² / 2 AWG–600 kcmil) and 4-core nacelle drip-loop torsion power cables.

Dimensions, weights & free-air ampacity
Order designationMetric / AWGRatingOuter Ø ≈
mm		Copper
kg/km		Weight ≈
kg/km		In air 30 °C
A		Min. bend R
mm		Enquiry
Single-Core 1000 V WTTC / RHW-2 Generator Drip-Loop Power Cables
WK 137-Torsion FT4 1×35 mm² (2 AWG)1×35 mm² (2 AWG)1000 V14.233646519885
WK 137-Torsion FT4 1×50 mm² (1/0 AWG)1×50 mm² (1/0 AWG)1000 V16.548063524599
WK 137-Torsion FT4 1×70 mm² (2/0 AWG)1×70 mm² (2/0 AWG)1000 V18.6672855305112
WK 137-Torsion FT4 1×95 mm² (3/0 AWG)1×95 mm² (3/0 AWG)1000 V21.29121,140370127
WK 137-Torsion FT4 1×120 mm² (4/0 AWG)1×120 mm² (4/0 AWG)1000 V23.41,1521,410430140
WK 137-Torsion FT4 1×150 mm² (300 kcmil)1×150 mm² (300 kcmil)1000 V25.81,4401,740495155
WK 137-Torsion FT4 1×185 mm² (350 kcmil)1×185 mm² (350 kcmil)1000 V28.21,7762,110565169
WK 137-Torsion FT4 1×240 mm² (500 kcmil)1×240 mm² (500 kcmil)1000 V31.82,3042,710670191
WK 137-Torsion FT4 1×300 mm² (600 kcmil)1×300 mm² (600 kcmil)1000 V35.02,8803,340770210
Multi-Core 1000 V WTTC / FT4 Nacelle Auxiliary Power Cables
WK 137-Torsion FT4 4G25 mm² (4×4 AWG)4G25 mm² (4×4 AWG)1000 V27.69601,420138166
WK 137-Torsion FT4 4G50 mm² (4×1/0 AWG)4G50 mm² (4×1/0 AWG)1000 V35.81,9202,680205215
  • Typical values for this cable type; dimensions and weights for your order are confirmed in the quotation.
  • Additional sizes from 16 mm² (6 AWG) up to 500 mm² (1000 kcmil) and 3- to 37-core control cables are also manufactured.

Quality & approvals

Testing & inspection

Routine tests on every production length, sample and type tests per batch — documented on an EN 10204 3.1 inspection certificate.

  1. ConductorClass 5 stranding
  2. Spark test100 % in-line
  3. Lay-upCores, earth, fillers
  4. SheathingInner, braid / screen, outer
  5. Electrical testsAC voltage, resistance
  6. DimensionsOD, wall thickness
  7. Inspection documents & dispatchDrum & dispatch
Testing & inspectionTest value / referenceFrequency
Routine tests
3.5 kV AC 5-min dielectric withstand & CSA FT4 vertical tray flame testZero breakdown; char height within CSA FT4 / IEEE 1202 limitsEvery batch
Sample tests
20-year wind-turbine yaw torsion endurance test (±100°/m at −40 °C)Zero strand breakage or jacket cracking after full life-cycle torsion simulationQualification type test

Inspection certificate

Issued with every drum, listing the routine test results for that length.

Product approvals

UL 2277 WTTC 1000 V & UL 44 RHW-2 ListedCSA C22.2 FT4 & IEC 60332-3-22 Cat A Flame Retardant−40 °C Cold Impact & ±100°/m Torsion Verified

Company certificates

ISO 9001ISO 14001ISO 45001VDE marks approvalUL / cULCE · LVD / EMC

Marking & supply

Ordering & delivery

Sheath marking

TEBAOFLEX WK 137-TORSION FT4 <mm²/AWG> WTTC 1000V RHW-2 90C -40C OIL RES I/II FT4 CE
Delivery form
Non-returnable fumigated wooden or steel drums
Standard lengths
250 m · 500 m · 1000 m standard drums
MOQ
250 m (stock sizes) · 500 m (custom)
Lead time
3–5 weeks ex-works
Incoterms
EXW, FCA, FOB, CIF, DAP

Technical documents

Downloads

PDFWK 137-Torsion FT4 Wind-Turbine Nacelle Drip-Loop Torsion Power Cable – technical datasheet11 sizes · construction, technical data, approvalsXLSXWK 137-Torsion FT4 spec data (Excel)All 11 sizes with dimensions and data, for your BOM or quotation
Revision
2026-10-20
Updated
2026-10-20

FAQ

Questions engineers ask first

Not covered here? Send your drawing — an engineer replies within 2 business hours.

What is UL 2277 WTTC and why is it required in North American wind turbines?
UL 2277 (Wind Turbine Tray Cable, WTTC) is the dedicated North American safety standard for flexible 1,000 V power and control cables installed inside wind-turbine nacelles and towers. Combining WTTC 1000 V with UL 44 RHW-2 and CSA FT4 allows a single continuous cable run from the nacelle converter through the free-hanging torsion drip loop and down the vertical tower ladder.
How is ±100°/m yaw torsion calculated in a wind-turbine drip loop?
As the nacelle rotates to track the wind, the control system typically allows ±2.5 to ±3.5 full rotations (±900° to ±1,260°) before untwisting. Over a 10 to 12.6 m free-hanging drip loop in the upper tower, this equals ±100° per metre of cable length.
Why does WK 137-Torsion FT4 carry both metric (mm²) and AWG/kcmil markings?
European and Asian turbine OEMs design global platforms around IEC metric cross-sections (e.g. 185 or 240 mm²), while US and Canadian electrical inspectors enforce NEC/CEC AWG and kcmil rules. Dual marking satisfies both without redesigning nacelle busbars.
What factory routine tests and certificates are supplied with HELUWIND WK 137-Torsion FT4?
Every production drum of HELUWIND WK 137-Torsion FT4 undergoes 100 % conductor DC resistance measurement at 20 °C, high-voltage AC/DC dielectric withstand testing, and dimensional verification per UL 2277 (WTTC 1000 V) / UL 44 (RHW-2) / CSA FT4 / IEC 60332-3-22, supplied with an EN 10204 3.1 inspection certificate.

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WK 137-Torsion FT4 Wind-Turbine Nacelle Drip-Loop Torsion Power Cable

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