1. Implementation Standards
The production and inspection of YTTW comply with multiple national and international standards:
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GB/T 34926-2017 "Mica Tape Mineral Insulated Corrugated Copper Sheathed Cables for Rated Voltages 0.6/1kV and Below"
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JG/T 313-2014 "Metal Sheathed Inorganic Mineral Insulated Cables and Terminations for Rated Voltages 0.6/1kV and Below"
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GB/T 12706-2020 Power cables with extruded insulation and their accessories for rated voltages from 1kV (Um=1.2kV) up to 35kV
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GB/T 19666-2019 "General Rules for Flame Retardant and Fire Resistant Wires and Cables or Optical Fiber Cables"
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BS 6387:2013 "Performance requirements for cables required to maintain circuit integrity under fire conditions"
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BS 8491:2008 "Method for assessment of fire integrity of large diameter power cables"
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IEC 60331 Tests for electric cables under fire conditions - Circuit integrity
2. Product Construction (From Inside to Outside)
YTTW adopts a multi-layer inorganic/metal composite structure to ensure circuit integrity under fire conditions:
🔹 Conductor
Stranded from high-purity annealed oxygen-free copper wires, available in Class 1 (solid) or Class 2 (stranded) conductor construction. The stranded design imparts excellent flexibility to the cable, making its bending performance far superior to the solid copper rod of BTTZ.
🔹 Insulation Layer
Multi-layer lapping of high-temperature resistant synthetic mica tape (phlogopite/muscovite). The mica tape is an inorganic material with a melting point as high as 1375±5℃, and it does not burn or carbonize and fail in a 1000℃ flame.
🔹 Filler Layer
Densely filled with alkali-free fiberglass rope, providing thermal insulation, cushioning, and auxiliary insulation.
🔹 Metallic Sheath
Copper tape is longitudinally applied and welded into a continuous tube, then formed through a corrugation (ripple) process. The corrugation treatment enhances mechanical protection capability while significantly improving flexibility, allowing the cable to be installed with bending. The copper sheath can be used as a PE grounding conductor.
🔹 Outer Sheath (Optional)
The YTTWY model is additionally provided with a low-smoke halogen-free flame-retardant polyolefin sheath, enhancing corrosion resistance and moisture resistance, suitable for harsh environments such as direct burial and outdoor exposure; the YTTWV model adopts a PVC outer sheath.
