Armored optical cable construction

Armored optical cables are designed with multiple protective layers, including a fiber core, strength members, metal armor, and an outer jacket, to ensure durability, crush resistance, and environmental protection.

Core Components

Fiber Core: The central component consists of one or more optical fibers, either single-mode or multi-mode, which transmit data as light pulses. These fibers are typically arranged in loose tubes or tight-buffered bundles depending on the design requirements. Strength Members: Surrounding the fiber core are materials that provide tensile strength and prevent stretching.

Common strength members include aramid yarns (Kevlar), fiber-reinforced plastic (FRP) rods, or metallic wires. These components protect the fibers from mechanical stress during installation and operation.

Armor Layer

The defining feature of armored cables is the metallic armor, which provides protection against crushing, rodent damage, and environmental hazards: Steel Tape Armor (STA): Corrugated steel tape wrapped around the fiber core, offering radial compression resistance and rodent protection. Steel Wire Armor (SWA): Layers of steel wires providing superior tensile and impact resistance, often used in heavy-duty or direct burial applications. Aluminum Armor: Interlocking or helically wrapped aluminum can be used for lightweight protection with good crush resistance.

Double Armor: Some specialized cables, such as submarine or mining cables, combine tape and wire armor for maximum protection.

Outer Jacket

The outermost layer shields the cable from environmental factors such as moisture, UV radiation, chemicals, and abrasion. Common materials include: Polyethylene (PE): Durable and UV-resistant, suitable for outdoor use. Polyvinyl Chloride (PVC): Flexible and flame-retardant, often used indoors.

Low Smoke Zero Halogen (LSZH): Fire-safe material producing minimal toxic smoke, compliant with building codes. Between the armor and outer jacket, a layer of aramid yarn may be added to enhance tensile strength and prevent stretching during installation.

Design Considerations

Armored optical cables are engineered for harsh environments, including direct burial, industrial sites, tunnels, and outdoor installations. Key design advantages include: Crush Resistance: Protects fibers from heavy loads in ducts or underground. Rodent Protection: Prevents damage from animals such as rats or termites.

Moisture Barrier: Steel or aluminum layers prevent water ingress and swelling. Longevity: Designed for 20–30 years of reliable service in extreme conditions. Flexibility in Installation: Armored cables can be installed without conduits, reducing labor and cost compared to traditional protective methods.

Variants

Indoor Armored Cables: Designed for routing through walls, ceilings, and floors, often using lighter armor and flexible jackets. Outdoor Armored Cables: Heavily armored for direct burial or exposure to harsh environmental conditions, available in light or heavy armor versions. In summary, armored optical cables combine a fiber core, strength members, metallic armor, and protective outer jacket to provide robust mechanical protection, environmental resistance, and long-term reliability, making them suitable for both indoor and outdoor applications in demanding conditions.