Temperature-sensing optical cables should be carefully routed, fixed, and bent according to specific guidelines to ensure accurate temperature measurement and system reliability.

General Principles

Temperature-sensing optical fibers act both as signal carriers and temperature sensors, so installation quality directly affects measurement accuracy. Fibers are typically single-mode or multimode, selected based on the interrogation method and system requirements, and must comply with ITU-T standards for low loss and bend insensitivity .

Laying Techniques

1. Direct Laying: The fiber is fixed along the surface of the asset (bus duct, high-voltage cable, or power line) using insulated zip ties or flame-retardant ties. The fiber should maintain close contact with the surface to accurately sense temperature .
2. Winding Laying: For precise measurement at critical points (e.g., busbar joints), a double-loop winding or circular arc is used. The unfolded length of the loop should be at least 5 meters, and the fiber must maintain a minimum bending radius of 3–5 cm to prevent signal loss .
3. S-Shaped Routing: When monitoring multiple cables simultaneously, an S-shaped layout maximizes coverage and reduces fiber usage while ensuring all cables are monitored .

Fixing and Protection

• Binding Spacing: Tie the fiber at intervals no greater than 50 cm, securing both the start and end of loops .
• Fiber Margin: Leave extra fiber (fiber ring) to allow positioning, ambient temperature measurement, and protection during installation .
• Connector Handling: Keep fiber end faces clean and protected with caps before connector installation to maintain measurement accuracy .
• Environmental Protection: In high-humidity or harsh environments, use moisture-proof measures and insulation climbers to prevent condensation and maintain sensor performance .

Testing and Commissioning

• Testing Sections: Reserve 20 m sections for system debugging and verification .
• Fiber Slack: Leave 1 m of fiber every 100 m to prevent tension and damage during installation .

Considerations for Power Utilities

• Cable Positioning: Avoid soil or loose media between the fiber and conductor to ensure accurate temperature readings .
• Thermal Coupling: Ensure all materials between the fiber and conductor are known to optimize distributed temperature sensing accuracy .
• Noise Mitigation: Route fibers away from vibration sources to reduce interference in distributed acoustic or temperature sensing systems . By following these methods—direct or winding laying, proper fixing, maintaining bending radius, environmental protection, and testing sections—temperature-sensing optical cables can provide reliable, high-accuracy monitoring for bus ducts, high-voltage cables, and power utility systems.