Project Overview

A substation upgrade on the Suffolk coast required reliable communications between sites across an 80km route. Modern substations depend on continuous data links: SCADA systems reporting the state of every part of the installation, load balancing between sites, thermal monitoring and protection systems operating in milliseconds. All of it runs on a communications network.

Birch Technical Services was appointed to design and install the fibre optic infrastructure carrying that link, across a route where distance, electrical interference and site security all ruled out conventional copper cabling.

Scope of Works

• Route survey and design across the full 80km corridor, including duct routing and section planning
• Duct installation along the route, installed, proved and tested ahead of any fibre
• Air-blown fibre installation using specialist jetting equipment, section by section
• Splicing and termination at each substation and intermediate joint position
• Testing and certification across the complete route, with results documented
• Commissioning support for the SCADA communications link

Why Fibre, Not Copper

Over 80km copper is not a serious option, but even at shorter distances a substation is close to the worst possible environment for a copper data cable.

Electromagnetic interference

Copper carries data as an electrical signal, and an electrical signal beside high-voltage switchgear is under constant attack. Fibre carries light through glass and is completely immune to electromagnetic interference.

Signal integrity over distance

Copper degrades. Over long routes that means repeaters, amplification and accumulated error. Fibre carries a clean signal across distances where copper would need intervention every few hundred metres.

No scrap value

Cable theft from unmanned infrastructure sites is a genuine and expensive problem. Fibre optic cable is glass, there is no scrap market for it, which removes the incentive entirely.

Harder to tap

A copper cable can be physically tapped without much difficulty. Tapping fibre is possible but considerably harder, and harder still to do undetected. On critical national infrastructure that difference matters.

Challenges

• Route length. At 80km, the installation method became the governing constraint. Pulled cable applies tension along its whole length, which over this distance risks damaging the fibre before it is ever commissioned.
• Live site operations. The route had to be built around an operational substation estate, so work was phased rather than continuous.
• Coastal environment. Exposure and ground conditions along a coastal corridor place additional demands on duct installation and jointing.
• Future access. Re-excavating an 80km route is not a realistic maintenance strategy, so the installation had to leave an upgrade path behind it.

The Solution: Air-Blown Fibre

An empty tube was installed along the full route first, then fibre bundles propelled through it using compressed air. The fibre travels on a cushion of air driven by specialist jetting equipment rather than being dragged through under tension.

• Lower installation stress. Blowing applies almost no tension, removing the limiting factor on long runs.
• Phased delivery. Duct goes in, is proved and left in place; fibre follows section by section around site operations.
• A permanent upgrade path. Because the tube remains in the ground, additional or replacement fibre can be blown through later without re-excavating the route.

Results

A communications network carrying SCADA data between substations across the full 80km route, immune to the electrical environment it runs through, with no scrap value to attract theft, and a duct network already in place for whatever the next upgrade requires.

Infrastructure designed to be uninteresting, which for something carrying control data for the electricity network is exactly the point.

Technologies Used

• Air-blown fibre installation with specialist jetting equipment
• Direct-buried and ducted fibre optic cable
• Fusion splicing and termination
• OTDR testing and route certification
• SCADA communications infrastructure

Got a route copper can’t cover? Get in touch to talk through the site and we’ll advise on the right approach.