ADSS stands for All Die-Electric Self Supporting cable. The self supporting means, this types of fiber cable doesn’t need any metallic supporting wire. And the die-electric means an insulator.
Since this ADSS fiber doesn’t need any running wire to support it, it has been widely used in outdoor environment. It is used by electrical utility companies as a communications medium, installed along existing overhead transmission lines. One of examples is NEA. Nepal Electricity Authority installs this ADSS fiber along its electricity grid lines in order to provide the fiber solution to enterprises/companies.
- Utilized for telecommunications by power utilities, telcos, railways, and private network groups
- Designed for installation on distribution and transmission lines
- Capable of being installed in close proximity to conductors
- Suitable for underbuild applications, minimizing the need for outages
- Used for telecom networks where quick, low-cost installation is a priority
- Used in FTT-X applications like FTTH (Fiber to the Home)
- Light weight, small cable diameter.
- Small effects of ice and wind.
- The load of the tower and support is small.
- Can withstand its own weight and external load.
- The span is large and the maximum span is more than 1000M.
- Excellent tensile and temperature characteristics.
- Eliminates bonding & grounding
- Live power line installation
- Lower cost
- can be laid while power on, a power line failure doesn’t influence ADSS function.
- Anti electro-corrosion, suitable for bad climate.
- Non-metal structure, good insulation, anti-thunder.
- Life expectancy is up to 30 years.
The core consists of optical fibers contained in one or more loose buffer tubes allowing the fibers to be free from strain even at high operating loads. Since, ADSS is used in overhead, the outer sheath is made capable of handling the harsh climate, tension and water.
The components of ADSS fiber extends with regard to the areas where it is used.
Types of ADSS fiber cable
There are two types of ADSS fiber cable on the basis of structure:
a) Central Tube Structure b) Stranded Structure
a) Central Tube Structure:
In a central tube design, the fibers are placed in a PBT loose tube filled with water-blocking material within a certain length. Polybutylene terephthalate (PBT) is a thermoplastic engineering polymer that is used as an insulator in the electrical and electronics industries.
Then they are wrapped with aramid yarn (heat-resistant and strong synthetic fibers) according to the desired tensile strength and extruded with PE (≤110KV electric field strength) or AT (≥100KV electric field strength) sheath. The PE is Polyethylene (PE), widely used thermoplastic polymer for fabricated parts and components. This structure features with small diameter and light weight but has limited lengths.
b) Stranded Structure:
The fiber loose tubes are surrounding around a central strength member (usually as FRP material). Fibre-reinforced polymer (FRP), also Fibre-reinforced plastic, is a composite material made of a polymer matrix reinforced with fibres. The fibres are usually glass, carbon, or aramid, although other fibres such as paper or wood or asbestos have been sometimes used.
And the rest parts are similar to the central tube structure. This type is able to obtain a longer fiber length. Although the diameter and weight are relatively big, it is better to be deployed for large span applications.
The working principle of ADSS is similar to the normal optical fiber. It has large number of fibers made up of silica or plastic surrounded by different protective layers. In the above figure, the core consists of optical fibers.
The core consists of optical fibers contained in one or more loose buffer tubes allowing the fibers to be free from strain even at high operating loads.
Each fiber is a single thread/hair like structure capable of transmitting the data in speed of light. Due to high speed, the bandwidth is very high. When large number of cores are combined, the bandwidth will be extremely huge. Both single mode and multi mode can be arranged in ADSS fiber.
How to care ADSS cable?
In order to endure the cable for long run, following things must be followed.
- not exceed the maximum pulling tension
- not exceed the minimum bending radius
- not exceed the maximum impact or crush resistance
- use of shock resistance grips
- taking care the outer jacket during installation. If outer jacket gets rugged, high chance the fiber will loose its durability very soon.
- cable should be at a height (at least 6 feet) not easily accessible by human beings.
- Joint box/ tiff-in box should be shield properly so water, insect couldn’t enter over there.
Conclusion: ADSS fiber is widely used in transmission lines because of its low cost and self supporting features.