All-Dielectric Self-Supporting (ADSS) cable is a type of fiber optic cable that contains no conductive metal elements. It is used as a communications medium, installed along existing overhead transmission lines and often sharing the same support structures. ADSS cable is adopted for high voltage, middle, small span conditions in Power Transmission System or mazy terrain, which offers a rapid and economical means for deploying optical fiber cables along existing aerial rights-of-way.
Construction Of ADSS Cable
The cable consists of 5 to 36 ﬁbers containing tubes or fillers stranded in up to 3 layers around a central strength member and bound under a PE jacket. Each tube contains 6 -12 ﬁbers. All the ﬁbers in the cores are filled with water blocking gel. Fillers may be used to preserve the cable geometry. A water swelling tape is helically wrapped around the cable core. Aramid yarns are helically laid to supply peripheral strengthening of the cable. The outer jacket is tightly bounded over the aramid yarn layer. The cable jacket incorporates an optional inner polyethylene jacket and an outer polyethylene or AT (anti-tracking) jacket. When the induction on cable surface is above 12KV, anti-tracking sheath material (AT) will be applied. With AT outer jacket, the maximum electric field strength at operating point can reach 35KV. For long span application, a double jacket design can be considered. An optional ripcord can be put under the jacket layer to faciliate its removal. The internal glass optical fibers are supported with no strain, to maintain low optical loss throughout the life of the cable. The cable is jacketed to prevent moisture from degrading the fibers. The jacket also protects the polymer strength elements from the effect of solar ultraviolet light.
The actual status of overhead power lines is taken into full consideration when ADSS fiber optic cable is being designed. For overhead power lines under 100kV, PE outer sheath is applied. For power lines equal to or over 110kV, AT outer sheath is applied. The delicate design of Aramid quantity and stranding process of the ADSS cable can meet the demand on various spans.
ADSS fiber cables are with the follow characteristics:
1. ADSS cables can be installed without shutting off the power.
2. ADSS cables are excellent AT performance. The maximum inductive at the operating point of AT sheath can reach 12kV.
3. ADSS is light weight and small diameter reducing the load caused by ice and wind and the load on towers and back props.
4. The ADSS cable is large span length and the largest span is over 1000 meters.
Advantages Of ADSS Cable
ADSS cable is a cost-effective and reliable technology has been used worldwide and many years. ADSS cable has a number of advantages over other types of aerial cable, including its small size, low weight, flexible and fully dielectric construction.
The type of telecommunication and control cable can exploit the considerable economic advantages offered by the installation of existing high voltage power lines over all types of terrain and competes with other technologies such as optical fibre ground wire (OPGW) and helically wrapped optical fibre cables. ADSS cable is designed to be light weight and small in diameter to reduce the load on tower structures due to cable weight, wind, and ice. More, ADSS cables are strong enough to allow lengths of up to 700 metres to be installed between support towers.
Installation ADSS cable is faster and easier than previous aerial designs. ADSS cable is available in fiber counts up to 144 fibers, as a multimode fiber cable. ADSS cable can be used for applications ranging from short span (40-50 meter) distribution lines to long span transmission lines (300-500 meter spans) to extraordinary spans required by some river canyon crossings exceeding 1800 meters.