Types of field optical cables

Types of power special optical cable and field optical fiber

Power special optical cable generally refers to OPGW (optical composite ground wire), OPPC (optical composite phase wire), MASS (metal self-supporting optical cable), ADSS (all-dielectric self-supporting optical cable), ADL (phase/ground bundled optical cable) and GWWOP (phase / ground wire winding optical cable) and so on. The power special optical cables that are widely used mainly include ADSS and OPGW.

Special Optical Cable

1. Optical Ground Wire - OPGW (Optical Ground Wire) OPGW, also known as ground wire composite optical cable, optical fiber overhead ground wire, etc., is an optical fiber unit used for communication in the ground wire of the power transmission line. It has two functions: one is as a lightning protection line for transmission lines, providing shielding protection for transmission lines against lightning discharge; the other is to transmit information through the optical fiber compounded in the ground wire. OPGW is a complex of overhead ground wire and optical cable, but it is not a simple addition between them.

OPGW optical cables are mainly used on 500KV, 220KV, and 110KV voltage level lines. Due to line power outages, safety and other factors, they are mostly used on new lines. The applicable characteristics of OPGW are: (1) For lines with high voltage exceeding 110kv, the span is relatively large (generally above 250M); (2) It is easy to maintain, and it is easy to solve the problem of line crossing, and its mechanical characteristics can meet the large span of lines; ( 3) The outer layer of OPGW is metal armor, which has no effect on high-voltage electric corrosion and degradation; (4) OPGW must be powered off during construction, and the loss of power outage is large, so OPGW should be used in new high-voltage lines above 110kv; (5) Among the performance indicators of OPGW, the greater the short-circuit current, the more it is necessary to use good conductors for armoring, which reduces the tensile strength accordingly. In the case of a certain tensile strength, the only way to increase the short-circuit current capacity is to increase the metal cross-sectional area , resulting in an increase in cable diameter and cable weight, which poses a safety problem to the strength of the line tower.

There are three main types of common OPGW structures, namely aluminum tube type, aluminum skeleton type and (stainless) steel pipe type.

2. Optical Phase Conductor——OPPC (Optical Phase Conductor)

In the power grid, some lines may not have overhead ground wires, but phase wires are essential. In order to meet the requirements of optical fiber networking, similar to OPGW technology, adding optical fibers to the traditional phase line structure in a suitable way becomes an optical fiber composite phase line (OPPC). Although their structures are similar, there are principled differences between OPPC and OPGW from design to installation and operation.

3. Metal self-supporting optical cable - MASS (Metal Aerial Self Supporting)

From a structural point of view, MASS is consistent with the OPGW of the central tube single-layer stranded wire. If there is no special requirement, the metal stranded wire is usually made of galvanized steel wire, so the structure is simple and the price is low. MASS is a product between OPGW and ADSS. When MASS is used as a self-supporting optical cable, the main considerations are strength and sag, as well as the safety distance from adjacent conductors/ground wires and to the ground. It does not need to consider short-circuit current and heat capacity like OPGW, nor does it need to consider insulation, current carrying capacity and impedance like OPPC, and it does not need to consider the field strength of the installation point like ADSS. The function of the outer metal strand is only to accommodate and Protect fiber optics. In the case of similar breaking force, although MASS is heavier than ADSS, its outer diameter is about 1/4 smaller than central tube ADSS, and about 1/3 smaller than layered ADSS. In the case of similar diameter, the breaking force and allowable tension of ADSS are much smaller than that of MASS.

4. All Dielectric Self Supporting Optical Cable - ADSS (All Dielectric Self Supporting)

ADSS optical cables are widely used on 220KV, 110KV, 35KV voltage level transmission lines, especially on established lines. It can meet the requirements of large span and large sag of power transmission lines. The standard ADSS design can reach 144 cores. Its characteristics are: (1) The theoretical value of optical fiber tension in ADSS is zero; (2) ADSS optical cable is a fully insulated structure, which can be operated live during installation and line maintenance, which can greatly reduce power failure losses; (3) The expansion rate of ADSS is within It can remain unchanged in a wide range of temperature differences, and it has stable optical characteristics under extreme temperatures; (4) The electric corrosion-resistant ADSS optical cable can reduce the electric corrosion of the optical cable caused by the high-voltage induction electric field; (5) The diameter of the ADSS optical cable is small , Light weight, can reduce the impact of ice and wind on the optical cable, and its impact on the strength of the tower is also small; (6) ADSS adopts new materials and smooth shape design, so that it has superior aerodynamic characteristics.

ADSS optical cable is mainly composed of cable core, reinforced aramid yarn (or other suitable materials) and outer sheath. A variety of ADSS optical cable structures can be summarized into two main types: central tube type and layer twisted type.

5. Additional optical cable - OPAC

Metal-free bundled overhead optical cable (AD-Lash) and metal-free wound optical cable GWWOP (Ground Wire Wrapped Optical Fiber Cable) optical cables are sometimes collectively referred to as additional optical cables - OPAC, which is a kind of optical fiber communication network built on power lines. Economical and quick way.