ADSS Optical Cable Installation Manual

The previous article has already talked about the scope of application of ADSS optical cable. In this article, the editor will tell you what aspects you need to pay attention to when installing ADSS optical cable.

Determination of control conditions during ADSS installation

The control condition (electrical or mechanical characteristics of ADSS optical cable) is an important part of ADSS installation design, which is related to the safe operation of the line and the service life of the optical cable. It is not only related to the operating conditions of the power line and meteorological conditions, but also related to the mechanical properties of the ADSS itself, which affects the determination of the ADSS type and the suspension position of the ADSS (electrical performance), crossing and tension, and the ADSS arc required by the tower load. Correct selection (mechanical properties).

1. Tower erection conditions and space potential distribution

Tower erection conditions mainly include: tower erection type and size, system voltage, wire type or outer diameter, coil, number of wire splits and split spacing, ground wire type or outer diameter, phase arrangement (double circuit or multiple times in the same tower) important).

2. Determine the allowable sag of the optical cable

In addition to the mechanical strength, the allowable sag of the ADSS optical cable depends on the distance between the low point of the sag of the optical cable and the ground (or crossing) and the position (or height) of the suspension point. The design of the suspension point location is directly related to the space potential at that point.

According to the relevant regulations or engineering requirements for the distance between the lowest point of sag of the cable and the ground, the allowable sag of the cable can be obtained. Engineers should be clear: this is one of the important control conditions of the project.

3. Optical cable tension-sag-span characteristics

Calculating the tension-sag-span characteristic requires two prerequisites: the design meteorological combination conditions and the initial installation sag of the fiber optic cable. There are several factors to consider when designing an ADSS fiber optic cable. The sag and tension of ADSS depend on the important intersection of lines and the strength of the tower structure, which are mutually constrained. When span or tower structures require ADSS suspension points, the distribution of electric field strength can be detrimental to ADSS cables. The location of the suspension point determined by the electric field distribution may not be conducive to determining the strength of the tower as well as the requirements of the span and the distance between the lines.

4. ADSS uses tension

The working tension of ADSS is determined according to the design load of the original power line tower. In the case of tower loading, the tension is increased to facilitate the crossing, but the effective span of the fiber optic cable can be reduced.

Engineers should determine the use tension of each stretch section according to each span in different stretch sections. When the ADSS must be suspended at a certain position according to the tower structure or span, etc., if a 110kV line is selected in a place where the space induced electric field is 20kV, the ADSS cable cannot be selected as the PE sheath. This situation should be determined according to the span of the tower in the line and the condition of the tower.

When necessary, engineers use ADSS optical cables with different tension and sheath types in the single-wire part of the line through economical comparison.

In short, in the actual engineering design, engineers should combine the actual situation of the built power line. When the above situation occurs, the control conditions should be correctly selected to make the installation design of the ADSS optical cable economical, safe and reasonable.

Anti-vibration and accessories for ADSS

The strength design safety factor of ADSS optical cable should be determined under the same meteorological conditions as the power line is installed. According to the mature operation experience of China's transmission lines, the design safety factor of ADSS optical cables should not be less than 2.5. Like metal strands, ADSS cables are subject to vibrations from wind and other environmental influences. Long-term vibration will cause fatigue damage to the cable itself and the joints. Therefore, the annual average working tension of the ADSS optical cable should be selected not to exceed 20% of the breaking force of the ADSS optical cable, and corresponding anti-vibration measures should be taken.

1. Anti-vibration measures
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Currently, there are two types of anti-vibration measures: installing anti-vibration hammers and spiral anti-vibration whips (SVD). If an anti-vibration hammer is used, a certain length of pre-twisted wire retention wire should be wrapped around the installation. Spiral anti-vibration whips are easy to use, so they are widely used. Field and laboratory tests have shown that anti-vibration whips are highly effective at reducing vibration levels.

The SVD should be installed according to design requirements. Two or more SVDs can be connected in parallel or in series, usually in parallel. Typically, four can be connected in parallel.

The industry generally believes that the installation position of the SVD is not sensitive to the anti-vibration effect. To avoid arcing at the end of the anti-vibration whip and the fitting's pre-twisted wire, the greater the distance from the end of the fitting's pre-twisted wire, the safer it is.

2. ADSS cable accessories

ADSS optical cable accessories mainly include sheet metal accessories, suspension accessories and splice boxes, which are usually provided by ADSS optical cable manufacturers. In recent years, domestically produced matching accessories have been widely used and are in good condition.