The Selection Principle of OPGW Fiber Optic Cable

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OPGW fiber optic cable is mainly used in 500KV, 220KV, and 110KV voltage level lines, affected by line blackout, security, and other factors, and mostly used in new lines.


We should consider the following points when choosing an OPGW optical fiber cable: 

1. the requirements of meteorological conditions, the requirements of its own tensile strength, and the requirements of the allowable design load of the tower should be met.

2. The main technical data to be considered in the design of OPGW are: fiber type, fiber core number, fiber diameter, fiber cross-sectional area, fiber unit mass, ultimate tension strength, short-circuit current, DC resistance, modulus of elasticity, coefficient of thermal expansion, average annual operating stress, minimum bending diameter, maximum coil length, etc.

3. OPGW fiber optic cable can be selected under the condition that the ambient temperature is +15℃, no ice, no wind, and the arc droop of another ground wire is kept consistent.

4. Determination of allowable short-circuit current of OPGW. First, determine the short-circuit current equivalent time, generally, the 220kV line in the short-circuit current is very large, and the fault current equivalent time can be considered by 0.3s. According to the short-circuit current provided by the system, calculate the total short-circuit current into the ground of the line. The short-circuit thermal stability value of the OPGW and another ground line is verified at the substation exit by calculating the short-circuit current distribution between the OPGW and the other ground line. When a single short circuit occurs on the line, a brief high current occurs on the overhead ground line and the heat generated by the current raises the temperature of the fiber optic cable and shunt line. Because the current lasts for a short time, the heat will not be distributed to the surrounding environment, causing the wire temperature to rise. When the temperature of the wire exceeds its allowable temperature, it will seriously affect the safe operation. Therefore, meeting the thermal stability requirements is an important condition for determining OPGW and shunt lines. For OPGW, the allowable short-circuit current and allowable temperature provided by the manufacturer are generally used, and we only calibrate them. OPGW can be selected in accordance with the short-circuit current situation in each part of the line.

5. OPGW should have a good lightning resistance level, the communication quality should not be affected when lightning strikes OPGW, and the metal part should not have broken strands.

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