Exploring The Grounding Problem Of OPGW Cable

July 06 14:56 2021

OPGW optical cable is mainly used on 500KV, 220KV, 110KV voltage level lines. Affected by factors such as line power outages, safety, etc., it is mostly used in newly-built lines. Overhead ground wire composite optical cable (OPGW) should be reliably grounded at the entry portal to prevent the optical cable from being broken by induced voltage and interrupted when a short circuit occurs in the line.

Pay attention to the following points for grounding requirements:

1. The grounding method of the optical cable of the splice box on the structure: the top of the structure, the lowest fixed point (before the remaining cable) and the end of the optical cable should be connected to the structure with a reliable electrical connection through a matching dedicated grounding wire. The remaining cable frame and the connection box and the frame should be fixed with matching fixing fixtures and insulating rubber. The remaining cable should be fixed on the remaining cable rack with θ1.6mm galvanized iron wire, and the binding points should not be less than 4, and the remaining cable and the remaining cable rack are in good contact.

2. Ground connection box optical cable grounding method: Reliable electrical connection should be made to the frame at the top of the frame and the head of the remaining cable through matching dedicated grounding wires.

3. The lead of the optical cable should be straight and beautiful. Install a fixing fixture every 1.5m-2m to prevent friction between the optical cable and the tower. The lead-down optical cable and the inner frame of the station should be fixed with matching fixing fixtures and insulating rubber, and the distance between the lowered optical cable and the frame should not be less than 20mm.

4. OPGW should be connected to the ground terminal of the frame with a matching dedicated grounding wire, the OPGW side should be connected with a parallel groove clamp, and the frame side should be connected with bolts, and no welding is allowed.

5. The guiding optical cable led from the connecting box on the rack to the buried part of the cable trench is protected by hot-dip galvanized steel pipes, and the two ends of the steel pipes are sealed with fireproof mud for waterproofing. The steel pipe is reliably connected to the grounding grid in the station. The diameter of the steel pipe should not be less than 50mm.

6. The optical cable installed by the floor-standing cable box is led from the frame to the buried part of the cable trench and is protected by hot-dip galvanized steel pipes, and insulated by insulating sleeves, and the two ends are sealed with fireproof mud for waterproofing. The remaining cable box and steel pipe are reliably connected to the grounding grid in the station. The diameter of the steel pipe should not be less than 50mm, the diameter of the insulating sleeve should not be less than 35mm, and the bending radius of the steel pipe should not be less than 15 times the diameter of the steel pipe. Reliable insulation between connection box, optical cable reel and box body.

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