Explain the lightning protection technology of urban optical cable lines, and use self-designed overhead poles or use power poles, tram poles, cable radio and television poles, etc. This paper mainly introduces the lightning protection treatment of different laying methods of urban electric (optical) cable lines.
Explain the lightning protection skills of urban optical cable lines
1. Cable line spacing grounding standard
When the cable line adopts the overhead mode, if the hanging type is adopted, the cable suspension wire should be separated and routed, and the cable metal sheath and shielding layer should be overlapped and grounded. From any grounding point, ground once every 250m, the maximum grounding interval should not exceed 350m. When on the same line as the power line, the suspension line must be connected to the vertical power ground. If the support type is adopted, the reinforcing members in the cable sheath should also be grounded at intervals. In addition to grounding at both ends of the cable metal shield, it should also be connected at the cable joint. Connect the cable shield to the suspension wire together for grounding. The shield grounding should be done at the cable joint as much as possible.
2. In order to prevent the infringement of inductive lightning, the number of local telephone electrical cables should not exceed two on the same route of overhead local telephone cables, and no more than four. If the power pole is used to hang the line or when it is erected with the power line, it should not exceed two. When the power line is the same as the 10KV power line, the power line is on the top and the telephone line is on the lower line. The vertical distance of the lowest point of the power line from the local telephone cable should be greater than or equal to 2.5m; when it is on the same line as the 1KV power line, the net distance between the two lines should be greater than or equal to 1.5m; When the TV broadcasts on the same pole, the cable TV broadcast line should be on, the telephone line is below, the clear distance between the two lines should be greater than or equal to 1.2m; when it is on the same line as the trolleybus line (direct current below 750V), the local telephone cable should also be at the bottom. .
3. Method and standard for installing lightning protection line on pole
When there are no tall buildings and large trees around the urban effect area or the relatively empty area, lightning protection devices must be installed at the top of the pole. The range of the lightning protection line installed on the pole is mainly: the urban line is equipped with more than 20 pairs of branching equipment or poles equipped with a junction box, PCM (peripheral control module), regenerative repeater, etc. (10m around the pole) If there is a lightning protection device installed in a building with a pole above the pole, the pole may not be equipped with a lightning protection line; the corner pole, the branch pole, the test pole, the spanning pole and the straight rod road of the suburban line every 5 - 10 pole poles; poles on both sides that cross the power line above 10KV, subjected to lightning poles.
4. Installation of electric pole lightning protection line
1) When there is a reserved lightning conductor threading hole on the cement pole, on the pole slightly, a wire with a diameter of 4.0 mm should be drawn upward from the nail nut and 10 cm above the pole top as a lightning protection line; the grounding of the lower part of the pole A steel wire with a diameter of 4.0 mm is taken into the ground at the nail nut, bent below the ground below 70 cm and horizontally extended as a ground wire.
2) When there is no reserved lightning-proof line on the cement rod, the lightning-proof line (4.0mm diameter wire) is bundled four times with a diameter of 3.0mm from the top of the pole, and bent upwards to penetrate the rod from the top of the pole. Inside the body, run down until the rod is placed in the ground, and then bend from the bottom of the rod and extend horizontally. The lightning protection line should be close to the shaft 10cm beyond the top of the pole. The shaft is wrapped around the middle of the shaft every 50cm with a diameter of 3.0mm. .
3) When using the pole pull wire as the lightning protection line, bundle the wire with a diameter of 4.0mm four times at a distance of 10cm and 60cm from the top of the pole, and then press it into the hoop of the cement rod; when the lightning rod is installed on the wooden pole, The steel wire with a diameter of 4.0 mm is nailed with a staple and pressed into the pull wire to the inside. The lightning protection line is 10cm above the pole top. The installation method of the cement rod and the wooden pole using the pull wire as the lightning protection line is the same.
4) When the urban pole road and the high voltage (10kv) power line cross, the wooden poles on both sides can be installed with a discharge gap type lightning protection line. The installation method and specifications are the same as above. If the cement is used on both sides of the crossover, the installation method and specifications are the same as above, except that the steel pole is replaced with a 3.0mm steel wire for four turns every 50cm to fix the lightning protection line.
5. The length of the lightning protection line in the underground extension line and the grounding resistance. After the lightning protection line of the overhead pole road in the city is buried in the ground along the pole of the pole, a 4.0mm steel wire is buried at 70cm below the ground as the underground extension line. It is determined by the requirements of soil quality and grounding resistance. The underground extension line can be bent in a "snake" shape, but it cannot be coiled. Underground extension lines are buried in the urban area. If the terrain cannot be extended and buried, the lower end of the lightning protection line can be buried below 1 m from the ground. The grounding device of the lightning protection line can also adopt the method of grounding the gas bar.
AMICI reflection prism called also roof prism or right angle roof prism,which deflects the beam through an angle of 90 degree and inverts the image. For this reason,this prism is perfect for erecting images inverted by the objectives.
We supply many types of high precision optical prisms,such as Wedge Prism,Right Angle Prism,rhombohedral prism,Dove prism,Penta prism,pyramid prism,dispersing prism,Reflection prism etc. Each having a particular geometry to achieve the reflections necessary to perform a specific imaging task.Reflecting prisms may invert,rotate,deviate or displace a beam.dispersing prisms produce spectral separation for spectroscopic applications or for tuning a laser output.Wedge prism is commonly used in laser system for eliminating the reflections from the second surface or for beam steering.Irregular-shaped or non-standard size prisms may be available by custom order.
Specification of our Amici roof prism as follow:
*Material BK7 Grade A optical glass,UV fused silica,MgF2,N-SF10 etc.
*Dimension:3-100mm.
*Dimension Tolerance +/-0.2mm
*Beam Deviation Up to 30 arc seconds
*Angle Tolerance Up to 5 arc seconds
*Flatness Up to λ/4 @633nm
*Surface Quality 60/40 scratch and dig,40/20 even better
*Chamfer 0.3mm+/-0.1mm
*Coating: AR coating,HR,PR upon request.
Roof Prism,Polished Roof Prisms,Amici Roof Prism,Right Angle Roof Prism
China Star Optics Technology Co.,Ltd. , https://www.csoptlens.com