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DOME Fiber Closure Has A Gap In Its Structure

  • March 11, 2019 1:48 AM EDT


    DOME Fiber Closure Has A Gap In Its Structure


    Reasonable design of the insulated grounding structure of Greentel DOME Fiber Closure : Insulating spacers commonly used in fiber optic splice closures typically consist of two spacers. The upper washer is a slotted washer and the lower washer is a protruding washer. Since the fixing bolts are connected to the reinforcing core of the optical cable, the upper and lower insulating spacers can be combined to form insulation between the metal parts of the optical fiber joint box and the cable reinforcing core. In the compressive strength test, a DC voltage of 15 kV was applied between the fixing bolt and the metal member. Most materials used for insulating gaskets are high molecular polymers. The dielectric strength of these materials is relatively high, typically between 500 and 1000 megavolts per meter. Therefore, in theory, only 0.1 mm of polymer-based insulation between the two electrodes provides 15 kV of protection.

    However, in practice, the insulating sheets used in the fiber splice closure are not complete. Since the structure is determined by the fact that it must be superimposed by two parts, there must be a gap, in which case the gap is unavoidable. Air is present, so the dielectric strength of the air and possible air and creep discharge must be considered at the same time. However, since the air passages present in the gap are not straight lines, but are fold lines or curves, the distance between the shortest air passages between the poles is the most dangerous distance. Therefore, the insulating property tested when a polymer insulating material is present is actually the shortest distance test of the gap tube in the two sheets of insulating sheets.

    According to the standard, the pressure resistance test in front of the fiber joint closure must be immersed in water of 1.5 meters for 24 hours, so if the seal is not good, the water vapor will infiltrate, which will inevitably affect the withstand voltage. However, the probability of this case is relatively small compared to the above case, so pay attention to it.

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