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Low-Medium voltage power cable in the winter construction, because the outdoor temperature is below the 零下10℃, the Low-temperature PVC and XLPE insulation and sheath materials appear hard and brittle characteristics, such as the installation process accidentally encountered accidental bump, insulation core and copper shielding is very easy to damage. Even after the installation of the cable after the test can be successfully passed, but after the cable continuous power, in the damaged parts through the capacitor current after the industry will trigger partial discharge, accelerated insulation aging, resulting in line breakdown failure. This situation in the Low-voltage cable performance is not outstanding, in the medium-voltage cable performance outstanding. Sometimes the cable factory test without any problems, installation of the site due to various conditions of restrictions on the cable did not take any measures in the winter direct construction, the cable after the laying of the site completed test all normal, but late power running very short time on the fault, anatomical fault point, appearance without any mechanical damage traces,
But the internal insulation is missing and there is a serious breakdown and ablation. In recent years, some newly laid 10kV, 35kV fault cable due to various conditions, in the scene did not take the cable heating measures, directly in the winter 零下10℃ around the site construction installation. Power running for a short period of time the cable appeared interphase and relative insulation breakdown (10 days, long 1 months or so), after the accident, cable production and factory test did not appear abnormal, on-site completion test is also smooth (26/35kv power cable Exchange 52kv/1h passed).
However, the power operation has a short time failure (short 10 days, a long 1 months or so), this is no doubt with the cable in the winter construction did not take heating measures on the cable.