There are many hidden dangers of power cable construction accidents in winter

Author：hlyb Add Time：2016-03-03 16:11:52

During the construction of low and medium voltage power cables in winter, because the outdoor temperature is below minus 10 ℃, the PVC and XLPE insulation and sheath materials at low temperature show hard and brittle characteristics. If they are accidentally bumped during laying, the insulated core and copper shield are very vulnerable. Even if the on-site completion test can be successfully passed after the power cable is laid, after the power cable is continuously energized in the later stage, after the capacitive current flows through the damaged part, it will cause partial discharge, accelerate the insulation aging, and lead to line breakdown fault. This situation is not prominent in low-voltage power cables and prominent in medium voltage power cables. Sometimes there are no problems in the factory test of power cables. Due to the limitations of various conditions, no measures are taken for the on-site laying and installation of power cables. The construction is carried out directly in winter. After the laying of power cables, the on-site completion test is normal, but the fault occurs in a short time after the power on operation in the later stage. The fault points are dissected, and the appearance has no traces of mechanical damage, However, serious breakdown and ablation occurred due to the lack of internal insulation.

In recent years, due to various conditions, some newly laid medium voltage 10kV and 35kV fault power cables have not taken heating measures for power cables on site, and have been directly constructed and installed at about minus 10 ℃ in winter. The interphase and phase to ground insulation breakdown fault occurred in the power cable within a short time of power on operation (the short time is 10 days, and the long time is about 1 month). After accident investigation, the production and delivery test of the power cable were normal, and the on-site completion test was also successful (the AC 52kv / 1h of 26 / 35kV Power cable passed). However, the power on operation failed in a short time (the short time is 10 days and the long time is about 1 month), which is undoubtedly related to the failure to take heating measures for power cables in winter construction.

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There are many hidden dangers of power cable construction accidents in winter