solar cables usually cannot enter the water during production, and the inside of the cable must be dry. Once the cable enters the water, under the action of the electric field, water tree aging will occur, which will eventually lead to cable breakdown. Water trees are a collection of voids filled with water in the diameter of 0.1m to several microns.
The local high electric field is formed by impurities, pores, and uneven junctions between the insulation and the inner and outer semiconducting layers in the insulation are the starting point for water treeing. Water directly enters the low-voltage power cable, causing corrosion of the steel strip, copper strip, and other metals, and the insulation performance is reduced. When water penetrates the insulation, it will cause the cable to puncture, even explode and injure people.
Causes of water ingress in solar cables
1. The newly bought coiled solar cable generally uses heat-shrinkable plastic sealing sleeves to seal the two ends. After the user has used it for a period of time, the remaining end is wrapped in plastic paper. The airtightness is not good, and the water vapor will penetrate into the cable after a long time.
2. When the solar cable is laid, the cable head wrapped in plastic paper is sometimes immersed in water to allow water to enter the cable; when towing and pipe, sometimes the outer sheath ruptures, causing water to enter the cable.
3. The cable head is not made in time after laying, so that the unsealed cable port is exposed to the air for a long time, or even immersed in water so that a large amount of water vapor enters the cable.
4. During the production of cable heads (including terminal heads and intermediate joints), due to the carelessness of the production staff, the cable ends sometimes slip into the cable well with water.
5. During cable operation, when a fault such as a breakdown of the intermediate joint occurs, the water in the cable well will enter the cable along the gap. Cable damage or breakdown caused by external forces on the construction site may also cause cable water ingress.
