The structure design of XLPE insulated cables is based on the relevant technical parameters. Firstly, the appropriate current carrying section, inner semi-conductive shielding and anti-emission shielding of high voltage cables are determined by the maximum allowable operating temperature.

For medium and low voltage XLPE insulated cables, the current-carrying section can be determined and then the structure design can be carried out. For high voltage cables, other related factors, such as core section, economic current density, allowable working temperature of insulating materials and insulation structure form, must be determined. If not taken seriously, cable insulation life and mechanical properties will be affected.

The inner and outer sheaths of medium and low pressure cross-linked polyethylene are usually made of PVC with a thickness of 3 ^ - 4 mm, and PE material is also used in heat shrinkable tubes of inner sheath. This is mainly to reduce water seepage, because the water absorption of PE is less than that of PVC. PVC material is generally used for sheath, because the fire-retardant and flame-retardant properties of PVC material are better than PE, this kind of cable structure has been widely used in Beijing area. For the outer sheath of 110 kV XLPE insulated cable with ultra-high voltage, because of the requirement of withstanding voltage, it is necessary to coat a layer of conductive graphite on the outer layer of PVC sheath for field test. When accepting the cable, it is necessary to check whether the conductive layer is complete or not. Otherwise, the test of the sheath will be meaningless.

交联聚乙烯绝缘电力电缆导体材料

XLPE绝缘电缆的结构设计是依据有关技术参数，首先通过最高允许工作温度确定合适的载流截面、内半导电屏蔽以及高压电缆的防发射屏蔽等来确定的。

对于中、低压XLPE绝缘电缆，载流截面确定后就可进行结构设计，而高压电缆还须确定其他相关因索，如线芯截面与经济电流密度、绝缘材料允许工作温度、绝缘结构形式等密切相关。如果不认真对待会影响电缆绝缘寿命及机械性能等。

中、低压交联聚乙烯的内外护套层一般采用PVC材料，厚度一般为3^-4 mm,内护套热缩管也有厂家使用PE材料，这主要是为了减少渗水，因为PE的吸水率小于PVC。外护套一般使用PVC材料，因为PVC材料的防火阻燃性能比 PE的好，这种结构的电缆已在北京地区大量采用。对于超高压的110 kV XLPE绝缘电缆外护套，由于有耐压要求，为了现场试验需要在PVC护套外层涂有一层导电石墨，电缆验收时一定要检查导电层是否完整，否则对护套的试验将没有意义。