What are the advantages and disadvantages of using solid dielectric cables compared to fluid-filled cables in underground distribution?

Solid dielectric cables, such as XLPE (cross-linked polyethylene) and EPR (ethylene propylene rubber) cables, and fluid-filled cables, typically oil-filled cables, are two types used in underground distribution. Solid dielectric cables offer several advantages. They are simpler to install and maintain, as they do not require oil pumping or monitoring systems. They have lower dielectric losses compared to oil-filled cables. They are less susceptible to leaks and environmental contamination. They are generally more flexible and easier to handle. However, solid dielectric cables also have disadvantages. They have a lower ampacity for a given conductor size compared to oil-filled cables due to their lower thermal conductivity. They are more susceptible to damage from partial discharge and water treeing. They can be more difficult to repair, requiring specialized splicing techniques. Fluid-filled cables offer advantages in terms of higher ampacity. The oil provides excellent cooling, allowing them to carry more current for a given conductor size. The oil also helps to fill voids and prevent partial discharge. However, fluid-filled cables have disadvantages. They are more complex to install and maintain, requiring oil pumping and monitoring systems. They are susceptible to oil leaks, which can be environmentally damaging. They require periodic oil testing and maintenance. They are generally more expensive than solid dielectric cables. Therefore, the choice between solid dielectric and fluid-filled cables depends on factors like ampacity requirements, installation costs, maintenance costs, and environmental considerations.