Cabelte began the manufacturing of high voltage cables in 2006, following a Project involving the purchase of an insulation manufacturing line, “dry curing” reticulation process, and the completion of a set of prototypes and tests aiming products approval and homologation.
Similarly, internal technical competences were strengthened, covering the areas usually involved in High Voltage Projects, from cable dimensioning and design up to its installation.
The 1st phase of this Project covered the cables up to 60kV, manufactured in accordance with the main national and international standards and also with customers own standards connected to installations for high voltage projects.
The 2nd phase of the Project is now being prepared and will include the production of cables up to 132kV.
For standard high voltage cables it is possible to identify 4 parts with different function characteristics:
- Conductors ensuring electric power transmission;
- Insulation coverings and internal / external semiconductors, simultaneously extruded, ensuring the appropriate level of electrical safety for the specified rated voltage;
- Metallic screens discharging defect current, to restrain the electric field and, in certain types of cables, for mechanical protection and water blocking proof;
- The sheaths suitable to external cable protection considering, namely, the installation conditions.
The most common materials used on conductors are copper and aluminium because of their high conductivity level and easiness of processing.
Regarding the insulation materials, currently, the most used is XLPE, for its own characteristics, easy handling and with lower cost.
In certain special applications, rubber compounds of ethylene propylene (EPR and HEPR) can also be used.
Polymeric materials are applied on sheaths for outer cable protection and, when a higher mechanical protection is required, armours of metallic tapes or wires can be adopted.
It is usual, in this range of products, the existence of requirements for water tightness, which is achieved with the adoption of special constructive solutions at the various components, to block longitudinal and radial water penetration that might contact with the cables during or after their installation.
Additionally, complementary technical requirements could be considered.