Introduction of 4000 mm2 AlMil conductor in HV cable systems

This paper presents the development and evaluation of a new 150 kV cable system using a 4000 mm² aluminium Milliken (AlMil) conductor. This system is an alternative to the conventional 2500 mm² copper Milliken (CuMil) conductor with insulated wires. This paper presents clear methods to accelerate project executions by explaining the new Dutch TSO installation policy. The goal is clear: to reduce cost and environmental impact while maintaining the performance and reliability of cable systems. The paper assesses the technical and operational implications of adopting the 4000 mm² AlMil design. A comparative evaluation is performed between the aluminium-based system and the conventional 2500 mm² copper alternative, considering total cost of ownership, environmental impact, and compliance with relevant design standards. The development process of the new conductor, including sizing principles and skin-effect mitigation, is outlined alongside the results of the associated R&D and type-testing program. A review of the installation aspects is conducted, with particular attention given to methods adapted to the increased conductor size.

These methods include trenchless techniques, pre-installed ducts, specialized pulling equipment, and controlled jointing conditions. Practical considerations related to supply, logistics, transport, on-site jointing, and commissioning are also addressed, as are the integration of dry-type accessories and newly developed outdoor terminations compatible with the AlMil conductor. The findings demonstrate that the proposed system offers a validated and scalable alternative for high-capacity underground transmission, supporting TSOs and manufacturers in future cable system selection and project execution.