Ningbo Orient Wires & Cables (NBO), also known as Orient Cable, has secured a landmark contract to supply a 200-km, 500 kV high-voltage alternating current (HVAC) subsea cable system for an East Asian interconnection project.

First 500 kV deep-sea HVAC subsea installation

According to information released on the company’s website (https://www.orientcable.com), the project represents Asia’s—and the world’s—first 500 kV deep-sea HVAC interconnection cable installation. The system will operate at water depths approaching 550 meters, setting new global benchmarks for voltage level, transmission capacity, and installation depth in HVAC subsea transmission.

Orient Cable stated that the project will establish three industry records for 500 kV HVAC subsea systems: highest operating voltage, largest transmission capacity, and deepest installation for an HVAC interconnection cable.

Advanced cable design for high voltage and deep water

The 500 kV HVAC cable will use a cross-linked polyethylene (XLPE) insulation system engineered to withstand high electrical stress and extreme underwater pressure. Each cable core will transmit hundreds of megawatts of power, supporting high-capacity, long-distance electricity transfer.

To ensure durability during deep-water installation, Orient Cable has designed the system with advanced steel wire armoring and a watertight outer sheath. This structure protects the cable against corrosion, mechanical loading, and installation-related stress in deep-sea environments.

Efficiency gains over existing subsea HVAC systems

Orient Cable described the project as a significant technical leap beyond existing HVAC subsea systems, which typically operate between 220 kV and 400 kV and are installed in shallower waters. By increasing the voltage level to 500 kV, the system reduces current and thermal losses while enabling higher transmission capacity and improved grid stability over longer distances.

The company noted that the project will serve as a showcase for next-generation HVAC subsea interconnection technology, combining large-scale manufacturing capability with advanced deep-water installation expertise. Cable production and testing will follow the latest international standards for high-voltage performance and marine environmental protection.

Positioning within global subsea cable benchmarks

Globally, the deepest subsea power cable installation remains Italy’s Tyrrhenian Link, where Nexans installed a 500 kV HVDC subsea cable between Sardinia and Sicily at depths of approximately 2,150 meters as part of a 970-km, 1,000-MW interconnector.

By contrast, Orient Cable’s East Asian project focuses on HVAC technology rather than HVDC and targets intermediate deep-sea depths of about 550 meters. While it does not challenge the absolute depth record, it marks a first-of-its-kind 500 kV deep-sea HVAC interconnection and a major milestone for the region’s offshore transmission infrastructure.