Electrical installation in a 3 km long cable tunnel in Hong Kong

The 275 kV cable connection between Lamma power station and Kennedy Road substation in Hong Kong island included a 3150 m section inside a underground cable tunnel, which was designed to cater for two circuits of 275 kV oil-filled cable at present, but with space and provision to add six circuits of 132 kV XLPE cable and four circuits of 11 kV XLPE cable in future. Forced air ventilation was provided for cooling the two circuits of 275 kV cable at present. For increased heat dissipation in the future, closed circuit chilled water cooling systems will be provided. Ventilation plants and auxiliary power supply substations of the cable tunnel are located in the Wah Fu portal (south end) and the Bowen portal (north end). All services were designed for unmanned operation