Operational experience of transmission oil filled and XLPE cables

The Hong Kong Electric Co. Ltd. has only one power station at Lamma Island with a generation capacity of about 2200 MW. More than ninety percent of the transmission capacity is carried by oil-filled cables at voltage level of 275 kV and 132 kV. The author outlines the general transmission network configuration, operational difficulties encountered with the present oil-filled cable system and system improvement design. Of the former, the most painstaking one is oil leak location and repair. One of the solutions to overcome the problems with oil-filled cables is to use XLPE cables, XLPE cables were first installed in the 66 kV system during the early 1980s and subsequently at the 132 kV level. Initially, short cable lengths are involved, such as transformer cables for connection between 132 kV gas insulated RMU and transformer. With the development of prefabricated joints, the first contract for the 132 kV XLPE cable circuits with sectionalised joints was awarded and installation was started early 1991