Modern cables with XLPE insulation can handle very high voltages without active oil cooling, here’s a 345/400kV rated underground cable assembly rated for 90C: https://assets.southwire.com/adaptivemedia/rendition?id=332f...
Yeah, the wires in the new London tunnels are XLPE. Despite being first used in the late 60s it took a long time to be commonly used. Though much of the infrastructure around is still very old.
Yeah, the wires in the new London tunnels are XLPE. Despite being first used in the late 60s it took a long time to be commonly used. Though much of the infrastructure around is still very old.