Anyone know why or what the mechanism is that causes large power transmission lines to differant power carrying capacities depending on which way the power is flowing. Was reading some Nemmco reports regarding the power outages of the last few days and discovered that the main power interconnector between Victoria and SA is rated at 500 MW in the direction of SA >
VIC but only 160 MW Vic > SA. Others are similar, VIc > NSW is more than NSW to VIC over the same power line. I would have thought that wires dont care about direction.