抄録
This paper has investigated a surge propagation characteristic on a crossbonded cable by applying a homogeneous model in comparison with a normal-bonded cable. It has been found that the former is basically determined by the inter-core mode of propagation and results in a surge voltage becoming a rather smooth and sinusoidal-like waveshape of which the oscillating frequency corresponds to the propagation velocity of the mode. On the contrary, the latter is dominated by the coaxial mode, i.e. the core-to-sheath mode, on each phase, and the surge voltage is square-like. The propagation velocity of the inter-core mode is roughly given as a difference between the coaxial and the earth-return mode velocities, and thus is smaller than the coaxial mode velocity. The maximum overvoltage on the crossbonded cable is greater than that on the normal-bonded cable in a tunnel-installed cable as is well-known, while the former has been found to be smaller in a directly buried underground cable.
