A surge analysis of a cable system composed of submarine and underground / overhead cables

This paper presents experimental observations of surge propagation characteristics on various cables, i.e. overhead, on a building floor, on the earth surface, underground and in water. From the measured results, it becomes clear that a coaxial mode of surge propagation does not depend on the cable outer medium, either overhead or underground, as is well-known. However, an earth return mode is heavily dependent on the outer medium. EMTP simulations of the experiments are carried out, and the simulation results show a satisfactory accuracy in comparison with the experimental results. Surge characteristics of a cable system composed of submarine and underground / overhead cables are investigated based on EMTP simulation results considering cable cross-bonding. It is found that the cross-bonding results in a higher over-voltage. Especially, the sheath overvoltage becomes much higher in a cross-bonded cable. Thus the cross-bonding should not be used in a submarine part which costs a lot for re-installation.