Cable crossings-derating considerations. II. Example of derivation of derating curves

For pt.I see ibid., vol.14, no.3, p.705-14 (1999). Cables crossing other heat sources either perpendicularly or at oblique angles will experience a rise in conductor temperature which should result in ampacity derating. In the first part of the paper a mathematical model for calculation of derating factors was presented. In this paper, a practical numerical example is considered with a 138 kV pipe-type cable crossing a 10 kV distribution circuit. The numerical analysis presented confirms experimental findings reported in the literature that the cable crossing may elevate conductor temperature by as much as 20/spl deg/C.