552 Power System Transients
cylindrical. The internal impedance of a conductor with an arbitrary cross
section was derived in Reference 19, which has been implemented in the
EMTP cable parameters program [20].
Reference 21 shows an approximation of a conductor with a T or hollow
rectangular shape by a cylindrical-shaped conductor. Although the internal
impedance of a conductor with an arbitrary cross section can be accurately
evaluated by a nite-element method of numerical calculation, this requires
a great deal of time and computer memory. Either an analytical formula or
an efcient numerical method needs to be developed.
8.1.2.3 Semiconducting Layer of Cables
It is well-known that a semiconducting layer exists on the surface of a cable
cond ...