Short circuit forces acting on the shielded three-phase supply

One of the serious tasks, that designer of heavy current equipment has to solve, is a sufficient mechanical fixing of electrical supply when exposed to short circuit forces. One method of reducing the values of the short circuit forces is the shielding of current-carrying conductors. Shielding is usually realized in such a way that the conductors are put in steel pipes of appropriate forms. This causes that short-circuit current carrying conductors are in a relatively weak magnetic field and, therefore, the Lorentz force acting on them is substantially weaker compared with unshielded conductors. The calculation of short-circuit forces for such a case was carried out for three-phase symmetrical line. The main disadvantage of the above method of shielding consists in the fact that eddy…