ABSTRACT
Arresters have been applied to lines without overhead ground wires. Thus the arresters are in a very hostile environment, where large current magnitude strokes can impinge on the arresters. Assessing the applicability of arresters to the backflash or stroke to tower event, the energies through the arresters seldom exceed 50 kJ, and the arrester currents are small, in the range of 10 kA. Of concern are the voltages beyond the protected line section, since voltages produced within the protected section may be magnified at the unprotected towers. To explain further, assume that the towers on one section of the line have high footing resistances and that arresters are installed at these locations. Adjacent to the last tower in this section are towers whose footing resistance is significantly smaller to the extent that no arresters are applied.
