By locating the PEXLINK on sections of lines with high footing impedance towers and one additional low footing-impedance tower at each end of the section, PEXLINK protects existing shielded and non-shielded lines from abnormal lightning surges (frequent or high amplitudes) and reduces the outages.
The reduced outages are beneficial also indirectly in that sensitive equipment is not damaged and the circuit breakers overhaul interval can be increased. Thus, total maintenance costs are also reduced.
This protection may be used for all system voltages where the stated abnormal conditions exist. Arresters with moderate energy capability are often sufficient. However, the high-current capability must be large and distribution-type arresters may not be suitable.
For long EHV lines, surge arresters usually are located at line-ends. In addition, by locating arresters at one or more points along the line e.g. at midpoint or 1/3 and 2/3 line length switching surge overvoltages and thus line insulation requirements could be limited without using pre-insertion resistors. Arresters used for this type of application should be designed for high energy capability. Usually a class 2 or 3 arrester will be sufficient out on the line but higher arrester classes may be necessary at the receiving end of the line.