The PEXLIM surge arrester uses gapless ZnO technology and its lightweight silicone housing permits installation on existing structures using standard hardware.
A computer program is used to determine the optimum number of locations for PEXLINK devices along the line (generally where the footing impedance is high) and to calculate the arrester stresses at each of the selected locations.
PEXLINK has been installed in many applications worldwide to provide lightning protection and switching overvoltage control for system voltages from 52kV to 800kV. The general experience is that availability and reliability of transmission lines have improved dramatically. Furthermore, the reduction in outages ensures that sensitive equipment is not damaged and the circuit breaker overhaul interval can be increased, resulting in a reduction of total maintenance costs.
Eskom, the South African utility, has nearly 200 PEXLINK units installed on seven key 275kV lines, with a total length of over 400km.Where PEXLINK has been installed on existing lines, the average number of faults per 100km per year has been reduced from nine to under three.
PEXLINK has also been installed on the Russian side of the 400kV link between Russia and Finland in order to reduce the annual number of lightning-related outages from two per 100km to a target of just one every two years. During the two lightning seasons since PEXLINK was installed, no double-circuit line trips have been reported on the Russian side of the link, while they have continued on the unprotected Finnish side.