Characteristics of Thyristor Surge Protection Devices Under Natural Lightning Surge Occurrences

This paper presents results of residual voltages of thyristor surge protection devices (TSPD) observed experimentally at the real telecommunication subscriber lines connected to customer premises equipment (CPE). TSPD with DC firing voltage of 120Vdc is chosen based on local telecommunication utility´s specification. Cumulative probability distribution of surge currents that discharged through TSPD and its energy dissipation are also demonstrated in this paper. The responses of TSPD against multiple-lightning-surges with up to six consecutive surges with the interval of several milliseconds are also shown here. The performance of TSPD against actual lightning surges is proven to be remarkable in which residual voltages measured are not more than 160V with the maximum discharged surge currents captured as high as 150A. Power utility´s earth with the earth resistance values of approximately 50Omega is quite effective to divert surge currents away from the TSPD during lightning surge occurrences