Single-phase auto-reclosure studies: secondary arc model research including a 500kV line experimental circuit

Brazilian electrical transmission system has radial sub-systems and not much meshed long EHV/HV lines, a profile that suggests single-phase auto-reclosure (SPAR) as usual procedure. Since year 2000, the national Electrical Energy Regulatory Agency (ANEEL) has required the use of SPAR in the design, construction and operation of new transmission lines. Analysis of SPAR success is basically related to secondary arc extinction in a reasonably short time. So, secondary arc modeling became an important issue on defining optimized solutions. In 2003, FURNAS, UFRJ and CEPEL - transmission utility, university and research center, respectively - started a research project related to secondary arc modeling. A test infra-structure was set up at CEPEL\´s high power laboratory, including an out door real 500 kV line piece, with three towers and two spans and necessary measuring devices (electrical parameters, visual - films - and wind records), where arcs have been generated and monitored. The main purpose of this research project is to obtain and validate a robust model of the primary and secondary arcs in a transmission line, allowing to investigate the interaction between the arc and the "network", at arc terminals, and the evaluation of SPAR procedure success (or not). This work presents: the basic aspects of the laboratorial work conception; some difficulties related to the accuracy quality of arc parameters evaluation, of some usual measurement and data processing procedures; the adopted solutions to overcome such difficulties. The results already obtained support the basic conception of a gray type arc model, developed previously, allowed the establishment of adequate research type procedures for measurements and data processing, supplied a huge amount of data for arc modeling, giving basis to obtain arc parameters in an important range of conditions. New results are still expected to complete the range of conditions covered by the research project.