EFFECTS OF AGRICULTURAL FIRES ON THE PERFORMANCE OF OVERHEAD TRANSMISSION-LINES

The occurrence of fires under transmission lines is responsable for a great number of line outages in many countries. Based on field investigations and laboratory tests under fire conditions the insulation requirements for lines of several voltage levels were established. The results obtained and the statistics presented indicate that for actual ac transmission lines with rated voltage up to 500 kV,faults are mainly due to conductor-to-ground short circuit at midspan or phase-to-phase short circuit, depending on line configuration. Another problem arising from the burning is the contamination of the insulators due to the accumulation of particles (soot, dust) on its surface. Pollution severity in terms of ESDD measured on insulators coming from regions of sugar cane fields in Brazil have shown values of up to 0.1 mg/cm2. © 1990 IEEE