An Outdoor Tracking and Erosion Test of Some Epoxide Resins

The resistance of epoxide resins to electrical discharges varies from poor to excellent depending upon the basic resin type and the associated hardener and accelerator. Fillers also have a marked influence on system performance. Epoxides show the greatest promise of the synthetic organic materials available at this time for use under electrical stress outdoors, particularly when the physical properties are considered. The general considerations covering the planning of an outdoor test station and the design of specimens are explained, as well as a general discussion of the results so far obtained at 0.5 and 1.0 kV/in. It has been found that trihydrated alumina is the best antitracking and erosion filler and that plaster of paris causes mechanical failure of the system. Of the resins tested, the cycloaliphatic types, which are now more flexible than when they were originally introduced, are by far the best for outdoor insulators.