Polypropylene for high voltage high frequency airborne applications

Polypropylene is characterized for airborne high-power applications under high-voltage, high-frequency conditions. The properties that are measured include the dielectric constant and dielectric loss (at electrical stresses of up to 40 V/ mu m) and the breakdown voltages at frequencies of up to 400 Hz. The aging characteristics of the film under these conditions were also determined. There is a slight decrease in the breakdown voltage of polypropylene as frequency is increased from 60 to 400 Hz. Also, life is reduced with an increase in frequency. This decrease is probably due to heat buildup in the insulating material caused by partial discharges and by dielectric losses. Dielectric properties show no change at low-voltage, high-frequency conditions. However, at high-field-stress, 60-Hz conditions, the dissipation factor shows an increase with an increase in electric field stress. This increase is most probably caused by partial discharges in voids and air bubbles of the insulating material. Based on the preliminary results obtained, polypropylene is suitable for low-stress, high-frequency airborne applications.<
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