Influence of Harmonic Distortion on the Breakdown Voltage of a Composite Material for the Use in Dry Type Transformers

In this contribution, an investigation about the influence of voltage harmonics on the breakdown voltage of a composite material intended for the use of dry-type transformers produced under the filament winding technology is discussed. A dielectric strength measurement was performed on samples of a composite applying voltage with different waveforms With the intention of recreating the structural disposition of the material, which originates as a result of the manufacturing process by rolling filaments, which are previously impregnated on a resin bath, on a rotating mandrel, a special arrangement has been used for the manufacture of the test objects, consisting of plates with fiberglass bundles under mechanical tension in an epoxy resin matrix. Test samples were exposed to six different voltage waveforms, differing in their total harmonic distortion (THD). The test voltage is generated through a programmable source and a high voltage test transformer. The performed measurements show differences on the RMS value of the breakdown voltage of the material according to the total harmonic distortion. A comparison between the values based on the RMS values and the peak values is given.