Partial Discharge Testing of Aerospace Electrical Systems

Modern aircraft are using more electrical equipment and are therefore using higher voltages. These higher voltage systems will become increasingly common in the future. The forms of systems that are being used operate under frequencies/waveshapes different from those normally used on ground based electrical power systems, and the testing regimes are relatively undeveloped in comparison with the other standardized tests available for aerospace components. The reasons why higher voltage systems in aircraft may be susceptible to partial discharge are first introduced. Then two electrical test techniques that can be used to measure partial discharge activity are introduced. One of these, the balanced technique, is used to examine the partial discharge performance of four test objects that are stressed with high voltages at varying frequencies of both sine and square waveforms. The results that are presented show that, while the level of damage that can be attributed to partial discharges can be significantly increased as frequency rises, the inception voltage of such discharges does not significantly vary.