PDIV Modeling for Rectangular Wire Turn-to-Turn Insulation of Inverter-Fed Motors at Different Cruising Altitudes

This study develops a predictive model for partial discharge inception voltage (PDIV) in turn-to-turn insulation of form-wound windings for inverter-fed motors considering a range of altitudes, from ground to cruise levels. Emphasis is placed on the application of rectangular insulated wires (i.e., edgewise insulated wires). Using Schumann's streamer inception criterion (SCSIC), the PDIV predictive model explores six distinct air pressures corresponding to altitudes: 1013 mbar (6.8 ft), 800 mbar (6.4k ft), 600 mbar (13.8k ft), 200 mbar (38.6k ft), 150 mbar (44.3k ft), and 100 mbar (51.8k ft). PDIV estimations are conducted under AC 50 Hz, unipolar positive (UP), and bipolar (BP) steep-fronted square waveform excitations, characterized by a switching frequency of 2.5 kHz, rise time of 80 ns, and pulse width duration of 100 μs. The PDIV model supports aerospace coil winding design by guiding wire geometry decisions, eliminating costly insulation experiments, and ensuring reliability at operational altitudes.