Assessment of Test Voltage Levels for Accurate Type II Insulation Lifetime Evaluation Under Different Pressure Conditions

The rapid increase in electric stress intensifies the risk of partial discharge (PD) and electrical aging in insulation. In aircraft applications where safety is critical, accurate lifetime estimation of the electrical machines (EMs) is paramount to ensure reliability. The electrical aging process of Type II insulated EMs induced by PD activity is significantly influenced by ambient pressure. Improper selection of test voltage during accelerated aging tests can lead to misleading estimations of lifetime. This article accurately determines the permissible voltage levels based on accelerated electrical aging tests and measurement of partial discharge inception voltage at six pressure levels. These findings provide valuable guidelines for insulation design and enable precise reliability assessment of EM for aircraft applications.