Determination of electrical aging test voltage level under a low-pressure environment for accurate lifetime prediction

Rapid growth of electric stress boosts the partial discharge (PD) risk of insulation and leads to electrical aging. For transportation applications (i.e., safety-critical), reliability is top-priority which means the lifetime of electrical machines (EMs) should be accurately estimated. Electrical aging of Type II insulated EMs caused by PD activity is greatly affected by ambient pressure. During accelerated aging tests, an improper test voltage selection might result in misleading lifetime estimation. In this paper, the allowable voltage levels are accurately determined by relying on aging tests under six different voltage levels at 600mbar, which gives a useful guideline for insulation design and the reliability of EMs could be accurately assessed.