A Method for Online Stator Insulation Prognosis for Inverter-Driven Machines

A significant portion of faults experienced by electrical machines is caused by degraded insulation. In order to reduce the effects of a failure, it is important to monitor the health of the insulation, preferably while the machine continues operation without any expensive equipment. In this paper, an online method to calculate the remaining useful lifetime (RUL) of the stator insulation with a simple equipment is proposed. The accelerated degradation testing was performed by exposing the stator of an electric machine to high temperatures. An extended Kalman filter algorithm is developed to calculate the RUL. A simple analog circuit is used to show how lower sampling rates can be used to capture the necessary information for prognosis. With this circuit, the same trend used to provide a prognosis for the insulation can be measured online without using any expensive or special technology.