A study of electrical endurance of MPPF capacitors and selection of end-point criteria

The self-healing property of MPPF capacitors results in reduction in capacitance and increase in tanδ with aging. With a view to establishing the service reliability of MPPF capacitors, long-term aging tests were performed. For estimation of the life of nonmetalized film capacitors, local breakdown of PP film at the weak spot is generally considered as the end-point criterion. However, this cannot be selected for MPPF capacitors because the metalized film continues to operate even after several such breakdowns due to its self-healing property. Sufficient information on some important aspects regarding life estimation of MPPF capacitors, e.g., the property to be selected as aging index, choice of its end point, the statistical model to be adapted, etc., is not available. In the current study capacitance and tanδ were examined as indicative of aging properties. The life of MPPF capacitors was estimated, selecting suitable end-point criteria and employing an appropriate statistical model