This paper describes the characteristics of capacitor elements at self healing. Self healing events were forced to be created by the over-rated voltage of the capacitor elements. The self healing site was photographed by the Scanning Electron Microscope and the by-products of self healing were analyzed by the Energy Dispersive X-ray Spectrometer. Also the self healing site was analyzed by the Differential Scanning Calorimeter and the Fourier Transform Infrared Spectrometer. As a result, the main component of by-products due to the hum cut at self healing was carbon. The Fourier Transform Infrared analysis result of the self-healing specimen was similar to that of the virgin specimen, however, different from that of the specimen thermally treated at 500$^{circ}C$. It was observed that heat flow peaks of virgin specimen were different from self-healing specimen by the Differential Scanning Calorimeter analysis.