The breakdown mode of an element may include overcurrent, overvoltage, overheat, etc. Causes of each breakdown mode have to be investigated. In the real world, however, it is difficult to identify the cause by the breakdown status of an IGBT module alone. It is important to consolidate information such as the breakdown voltage VCE, current IC, gate voltage VGE, and to make comprehensive investigations. For details, refer to the Application Manual.