ATPDesigner is a Control Center for Interactive Design and Simulation of Electrical Power Networks. ATPDesigner can be used as a graphical pre-processor to the ATP version of the Electromagnetic Transients Program (EMTP) executed on Windows operating systems. ATPDesigner provides the user analyzing faults and disturbances in electrical power networks. In addition a lot of high-sophisticated features are implemented to make ATP based network simulation more easy. All these features are based on the processing of the ATP specific .PL4 - files or COMTRADE - files. ATPDesigner is able to read and write the both formats COMTRADE 1999 and 2001 according the international standard IEC 60255-24. ATPDesigner also provides the conversion of the ATP specific .PL4 - files into the COMTRADE format.