First, we will rapidly describe the state of the art for switching losses measurement: the Double Pulse Tester. Then, we will analyze how to measure or simulate losses during all possible transitions (Hard-, Soft- and Partial-Soft-switching transitions). A new Losses Transition Tester will be introduced, and its operation will be described. Finally, new losses PLECS model implementation with onsemi Self-Service PLECS Model Generator will be explained, and an example will be shown.