The reliability of an electronic device is much better when operated at or below its maximum derating level. Built-in derating limits are used when running prediction calculations to verify that parts are operating under their maximum limits. You can store custom derating limits for each part in each model in the Project’s Prediction Derating file. These custom derating limits are then used in addition to the built-in derating limits.

A part is overstressed if it has a stress ratio over 100% or the temperature is over the rated temperature for the part. The built-in derating limits are used as a minimum derating level for all parts included in the Prediction Derating file.

If the derating limits for a part are ever exceeded, the text for the part is shown in red by default in both the System Tree Items table and Parts Table. Under Prediction in the Options window, Overstressed part row text color specifies the color to use for overstressed parts. For more information, see Prediction User Options. The cause for overstress can be viewed in the Pi Factors window for the part. For more information, see Part Pi Factors.

You can report on parts that are over your own custom derating limits as well as on parts that are over the built-in derating limits. You can generate an Operating Stress report or Overstressed Parts report using the supplied Report Design files, Prediction Operating Stress and Prediction Overstressed Parts.