GB/T 11026.3 - 2017 is the third part of the standard for heat resistance of electrical insulating materials, focusing on the procedures for calculating heat resistance characteristic parameters. It elaborates the specific method for calculating the key parameters of heat resistance of insulating materials, covering the scope of application, basic theory and calculation process. Clarify the acquisition and processing methods of various parameters, and guide the calculation of the heat resistance grade and other characteristics of materials through test data. The standard provides calculation basis for electrical equipment manufacturers and researchers to help accurately evaluate the performance of insulating materials at different temperatures and ensure the reliable operation of electrical equipment in complex thermal environments.