GB/T 11026.7-2014 is the seventh part of the standard for heat resistance of electrical insulating materials, which focuses on determining the relative heat resistance index (RTE) of insulating materials. The standard elaborates on the test principle, specifies the test equipment, sample preparation and test procedures. By comparing with reference materials with known heat resistance index, the sample is tested under specific temperature conditions, and the RTE is determined according to the performance change. The standard provides a scientific method for accurately assessing the relative heat resistance of insulating materials, helping electrical equipment manufacturers to select materials reasonably and ensure stable operation of equipment in different temperature environments.