This standard specifies the model and size, ratings and characteristics, inspection rules, and quality assessment of fast reverse blocking three-pole thyristors (hereinafter referred to as fast thyristors) with a rated on-state average current of 100A to 3000A and symmetrical blocking characteristics. Categories, logos, packaging, etc. This standard applies to symmetrical fast thyristors. Asymmetric fast thyristors can also be used for reference. This standard does not apply to fast gate turn-off thyristors.