This International Standard specifies test circuits and methods standard for thyristor surge suppressor (TSS) components. These surge protective components, SPCs, are specially formulated thyristors designed to limit overvoltages and divert surge currents by clamping and switching actions. These SPCs are used in the construction of surge protective devices (SPDs) and equipment used in Information & Communications Technologies, (ICT) networks with voltages up to AC 1000 V and DC 1500 V. This International Standard is applicable to gated or non-gated TSS components with third quadrant (-v and i) characteristics of blocking, conducting or switching. This standard contains information on - terminology; - letter symbols; - essential ratings and characteristics; rating verification and characteristic measurement; This standard does not apply to the conventional three-terminal thyristors as covered by IEC 190 60747-6.