Solid-state pulsed power switching thyristor devices and ‘thyristor modules’, using either electrically, optically or electron radiation controlled switch methods and having any of the following: 1. A maximum turn-on current rate of rise (di/dt) greater than 30 000 A/μs and off-state voltage greater than 1 100 V; or 2. A maximum turn-on current rate of rise (di/dt) greater than 2 000 A/μs and having all of the following: a. An off-state peak voltage equal to or greater than 3 000 V; and b. A peak (surge) current equal to or greater than 3 000 A; Notes: 1. Item (g) above includes: — Silicon Controlled Rectifiers (SCRs); — Electrical Triggering Thyristors (ETTs); — Light Triggering Thyristors (LTTs); — Integrated Gate Commutated Thyristors (IGCTs); — Gate Turn-off Thyristors (GTOs); — MOS Controlled Thyristors (MCTs); — Solidtrons. 2. Item (g) above does not apply to thyristor devices and ‘thyristor modules’ incorporated into equipment designed for civil railway or ‘civil aircraft’ applications. Technical note : For the purposes of item (g) above, a ‘thyristor module’ contains one or more thyristor devices.