Defines type, production and optional test on thyristor valves used in thyristor controlled reactots (TCR), Thyristor switched reactor (TSR) and thyristor switched capacitors (TSC) forming part of static VAR compensators (SVC) for power system applications. the requirements of the standard apply both to single valve units (one phase) and to multiple valve units (several phases). Clauses 4 to 7 detail the type tests, clause 8 covers the production tests, clauses 9 and 7 detail optional tests.