Water-cooled converter technology with indirect firing and monitoring of thyristors via synthetic optical fiber cables for Thyristor-Controlled Reactor (TCR) applications of Static Var Compensators (SVC). SVCs are used for flicker control and reactive power control of electric arc furnaces and rolling mills. For direct connection of the thyristor valve to common system voltages up to 12kV with one converter, up to 24kV with two converters and up to 36kV with three converters. Antiparallel thyristor tiers with 50 mm (2 inch), 75 mm (3 inch) and 100 mm (4 inch) disk type thyristors. Coverage of a large power range of from e.g. 18Mvar (5kV, 50 mm thyristors) to 400Mvar (33kV, 100 mm thyristors). Open loop and high-speed closed loop control by means of digital systems from our company.