Air-cooled converter technology with direct magnetic thyristor firing and indirect monitoring of thyristors via synthetic optical fiber cables for smaller Thyristor-Controlled Reactor (TCR) applications of Static Var Compensators (SVC). Smaller SVCs are used for flicker control and reactive power control of rolling mills. For direct connection of the thyristor valve to system voltages up to 4.4kV (nominal) with up to four thyristors in series. Convenient exchangeable modules with antiparallel 75 mm (3 inch) thyristors. Coverage of a smaller power range of from e.g. 5MVAR at 1.1kV to 22Mvar at 4.4kV. Open loop and high-speed closed loop control by means of digital systems from our company.