The thyroswitch is controlled via the multicomp reactive power controller or directly via the machine control. The thyroswitch 2P has two thyristors which switch phases L1 and L3. Phase L2 is connected, but not switched on. If the switch-on procedure is activated via a reactive power controller or a control, there is a voltage comparison between the capacitor voltage and the mains voltage. If there is a slight difference, the stage is switched on.