Thyristor switching modules CTU01 are designed for dynamic and hybrid PFC based on three-phase capacitors. CTU01 module have semiconductor switcher in two phases only and together with fast discharging resistor can reach possible speed of reconnection about 1 operation per 3 - 5 seconds. Switching is realized within 10 ms from receiving the signal from PF controller in case that capacitor is already discharged to voltage level ≤ Umax.

Device function

ctu fce Thyristor switching modules CTU are constructed for switching of LC circuits with prevailing capacitive part (detuned compensation stages). Advantage of CTU modules comparing to the classic contactor switching of capacitor stages is immediate capacitor connection without its previous discharging. This is possible thanks to special construction which assures that capacitor is ready for another connection immediately after its previous disconnection. Switching of capacitor is realized at the moment when the difference between the capacitor voltage and system voltage before the switching element is equal to zero. From this feature comes another important advantage and this is significant current surges reduction. Current surges are causing disturbances which can affect proper running of electronic devices and can severely damage and even destroy them. Further more, lifetime of capacitors is increased, because only nominal current flows through the circuit. For the protection of power switching element against current peaks (di/dt) it is necessary to connect in the series with module also inrush reactor.

Temperature protection

Inside the aluminium cooler of CTU01 module is installed temperature sensor which is used for protection of semiconductors against damage by high temperature. Temperature level is set on 80°C.

Forced ventilation

CTU01-400-50 and CTU01-400-72 have a ventilator for forced ventilation of aluminium cooler. The ventilator is started automatically when temperature of CTU01 rise over the defined level.


Main features

  • Designed for three-phase capacitors
  • Switching elements in two phases
  • Control voltage 24 VDC or 230 VAC
  • Operation status signalization
  • Ready for static and hybrid PFC