4. Single-phase catenary input converter

In Europe, the two types of single-phase voltage supply networks are :

• 25 kV at 50 Hz (France, Denmark, Spain, Luxembourg...) ;

• 15 kV at 16 2/3 Hz (Germany, Austria, Switzerland...).

To adapt this voltage inside the traction unit, there are two types of rectifier bridge:

• naturally commutated single-phase bridge ;

• single-phase forced-switching bridge.

Switching the current between semiconductors is referred to as "natural switching" when it takes place by means of the mains voltage. The semiconductors used are conventional diodes and thyristors.

Switching the current between semiconductors is called "forced switching" when it's done...