Abstract: A static converter circuit has a voltage summing transformer (Tr-Tr13) with several part transformers (Tr1-Tr13) the static-converter-side winding of which are connected via one four-quadrant actuator each to a direct-voltage link circuit. The four-quadrant actuators are single-phase bridge circuits with one GTO thyristor each and a diode, which is antiparallel thereto, per bridge branch. The static-converter-side windings of the part transformers can be short circuited in each case by means of an alternating-current circuit breaker with antiparallel-connected thyristors. Each part transformer has a separate core. The power-system-side windings of the power transformers are connected in series and are connected at their ends to a railroad power system with 162/3-Hz. The direct-voltage link circuit is connected via power-system-commutated static converters and a static converter transformer to a national power system with 50 Hz.

Abstract: A circuit arrangement is disclosed for reducing field voltage peaks in direct current motors which are energized by way of an electronic D.C. regulator, and which have an exciter winding connected with the armature and commutating pole windings by means of diodes. The circuit arrangement includes a choke coil connected in series with the exciter winding. In addition, a resistor is connected in parallel with the exciter winding. This arrangement prevents a rapid rise in the field current or the magnetic field flux of the motor.