Compound excited DC motor forward and reverse circuit

The circuit is shown in Figure 3-194. The motor is a compound excited DC motor . The motor has six terminals, sl and S2
are armature windings; cl and cz are series (magnetic field) windings; Ti and Tz are shunt (magnetic field) windings. In order to achieve
forward and reverse operation, the magnetic field directions of cl, C2 and Ti, Tz are fixed, and the current directions of the armature S1 and S2 windings are changed.
    This circuit adopts reverse braking mode. When stopping, both ends of the motor armature are short-circuited through the braking resistor R, and the motor
stops quickly.
    This line has overcurrent protection (KIl) and field weakening protection (KI2).