Separate Excitated Shunt Connection
On these motors the armature and field winding are connected to different voltage sources. The armature winding and the field winding therefor form independent circuits. The characteristics of such motors correspond to that of a self excitated shunt motors. Even on these motors the speed remains constant under changing loads. Another advantage is the wide speed range, which is achieved by controlling the armature voltage. The typical speed range on a self-ventilated is 10:1. Provided The excitation stays constant the motor speed changes proportionally to the armature voltage, the speed range can be increased dramatically by the use of forced-ventilation.
Self Excitated Shunt Connection
On these motors the armature and the field windings are connected to the same voltage source. Such shunt motors are mainly used as low voltage powered motors. An important characteristic of shunt motors is the constant speed under alternating loads. If the starting current has to be restricted, starting resistance is required.