Although the field coils of a dc motor may be separately excited they are usually connected to the armature in one of two ways – series or shunt.
The current in series wound motors varies making the speed difficult to control but the starting torque is large. For uses requiring a lot of torque – cranes, anchor winches – or where a constant speed is not required, the series motor may be used.
The speed of shunt wound motors vanes less with the load but the starting torque is less than for a series motor. Shunt-wound motors are used in machines where speed control is important – record players and machine tools.