Direct current motors are reversed by changing the direction of current flow through the armature or through the field. In series motors, the usual procedure is to reverse the current through the armature. Figure 1 shows this method.
All that is necessary is to interchange the leads on the brush holders. Figure 2 shows the series motor reversed by changing the current in the field circuits.
|Figure 1: Reversing of a two-pole series motor by interchanging armature leads|
|Figure 2: Reversing of a two-pole series motor by interchanging field leads|
Reversing the armature leads without the interpole will cause the motor to have incorrect interpole polarity, which will make the motor run excessively hot and will produce sparking at the brushes.
|Figure 3: A two-pole shunt-interpole motor with its armature and leads are reversed as a unit.|
|Figure 4: A two-pole compound-interpole motor with six wires brought out of the motor.|
|Figure 5: The armature circuit including interpole reversed as a unit for opposite rotation from that of figure 4.|