Commutating Field (Interpole) of DC Motors

Nearly all shunt and compound motors of 1/2 horsepower or more have commutating fields or interpoles located between the main poles. These interpoles have one winding of heavy wire and are connected in series with the armature as shown in figure 1. The purpose of the interpole is to prevent sparking.

Types of Direct Current (DC) Compound Motors

Figure 1: Two-pole compound DC motor

The motor shown in figure 1 above is one of the four different types of compound wound DC (direct current) motors. Although this type is known as the most common form of connection, it is the one used most often and the one which should be used unless otherwise specified. It is essential also to discuss the other types of compound wound DC motors.

Wiring Connection of Direct Current (DC) Motor

Connecting Direct Current (DC) Motors

It is of utmost importance to firstly know and understand the various internal configuration of the different types of DC motors before doing the actual wiring connection.  Although DC motors may appear to only have two leads for its external wiring connection terminals, it will serve best to habitually apply a good practice of knowing first the type of DC motor you are about to install before attempting any wiring connection and supplying power to run the motor.

Types of Direct Current (DC) Motors

Fundamental types of Direct Current (DC) motors:

1.) Series Field DC Motor - The series field DC motor contains field coils composed of a few turns of wire connected in series with the armature as shown in Figure 1 below.  This motor has high starting torque and a variable speed characteristic.  The greater the load the motor carries, the lower the speed.

Fundamental Overview of a DC Motor

Direct Current Motors - DC Motors are used to convert DC energy into mechanical energy. They are well suited for use as either constant-speed or adjustable speed motors. The three types (Shunt, Series, and Compound) which are available provide the range of speed torque characteristics for applications which require: