Circuits of the DC Machine

A DC motor or machine has three basic circuits:

Armature and interpole leads, Al and A2

Series field leads, Sl and S2

Shunt field leads, Fl and F2

They are designed with various combinations and connections to suit the needs of a given load. A more in-depth explanation of each component will come later in this chapter.

As previously stated, the DC machine is interchangeable as a motor or a generator, so the word machine is used in this book when explanations apply to both motor and generator.

The armature generates all the power as a generator. It creates all the torque as a motor. The armature and interpoles are a series circuit. The purpose of the interpoles is to improve brush commutation. They are

connected either between Al and the armature or between the armature and A2.

The series field is connected in series with the armature and interpoles.

Its purpose is to stabilize the output of the machine as the load changes.

The shunt field provides magnetism for the armature. Lines of force or flux (produced by the shunt field) create power (VA) in the armature as a generator and create torque as a motor.