ITC Learning’s AC/DC Motor Theory library was specifically developed for electricians and electronic technicians as well as for the multi-craft training needs of process and manufacturing facilities. This library consists of 11 interactive, on-line lessons that address AC and DC motor theory. These lessons take approximately 30 to 45 minutes to complete.

Introduction to AC Components and Motors


Advanced AC Motor Principles


Three-Phase Motors - Part 1


Three-Phase Motors - Part 2


Single-Phase Motors


Introduction to DC Motors


Introduction to DC Motor Theory


Armature Reaction, Compensation, and Induced Voltage


Series, Shunt, and Compound DC Motors


Permanent Magnet, Universal, and Brushless DC Motors


DC Motor Controls

• Identify the components of an AC Motor and explain their function.
• Explain the basic principles of magnetism.
• Interpret the characteristics of a current as represented on a sine wave.
• Describe the effect of AC current on a conductor.
• Describe the methods of increasing magnetic flux in a conductor.
• Explain how a rotating field is created in an AC Motor.

• Explain and be able to calculate synchronous speed.
• Explain induction and its effect on a rotor.
• Explain the relationship between phased current and rotor spin.
• Explain slip and know its formula.

• Describe the design of a squirrel cage rotor.
• Explain the function of a squirrel cage rotor's components.
• Describe the design of a wound rotor.
• Explain the function of a wound rotor's components.
• Define torque and explain its role in motor operation.
• Explain the design of a reluctance motor and how it works.

• Explain the design of an externally excited motor.
• Explain how an externally excited motor works.
• Explain the function of a motor starter.
• Describe the most common types of motor starters.
• Describe a variable speed drive and its effect on voltage and frequency.

• Distinguish a single-phase motor from a three-phase motor.
• Explain the design of a split-phase motor and how it works.
• Explain the design of a capacitance start motor and how it works.

• Identify the general characteristics of a DC motor.
• Identify the advantages of a DC motor.
• Identify the basic components of a DC motor.
• Explain the function of DC motor components.
• Identify the components of the armature and explain their function.
• Identify the components of the brush assembly and explain their function.

• Explain the effect of armature current on the main flux field and how it results in motor action.
• Explain the process of commutation and how it maintains direct current in a DC motor.
• Describe how the number of windings and commutator segments effects torque and mechanical power of a DC motor.

• Explain how armature reaction shifts the neutral plane in a DC motor.
• Explain how armature reaction affects motor operation.
• Explain what measures will correct armature reaction.
• List the requirements for induced voltage in a motor.
• Explain counter-EMF.

• Explain the design of a series wound DC motor.
• Explain how a series wound DC motor works.
• Explain the design of a shunt wound DC motor.
• Explain how a shunt wound DC motor works.
• Explain the design of a compound wound DC motor.
• Explain how a compound wound DC motor works.

• Explain the design of a permanent magnet DC motor.
• Explain how a permanent magnet DC motor works.
• Explain how a universal motor runs off of DC power.
• Explain the design of a brushless DC motor.
• Explain how a brushless DC motor works.

• Explain why a reduced voltage starter is sometimes needed in a motor.
• Explain how a reduced voltage starter works.
• Explain what determines the direction of rotation of a DC motor.
• Explain how a reverse contactor works.
• Explain how to control the speed of a DC motor.
• Explain how a tapped resistor works.
• Explain how a field rheostat works.
• Explain a DC drive’s control system.
• Explain how a DC drive control system works.