Motor Controls Training

Class Information
Motor Controls Training Tooling U-SME classes are offered at the beginner, intermediate, and advanced levels. The typical class consists of 12 to 25 lessons and will take approximately one hour to complete.
Class Name:DC Motor Applications 230
Description:This class focuses on DC motors, their main parts, and how they are used and maintained. Includes an Interactive Lab.
Number of Lessons:16
Language:English, Spanish
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Class Outline
  • Objectives
  • What Is a DC Motor?
  • Pros and Cons of DC Motors
  • DC Motor Construction
  • Armature
  • Armature Windings
  • Commutator
  • Brushes
  • Field Windings
  • Series Motors
  • Shunt Motors
  • Compound Motors
  • Permanent Magnet Motors
  • Speed Control
  • Troubleshooting DC Motors
  • Summary
Class Objectives
  • Define DC motor.
  • Distinguish between DC and AC motors.
  • Identify the major parts of DC motors.
  • Describe the armature of a DC motor.
  • Identify the different types of armature windings.
  • Explain the function of a commutator in DC motors.
  • Describe the brushes used in DC motors.
  • Describe the field windings used in DC motors.
  • Describe the characteristics of DC series motors.
  • Describe the characteristics of DC shunt motors.
  • Describe the characteristics of DC compound motors.
  • Describe the characteristics of DC permanent magnet motors.
  • Explain how DC motors control speed.
  • Describe common DC motor troubleshooting practices.

Class Vocabulary

Vocabulary TermDefinition
armature The part of a motor in which a current is induced by a magnetic field. The armature consists of a series of coils mounted on a shaft and rotates through the magnetic field.
base speed The speed (in rpm) at which the motor runs with full-line voltage applied to the armature and the field.
brushes Sliding electrical contacts used to provide a connection between the armature and the external circuit. The brushes are stationary and are contacted by the rotating commutator.
chattering The occasional unwanted vibration between components. Chatter decreases productivity and can cause wear.
commutator The rotating switch that contacts the brushes of a DC motor. The commutator maintains DC when the rotation of the armature switches the polarity of the conductor.
compound motor A DC motor that uses both series and shunt field windings. Compound motors provide most of the positives of both types.
constant speed A type of motor that maintains a steady rate of rpm from no load to full load. DC shunt motors are often referred to as constant speed because they run at constant speed.
counter emf The voltage induced in the armature of a DC motor that opposes the applied voltage and limits armature current.
DMM A device that can measure voltage, current, or resistance. A digital multimeter is the most versatile and common meter used today for electrical maintenance.
electric motor A machine that converts electrical energy into mechanical motion. Electric motors use magnetic induction to produce torque.
field windings The conducting wire connected to the armature that energize the pole pieces. Field windings are connected in series or parallel.
frogleg wound armature Term used to describe a series-parallel combination armature winding. Froglegs are the most commonly used winding.
grounded circuit A circuit where current strays from its intended path and flows through the frame of the motor. Grounded circuits are caused when conductor insultation breaks down or is damaged.
horsepower A unit of power used to describe machine strength. One horsepower equals 33,000 ft-lbs of work per minute, or 746 watts.
inrush current The initial surge of current into the windings. Inrush current can be up to ten times higher than the continuously needed current because there is low initial resistance.
lap wound armature Term used to describe a parallel armature winding. Lap connections are used for high current, low voltage loads.
lockout/tagout A method of protecting employees from accidental machine startup through proper locking and labeling of machines that are undergoing maintenance.
lubricate To use a fluid to reduce the friction between components. Typically a lubricant reduces resistance, heat, and wear, but brushes cannot be lubricated.
magnetic induction The use of magnets to cause voltage in a conductor. Magnetic induction occurs whenever a conductor passes through magnetic lines of flux.
permanent magnet motor A type of motor that uses permanent magnets instead of field windings as a way to create torque. A permanent magnet is one that retains its magnetism after the magnetizing force has been removed.
polarity Having two oppositely charged poles, one positive and one negative. Polarity determines the direction in which current tends to flow.
pole piece Devices mounted on the inside of a motor housing. When connected to field windings, the pole pieces form the electromagnets that create lines of flux.
rheostat A continuously variable electrical resistor used to regulate current.
right-hand motor rule The relationship between the factors involved in determining the movement of a conductor in a magnetic field. The current flow is opposite in generators.
self-excited shunt field Field windings connected in parallel with the armature that are supplied with current by the same power supply as the armature.
separately excited shunt field Field windings connected in parallel with the armature that are supplied with current from a source other than the armature. A separately excited field helps maintain constant speed.
series motor A method of connecting field windings in series with the armature. A DC series motor provides very high start-up torque but must never be run without a load.
series-parallel A compound connection that uses both series and parallel connections.
short circuit A circuit where current takes a shorter, unintended path between two conductors. Short circuits are caused when the insultation of two conductors is worn or damaged.
shunt motor A method of connecting field windings in parallel with the armature. The shunt DC motor is commonly used because of its excellent speed regulation.
speed The amount of distance an object travels in a given period of time. In motors, speed reflects rotational movement and is measured in revolutions per minute.
speed control The external means of varying the speed of a motor under any type of load.
speed regulation The ability of a motor to maintain its speed when a load is applied. A motor's speed regulation is fixed based on its design.
torque A force that produces rotation. Torque is measured in pounds-feet in the English system and Newton meters in the metric system.
wave wound armature Term used to describe a series armature winding. Wave windings are used for high voltage, low current loads.