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Motor Controls and Drives

ET 140

Motor Controls and Drives

ET 140

Course Description

Prerequisite: ET 130 with a minimum grade of "C". Applies the basic principles of control circuits to an intermediate study of DC motors, AC motors, and servo motors. Performs armature reaction, CEMF, and basic motor calculations. Analyzes motor control including starting requirements, forward/reverse control, and sequencing of motors. Emphasizes the extension of motor control to drive systems including SCR armature control, field weakening, Pulse Width Modulation, and Variable Frequency Drives. Explains principles of drive operation, set-up, calibration, and troubleshooting in lecture and applies in laboratory exercises. Credit may be earned in SKET 140 or ET 140 but not both. (30-30)

Outcomes and Objectives

Explain the operation of DC motors and generators.

Objectives:

  • Identify the primary components of a DC motor and generator.
  • Describe the basic operation of a DC motor and generator.
  • Explain the concepts of torque, armature reaction, and CEMF.
  • Apply knowledge of what compensating windings are, and why they are used.
  • Describe the winding configurations for shunt, series, and compound wound DC motors.
  • Interpret motor nameplate data.
  • Perform calculations to determine speed regulation, horsepower, and efficiency for DC motors.

Explain the operation of AC motors and alternators.

Objectives:

  • Identify the primary components of an AC motor and alternator.
  • Describe the basic operation of an AC motor and alternator.
  • Differentiate between revolving armature and revolving field alternators.
  • Explain the generation of 3 phase power and differentiate between delta and wye connections.
  • Explain how the rotating field of an AC motor is produced.
  • Describe the wiring configurations for dual voltage AC motors.
  • Differentiate between synchronous, wound round, and squirrel cage AC motors.
  • Interpret motor nameplate data.
  • Perform calculations to determine frequency, speed, starting current, and percent slip.
  • Differentiate between different types of single phase AC motors.

Apply knowledge of basic control circuitry to motor applications.

Objectives:

  • Identify the components of a motor starter and explain the operation of motor circuits.
  • Utilize NEMA starter ratings to determine the correct size starter for an application.
  • Integrate timing controls to properly sequence the starting of multiple motor loads.
  • Integrate timing controls to properly sequence the stopping of multiple motor loads.
  • Integrate forward and reversing motor starters to properly reverse the direction of a motor.

Apply knowledge of DC motors and electronic circuits to DC drive systems.

Objectives:

  • Explain the firing operation of SCRs to provide armature control for a DC motor.
  • Explain the process of field weakening to run a DC motor above base speed.
  • Explain the process of Pulse Width Modulation to control a DC motor.
  • Describe the method used for reversing a motor using a DC drive system.
  • Describe how speed control is integrated into a DC drive system.
  • Define the proper set-up and calibration procedures for a DC drive system.

Apply knowledge of AC motors and electronic circuits to AC drive systems.

Objectives:

  • Explain the operation of Variable Frequency drives to control an AC motor.
  • Describe the method used for reversing a motor using an AC drive system.
  • Describe how speed control is integrated into an AC drive system.
  • Define the methods required to adjust parameters in an AC drive system.
  • Define the proper set-up and calibration procedures for an AC drive system.
  • Describe how closed loop systems operate and explain the operation of common feedback devices.
  • Explain the general operation of a servo system including main feedback loops and the integration of control signals.

Conduct laboratory experiments to reinforce lecture material.

Objectives:

  • State, comprehend, and comply with safety precautions when working on electrical equipment.
  • Demonstrate the ability to operate, set-up, and calibrate DC and AC drive systems.
  • Demonstrate the ability to troubleshoot DC and AC drive systems.
  • Demonstrate the ability to utilize meters to measure signals on DC and AC drive systems.
  • Demonstrate the ability to utilize oscilloscopes to analyze waveforms on DC and AC drive systems.
  • Demonstrate the ability to utilize programming tools to modify parameters in AC drive systems.
  • Develop troubleshooting techniques.