Motor Control

Course Number:
EET 141
Transcript Title:
Motor Control
Created:
Aug 10, 2022
Updated:
Aug 10, 2022
Total Credits:
5
Lecture Hours:
40
Lecture / Lab Hours:
0
Lab Hours:
30
Satisfies Cultural Literacy requirement:
No
Satisfies General Education requirement:
No
Grading Options
A-F, Audit
Default Grading Options
A-F
Repeats available for credit:
0
Prerequisites

EET 112

Course Description

Examines electromagnetism and motor theory, circuit protection elements (fuses and circuit breakers), control transformers, electromechanical and solid state switches, ladder logic, control relays, contactors, overload elements, manual motor starters, 2 and 3 wire motor starters, motor starters with jogging, friction brakes, reversing motor starters with interlocks, reduced voltage starters, timers, motor drives, and programmable logic controllers (PLCs). Students will build, test, and troubleshoot practical motor control circuits using industrial components on a motor control trainer board. Prerequisites: EET 112. Audit available.

Course Outcomes

Upon successful completion of this course, students will be able to:

  1. Apply operational theory of industrial three phase AC motors.
  2. Interpret manufacturer specifications of motors, circuit protection elements, contactors, auxiliary contact blocks, control relays, overloads, timers, switches, indicators, and other electromechanical elements.
  3. Interpret ladder logic diagrams and properly document them by numbering rungs, identify terminals, numbering wires, and numerically cross referencing rungs and mechanically interlocked devices.
  4. Build, operate, and troubleshoot electromechanical manual motor starters, two wire control circuits, three wire control circuits, reversing motor starters with interlocks, jogging circuits, reduced voltage starters, and timer controlled circuits.
  5. Build, operate, and troubleshoot motor drive controlled circuits and examine motor drive operational theory.
  6. Build, operate, and troubleshoot basic programmable logic controller (PLC) controlled circuits.

Suggested Outcome Assessment Strategies

Assessment methods are to be determined by the instructor. Typically, in class exams and quizzes along with homework assignments are used. Lab work is typically assessed by informal and formal lab reports, oral presentation, and possibly a lab exam. Evaluation is by unit exams, homework, and a comprehensive final exam.

Course Activities and Design

The determination of teaching strategies used in the delivery of outcomes is generally left to the discretion of the instructor. Here are some strategies that you might consider when designing your course: lecture, small group/forum discussion, flipped classroom, dyads, oral presentation, role play, simulation scenarios, group projects, service learning projects, hands-on lab, peer review/workshops, cooperative learning (jigsaw, fishbowl), inquiry based instruction, differentiated instruction (learning centers), graphic organizers, etc.

Course Content

Apply safety principals to electrical and mechanical circuits.

1.0 Electrical Diagramming Skills.

  • draw electrical circuits using standard symbols known as schematic diagrams, One-line, Line and Ladder diagrams.
  • apply the rules of line diagrams; load, control, switch, numbering systems, signals, decisions, actions, logic functions, memory, common circuits and component symbols.

2.0 Magnetism and Motion, DC.

Instructional Goal: To introduce magnetic fields, solenoids, DC motors, and DC generators.

Objectives:

  • describe the characteristics and causes of magnetic fields.
  • describe the Hysteresis curve and how it applies to relays and motors.
  • identify control mechanisms for relays and DC motors.
  • draw a control circuit, and identify the proper components to use in the circuit.
  • describe the operation and construction of a DC generator and motors.
  • describe the various types and characteristics of DC generators and motors.
  • identify types of DC motors and their characteristic torque curve.
  • describe the operation and construction of a DC motor.
  • connect a DC motor to a source by understanding the standard motor connections.

3.0 AC Generators, Transformers, and Motors.

Instructional Goal: To introduce the concepts of AC solenoids, transformers, generators, and motors and manufacturers specifications.

Objectives:

  • describe the characteristics and causes of an AC magnetic field.
  • describe the operation and construction of common types of AC generators and motors.
  • describe what a shading coil is and what it is used for.
  • identify control mechanisms for relays, AC generators, and AC motors.
  • draw a control circuit, and identify the proper components to use in the circuit.
  • identify types of AC motors and their characteristic torque curve.
  • connect an AC motor to a source.
  • analyze the operation and characteristics of circuit protection devices.
  • describe transformer operation and standard connections.
  • describe Delta and Wye operation and connections of an AC motor and generator.
  • determine the differences between single phase, three phase, and the different voltages transformers create.
  • troubleshoot motors and generators.

4.0 Contactors and Motor Starters.

Instructional Goal: To explore types of switching used to control motors and generators.

Objectives:

  • describe the problems associated with switching high current devices and describe solutions to the problems.
  • describe common types of contactors, their construction, protection ratings, operation, and use.
  • draw line diagrams for contactor circuits.
  • recognize common types of contactors and the connections on the contactors and implement them in a control circuit.
  • describe problems and solutions using AC and DC contacts.
  • describe common types of overload relays and their construction and use.
  • select for use, identify, and size control switches.
  • understand theory and use of common control switches and associated wiring diagrams.
  • troubleshoot control devices.

5.0 Control Devices, Reversing Motor Circuits.

Instructional Goal: To introduce concepts of motor reversing control circuits.

Objectives:

  • understand, identify, and create motor reversing circuits from common components.
  • understand operation and construction of motor reversing controls.
  • understand Control and motor connections.
  • identify and understand operation and construction of common types of reversing motor switches.
  • understand Start, Stop, forward and reverse jogging circuits.
  • understand motor control wiring methods, and wiring diagrams.
  • Troubleshoot reversing motor control circuits.

6.0 Relays and Solid State Starters.

Instructional Goal: To introduce Relays and solid state starters.

Objectives:

  • describe and use common types of solid state relays, their construction, theory of operation and technical specifications.
  • describe and use common types of general purpose electromechanical relays, their construction, use, theory of operation, circuit diagrams, and troubleshooting.
  • understand troubleshooting problems associated with electromechanical and solid state relays.

7.0 Series - Power Distribution Systems.

Instructional Goal: To understand utilities role in power generation and transmission, and determine the common voltage sources associated with power distribution systems.

Objectives:

  • describe the power generation and transmission system.
  • describe the components and read the electrical diagrams of a substation.
  • understand the differences between the different voltages common to industrial installations.
  • understand the voltages on high tension power lines, transformers, and power lines, and how they are created and used.
  • understand phase connections and Delta and Wye connections.
  • understand transformers connected for Delta and Wye distribution systems.
  • understand three phase and balancing loads.
  • understand the purpose of all the components of a power system.
  • understand switchboards, busways, feeders, and troubleshooting devices found inside a substation.
  • understand and describe the connection between an electric generation utility and the power grid.

8.0 High Power Solid State Devices.

Instructional Goal: Introduce high power solid state devices, common sensors and control devices.

Objectives:

  • understand theory and use of diodes in power transmission and motor control.
  • understand theory and use of the silicon controlled rectifier in power transmission and motor control.
  • understand industrial timers and counters.
  • understand electrical diagrams of timers, counters, SCR’s and diodes.
  • understand the use of common industrial sensors.
  • understand the conditions for mounting sensors in an industrial environment.

9.0 Reduced Voltage Starting.

Instructional Goal: Introduce methods of starting electric motors and solving related current surges.

Objectives:

  • determine load torque and starting requirements for single phase and 3 phase electric motors.
  • read motor characteristic charts.
  • determine common methods of starting motors using reduced voltage methods such as primary resistor, autotransformer, part winding, wye and delta. Use solid state switches such as SCR, triacs, alternistors, soft starters.
  • read electrical motor diagrams.
  • determine which starting method is best for a given situation.
  • troubleshoot starting circuits.

10.0 Motor Speed Control, Acceleration and Deceleration Methods.

Instructional Goal: Introduce methods of controlling motor speed and motor braking.

11.0 PLC.  Automatic control of motor and generator circuits.

Objectives:

  • implement and describe common methods of motor braking: friction brake pads, plugging, DC injection braking, and dynamic braking.
  • calculate torque, locked rotor torque, pull up torque, breakdown torque, full load torque and braking torque of a motor.
  • determine the speed control scheme for common types of motors with respect to the kind of load it will drive.
  • calculate motor horsepower, and understand the relationship between speed, horsepower and torque.