Understanding Motor Controls

Stephen L. Herman was an electrician and proficient instructor with over 30 years of practical experience, and was known for his reader-friendly approach. A seasoned author, Mr. Herman wrote leading books on electricity and mathematics that are popular with students and instructors alike. For two decades, Mr. Herman served as lead instructor for the Electrical Technology Curriculum at Lee College in Baytown, Texas, where he received an Excellence in Education Award from the Halliburton Education Foundation. He also taught at Randolph Community College in Asheboro, North Carolina, for nine years and helped pioneer an electrical curriculum for Northeast Texas Community College in Mount Pleasant, Texas. His additional publications include "Electric Motor Control," "Electricity and Controls for HVAC/R," "Industrial Motor Controls," "Understanding Motor Controls," "Electronics for Electricians," "Alternating Current Fundamentals," "Direct Current Fundamentals," "Electrical Studies for Trades," "Electrical Principles," "Experiments in Electricity For Use with Lab Volt Equipment," "The Complete Laboratory Manual for Electricity" and "Practical Problems in Mathematics for Electricians."

• Safety. Section I: BASIC CONTROL CIRCUITS AND COMPONENTS.1. General Principles of Motor Control.2. Symbols and Schematic Diagrams.3. Manual Starters.4. Overload Relays.5. Relays, Contactors, and Motor Starters.6. The Control Transformer.Section II: BASIC CONTROL CIRCUITS.7. Start-Stop Pushbutton Control.8. Multiple Pushbutton Stations.9. Forward-Reverse Control.10. Jogging and Inching.11. Timing Relays.12. Sequence Control.Section III: SENSING DEVICES.13. Pressure Switches and Sensors.14. Float Switches and Liquid Level Sensors.15. Flow Switches.16. Limit Switches.17. Temperature Sensing Devices.18. Hall Effect Sensors.19. Proximity Detectors.20. Photodetectors.21. Reading Large Schematic Diagrams.22. Installing Control Systems.Section IV: STARTING AND BRAKING METHODS.23. Across-the-Line Starting.24. Resistor and Reactor Starting for AC Motors.25. Autotransformer Starting.26. Wye-Delta Starting.27. Part Winding Starting.28. DC Motors.29. Single-Phase Motors.30. Braking.Section V: WOUND ROTOR, SYNCHRONOUS, AND CONSEQUENT POLE MOTORS.31. Wound Rotor Motors.32. Synchronous Motors.33. Consequent Pole Motors.Section VI: VARIABLE SPEED DRIVES.34. Variable Voltage and Magnetic Clutches.35. Solid State DC Motor Controls.36. Variable Frequency Control.Section VII: MOTOR INSTALLATION.37. Motor Installation.Section VIII: PROGRAMMABLE LOGIC CONTROLLERS.38. Programmable Logic Controllers.39. Programming a PLC.40. Analog Sensing for PLCs.Section IX: DEVELOPING CONTROL CIRCUITS AND TROUBLESHOOTING.41. Developing Control Circuits.42. Troubleshooting.Section X: ELECTRONICS FOR INDUSTRIAL MOTOR CONTROL43. Direct Drives and Pulley Drives44. Semiconductors.45. The PN Junction.46. The Zener Diode.47. Light Emitting Diodes and Photodiodes.48. The Transistor.49. The Unijunction Transistor.50. The SCR.51. The Diac.52. The Triac.53. The 555 Timer.54. The Operational Amplifier.Section XI: LAB EXERCISES.