Solution and Answer Guide: Stephen L. Herman & Frank Seiler, Understanding Motor Controls, 5th Ed., 2026, 9798214114040; Chapter 1:
General Principles of Motor Control
Solution and Answer Guide
STEPHEN L. HERMAN & FRANK SEILER, UNDERSTANDING MOTOR CONTROLS, 5TH ED., 2026,
9798214114040; CHAPTER 1: GENERAL PRINCIPLES OF MOTOR CONTROL
TABLE OF CONTENTS
Section 1: Basic Control Circuits and Components.....................................................1
CHAPTER 1 — General Principles of Motor Control.................................................1
Chapter 1 Objectives..................................................................................................................................1
Chapter 1 — End of Chapter Exercise Solutions.......................................................................................1
SECTION 1: BASIC CONTROL CIRCUITS AND
COMPONENTS
CHAPTER 1 — GENERAL PRINCIPLES OF MOTOR
CONTROL
CHAPTER 1 OBJECTIVES
State the purpose and general principles of motor control.
Explain what codes and standards apply to motors, machine control, and electrical
installations.
Differentiate between manual and automatic motor control.
Discuss considerations when installing motors or control equipment.
Identify the basic functions of a control system.
Discuss surge protection for control systems.
CHAPTER 1 — END OF CHAPTER EXERCISE SOLUTIONS
1. When installing a motor control system, list four major factors to consider concerning the power system.
ANSWER:
- Is the motor single-phase or three-phase?
- What is motor horsepower?
- Must the inrush current be reduced?
- Is the present power system capable of handling the new installation?
2. Where is the best place to look to find specific information about a motor, such as horsepower, voltage, full
load current, service factor, and full load speed?
© 2026 Cengage Learning, Inc. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly 1
accessible website, in whole or in part.
, Solution and Answer Guide: Stephen L. Herman & Frank Seiler, Understanding Motor Controls, 5th Ed., 2026, 9798214114040; Chapter 1:
General Principles of Motor Control
ANSWER:
The motor nameplate
3. Is the National Electrical Code® a law?
ANSWER:
No. According to the publishers, the National Electrical Code® is a standard made available for a wide
variety of uses. Many state or municipal jurisdictions adopt a version of the NEC® to enforce through their
construction compliance programs.
4. Explain the difference between manual control, semiautomatic control, and automatic control.
ANSWER:
Manual control is characterized by the fact that the operator must go to the location of the controller to
perform some change of action in the control system. Semiautomatic control uses magnetic contactors and
starters, and other pilot devices to control the operation of the motor. The operator must initiate certain
actions in the control system. Automatic control also uses devices similar to semiautomatic control, but
once set by the operator, the control circuit continues to operate without further operator assistance.
5. What is the simplest of all starting methods for a motor?
ANSWER:
Across-the-line starting. Energizing the motor with full voltage.
6. Explain the difference between jogging and inching.
ANSWER:
Jogging is accomplished by applying power in short intervals at full voltage, while inching is accomplished
by applying power in short bursts at a reduced voltage.
7. What is the most common method of controlling the speed of an alternating current motor?
ANSWER:
Variable Frequency Control. Alternating current induction motors operate on a set speed based on the
source voltage frequency. Altering the frequency thus alters the motor’s resulting speed.
8. What agency requires employers to provide a workplace free of recognized hazards for its employees?
ANSWER:
Occupational Safety and Health Administration (OSHA) as a federal agency. Some states opt to provide
OSHA compliance at the state level.
9. What is meant by the term ramping?
ANSWER:
To permit the motor to accelerate to its full speed over some period of time. The result is that less current is
drawn from the electrical system at start-up as opposed to across-the line starting.
10. What is the most important function of any control system?
ANSWER:
Safety—to provide electrical and mechanical protection for the operator or other persons in the vicinity of
the machine.
© 2026 Cengage Learning, Inc. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly 2
accessible website, in whole or in part.
, Solution and Answer Guide: Stephen L. Herman & Frank Seiler, Understanding Motor Controls, 5th Ed., 2026, 9798214114040; Chapter 2:
Symbols and Schematic Diagrams
Solution and Answer Guide
STEPHEN L. HERMAN & FRANK SEILER, UNDERSTANDING MOTOR CONTROLS, 5TH ED., 2026,
9798214114040; CHAPTER 2: SYMBOLS AND SCHEMATIC DIAGRAMS
TABLE OF CONTENTS
Section 1: Basic Control Circuits and Components.....................................................1
CHAPTER 2 — Symbols and Schematic Diagrams.....................................................1
Chapter 2 Objectives..................................................................................................................................1
Chapter 2 — End of Chapter Exercise Solutions.......................................................................................1
SECTION 1: BASIC CONTROL CIRCUITS AND
COMPONENTS
CHAPTER 2 — SYMBOLS AND SCHEMATIC
DIAGRAMS
CHAPTER 2 OBJECTIVES
Identify the meaning and use of common symbols used in the drawing of schematic
diagrams.
Determine the difference between switches that are drawn normally open, normally
closed, normally open held closed, and normally closed held open.
Draw standard NEMA control symbols.
State rules that apply to schematic or ladder diagrams.
Interpret the logic of simple ladder diagrams.
CHAPTER 2 — END OF CHAPTER EXERCISE SOLUTIONS
1. The symbol shown is:
a. Polarized capacitor
b. Normally closed switch
c. Normally open held closed switch
d. Normally open contact
© 2026 Cengage Learning, Inc. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly 1
accessible website, in whole or in part.
, Solution and Answer Guide: Stephen L. Herman & Frank Seiler, Understanding Motor Controls, 5th Ed., 2026, 9798214114040; Chapter 2:
Symbols and Schematic Diagrams
ANSWER:
d. Normally open contact (see Fig 2.44)
2. The symbol shown is:
a. Normally closed float switch
b. Normally open held closed float switch
c. Normally open float switch
d. Normally closed held open float switch
ANSWER:
c. Normally open float switch (see Fig 2.44)
3. The symbol shown is:
a. Iron core transformer
b. Auto transformer
c. Current transformer
d. Air core transformer
ANSWER:
a. Iron core transformer (see Fig 2.44)
4. The symbol shown is:
a. Normally open pressure switch
b. Normally open flow switch
c. Normally open float switch
d. Normally open temperature switch
ANSWER:
d. Normally open temperature switch (see Fig 2.44)
5. The symbol shown is:
a. Double acting push button
b. Two-position selector switch
c. Three-position selector switch
d. Maintained contact push button
ANSWER:
c. Three-position selector switch
6. If you were installing the circuit in Figure 2.35, what type of push button would you use for the silence
button?
a. Normally closed
b. Normally open
© 2026 Cengage Learning, Inc. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly 2
accessible website, in whole or in part.
General Principles of Motor Control
Solution and Answer Guide
STEPHEN L. HERMAN & FRANK SEILER, UNDERSTANDING MOTOR CONTROLS, 5TH ED., 2026,
9798214114040; CHAPTER 1: GENERAL PRINCIPLES OF MOTOR CONTROL
TABLE OF CONTENTS
Section 1: Basic Control Circuits and Components.....................................................1
CHAPTER 1 — General Principles of Motor Control.................................................1
Chapter 1 Objectives..................................................................................................................................1
Chapter 1 — End of Chapter Exercise Solutions.......................................................................................1
SECTION 1: BASIC CONTROL CIRCUITS AND
COMPONENTS
CHAPTER 1 — GENERAL PRINCIPLES OF MOTOR
CONTROL
CHAPTER 1 OBJECTIVES
State the purpose and general principles of motor control.
Explain what codes and standards apply to motors, machine control, and electrical
installations.
Differentiate between manual and automatic motor control.
Discuss considerations when installing motors or control equipment.
Identify the basic functions of a control system.
Discuss surge protection for control systems.
CHAPTER 1 — END OF CHAPTER EXERCISE SOLUTIONS
1. When installing a motor control system, list four major factors to consider concerning the power system.
ANSWER:
- Is the motor single-phase or three-phase?
- What is motor horsepower?
- Must the inrush current be reduced?
- Is the present power system capable of handling the new installation?
2. Where is the best place to look to find specific information about a motor, such as horsepower, voltage, full
load current, service factor, and full load speed?
© 2026 Cengage Learning, Inc. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly 1
accessible website, in whole or in part.
, Solution and Answer Guide: Stephen L. Herman & Frank Seiler, Understanding Motor Controls, 5th Ed., 2026, 9798214114040; Chapter 1:
General Principles of Motor Control
ANSWER:
The motor nameplate
3. Is the National Electrical Code® a law?
ANSWER:
No. According to the publishers, the National Electrical Code® is a standard made available for a wide
variety of uses. Many state or municipal jurisdictions adopt a version of the NEC® to enforce through their
construction compliance programs.
4. Explain the difference between manual control, semiautomatic control, and automatic control.
ANSWER:
Manual control is characterized by the fact that the operator must go to the location of the controller to
perform some change of action in the control system. Semiautomatic control uses magnetic contactors and
starters, and other pilot devices to control the operation of the motor. The operator must initiate certain
actions in the control system. Automatic control also uses devices similar to semiautomatic control, but
once set by the operator, the control circuit continues to operate without further operator assistance.
5. What is the simplest of all starting methods for a motor?
ANSWER:
Across-the-line starting. Energizing the motor with full voltage.
6. Explain the difference between jogging and inching.
ANSWER:
Jogging is accomplished by applying power in short intervals at full voltage, while inching is accomplished
by applying power in short bursts at a reduced voltage.
7. What is the most common method of controlling the speed of an alternating current motor?
ANSWER:
Variable Frequency Control. Alternating current induction motors operate on a set speed based on the
source voltage frequency. Altering the frequency thus alters the motor’s resulting speed.
8. What agency requires employers to provide a workplace free of recognized hazards for its employees?
ANSWER:
Occupational Safety and Health Administration (OSHA) as a federal agency. Some states opt to provide
OSHA compliance at the state level.
9. What is meant by the term ramping?
ANSWER:
To permit the motor to accelerate to its full speed over some period of time. The result is that less current is
drawn from the electrical system at start-up as opposed to across-the line starting.
10. What is the most important function of any control system?
ANSWER:
Safety—to provide electrical and mechanical protection for the operator or other persons in the vicinity of
the machine.
© 2026 Cengage Learning, Inc. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly 2
accessible website, in whole or in part.
, Solution and Answer Guide: Stephen L. Herman & Frank Seiler, Understanding Motor Controls, 5th Ed., 2026, 9798214114040; Chapter 2:
Symbols and Schematic Diagrams
Solution and Answer Guide
STEPHEN L. HERMAN & FRANK SEILER, UNDERSTANDING MOTOR CONTROLS, 5TH ED., 2026,
9798214114040; CHAPTER 2: SYMBOLS AND SCHEMATIC DIAGRAMS
TABLE OF CONTENTS
Section 1: Basic Control Circuits and Components.....................................................1
CHAPTER 2 — Symbols and Schematic Diagrams.....................................................1
Chapter 2 Objectives..................................................................................................................................1
Chapter 2 — End of Chapter Exercise Solutions.......................................................................................1
SECTION 1: BASIC CONTROL CIRCUITS AND
COMPONENTS
CHAPTER 2 — SYMBOLS AND SCHEMATIC
DIAGRAMS
CHAPTER 2 OBJECTIVES
Identify the meaning and use of common symbols used in the drawing of schematic
diagrams.
Determine the difference between switches that are drawn normally open, normally
closed, normally open held closed, and normally closed held open.
Draw standard NEMA control symbols.
State rules that apply to schematic or ladder diagrams.
Interpret the logic of simple ladder diagrams.
CHAPTER 2 — END OF CHAPTER EXERCISE SOLUTIONS
1. The symbol shown is:
a. Polarized capacitor
b. Normally closed switch
c. Normally open held closed switch
d. Normally open contact
© 2026 Cengage Learning, Inc. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly 1
accessible website, in whole or in part.
, Solution and Answer Guide: Stephen L. Herman & Frank Seiler, Understanding Motor Controls, 5th Ed., 2026, 9798214114040; Chapter 2:
Symbols and Schematic Diagrams
ANSWER:
d. Normally open contact (see Fig 2.44)
2. The symbol shown is:
a. Normally closed float switch
b. Normally open held closed float switch
c. Normally open float switch
d. Normally closed held open float switch
ANSWER:
c. Normally open float switch (see Fig 2.44)
3. The symbol shown is:
a. Iron core transformer
b. Auto transformer
c. Current transformer
d. Air core transformer
ANSWER:
a. Iron core transformer (see Fig 2.44)
4. The symbol shown is:
a. Normally open pressure switch
b. Normally open flow switch
c. Normally open float switch
d. Normally open temperature switch
ANSWER:
d. Normally open temperature switch (see Fig 2.44)
5. The symbol shown is:
a. Double acting push button
b. Two-position selector switch
c. Three-position selector switch
d. Maintained contact push button
ANSWER:
c. Three-position selector switch
6. If you were installing the circuit in Figure 2.35, what type of push button would you use for the silence
button?
a. Normally closed
b. Normally open
© 2026 Cengage Learning, Inc. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly 2
accessible website, in whole or in part.
