Circuit Breakers 1

COURSE DESCRIPTION

Part one of this course provides the trainee with an overview of circuit breakers and their operating principles. It also introduces the student to the fundamental concepts of arc extinguishing and circuit interruption. At the conclusion of this course, students should be able to describe the main functions of circuit breakers and identify them by their classification. In addition, they should be able to identify air-magnetic, air-blast, oil, and vacuum circuit breakers, and briefly describe how each one operates.

COURSE GOALS

• Describe the function, purpose, and classifications of circuit breakers.

• Describe how circuit breakers work.

• Explain how the interrupting and operating mechanisms operate.

• Describe the main features and basic operation of four common types of circuit breakers.

SUBJECTS AND OBJECTIVES

Introduction to Circuit Breakers

• Discuss the two main functions of circuit breakers.

• Explain why it is important to extinguish arcs quickly.

• Discuss the roles of speed, distance, cooling, dielectric strength, and current zero in extinguishing arcs.

• Identify the dielectric mediums that are commonly used in circuit breakers to extinguish arcs.

Air-Magnetic and Air-Blast Circuit Breakers

• Describe the main arc extinguishing features of an air-magnetic circuit breaker.

• Explain how an arc is extinguished in an air-magnetic circuit breaker.

• Describe the main arc extinguishing features of an air-blast circuit breaker.

• Explain how an arc is extinguished in an air-blast circuit breaker.

Oil and Vacuum Circuit Breakers

• Describe the arc extinguishing features of an oil circuit breaker.

• Explain how an arc is extinguished in an oil circuit breaker.

• Describe the arc extinguishing features of a vacuum circuit breaker.

• Explain how an arc is extinguished in a vacuum circuit breaker.