Maintenance of Low-Voltage Circuit Breakers

Basic Parts and Operation Identify and describe common types of low-voltage circuit breakers. Describe the basic functions of a circuit breaker. Identify and describe major components of a typical low-voltage circuit breaker. Describe ways in which circuit breaker contacts can be closed. Identify the three sections of a typical switchgear assembly and describe the function of each section. Describe how a typical circuit breaker is connected to primary power and control power Principles of Circuit Interruption Describe what arcing is and how arcs form. Describe safety measures that should be followed to minimize risks associated with arcing and other electrical hazards. Describe factors that can affect how an arc is extinguished. Describe how a metal fin arc chute can be used to extinguish an arc in a typical circuit breaker. Explain what current zero is. Maintenance Describe a procedure for racking out a typical circuit breaker for maintenance. Describe basic maintenance procedures that are performed on a typical circuit breaker. Describe three checks that can be performed on the movable and stationary contacts of a typical circuit breaker. Describe how to perform an instantaneous trip test and a time delay trip test on a typical circuit breaker.