Air circuit breaker principles course, in this course we will learn about the Air Circuit Breaker principles, focusing on the key concepts and operational mechanisms that ensure the effective protection of electrical systems. Students will explore the fundamentals of air circuit breakers (ACBs), including their design, construction, and functionality. Key topics include the principles of arc extinction, where the arc is quenched in an air medium, the operational mechanisms that control the opening and closing of contacts, and the types of protection ACBs offer, such as overcurrent, short circuit, and ground fault protection. The course will delve into the different types of ACBs, their applications in various electrical systems, and the standards they must meet. Emphasis will be placed on the importance of regular maintenance and testing to ensure reliability and safety. Practical sessions will provide hands-on experience with ACB components, testing procedures, and troubleshooting common issues. By the end of the course, participants will have a comprehensive understanding of how air circuit breakers work, how to apply them in different scenarios, and how to maintain them to ensure optimal performance and safety in electrical installations.