In this free online course, you will learn about the working principles of electrical switches and protective devices known as circuit breakers. We will explain the fundamentals of a circuit breaker and teach you about the different types and their specifications. We will also show you how to select an appropriate size for the connected load. A circuit breaker is an automatically operated electrical switch designed to protect an electrical circuit from damage caused by excess current from an overload or short circuit. It will act like a normal switch under normal conditions that can be used to trip the circuit for the purpose of maintenance. The basic function of all circuit breakers is to interrupt heavy current flow after a fault is detected in an electrical circuit. Unlike a fuse, which operates once and then must be replaced, these electrical switches can be reset, either manually or automatically, to resume normal operation.

This short course will not only give you an idea of how to select an appropriate circuit breaker based on the type of electrical load but you will also come to know the working principles of a miniature circuit breaker in detail. You will familiarize yourself with the size calculation of the circuit breaker as per the US National Electrical Codes’ (NEC) rule. On finishing this course, you will know the definition of a circuit breaker and the difference between short circuit and overload current. After explaining the technical specifications, the material moves to arc extinction, where you will learn more about high and low resistance interruption. As you will see, a suitable energy dissipating device must be incorporated in the design, as the arc can lead to the danger of fire or explosion. You will find out what an arc consists of, what methods are used in the arc extinction process, what forms of protection may be employed to reduce the rate of erosion of contacts, and how the blast principle - where we use air, oil, gas or water - works.

By the end, you will be able to understand and design a circuit breaker for any low voltage electrical system projects and know the correct way to make a selection. You will also be amazed to find out how much information you can receive in a bite-sized course like this one! To reinforce the information obtained in these topics, you will have the chance to test your knowledge by going through several questions before the final assessment.