Circuit Breakers are reusable overcurrent protection devices. After tripping to break the circuit, the breaker can be reset to protect the circuit again. There are two accepted definitions for circuit breakers. The National Electrical Manufacturers Association (NEMA) defines a circuit breaker as a device designed to open and close a circuit, by non-automatic means, and to open the circuit automatically on a predetermined overcurrent without injury to itself when properly applied within its rating. The American National Standards Institute (ANSI) states that a circuit breaker is a mechanical switching device capable of making, carrying and breaking currents under normal circuit conditions. Also, it is capable of making and carrying a current for a specified time, and breaking currents under specified abnormal circuit conditions such as those of a short circuit. All circuit breakers have the following common design and functional characteristics:Frame
The circuit breakers frame provides a method by which all the required components can be mounted and kept in place, ensuring the proper operation of the circuit breaker. The circuit breaker frame provides the rigidity and strength required to successfully deal with the interruption process and achieve the desired Interrupting Ratings. The frame’s mechanical strength must be sufficient to withstand the forces created by the square of the current (I2), which could be quite large and potentially destructive. The frame provides for insulation
