In the United States, three different types of relays are used: electromechanical, solid state, and microprocessor. In the United States, about 50% of relays are electromechanical products, and 50% of them contain 8-10% of solid state relays. To diversify, it is necessary to design a training program covering both new and old technologies. Although the relay protection technology has made significant progress, the basic principles of relay protection have not changed. The concepts developed in the early days of relay protection are still very active. It is the implementation of those concepts that have undergone major changes. Relay protection devices are not Aims to implement relatively new concepts and algorithms.

 

        Relay protection devices must contain three elements: basic protection principles, understanding of relay protection devices and understanding of microcomputer processors. These are what developers need to understand when doing experiments. It will be handy when experimenting.