The article provides an overview of protective relaying principles and their applications for high-voltage power system components. It covers the protection methods for generators, transformers, buses, and transmission lines using various relay types to detect and. There are two ways to classify the different types of protection used on the generator: Relays provide protection by identifying problems outside the generator. Protective relays are used to identify internal problems in generators. The machine and its auxiliaries are supervised by monitoring devices to keep the incidences of abnormal working conditions down to a minimum. The. Generator Protections are broadly classified into three types: Class A, B and C.