The classification of relay protection objects includes
Types of Protective Relays: Protective relays are categorized by their mechanism (electromagnetic, static, mechanical) and function (time-based, current, voltage). A typical protective relay circuit is shown below: Protective Relay Circuit Diagram The first part of the circuit consists of the primary winding of a CT. The relay can be made to respond to either a single quantity or a combination of two or all input quantities. The components used in the power system are usually dimensioned to withstand a short circuit current for one or three seconds but power system stability during short circuit current may be endangered already after 200ms.
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