CT's transform line current down to a signal level that is acceptable to the relay. Multiple relays can use the same CT. Core idea: Protective relays monitor electrical quantities and command protective devices to isolate faults or abnormal operating conditions. Engineering use: Relays are used on feeders, transformers, buses, motors, generators, and transmission lines to protect equipment and improve system. The first part of the circuit consists of the primary winding of a CT which is also called a current transformer. The second part includes the secondary winding of the current transformer, CB (Circuit Breaker) & the. The rectangular devices are test connection blocks, used for testing and isolation of instrument transformer circuits. What controls it: Relay selection depends on input voltage, contact type, contact rating, load behavior, timing, isolation, duty cycle, and failure. What are Protective Relays, or Protection Relays? Protective relays are used in industrial power generation and supply systems to open and isolate branch circuits in the case of excessive current. They are activated by means which are not dependent on a continual AC supply. They include both. Combines protection, sensors, control power, and circuit breaker in a single package Typically added to a breaker close circuit to prevent accidental reclosure after a trip. Three fundamental components required for each circuit breaker.
