Tag: Relays
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Protective Relays: Function, Features & Operation
A protective relay is basically an electrical device that detects a fault in a power system and initiates the operation of the circuit breaker to isolate the defective section or component from the rest of the system. In other words, the prime function of protective relays is the timely and discriminative clearance of system faults.…
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Electromechanical Relays (EMR)
Electromechanical relay (EMR) is a device that uses an electromagnet to provide the force to close or open switch contacts i.e. it is an electrically powered switch. When the electromagnet (also called coil) is energized, it pulls down on the spring-loaded armature. Relay contacts can be described as normally open contacts (NO), which are open…
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Features of a Reed Relay
The reed like contacts of a reed relay are encapsulated in a small sealed glass tube that is evacuated or filled with an inert gas like dry nitrogen as illustrated in the figure below: The contacts are activated by an external magnetic field. The contacts are either dry or mercury-wetted. Mercury-wetted contacts have a thin…