Refer to the Safety Precautions for individual Relays for precautions specific to each Relay. Selectivity is a mandatory requirement for all protection, but the importance of it depends on the application. For example, unselective protection operation during a medium voltage network fault will cause an outage for an unnecessarily large number of consumers. While this is bad, It's not a. Protective Relays - Technical Seminar Nov 2016 - Copyright: IEEE 2 Abstract: Protective relays and devices have been developed over 100 years ago to provide “lastline”of defense for the electrical systems. Also principles of various protective relays and schemes including special protection. One of the key components in an electrical panel is a relay, an electromechanical switch that operates its mechanical contacts when electrically energized. In essence it serves as a contact between two circuits and divides them.
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