Relay protection safety levels are divided into
Like IEC61508, it stipulates Safety Integrity Levels (SIL) that can be divided into 3 levels within the machinery field: SIL1, SIL2, SIL3. ISO13849 defines the use of Performance Levels (PL) to evaluate a complete safety system or safety-related components. Abstract: Protective relays and devices have been developed over 100 years ago to provide "lastline"of defense for the electrical systems. 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. Electromechanical relays can be classified into several different types as follows: "Armature"-type relays have a pivoted lever supported on a hinge or knife-edge pivot, which carries a moving contact.
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