To provide effective and reliable protection to the power system, a protective relay must have the following essential functional characteristics: Selective, Fast, Stable, Reliability, Sensitivity, Simple Construction and Installation Mechanism, and Cost-effective. The rectangular devices are test connection blocks, used for testing and isolation of instrument transformer circuits. : 4 The first protective relays were electromagnetic. (1) Selectivity: refers to that when the Electrical fault occurs, the relay protection device acts and only removes the fault element. Eng, IEEE Life Fellow IEEE/IAS/I&CPSD Protection & Coordination WG Chair Jacobs Canada, Calgary, AB rasheek. Based on Operating Principle Electromechanical Relays: Work using moving parts and electromagnetic forces (traditional.
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