A protective relay is an intelligent device that senses abnormal electrical conditions, such as overcurrent, under-voltage, or frequency deviations. It initiates the operation of circuit breakers to isolate the affected section. Product Specialist (West Region) for Digital Substation Products at ABB Inc. Currently residing in Denver, Colorado. Previous experience in designing low voltage and medium voltage switchgear, relay panels and custom control panels as an Electrical Engineer at ESSMetron, Denver CO. Types of Protective Relays: Protective relays are categorized by their mechanism (electromagnetic, static, mechanical) and function. The rectangular devices are test connection blocks, used for testing and isolation of instrument transformer circuits.
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