Siemens Reyrolle 7SR45 Argus Device Manual

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Time-Delayed Overcurrent Protection (51)Overview of the Function (51)Time-delayed overcurrent protection is used to provide:• Short-circuit detection in electric equipment• Coordinated operation with other devices using current and time-graded settingsStructure of the Function (51)The time-delayed overcurrent protection function element has group-dependent settings. These settings canbe different in each settings group – group numbers (Gn) 1 and 2.The function monitors the primary system current using the 3-phase current transformer inputs, for exampleCT1/2/3.The basic time-delayed overcurrent protection function (51) is characterized by the following:• Current measurement is based on the fundamental current.• A number of time versus current operate curves are selectable based on IEC and ANSI standards.• LED operations are provided for each phase. A general pickup and 51‑n output are also provided.3.3Functions3.3 Time-Delayed Overcurrent Protection (51)44 Reyrolle, 7SR45, Device ManualC53000-G7040-C101-2, Edition 09.2020