{"schemaVersion":1,"slug":"49r-rtd-based-thermal-protection","name":"RTD-based thermal protection","kind":"function","abbreviation":"49R","aliases":["RTD thermal overload","resistance temperature detector protection","ANSI 49R","IEEE 49R"],"category":"measurement-protection","drawingTypes":["SLD","Schematic"],"referenceFamilies":["IEEE / ANSI","Manufacturer"],"summary":"Uses resistance-temperature-detector measurements for an equipment thermal protection function.","description":["Uses resistance-temperature-detector measurements for an equipment thermal protection function.","The drafting record should connect this function to the RTD channel assignments, sensor wiring and monitored locations, then trace the thermal alarm and equipment trip outputs. Keep the complete designation and equipment tag together so that the SLD, relay logic and terminal schedule describe the same implementation.","The cited mapping is a public manufacturer example (SEL generator protection feature table). Suffixes are not universal equivalences across products, and this reference supplies neither a protection setting nor certification of the selected scheme."],"readingNotes":["Identify the RTD channel assignments, sensor wiring and monitored locations.","Trace the thermal alarm and equipment trip outputs."],"drawingChecklist":["Label the RTD channel assignments, sensor wiring and monitored locations.","Cross-reference the thermal alarm and equipment trip outputs.","Retain the complete suffix, selected device tag and manufacturer manual revision."],"distinction":"RTD-based 49R uses measured temperature; a current-driven thermal model can have a separate response and wiring arrangement.","facts":[{"label":"Function designation","value":"49R"},{"label":"Base function","value":"49 — Thermal protection"},{"label":"Published mapping","value":"SEL generator protection feature table"},{"label":"Suffix scope","value":"Application or manufacturer specific; check the complete drawing legend and selected device manual."}],"references":[{"sourceId":"pub-function-sel-generator","relevance":"Public primary-source function or application mapping used to identify this designation; wording and drafting notes are original."},{"sourceId":"ieee-functions","relevance":"Device-number and suffix convention. This page is not a reproduction of the full licensed standard."}],"related":["49-thermal-protection","current-transformer"],"artwork":"pub-function-box","publishedOn":"2026-10-13","updatedOn":"2026-10-13","provenance":"independent-public-research","url":"https://eloragrid.ai/protection-functions/49r-rtd-based-thermal-protection","illustration":{"url":"https://eloragrid.ai/library/illustrations/49r-rtd-based-thermal-protection.svg","scope":"Original educational concept; not an official standard graphic or product footprint","license":"https://creativecommons.org/licenses/by/4.0/"},"sources":[{"id":"pub-function-sel-generator","title":"Generator protection feature and function comparison","publisher":"Schweitzer Engineering Laboratories","url":"https://selinc.com/products/comparisons/generator-protection/","type":"manufacturer","scope":"Public mappings for generator functions, including phase distance, field/stator ground, thermal RTD, sequence-current and vector-shift applications. Product availability depends on model/options; no settings are provided here.","checkedOn":"2026-10-13","reuse":"link-only","relevance":"Public primary-source function or application mapping used to identify this designation; wording and drafting notes are original."},{"id":"ieee-functions","title":"IEEE C37.2-2022: power-system device function numbers","publisher":"IEEE","url":"https://ieeexplore.ieee.org/document/9984140","type":"standard","scope":"Device function numbers, acronyms and contact designations. The full publication may require access through IEEE.","checkedOn":"2026-10-13","reuse":"link-only","relevance":"Device-number and suffix convention. This page is not a reproduction of the full licensed standard."}]}