{"schemaVersion":1,"slug":"70-rheostat","name":"Rheostat","kind":"function","abbreviation":"70","aliases":["field rheostat","adjustable resistance","ANSI 70","IEEE device 70"],"category":"measurement-protection","drawingTypes":["SLD","Schematic"],"referenceFamilies":["IEEE / ANSI"],"summary":"Provides adjustable resistance in a control, excitation or machine circuit.","description":["Provides adjustable resistance in a control, excitation or machine circuit.","In a drafting package, connect this reference to the resistance circuit, adjustment mechanism and operating range reference. The associated drawing should trace the rheostat terminals and drive/control interface; the number identifies the role and does not specify the terminal arrangement, ratings or operating settings.","This designation is useful when reading machine and legacy control drawings. Retain the documented function on an existing drawing and consult the original equipment manual before assigning it to a new design."],"readingNotes":["Identify the resistance circuit, adjustment mechanism and operating range reference.","Trace the rheostat terminals and drive/control interface."],"drawingChecklist":["Label the resistance circuit, adjustment mechanism and operating range reference.","Cross-reference the rheostat terminals and drive/control interface.","Identify the device tag, manual revision and logic drawing that define this implementation."],"distinction":"A rheostat is a variable resistor arrangement; it is not a complete voltage regulator.","facts":[{"label":"ANSI / IEEE function number","value":"70"},{"label":"Drawing context","value":"The resistance circuit, adjustment mechanism and operating range reference"},{"label":"Application scope","value":"Specialist or legacy machine-control use; interpret with the equipment legend."}],"references":[{"sourceId":"pub-function-sel-numbers","relevance":"Public manufacturer number/name association. Drafting explanations are independently written."},{"sourceId":"ieee-functions","relevance":"Normative device-number publication; exact edition wording and compliance require the licensed standard."}],"related":["resistor","52-ac-circuit-breaker"],"artwork":"pub-function-box","publishedOn":"2026-10-13","updatedOn":"2026-10-13","provenance":"independent-public-research","url":"https://eloragrid.ai/protection-functions/70-rheostat","illustration":{"url":"https://eloragrid.ai/library/illustrations/70-rheostat.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-numbers","title":"ANSI device-number and suffix reference table","publisher":"Schweitzer Engineering Laboratories","url":"https://selinc.com/pt/products/tables/ansi/","type":"manufacturer","scope":"Public Portuguese-language base-number and application-suffix table. Used to cross-check public number associations. Application-specific and historical labels need the selected drawing legend; this table is not a substitute for the licensed IEEE standard.","checkedOn":"2026-10-13","reuse":"link-only","relevance":"Public manufacturer number/name association. Drafting explanations are independently written."},{"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":"Normative device-number publication; exact edition wording and compliance require the licensed standard."}]}