{"schemaVersion":1,"slug":"73-load-resistor-contactor","name":"Load-resistor contactor","kind":"function","abbreviation":"73","aliases":["load resistor switch","resistor contactor","ANSI 73","IEEE device 73"],"category":"measurement-protection","drawingTypes":["SLD","Schematic"],"referenceFamilies":["IEEE / ANSI"],"summary":"Switches a resistor used to impose, remove or change electrical load in a machine arrangement.","description":["Switches a resistor used to impose, remove or change electrical load in a machine arrangement.","In a drafting package, connect this reference to the load resistor and switched power connection. The associated drawing should trace the contactor control and resistor duty references; 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 load resistor and switched power connection.","Trace the contactor control and resistor duty references."],"drawingChecklist":["Label the load resistor and switched power connection.","Cross-reference the contactor control and resistor duty references.","Identify the device tag, manual revision and logic drawing that define this implementation."],"distinction":"A load-resistor contactor switches the resistor circuit; the resistor's rating and ventilation remain separate design data.","facts":[{"label":"ANSI / IEEE function number","value":"73"},{"label":"Drawing context","value":"The load resistor and switched power connection"},{"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/73-load-resistor-contactor","illustration":{"url":"https://eloragrid.ai/library/illustrations/73-load-resistor-contactor.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."}]}