{"schemaVersion":1,"slug":"ansi-on-delay-normally-open-contact","name":"ANSI/IEEE on-delay normally-open contact symbol","kind":"symbol","abbreviation":"TON NO","aliases":["IEEE on-delay normally-open contact symbol","ANSI on-delay normally-open contact symbol","HTD21N"],"category":"control-circuits","drawingTypes":["Schematic"],"referenceFamilies":["IEEE / ANSI","Manufacturer"],"summary":"IEEE-oriented graphical reference for on-delay normally-open contact, with public vendor evidence and drawing-reading notes.","description":["The on-delay NO contact form specifically describes a delayed-closing transition. Its timer reference supplies the initiating condition and interval, while the unoperated contact remains open; release or reset behaviour comes from the documented timing chart.","This is a convention-specific lookup based on the publisher's IEEE-labelled preview. The geometry here is independently drawn to explain the connection or operation; it is not a certified reproduction of the standard graphic."],"readingNotes":["Separate the delay-close transition from the contact's return action.","Read the selected library and the project legend together. A vendor block identifier is meaningful within its named library and is not a universal standard-symbol code."],"drawingChecklist":["Link timer element","State closing delay","Reference reset behaviour"],"distinction":"A timed output contact differs from the timer coil or trigger that initiates its timing.","facts":[{"label":"Convention evidence","value":"Autodesk IEEE Symbol Preview — Time Delay Relays"},{"label":"Public vendor block name","value":"HTD21N (Autodesk identifier; not an IEEE symbol number)"},{"label":"Standards context","value":"IEEE/ANSI 315-1975 covers diagram graphics. IEEE lists this edition as Inactive-Reserved."},{"label":"Artwork scope","value":"Original functional illustration; exact standard glyph and compliance are not certified"}],"references":[{"sourceId":"ansi-autodesk-bbff0443-6ea2-4a05-a761-f411e16ba070","relevance":"Exact public IEEE-oriented category page verifying the component name and vendor block identifier."},{"sourceId":"ieee-315","relevance":"Graphic-symbol standards context and official status; not a source of reproduced artwork."}],"related":["on-delay-normally-open-contact","relay-coil","normally-closed-contact"],"artwork":"edu-ansi-on-delay-normally-open-contact","publishedOn":"2026-10-14","updatedOn":"2026-10-14","provenance":"independent-public-research","symbolVariant":{"convention":"IEEE / ANSI","form":"Autodesk IEEE-oriented Time Delay Relays functional form","counterpart":"on-delay-normally-open-contact","reference":"Autodesk explicitly publishes this block under IEEE Symbol Preview. The counterpart is the matching functional concept; no equivalence of every detailed standard graphic is asserted."},"url":"https://eloragrid.ai/symbols/ansi-on-delay-normally-open-contact","illustration":{"url":"https://eloragrid.ai/library/illustrations/ansi-on-delay-normally-open-contact.svg","scope":"Original educational concept; not an official standard graphic or product footprint","license":"https://creativecommons.org/licenses/by/4.0/"},"sources":[{"id":"ansi-autodesk-bbff0443-6ea2-4a05-a761-f411e16ba070","title":"Autodesk IEEE Symbol Preview — Time Delay Relays","publisher":"Autodesk","url":"https://help.autodesk.com/cloudhelp/2021/ENU/AutoCAD-Electrical/files/GUID-BBFF0443-6EA2-4A05-A761-F411E16BA070.htm","type":"cad-reference","scope":"Verified public IEEE-oriented vendor catalogue. Block names identify vendor symbols, not IEEE standard symbol numbers. Linked only; graphics and CAD files are not redistributed. IEEE/ANSI 315-1975 is a historical graphics reference with Inactive-Reserved status; this page does not certify current standards compliance.","checkedOn":"2026-10-14","reuse":"link-only","relevance":"Exact public IEEE-oriented category page verifying the component name and vendor block identifier."},{"id":"ieee-315","title":"IEEE/ANSI 315-1975: graphic symbols for electrical and electronics diagrams","publisher":"IEEE Standards Association","url":"https://standards.ieee.org/ieee/315/515/","type":"standard","scope":"Graphic symbols and designation letters. IEEE lists this edition as Inactive-Reserved; it is a historical reference, not a claim of current compliance.","checkedOn":"2026-10-13","reuse":"link-only","relevance":"Graphic-symbol standards context and official status; not a source of reproduced artwork."}]}