# ANSI/IEEE on-delay normally-closed contact symbol

Canonical URL: https://eloragrid.ai/symbols/ansi-on-delay-normally-closed-contact
Publisher: Elora Grid
Updated: 2026-10-14
Lookup label: TON NC
Drawing use: Schematic
Reference families: IEEE / ANSI, Manufacturer

## Symbol convention

Convention: IEEE / ANSI
Form: Autodesk IEEE-oriented Time Delay Relays functional form
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.
Related representation: [On-delay normally-closed contact](https://eloragrid.ai/symbols/on-delay-normally-closed-contact)

IEEE-oriented graphical reference for on-delay normally-closed contact, with public vendor evidence and drawing-reading notes.

## What it represents

The on-delay NC contact form specifically describes delayed opening from its reference closed state. The controlled path remains continuous while the specified delay runs, so the timer tag and timing condition are essential circuit-reading information.
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.

## How to read it

- Trace the permissive or command during the delay interval.
- 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.

## Information to show or reference

- Identify timer tag
- State opening delay
- Reference reset condition

## Important distinction

Normally closed describes the initial contact state while on-delay identifies the specified operating transition.

## Facts

- Convention evidence: Autodesk IEEE Symbol Preview — Time Delay Relays
- Public vendor block name: HTD22N (Autodesk identifier; not an IEEE symbol number)
- Standards context: IEEE/ANSI 315-1975 covers diagram graphics. IEEE lists this edition as Inactive-Reserved.
- Artwork scope: Original functional illustration; exact standard glyph and compliance are not certified

## Public references

- [Autodesk IEEE Symbol Preview — Time Delay Relays](https://help.autodesk.com/cloudhelp/2021/ENU/AutoCAD-Electrical/files/GUID-BBFF0443-6EA2-4A05-A761-F411E16BA070.htm) — Autodesk. Exact public IEEE-oriented category page verifying the component name and vendor block identifier.
- [IEEE/ANSI 315-1975: graphic symbols for electrical and electronics diagrams](https://standards.ieee.org/ieee/315/515/) — IEEE Standards Association. Graphic-symbol standards context and official status; not a source of reproduced artwork.

## Graphic scope

Independent original educational concept illustration by Elora Grid. Not a certified standards graphic or manufacturer footprint. Unitless; not to scale. Original artwork licence: https://creativecommons.org/licenses/by/4.0/. Publisher material is linked only.