# On-delay timer relay

Canonical URL: https://eloragrid.ai/symbols/on-delay-timer-relay
Publisher: Elora Grid
Updated: 2026-10-13
Lookup label: TON
Drawing use: Schematic
Reference families: IEC, Manufacturer

An on-delay timer postpones a specified output transition after its timing condition becomes active.

## What it represents

An on-delay timer postpones a specified output transition after its timing condition becomes active. The timing input, auxiliary supply and delayed output must be distinguished in the schematic.

## How to read it

- Read the timing diagram to establish when the interval starts and how interruption resets it.
- The preview is an original explanation of this function. Match the actual drawing convention to its legend and the selected equipment documentation.

## Information to show or reference

- Show initiating condition
- State time setting
- Link delayed output contact

## Important distinction

On-delay postpones the specified transition on operation; off-delay postpones a transition after removal of the initiating condition.

## Facts

- Drawing role: Timed operation
- Representation scope: Functional concept; not an official standard graphic or a product footprint
- Public vendor block reference: HTD1N, VTD1N (Autodesk identifiers; not IEC symbol numbers)
- Identifier status: The short label is a functional lookup label, not an assigned IEC or IEEE symbol number. Any separately listed Autodesk code is a verified vendor block name.

## Public references

- [AutoCAD Electrical: Time-delay relays](https://help.autodesk.com/cloudhelp/2021/ENU/AutoCAD-Electrical/files/GUID-DA927086-EEAF-48CB-B9B1-634A4B48C8C7.htm) — Autodesk. Public documentation of this equipment function or named vendor variant; the illustration is independently authored and is not the source graphic.

## 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.