# Single-phase autotransformer

Canonical URL: https://eloragrid.ai/symbols/single-phase-autotransformer
Publisher: Elora Grid
Updated: 2026-10-13
Lookup label: AT 1PH
Drawing use: SLD, Schematic
Reference families: IEC, Manufacturer

A single-phase autotransformer uses a winding portion shared electrically by its input and output circuits.

## What it represents

A single-phase autotransformer uses a winding portion shared electrically by its input and output circuits. Its drawing must make the common connection clear because it does not provide winding separation like a two-winding transformer.

## How to read it

- Trace the common winding terminal and identify the supply and load tap positions.
- 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

- State input and output voltages
- Show common winding connection
- Reference tap and rating data

## Important distinction

An autotransformer is not an isolating two-winding transformer.

## Facts

- Drawing role: Winding connection
- Representation scope: Functional concept; not an official standard graphic or a product footprint
- Public vendor block reference: HXF1P1AUTO, VXF1P1AUTO (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

- [Power, potential and autotransformer symbols](https://help.autodesk.com/cloudhelp/2021/ENU/AutoCAD-Electrical/files/GUID-C1FE1690-DBF4-4F69-85C4-28E41F0A6392.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.