# Residual-voltage monitoring relay

Canonical URL: https://eloragrid.ai/symbols/residual-voltage-monitoring-relay
Publisher: Elora Grid
Updated: 2026-10-13
Lookup label: U RES
Drawing use: SLD, Schematic
Reference families: Manufacturer

A residual-voltage relay responds to the specified residual-voltage measurement.

## What it represents

A residual-voltage relay responds to the specified residual-voltage measurement. Its drawing needs the voltage-transformer connection and the input quantity definition.

## How to read it

- Check the measurement circuit that produces the residual voltage.
- 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 VT connection
- State residual input scaling
- Reference operating threshold

## Important distinction

Residual voltage is different from phase-to-neutral voltage at an arbitrary single phase.

## Facts

- Drawing role: Monitoring element
- Representation scope: Functional concept; not an official standard graphic or a product footprint
- Public vendor block reference: HCR1F38, VCR1F38 (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: Voltage monitoring relays](https://help.autodesk.com/cloudhelp/2021/ENU/AutoCAD-Electrical/files/GUID-5296749E-9336-4B07-9956-160963D6C848.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.