# Unrestrained high-set differential protection

Canonical URL: https://eloragrid.ai/protection-functions/87h-unrestrained-high-set-differential-protection
Publisher: Elora Grid
Updated: 2026-10-13
Lookup label: 87H
Drawing use: SLD, Schematic
Reference families: IEEE / ANSI, Manufacturer

Provides the documented high-set or unrestrained differential element in the cited relay family.

## What it represents

Provides the documented high-set or unrestrained differential element in the cited relay family.
The drafting record should connect this function to the same protected-zone CT inputs and high-set element reference, then trace the unrestrained differential trip output. Keep the complete designation and equipment tag together so that the SLD, relay logic and terminal schedule describe the same implementation.
The cited mapping is a public manufacturer example (Eaton ETR family). Suffixes are not universal equivalences across products, and this reference supplies neither a protection setting nor certification of the selected scheme.

## How to read it

- Identify the same protected-zone CT inputs and high-set element reference.
- Trace the unrestrained differential trip output.

## Information to show or reference

- Label the same protected-zone CT inputs and high-set element reference.
- Cross-reference the unrestrained differential trip output.
- Retain the complete suffix, selected device tag and manufacturer manual revision.

## Important distinction

An unrestrained high-set element differs from the percentage-restrained differential element and must retain its own setting reference.

## Facts

- Function designation: 87H
- Base function: 87 — Differential protection
- Published mapping: Eaton ETR family
- Suffix scope: Application or manufacturer specific; check the complete drawing legend and selected device manual.

## Public references

- [ETR-4000 and ETR-5000 transformer protection function tables](https://www.eaton.com/us/en-us/catalog/electrical-circuit-protection/transformer-relays.html) — Eaton. Public primary-source function or application mapping used to identify this designation; wording and drafting notes are original.
- [IEEE C37.2-2022: power-system device function numbers](https://ieeexplore.ieee.org/document/9984140) — IEEE. Device-number and suffix convention. This page is not a reproduction of the full licensed standard.

## 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.