87
Differential protection
A function comparing documented electrical quantities across a protection zone.
Protection functions
Protection functions · 87H
Unrestrained high-set differential protection
Provides the documented high-set or unrestrained differential element in the cited relay family.
SLD / Schematic · 87H
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.
A distinction that matters
An unrestrained high-set element differs from the percentage-restrained differential element and must retain its own setting reference.
Sources you can follow
These public references support the explanation and provide further detail. Their graphics and downloadable files remain with their publishers.
ETR-4000 and ETR-5000 transformer protection function tables
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
Device-number and suffix convention. This page is not a reproduction of the full licensed standard.
About this graphic
This illustration was authored independently by Elora Grid to explain the concept. It is not reproduced from a customer drawing, an official standard graphic or a manufacturer CAD file. Its correspondence to an exact IEC or IEEE symbol identifier has not been certified.
SVG and DXF downloads contain this original artwork. DXF uses unscaled drawing units; a GA envelope supplies no product dimensions, clearances or fabrication information. Original artwork is available under CC BY 4.0. Third-party references retain their own terms.
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