51
Time overcurrent
An overcurrent function with a documented time characteristic.
Protection functions
Protection functions · 51V
Voltage-dependent overcurrent
Changes overcurrent operation according to the measured voltage using the relay's documented voltage-dependent method.
SLD / Schematic · 51V
What it represents
Changes overcurrent operation according to the measured voltage using the relay's documented voltage-dependent method.
The drafting record should connect this function to the current inputs, VT circuit and selected voltage-dependence mode, then trace the overcurrent trip logic and voltage-supervision reference. 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 current inputs, VT circuit and selected voltage-dependence mode.
- Trace the overcurrent trip logic and voltage-supervision reference.
Information to show or reference
- Label the current inputs, VT circuit and selected voltage-dependence mode.
- Cross-reference the overcurrent trip logic and voltage-supervision reference.
- Retain the complete suffix, selected device tag and manufacturer manual revision.
A distinction that matters
Voltage restraint and voltage control are distinct implementations; a 51V label must be accompanied by the selected device's mode.
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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