51
Time overcurrent
An overcurrent function with a documented time characteristic.
Protection functions
Protection functions · 51R
Calculated residual time-overcurrent
Applies time-overcurrent protection to the calculated residual-current input in the cited Eaton family.
SLD / Schematic · 51R
What it represents
Applies time-overcurrent protection to the calculated residual-current input in the cited Eaton family.
The drafting record should connect this function to the phase CT inputs and calculated residual-current channel, then trace the residual time-current element and earth-fault trip. 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 phase CT inputs and calculated residual-current channel.
- Trace the residual time-current element and earth-fault trip.
Information to show or reference
- Label the phase CT inputs and calculated residual-current channel.
- Cross-reference the residual time-current element and earth-fault trip.
- Retain the complete suffix, selected device tag and manufacturer manual revision.
A distinction that matters
Eaton's 51R uses a calculated quantity; 51X uses a separately measured ground or neutral input.
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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