50
Instantaneous overcurrent
An overcurrent function without an intentional operating time delay in its instantaneous application.
Protection functions
Protection functions · 50P
Instantaneous phase overcurrent
Supervises phase-current magnitude for the instantaneous overcurrent element.
SLD / Schematic · 50P
What it represents
Supervises phase-current magnitude for the instantaneous overcurrent element.
The drafting record should connect this function to the individual phase CT inputs and protected feeder direction reference, then trace the phase overcurrent trip and any intentional timer stage. 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 EMR 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 individual phase CT inputs and protected feeder direction reference.
- Trace the phase overcurrent trip and any intentional timer stage.
Information to show or reference
- Label the individual phase CT inputs and protected feeder direction reference.
- Cross-reference the phase overcurrent trip and any intentional timer stage.
- Retain the complete suffix, selected device tag and manufacturer manual revision.
A distinction that matters
P identifies phase-current elements in the cited families; 50N and 50G concern separately defined neutral or ground-current inputs.
Sources you can follow
These public references support the explanation and provide further detail. Their graphics and downloadable files remain with their publishers.
EMR motor protection: public function comparison
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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