# Instantaneous phase overcurrent

Canonical URL: https://eloragrid.ai/protection-functions/50p-instantaneous-phase-overcurrent
Publisher: Elora Grid
Updated: 2026-10-13
Lookup label: 50P
Drawing use: SLD, Schematic
Reference families: IEEE / ANSI, Manufacturer

Supervises phase-current magnitude for the instantaneous overcurrent element.

## 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.

## Important distinction

P identifies phase-current elements in the cited families; 50N and 50G concern separately defined neutral or ground-current inputs.

## Facts

- Function designation: 50P
- Base function: 50 — Instantaneous overcurrent
- Published mapping: Eaton EMR family
- Suffix scope: Application or manufacturer specific; check the complete drawing legend and selected device manual.

## Public references

- [EMR motor protection: public function comparison](https://www.eaton.com/us/en-us/catalog/electrical-circuit-protection/motor-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.