# Motor jam or stall protection

Canonical URL: https://eloragrid.ai/protection-functions/50j-motor-jam-or-stall-protection
Publisher: Elora Grid
Updated: 2026-10-13
Lookup label: 50J
Drawing use: SLD, Schematic
Reference families: IEEE / ANSI, Manufacturer

Supervises a motor current condition associated with a jam or stall in the cited relay application.

## What it represents

Supervises a motor current condition associated with a jam or stall in the cited relay application.
The drafting record should connect this function to the motor CT inputs and running/starting-state logic, then trace the jam or stall trip and reset/restart interface. 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 motor CT inputs and running/starting-state logic.
- Trace the jam or stall trip and reset/restart interface.

## Information to show or reference

- Label the motor CT inputs and running/starting-state logic.
- Cross-reference the jam or stall trip and reset/restart interface.
- Retain the complete suffix, selected device tag and manufacturer manual revision.

## Important distinction

A jam/stall element requires its application context; starting locked-rotor and running jam protection can use different supervision.

## Facts

- Function designation: 50J
- 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.