50
Instantaneous overcurrent
An overcurrent function without an intentional operating time delay in its instantaneous application.
Protection functions
Protection functions · 50BF
Circuit-breaker failure protection
Initiates the documented backup action when a breaker does not clear the monitored condition after a trip initiation.
SLD / Schematic · 50BF
What it represents
Initiates the documented backup action when a breaker does not clear the monitored condition after a trip initiation.
The drafting record should connect this function to the initiating trips, breaker current/status and failure timer, then trace the retrip and upstream or adjacent breaker trip matrix. 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 initiating trips, breaker current/status and failure timer.
- Trace the retrip and upstream or adjacent breaker trip matrix.
Information to show or reference
- Label the initiating trips, breaker current/status and failure timer.
- Cross-reference the retrip and upstream or adjacent breaker trip matrix.
- Retain the complete suffix, selected device tag and manufacturer manual revision.
A distinction that matters
Breaker failure is a sequence involving initiation and clearance supervision; it is not ordinary instantaneous feeder overcurrent.
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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