59
Overvoltage
A function responding to voltage above its configured operating criteria.
Protection functions
Protection functions · 59Q
Negative-sequence overvoltage
Supervises the negative-sequence component derived from three-phase voltage measurements.
SLD / Schematic · 59Q
What it represents
Supervises the negative-sequence component derived from three-phase voltage measurements.
The drafting record should connect this function to the three phase voltage inputs and sequence calculation reference, then trace the voltage-unbalance-sensitive element and selected output. 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 (SEL public device-number table). 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 three phase voltage inputs and sequence calculation reference.
- Trace the voltage-unbalance-sensitive element and selected output.
Information to show or reference
- Label the three phase voltage inputs and sequence calculation reference.
- Cross-reference the voltage-unbalance-sensitive element and selected output.
- Retain the complete suffix, selected device tag and manufacturer manual revision.
A distinction that matters
Negative-sequence overvoltage indicates an unbalanced voltage component; it differs from a high positive-sequence or phase-voltage threshold.
Sources you can follow
These public references support the explanation and provide further detail. Their graphics and downloadable files remain with their publishers.
ANSI device-number and suffix reference table
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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