K
Reverse-current measuring relay
Measuring relay that operates when current flows in the opposite direction to normal, such as back-feed into a DC source.
Schematic / SLD
Symbols · →
Directional measuring element qualifier
Arrow qualifier on a measuring relay showing that it operates only for power or current in the marked direction.
In plain English
What does Directional measuring element qualifier mean?
A directional additional drawing mark is an arrow added to a measuring relay symbol, showing that the element responds only when the measured quantity flows in the indicated direction. On single-line diagrams the arrow usually points away from or towards the busbar, which tells the reader which faults the element is meant to see.
A simple example
The arrow depends on correct CT and VT polarity to mean anything in practice. The symbol does not show the characteristic angle or the polarising quantity, so the drawing direction must be confirmed against the relay settings and commissioning tests.
What the drawings help you do
Note whether the arrow points towards or away from the busbar. Check CT and VT polarity supports the shown direction. A directional additional drawing mark restricts operation to one direction; a non-directional element operates for either direction.
This particular reference
Arrow additional drawing mark on a measuring relay showing that it operates only for power or current in the marked direction. A directional additional drawing mark restricts operation to one direction; a non-directional element operates for either direction.
- Coil
- A wound conductor that can produce a magnetic field when energised.
- Schematic
- A drawing showing function and connections rather than physical appearance.
Read the source: IEC graphical symbols for diagrams · Autodesk IEC-60617 preview: Energy-flow qualifiers
Schematic / SLD · →
What it represents
A directional qualifier is an arrow added to a measuring relay symbol, showing that the element responds only when the measured quantity flows in the indicated direction. On single-line diagrams the arrow usually points away from or towards the busbar, which tells the reader which faults the element is meant to see.
The arrow depends on correct CT and VT polarity to mean anything in practice. The symbol does not show the characteristic angle or the polarising quantity, so the drawing direction must be confirmed against the relay settings and commissioning tests.
How to read it
- Note whether the arrow points towards or away from the busbar.
- Check CT and VT polarity supports the shown direction.
Information to show or reference
- Show arrow relative to the busbar
- State characteristic angle
- Reference polarity checks
A distinction that matters
A directional qualifier restricts operation to one direction; a non-directional element operates for either direction.
Sources you can follow
These public references support the explanation and provide further detail. Their graphics and downloadable files remain with their publishers.
IEC graphical symbols for diagrams
IEC context for graphical symbols used in diagrams; no IEC graphic is reproduced.
Autodesk IEC-60617 preview: Energy-flow qualifiers
Public IEC-context energy-flow qualifier family showing direction arrows.
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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