Side-by-side reference

Understand the difference.

Compare the meaning, drawing context and source references of two entries. A similar graphic or shared abbreviation does not establish equivalence.

First referenceCompare with

→

Symbols

Directional measuring element qualifier

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.

Drawing use: Schematic / SLD
Application: Metering & protection
Reference family: IEC

A distinction that matters

A directional qualifier restricts operation to one direction; a non-directional element operates for either direction.

Full reference

Symbols

Reverse-current measuring relay

A reverse-current relay compares the direction of current with a reference and operates when current flows the wrong way. Classic uses are DC generators and battery chargers in parallel, where a failed source would otherwise draw current from the bus, and rectifier feeders where back-feed indicates a fault.

Drawing use: Schematic / SLD
Application: Metering & protection
Reference family: IEC / Manufacturer

A distinction that matters

A reverse-current relay responds to current direction; a maximum-current relay responds to magnitude regardless of direction.

Full reference

Original educational previews. Follow the source references on each full entry for the appropriate standard or selected product.