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

87B

Protection functions

Busbar differential protection

Compares currents at the boundaries of a busbar protection zone.

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

A distinction that matters

87B commonly identifies bus differential, but ABB also uses 87B for a phase-B high-impedance element; the application legend resolves the meaning.

Full reference

Protection functions

Differential protection

Differential protection compares quantities associated with the boundaries of a protection zone according to the selected implementation. Equipment and application suffixes can distinguish transformer, busbar, line or other arrangements. The base number alone does not define the zone or measurements.

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

A distinction that matters

Transformer differential, busbar differential and other differential applications are not interchangeable merely because they share the base number 87.

Full reference

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