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

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55D

Protection functions

Displacement power-factor supervision

Supervises displacement power factor as defined by the relay's fundamental-frequency measurements.

55D is not interchangeable with the apparent power-factor element 55A when the waveform contains harmonics.

Protection functions

Supervises power factor according to the selected relay's electrical measurement method.

Power factor is a ratio or angular relationship; reactive-power protection 32V uses a power quantity.

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