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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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21P

Protection functions

Phase distance protection

Evaluates an impedance characteristic for phase-fault loops on the protected circuit.

A phase distance element uses phase-fault loops; ground distance 21G includes the earth-return circuit treatment.

Protection functions

Uses measured voltage and current to assess an electrical distance or impedance characteristic.

Distance protection uses impedance-related criteria; directional overcurrent 67 uses current and directional supervision.

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