Protective Elements
Identification of the Faulty Phase
The purpose of the fault type classification in the distance protection function is to provide information about the
involved phases in order to select the appropriate impedance loop. The fault type classification uses the
symmetrical component for the fault type classification in the following way and sequence:
• If the positive sequence current is lower than 0.01⋅In, we decide for a non-fault situation.
• If the negative-sequence current is lower than 30% of the positive-sequence current, we decide for the
symmetrical fault L1–L2–L3 and select loop L1–L2.
• Otherwise, the phase shift between positive and negative-sequence currents is used as shown in the
following table.
Positive and negative phase sequence current phasors for different fault types.
816 MCDGV4 DOK-HB-MCDGV4-2E
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