ABB RELION 611 Series Technical Manual page 197

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1MRS757454 D

Technical Manual

Iocos(φ) criterion selected, reverse-type fault

=> FAULT_DIR = 2

GUID-54ACB854-F11D-4AF2-8BDB-69E5F6C13EF1 V2 EN

Operating characteristic Iocos(φ) in reverse fault

Phase angle 80

The operation criterion phase angle 80 is selected with the Operation mode setting by

using the value "Phase angle 80".

Phase angle 80 implements the same functionality as the phase angle but with the

following differences:

The Max forward angle and Max reverse angle settings cannot be set but they

have a fixed value of 80 degrees

The sector limits of the fixed sectors are rounded.

The sector rounding is used for cancelling the CT measurement errors at low current

amplitudes. When the current amplitude falls below three percent of the nominal

current, the sector is reduced to 70 degrees at the fixed sector side. This makes the

protection more selective, which means that the phase angle measurement errors do

not cause faulty operation.

There is no sector rounding on the other side of the sector.

Protection functions