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.
Figure 267: Operating characteristic for phase angle 80
Protection functions
1MRS759142 F
470 REX640
Technical Manual
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