will be active see figure 150. Only one sector signal is allowed to be activated at the
same time.
The sector function for condition 1 has an internal release signal which is active if the
main sequence function has classified the angle between V
0
and I
0
as valid. The
following conditions must be fulfilled for activating the release signals:
|V
2
|>V2MinOp
|3I
0
|> 0.05 · IBase
|3I
0
|>maxIph · INRelPG
where:
V
2
and IN are the magnitude of the negative sequence voltage and zero-
sequence current (3I
0
)
V2MinOp
is the setting parameter for minimum operating negative sequence
voltage
maxIph is the maximum phase current
The angle difference is phase shifted by 180 degrees if the fault is in reverse direction.
The condition 2 looks at the angle relationship between the negative sequence voltage
V
2
and the positive sequence voltage V
1
. Since this is a phase-to-phase voltage
relationship, there is no need for shifting phases if the fault is in reverse direction. A
phase shift is introduced so that the fault sectors will have the same angle boarders as
for condition 1. If the calculated angle between V
2
and V
1
lies within one sector, the
corresponding phase for that sector will be activated. The condition 2 is released if
both the following conditions are fulfilled:
|V
2
|>V2MinOp
|V
1
|>V1MinOp
where:
|V
1
| and |V
2
| are the magnitude of the positive and negative sequence voltages.
V1MinOP
and
V2MinOP
are the setting parameters for positive sequence and negative sequence
minimum operating voltages.
Section 6 1MRK505222-UUS C
Impedance protection
296
Technical reference manual
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