Instruction manual
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AQ F3x0 Feeder protection IED
86 (162
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Table 3-37 Output signals of the characteristics logic.
Output values
Zones
Explanation
ZL1_n
1
…
5
The impedance in the fault loop L1N is inside the characteristics
ZL2_n
1
…
5
The impedance in the fault loop L2N is inside the characteristics
ZL3_n
1
…
5
The impedance in the fault loop L3N is inside the characteristics
ZL1L2_n
1
…
5
The impedance in the fault loop L1L2 is inside the characteristics
ZL2L3_n
1
…
5
The impedance in the fault loop L2L3 is inside the characteristics
ZL3L1_n
1
…
5
The impedance in the fault loop L3L1 is inside the characteristics
Current conditions of the distance protection function
The distance protection function can operate only if the current is sufficient for impedance
calculation. Additionally, a phase-to-ground fault is detected only if there is sufficient zero
sequence current. This function performs these preliminary decisions.
The current is considered to be sufficient for impedance calculation if it is above the level
set by parameter DIS21_Imin_IPar_ (IPh Base Sens).
To decide the presence or absence of the zero sequence current, biased characteristics
are applied. The minimal setting current DIS21_IoBase_IPar_ (Io Base sens.) and a
percentage biasing DIS21_IoBias_IPar_ (Io bias) must be set. The biasing is applied for the
detection of zero sequence current in the case of increased phase currents.
Figure 3-47: Percentage characteristic for earth-fault detection.