ABB Relion 670 series - Page 448

i1Mag
i2Mag
i3Mag
a==b
a
b
a==b
a
b
a==b
a
b
MAX
NOT
AND
OR NOT
AND
A
B
C
pickupPh1
pickupPh2
pickupPh3
AND
AND
AND
OR
pickup
ANSI11000307_1_en.vsd
ANSI11000307 V1 EN-US
Figure 240: Logic diagram for the selection of the maximum current loop
The phase-to-ground voltage is compensated with zero sequence voltage in order to avoid the
function operating for ground faults in zone 1, that is, complete generator stator winding and LV
winding of the power transformer.
The reach settings for zone 2 can be provided using the
Z2Fwd , Z2Rev and ImpedanceAng
settings. The Z2Fwd is forward reach setting and Z2Rev is reverse reach setting. The offset mho
characteristic for phase-to-ground loop is shown in Figure 241. The offset mho characteristics for
phase-to-phase loop is shown in Figure
242.
ß
2I A Z FW×
1 0 2Vcomp V AG V I A Z FW= - - ×
2 0 2Vcomp V AG V I A Z REV= - + ×
2I A Z REV- ×
I A jX×
I A jX×
ANSI11000299_1_en.vsd
ANSI11000299 V1 EN-US
Figure 241: Simplified offset mho characteristics for A-to-G fault in zone 2
Section 7 1MRK 502 066-UUS B
Impedance protection
442
Technical manual