Comparator
ZAB
<
Comparator
ZBC
<
Comparator
ZCA
<
Timer Logic
tOpDelayZ1
opModetZ1
tripZone1
BLOCK
BLKZ
EnableZone1
EnableZone1
EnableZone1
V3P
I3P
pickupZone1
Z1Fw
Z1Rev
Z1Fw
Z1Rev
Z1Fw
Z1Rev
ANSI11000297_1.en.vsd
OR
ANSI11000297 V1 EN-US
Figure 237: Block diagram of zone 1
The functionality included in zone 1:
• Comparator to detect, if the operating impedance has entered inside zone 1 offset mho
characteristic.
• All three phase-to-phase loops are implemented separately.
• Forward and reverse reach values are provided in percentage of impedance base value at
generator.
• Trip time delay is provided.
Comparator characteristics
The comparator consists of offset mho characteristics. Three individual comparators are provided
in the three phase-to-phase loops. The offset mho characteristic is as shown in figure
238.
1MRK 502 066-UUS B Section 7
Impedance protection
439
Technical manual
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