Sl.No Measuring Loop Voltage Phasor Current Phasor
1
IA
1)
2
IB
1)
3
IC
1)
1) Only the loop with maximum current is allowed to operate
Trip time
The operate time delay for zone 2 can be provided using the setting
tZ2
.
Zone 2 is provided load encroachment detection feature based on positive sequence components
measurements.. This feature avoids the function from operating due to load encroachment. The
load encroachment feature for zone 2 can be set using
LoadEnchModZ2
to
Enabled
or
Disabled
.
7.15.7.3 Operation principle of zone 3
GUID-23971D73-2CDE-4757-82A7-14691C34CCCB v3
Zone 3 is used to cover up to the HV side of the transformer, interconnecting bus network and
outgoing lines. The time to trip should be provided in order to coordinate with the transmission
line protection.
The Zone3 functionality is same as zone2, hence the explanation of zone 2 applies for zone 3,
except the zone 3 has separate reach (
Z3Fw
,
Z3Rev
), operate timer (
tZ3
) and load encroachment
enable (
LoadEnchModZ3
) settings.
7.15.7.4 Load encroachment
GUID-DA94E18E-983C-44FA-B643-CAF016CB87F7 v3
The load encroachment characteristics can be set for zone2 and zone3. Load encroachment can be
enabled for zone 2 by setting
LoadEnchModZ2
to
Enabled
. Similarly the load encroachment for
zone 3 can be enabled by setting
LoadEnchModZ3
to
Enabled
.
The load encroachment characteristic is based on positive sequence quantities and can be set
using the settings
RLd
and
LdAngle
.
RLd
is the positive sequence resistive reach value in percentage.
LdAngle
is angle in degrees from
the origin to the resistive axis as shown in Figure
243.
Section 7 1MRK 502 066-UUS B
Impedance protection
444
Technical manual
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