It is calculated according to equation 172.
( / 3) /ZBase URated IRated=
GUID-90239033-D824-4479-A03A-41EE034C9021 V1 EN (Equation 172)
The ArgLd is a separate setting.
8.9.2.8 External block signals
The under impedance function will have to be blocked in the event of PT fuse fail. A
BLKZ input for this purpose is provided. Also a BLOCK input is provided.
8.9.3 Setting Guidelines
8.9.3.1 General
The settings for the underimpedance protection for generator (ZGVPDIS) are done in
percentage and base impedance is calculated from the UBase and IBase settings. The
base impedance is calculated according to equation 173.
IECEQUATION14000027 V1 EN (Equation 173)
ImpedanceAng: The common characteristic angle for all the three zone distance
elements
IMinOp: The minimum operating current in %IBase.
Zone 1
ZGVPDIS function has an offset mho characteristic and it can evaluate three phase-
to-phase impedance measuring loops.
OpModeZ1: Zone 1 distance element can be selected as Off or PP Loops.
Z1Fwd: Zone 1 forward reach in percentage. It is recommended to set zone 1 forward
reach to 75% of transformer impedance.
Z1Rev: Zone 1 reverse reach in percentage. It is recommended to set zone 1 reverse
reach same as Z1Fwd.
tZ1: Zone 1 operate time delay in seconds.
Zone 2
Zone 2 in ZGVPDIS function has offset mho characteristic and it can evaluate three
phase-to-phase impedance measuring loops or Enhanced reach loop.
Section 8 1MRK 502 071-UEN -
Impedance protection
314 Generator protection REG670 2.2 IEC and Injection equipment REX060, REX061, REX062
Application manual
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