Distance - GE UR Series Instruction Manual

5.5 GROUPED ELEMENTS
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PATH: SETTINGS GROUPED ELEMENTS
„

DISTANCE

„
Two common settings (
tance protection are available. The
The MHO distance functions use a dynamic characteristic: the positive-sequence voltage – either memorized or actual – is
used as a polarizing signal. The memory voltage is also used by the built-in directional supervising functions applied for
both the MHO and QUAD characteristics.
The
MEMORY DURATION
distance calculations. After this interval expires, the relay checks the magnitude of the actual positive-sequence voltage. If
it is higher than 10% of the nominal, the actual voltage is used, if lower – the memory voltage continues to be used.
The memory is established when the positive-sequence voltage stays above 80% of its nominal value for five power sys-
tem cycles. For this reason it is important to ensure that the nominal secondary voltage of the VT is entered correctly under
5
Ø
the
SETTINGS SYSTEM SETUP
Set
MEMORY DURATION
mum fault clearing time (breaker fail time) in the substation should be considered. On the other hand, the
cannot be too long as the power system may experience power swing conditions rotating the voltage and current
TION
phasors slowly while the memory voltage is static, as frozen at the beginning of the fault. Keeping the memory in effect for
too long may eventually cause maloperation of the distance functions.
SETTING
DISTANCE SOURCE:
V_1
IA
IB
IC
5-60
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SETTING GROUP 1(8)
DISTANCE
SOURCE: SRC 1
MEMORY
MESSAGE
DURATION: 10 cycles
„
PHASE DISTANCE Z2
„
MESSAGE
„
GROUND DISTANCE Z2
„
MESSAGE
and
DISTANCE SOURCE MEMORY DURATION
DISTANCE SOURCE
setting specifies the length of time a memorized positive-sequence voltage should be used in the
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AC INPUTS VOLTAGE BANK
long enough to ensure stability on close-in reverse three-phase faults. For this purpose, the maxi-
UPDATE MEMORY
RUN
5 cy
V_1 > 0.8 pu
IA < 0.05 pu
IB < 0.05 pu
IC < 0.05 pu
V_1 < 0.1 pu
Figure 5–21: MEMORY VOLTAGE LOGIC
L90 Line Differential Relay
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DISTANCE
Range: SRC 1, SRC 2,..., SRC 6
Range: 5 to 25 cycles
) and two menus for one zone of phase and ground dis-
identifies the Signal Source for all distance functions.
menu.
SETTING
MEMORY DURATION:
0
t
RST
S Q
0
R
AND
5 SETTINGS
5.5.7 DISTANCE
MEMORY DURA-
AND
Use V_1 mem
OR
Use V_1
AND
827842A2.CDR
GE Power Management