Distance - GE L90 Instruction Manual

5.5 GROUPED ELEMENTS
a) MAIN MENU
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PATH: SETTINGS GROUPED ELEMENTS

# DISTANCE

#
5
Three common settings (
phase and ground distance protection are available. The
functions. 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 system
cycles. For this reason it is important to ensure that the nominal secondary voltage of the VT is entered correctly under the
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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 lead to incorrect operation of the distance functions.
The distance zones can be forced to become self-polarized through the
dition (FlexLogic™ operand) can be configured to force self-polarization. When the selected operand is asserted (logic 1),
the distance functions become self-polarized regardless of other memory voltage logic conditions. When the selected oper-
and is de-asserted (logic 0), the distance functions follow other conditions of the memory voltage logic as shown below.
The distance zones of the L90 is are identical to that of the UR-series D60 Line Distance Relay. For additional infor-
mation on the L90 distance functions, please refer to Chapter 8 of the D60 manual, available on the enerVista CD
or free of charge on the GE Multilin web page.
NOTE
5-80
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SETTING GROUP 1(6)
DISTANCE
SOURCE: SRC 1
MEMORY
MESSAGE
DURATION: 10 cycles
FORCE SELF-POLAR:
MESSAGE
Off
# PHASE DISTANCE Z1
MESSAGE
#
# PHASE DISTANCE Z2
MESSAGE
#
# PHASE DISTANCE Z3
MESSAGE
#
# GROUND DISTANCE Z1
MESSAGE
#
# GROUND DISTANCE Z2
MESSAGE
#
# GROUND DISTANCE Z3
MESSAGE
#
,
DISTANCE SOURCE MEMORY DURATION
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-
L90 Line Differential Relay
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DISTANCE
Range: SRC 1, SRC 2
Range: 5 to 25 cycles in steps of 1
Range: FlexLogic™ operand
See page 5–81.
See page 5–81.
See page 5–81.
See page 5–90.
See page 5–90.
See page 5–90.
, and
FORCE SELF-POLAR
identifies the Signal Source for all distance
DISTANCE SOURCE
menu.
FORCE SELF-POLAR
5 SETTINGS
5.5.5 DISTANCE
) and six menus for three zone of
MEMORY DURA-
setting. Any user-selected con-
GE Multilin