GE T60 Instruction Manual page 327

5 SETTINGS
a) COMMON DISTANCE SETTINGS
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PATH: SETTINGS GROUPED ELEMENTS
 DISTANCE

MESSAGE
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The identifies the signal source for all distance functions. The mho distance functions use a dynamic
DISTANCE SOURCE
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 setting specifies the length of time a memorized positive-sequence voltage should be used in 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

SETTINGS SYSTEM SETUP
Set long enough to ensure stability on close-in reverse three-phase faults. For this purpose, the maxi-
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.
GE Multilin

SETTING GROUP 1(6)
DISTANCE
SOURCE: SRC 1
MEMORY
DURATION: 10 cycles
FORCE SELF-POLAR:
Off
FORCE MEM-POLAR:
Off
 PHASE DISTANCE Z1

 PHASE DISTANCE Z2
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 PHASE DISTANCE Z3

 PHASE DISTANCE Z4

 PHASE DISTANCE Z5

 GROUND DISTANCE Z1

 GROUND DISTANCE Z2
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 GROUND DISTANCE Z3
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 GROUND DISTANCE Z4
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 GROUND DISTANCE Z5
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 
AC INPUTS VOLTAGE BANK
T60 Transformer Protection System

DISTANCE
Range: SRC 1, SRC 2, SRC 3, SRC 4, SRC 5, SRC 6
Range: 5 to 25 cycles in steps of 1
Range: FlexLogic operand
Range: FlexLogic operand
See page 5–182.
See page 5–182.
See page 5–182.
See page 5–182.
See page 5–182.
See page 5–192.
See page 5–192.
See page 5–192.
See page 5–192.
See page 5–192.
menu.
5.6 GROUPED ELEMENTS
5.6.3 DISTANCE
MEMORY DURA-
5-181
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