GE T60 User Manual

GE Multilin T60 Transformer Protection System 5-181
5 SETTINGS 5.6 GROUPED ELEMENTS
5
5.6.3 DISTANCE
a) COMMON DISTANCE SETTINGS
PATH: SETTINGS  GROUPED ELEMENTS  SETTING GROUP 1(6)  DISTANCE
Four common settings are available for distance protection. The DISTANCE SOURCE identifies the signal source for all dis-
tance functions. The mho distance functions use a dynamic characteristic: the positive-sequence voltage – either memo-
rized 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 setting specifies the length of time a memorized positive-sequence voltage should be used in the
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  AC INPUTS  VOLTAGE BANK menu.
Set
MEMORY DURATION long enough to ensure stability on close-in reverse three-phase faults. For this purpose, the maxi-
mum fault clearing time (breaker fail time) in the substation should be considered. On the other hand, the
MEMORY DURA-
TION
cannot be too long as the power system may experience power swing conditions rotating the voltage and current
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.
 DISTANCE

DISTANCE
SOURCE: SRC 1
Range: SRC 1, SRC 2, SRC 3, SRC 4, SRC 5, SRC 6
MESSAGE
MEMORY
DURATION: 10 cycles
Range: 5 to 25 cycles in steps of 1
MESSAGE
FORCE SELF-POLAR:
Off
Range: FlexLogic operand
MESSAGE
FORCE MEM-POLAR:
Off
Range: FlexLogic operand
MESSAGE
 PHASE DISTANCE Z1

See page 5–182.
MESSAGE
 PHASE DISTANCE Z2

See page 5–182.
MESSAGE
 PHASE DISTANCE Z3

See page 5–182.
MESSAGE
 PHASE DISTANCE Z4

See page 5–182.
MESSAGE
 PHASE DISTANCE Z5

See page 5–182.
MESSAGE
 GROUND DISTANCE Z1

See page 5–192.
MESSAGE
 GROUND DISTANCE Z2

See page 5–192.
MESSAGE
 GROUND DISTANCE Z3

See page 5–192.
MESSAGE
 GROUND DISTANCE Z4

See page 5–192.
MESSAGE
 GROUND DISTANCE Z5

See page 5–192.

GE T60 Specifications

General

Brand	GE
Model	T60
Category	Relays
Language	English