Instruction manual
–
AQ G3x7 Generator protection IED
167 (211
)
Table 3-75Setting parameters of the dead line detection function
Parameter
Setting value, range
and step
Description
Operation
On
Off
Operating mode selection for the function. Operation can be
either disabled
“
Off
”
or enabled
“
On
”
. Default setting is
enabled.
Min. operate
voltage
10
…
100 % by step of
1 %
Minimum voltage threshold for detecting the live line status.
All measured phase to ground voltages have to be under this
setting level. Default setting is 60 %.
Min. operate
current
8
…
100 % by step of
1 %
Minimum current threshold for detecting the dead line status.
If all the phase to ground voltages are under the setting
“
Min.
operate voltage
”
and also all the phase currents are under
the
“
Min. operate current
”
setting the line status is considered
“
Dead
”
. Default setting is 10 %.
3.3.4
V
OLTAGE TRANSFORMER SUPERVISION
(VTS)
The voltage transformer supervision function generates a signal to indicate an error in the
voltage transformer secondary circuit. This signal can serve, for example, a warning,
indicating disturbances in the measurement, or it can disable the operation of the distance
protection function if appropriate measured voltage signals are not available for a distance
decision.
The voltage transformer supervision function is designed to detect faulty asymmetrical
states of the voltage transformer circuit caused, for example, by a broken conductor in the
secondary circuit. The voltage transformer supervision function can be used for either
tripping or alarming purposes.
The voltage transformer supervision function can be used in three different modes of
application:
Zero sequence detection (for typical applications in systems with grounded neutral):
“
VT
failure
”
signal is generated if the residual voltage (3Uo) is above the preset voltage value
AND the residual current (3Io) is below the preset current value
Negative sequence detection (for typical applications in systems with isolated or resonant
grounded (Petersen) neutral):
“
VT failure
”
signal is generated if the negative sequence
voltage component (U2) is above the preset voltage value AND the negative sequence
current component (I2) is below the preset current value.