Instruction manual
–
AQ G3x7 Generator protection IED
168 (211
)
Special application:
“
VT failure
”
signal is generated if the residual voltage (3Uo) is above
the preset voltage value AND the residual current (3Io) AND the negative sequence current
component (I2) are below the preset current values.
The voltage transformer supervision function can be triggered if
“
Live line
”
status is detected
for at least 200 ms. The purpose of this delay is to avoid mal-operation at line energizing if
the poles of the circuit breaker make contact with a time delay. The function is set to be
inactive if
“
Dead line
”
status is detected. If the conditions specified by the selected mode of
operation are fulfilled then the voltage transformer supervision function is triggered and the
operation signal is generated. When the conditions for operation are no longer fulfilled, the
resetting of the function depends on the mode of operation of the primary circuit:
•
If the
“
Live line
”
state is valid, then the function resets after approx. 200 ms of time
delay.
•
If the
“
Dead line
”
state is started and the
“
VTS Failure
”
signal has been continuous
for at least 100 ms, then the
“
VTS failure
”
signal does not reset; it is generated
continuously even when the line is in a disconnected state. Thus, the
“
VTS Failure
”
signal remains active at reclosing.
•
If the
“
Dead line
”
state is started and the
“
VTS Failure
”
signal has not been continuous
for at least 100 ms, then the
“
VTS failure
”
signal resets.