ABB RELION Series, Technical Manual

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change and a false fuse failure can occur. To prevent this, the minimum phase current
criterion is checked.
The fuse failure detection is active until the voltages return above the Min Op voltage
delta setting. If a voltage in a phase is below the Min Op voltage delta setting, a new
fuse failure detection for that phase is not possible until the voltage returns above the
setting value.
Decision logic
If voltages are Wye-connected, it is recommended to scale the default
values of voltage-based settings with 1/sqrt(3) because the default
setting values apply for Delta-connected settings.
The fuse failure detection outputs
FUSEF_U
and
FUSEF_3PH
are controlled
according to the detection criteria or external signals.
Table 536: Fuse failure output control
Fuse failure detection criterion Conditions and function response
Negative-sequence criterion If a fuse failure is detected based on the negative
sequence criterion, the
FUSEF_U
output is
activated.
If the fuse failure detection is active for more than
five seconds and at the same time all the phase
voltage values are below the set value of the
Seal
in voltage setting with Enable seal in turned to
"True", the function activates the
FUSE_3PH
output signal.
The
FUSEF_U
output signal is also activated if all
the phase voltages are above the
Seal in voltage
setting for more than 60 seconds and at the same
time the negative sequence voltage is above
Neg
Seq voltage Lev for more than 5 seconds, all the
phase currents are below the
Current dead Lin Val
setting and the circuit breaker is closed, that
is,
CB_CLOSED
is TRUE.
Table continues on next page
Section 6
1MRS758755 A
Supervision functions
522 REC615 and RER615
Technical Manual