ABB 615 series Technical Manual page 875

1MAC059074-MB A
615 series ANSI
Technical Manual
line from the other end onto a fault could lead to an improper operation of 60 with an open
breaker. If this is considered to be an important disadvantage, the CB_CLOSED input is to
be connected to FALSE. In this way only the second criterion can activate the delta
function.
The second condition requires the delta criterion to be fulfilled in one phase together with
a high current for the same phase. The measured phase current is used to reduce the risk
of a false fuse failure detection. If the current on the protected line is low, a voltage drop
in the system (not caused by the fuse failure) is not followed by a current 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_V and FUSEF_3PH are controlled according
to the detection criteria or external signals.
Table 768: Fuse failure output control
Fuse failure detection criterion
Negative-sequence criterion
Table continues on next page
Supervision functions
Conditions and function response
If a fuse failure is detected based on the negative
sequence criterion, the FUSEF_V 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
Enable seal in turned to "True", the
setting with
function activates the FUSE_3PH output signal.
The FUSEF_V output signal is also activated if all the
phase voltages are above the
for more than 60 seconds and at the same time the
negative sequence voltage is above
voltage Lev for more than 5 seconds, all the phase
Current dead Lin Val setting
currents are below the
and the circuit breaker is closed, that is CB_CLOSED
is TRUE.
Section 6
Seal in voltage
Seal in voltage setting
Neg Seq
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