setting, a new fuse failure detection for that phase is not possible until the voltage
returns above the setting value.
Decision logic
The fuse failure detection outputs FUSEF_U and FUSEF_3PH are controlled
according to the detection criteria or external signals.
Table 510: 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.
Current and voltage delta function criterion If the current and voltage delta criterion detects a
fuse failure condition, but all the voltages are not
below the
Seal in voltage
setting, only 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.
External fuse failure detection The MINCB_OPEN input signal is supposed to be
connected through an IED binary input to the
N.C. auxiliary contact of the miniature circuit
breaker protecting the VT secondary circuit.The
MINCB_OPEN signal sets the FUSEF_U output
signal to block all the voltage-related functions
when MCB is in the open state.
The DISCON_OPEN input signal is supposed to
be connected through an IED binary input to the
N.C. auxiliary contact of the line disconnector. The
DISCON_OPEN signal sets the FUSEF_U output
signal to block the voltage-related functions
when the line disconnector is in the open state.
It is recommended to always set Enable seal in to "True". This
secures that the blocked protection functions remain blocked until
normal voltage conditions are restored if the fuse failure has been
Section 6 1YHT530004D05 D
Supervision functions
596 615 series
Technical Manual
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