ABB RELION 620 Series Technical Manual page 612

Section 6
Supervision functions
606
Table 437: Fuse failure output control
Fuse failure detection criterion
Negative-sequence criterion
Current and voltage delta function criterion
External fuse failure detection
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 active for 5 seconds,
that is, the fuse failure outputs are deactivated when the normal voltage
conditions are restored.
The activation of the BLOCK input deactivates both FUSEF_V and FUSEF_3PH outputs.
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
setting with Enable seal in turned to "True", the
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
currents are below the Current dead Lin Val setting
and the circuit breaker is closed, that is CB_CLOSED
is TRUE.
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_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
setting with Enable seal in turned to "True", the
function activates the FUSE_3PH output signal.
The MINCB_OPEN input signal is supposed to be
connected through a protection relay 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_V 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 a protection relay binary input to
the N.C. auxiliary contact of the line disconnector.
The DISCON_OPEN signal sets the FUSEF_V output
signal to block the voltage-related functions when the
line disconnector is in the open state.
1MAC504801-IB E
Seal in voltage
Seal in voltage setting
Neg Seq
Seal in voltage
620 series ANSI
Technical Manual