ABB RELION REX640 Technical Manual page 1335

1MRS759142 F
Fuse failure detection criterion
Current and voltage delta function criterion
External fuse failure detection
The activation of the BLOCK input deactivates both FUSEF_U and FUSEF_3PH
outputs.
6.5.6 Application
Some protection functions operate on the basis of the measured voltage value
in the protection relay point. These functions can fail if there is a fault in the
measuring circuits between the voltage transformer (or combi sensor or voltage
sensor) and protection relay.
REX640
Technical Manual
It is recommended to always set
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.
Supervision functions
Conditions and function response
The output signal is also activated
FUSEF_U
if all the phase voltages are above the
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
Current dead Lin Val setting
are below the
and the circuit breaker is closed, that is,
is TRUE.
CB_CLOSED
If the current and voltage delta criterion de-
tects a fuse failure condition, but all the vol-
tages are not below the
ting, only the
FUSEF_U
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
Seal in voltage setting with Ena-
value of the
ble seal in turned to "True", the function acti-
vates the output signal.
FUSE_3PH
The input signal is supposed
MINCB_OPEN
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
nal sets the output signal to block
FUSEF_U
all the voltage-related functions when MCB is
in the open state.
The input signal is supposed
DISCON_OPEN
to be connected through a protection relay
binary input to the N.C. auxiliary contact of
the line disconnector. The
signal sets the
FUSEF_U
block the voltage-related functions when the
line disconnector is in the open state.
Enable seal in to "True". This secures
Seal
Seal in voltage set-
output is activated.
sig-
MINCB_OPEN
DISCON_OPEN
output signal to
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