ABB RER620 Technical Manual

1MAC309294-MB F Section 6
Condition monitoring functions
RER620 379
Technical Manual
Table 331: Fuse failure output control
The activation of the BLOCK input deactivates both FUSEF_U and FUSEF_3PH outputs.
6.2.5 Application
Some protection functions operate on the basis of the measured voltage value in the relay
point. These functions can fail if there is a fault in the measuring circuits between the
voltage transformers and the relay.
A fault in the voltage measuring circuit is referred to as a fuse failure. This term is
misleading since a blown fuse is just one of the many possible reasons for a broken circuit.
Fuse-failure detection criterion Conditions and function response
Negative phase sequence criterion If a fuse failure is detected based on the negative
phase-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 “ Yes ” ,
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 “ Yes ” ,
the function activates the FUSE_3PH output signal.
External fuse-failure detection The MINCB_OPEN input signal is supposed to be
connected through a 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_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 a relay 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 “Yes”. 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.

ABB RER620 Specifications

General

Brand	ABB
Model	RER620
Category	Controller
Language	English