1MRS751802-MUM
REX 521
209
Protection Relay
Technical Reference Manual, Standard Configurations
Fig. 11.2.5.1.-1 Overcurrent blocking diagram
11.2.5.2. Blocking signal from 3I>-> stage to 3I>> stage
In addition to the blocking described in Section 10.2.5.1. Start signal from the
second residual voltage stage to release blocking the blocking signal from the
directional overcurrent stage 3I>-> can be used for blocking the 3I>> stage of the
same relay. With this arrangement we can set the operating time of the 3I>> shorter.
External wiring is needed for this blocking. The start signal of the 3I>-> is routed to
the signal output SO1. The output is connected to the input DI9 which is routing
blocking signal to the BS1 input of the overcurrent stage 3I>> as described in
Section 10.2.5.1. Start signal from the second residual voltage stage to release
blocking.
11.2.5.3. Circuit-breaker failure protection
All of the current-based protection functions in the standard configuration H02
provide a delayed trip signal CBFP after the trip signal unless the fault has not
disappeared during the set CBFP time delay. In the circuit-breaker failure protection,
the CBFP output can be used for operating an upstream circuit breaker.
The settings for breaker failure are set separately for each protection function. For
example, to set the CBFP time for 3I>>-> go to
Main menu\Protection\3I>>->\Control setting where it is possible
to set the CBFP time from 100 ms to 1000 ms. The control parameter Trip
pulse sets the width of the trip output signal, but also of the CBFP output signal.
3I>
3I>
3I>>
Trip 1
3I>
3I>>
3I>>>
REX 521
REX 521
BS
BS
START 3 I>->
START 3I>
TRIP
3I>
3I>>
3I>>>
REX 521
START 3I>>
TRIP
Incoming feeder
(H02)
3I>
3I>>
3I>>>
REX 521
3I>
3I>>
3I>>>
REX 521
REX 521
BS
BS
TRIP
3I>
3I>>
3I>>>
REX 521
START 3I>>
TRIP
TRIP
START 3I>>
BS
Trip 2
Trip 2
3I>
3I>
3I>>
Trip 1
START 3 I>->
START 3I>
Bus sectionalizer (H03)
Outgoing feeder (H04)
Outgoing feeder (H04)
Blocking_High
Incoming feeder
(H02)
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