ABB RELION REX640 Technical Manual page 1240

Protection related functions
In the permissive underreach scheme, the start signal from the underreaching zone
Z1 is connected to the CSUR input to create a CS_PRM signal. The duration of the
CSUR input signal can be prolonged by the
sufficient duration of the CS_PRM signal.
In the permissive underreach scheme, the CS_PRM signal, or the CRL signal if the
unblocking function is enabled, is used to allow the overreaching zone Z2 to trip
(activation of the OPERATE output) after the pick-up delay
start signal from the overreaching zone Z2 is connected to the CACC input.
Activating the BLOCK input totally blocks the permissive underreach scheme. The
CS_PRM and OPERATE outputs can be blocked by the BLK_CS_OPR input.
Bus A
~
Z2_START
Figure 705: Simplified functional diagram of the permissive underreach scheme
Permissive overrreaching transfer trip scheme POTT
The permissive overreach scheme is enabled with
Overreach".
In this scheme, the start signal from the overreaching zone Z2 is connected to
the CSOR input to create a CS_PRM signal. The CS_PRM signal can also be issued
simultaneously from the underreaching zone Z1. In this case, the start signal from
the underreaching zone Z1 is connected to the CSUR input. The duration of the
CSUR input signal is prolonged by the
duration of the CS_PRM signal.
1240
Z1
3
CB_A
Z2
TRIP_CB_A
In case of parallel feeders, and when the external current reversal logic
(CRWPSCH) is enabled, the CS_PRM signal is not prolonged and the value
Carrier Min Dur is set to zero to secure correct operation.
of
Carrier Min Dur setting to ensure a
Z2
CB_B
Z1
Z2_START
Z1_START
Scheme type = "Permissive
Carrier Min Dur setting to ensure a sufficient
1MRS759142 F
Coordination Time . The
Bus B
~
3
TRIP_CB_B
REX640
Technical Manual