ABB RELION REX640 - Page 1240

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 Carrier Min Dur setting to ensure a
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
Coordination Time . The
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.
Z2
Z2
Bus A
Bus B
~
~
Z1
Z1
CB_A
CB_B
Z2_START
TRIP_CB_A
TRIP_CB_B
Z1_START
Z2_START
3
3
Figure 705: Simplified functional diagram of the permissive underreach scheme
Permissive overrreaching transfer trip scheme POTT
The permissive overreach scheme is enabled with Scheme type = "Permissive
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 Carrier Min Dur setting to ensure a sufficient
duration of the CS_PRM signal.
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
of Carrier Min Dur is set to zero to secure correct operation.
Protection related functions 1MRS759142 F
1240 REX640
Technical Manual