ABB RELION REX640 Technical Manual page 1254

Protection related functions
Permissive underreaching transfer trip scheme PUTT
The permissive underreach scheme is enabled with
Underreach".
In the permissive underreach scheme, the start signal from the underreaching
(instantaneous) residual overcurrent function DEFHPDEF is connected to the CSUR
input to create a CS_PRM signal. The duration of the CSUR input signal can be
prolonged by the
CS_PRM signal.
In the permissive underreach scheme, the CR_PRM signal or CRL signal, if
the unblocking function is enabled, is used to allow the overreaching residual
overcurrent function DEFLPDEF to trip (activation of the OPERATE output) after the
pick-up delay
connected to the CACC input. A general start signal in the forward direction can also
be connected to the CACC input.
The CS_PRM signal is also generated if the CR_PRM signal is received and the local
carrier acceleration signal CACC is active.
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 712: 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 residual overcurrent
function DEFLPDEF is connected to the CSOR input to create a CS_PRM signal.
The CS_PRM signal can also be issued simultaneously from the underreaching
residual overcurrent function DEFHPDEF. In this case, the start signal from the
1254
Carrier Min Dur setting to ensure a sufficient duration of the
Coordination time . The start signal from the overreaching function is
3
CB_A
TRIP_CB_A
Scheme type = "Permissive
CB_B
DEFL_START
DEFH_START
Scheme type = "Permissive
1MRS759142 F
Bus B
~
3
TRIP_CB_B
REX640
Technical Manual