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