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10-8
SIG-00-22-02 JUNE 2022 (Revised September 2022)
Version: B.1
10.1.2.2.4
Traffic System Health IP Used
If the Traffic Sys. Health IP Used is set to
Yes
, then the Traffic Sys Health is available in the list
of
System Inputs.
This can be assigned to a vital input. When the Traffic Sys Health is de-
energized, it will switch the system from advance preemption to simultaneous preemption. Thus,
when the PSO circuit becomes occupied, the advance preempt OP will drop immediately
(assuming no PSO drop delay).
10.1.2.2.5
Gate Down Logic
When Gate Down Logic is used the user can select which of the gate down contact (GDs) are to
be used in the gate logic. The number of GDs shown will depend on how many are configured
in the SSCC-1 and SSCC-2 with the Number of GDs parameter. The Gate Down OP will be
made available in the
System Outputs
so it can be assigned to a vital output.
The Gate Down Output will be energized when:
a) The Adv Preempt OP is de-energized and
b) (All selected gates have their GDs energized or
c) Any internal island used in AND 1 XR reports occupied and is healthy)
WARNING
INCORRECT DESIGN AND/OR CONFIGURATION OF GATE DOWN
MAY RESULT IN INCORRECT TERMINATION OF CLEAROUT CYCLE
IN TRAFFIC CONTROLLER
NOTE
The external island that is brought in via a vital input is not included in
this logic, as their health cannot be proved.
10.1.2.2.6
Simultaneous Preemption
When simultaneous preemption is used in the GCE, when the PSO becomes occupied, it will
drop the Simult Preempt OP and drop AND 1 XR and thus activate the crossing (assuming
SSCC-1 and 2 are controlled by AND 1 XR) at the same time. The simultaneous preemption will
only affect PSO modules that are:
•
set to PSO Module Mode = Crossing and (see PSO Transmitter section)
•
Included in AND 1 XR, e.g., AND 1 XR PSO 1 Used = Yes (see Logic: PSO ANDing
section)
NOTE
If the PSO receiver is configured with a drop delay, when the PSO
becomes occupied it will first run the drop delay, then once the drop
delay has expired, the Simult Preempt OP will drop.
When simultaneous preemption is used, the Sim Preempt OP is available in the list of
System
Outputs.
The preempt health input can be used with Simultaneous Preemption in the same manner as
with Advance preemption.