889-3819-00
MMU2-1600GE series Operations Manual Rev Apr 2020 Page
12
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the Yellow was skipped. When a Yellow turns on for at least 100 milliseconds another 2.7 second timer is started
and must reach zero before the yellow turns off or a short Yellow fault will be generated. The normal voltage
thresholds for this test are: Reds – ON when above 70V
RMS
and OFF when below 50V
RMS
, Greens, Walks, and
Yellows – ON when above 25V
RMS
and OFF when below 15V
RMS
.
Fault Action:
The monitor transfers the Output relay contacts to the fault condition (continuity between the
Normally Open and Common contacts), illuminates the
SHORT YEL
indicator on the front panel, and sets the
Minimum Clearance Failure bit (bit 74) of the Type 129 Frame to 1. The Signal Sequence log and the Prior Faults
log will record this fault.
Resetting the Fault:
The monitor remains in this fault condition until the unit is reset by the activation of the front
panel reset pushbutton or the activation of the reset input. Power loss or power interruption will not reset this fault.
The Reset log will record the resetting of this fault.
Modifying Inputs:
Red Enable
: All short Yellow testing will be disabled when this input is below 70V
RMS
.
Load Switch Flash bit (bit 112) of the Type 0 Frame
: All short Yellow testing will be disabled when this bit is
set to one.
Feature Interactions:
LED Thresholds
: When LED Thresholds is enabled the monitor senses Greens, Yellows, Reds, and Walks as
ON when their voltage is above 70V
RMS
and OFF when below 50V
RMS
for the short Yellow test.
Flashing Yellow Arrow Left Turns:
Following a Green or Flashing Yellow Arrow indication on a FYA
channel the Yellow Arrow of the FYA channel will be checked for short yellow and skipped yellow.
If FYA GREEN SOLO is selected and IGNORE UNUSED CHAN is YES the Yellow signal of the FYA
parent channel is ignored for Short Yellow.
If FYA SOLO is selected, the channel must have both RED ENABLE and FIELD CHECK/DUAL
INDICATION OFF, no MYCD jumper, and is not selected as a pedestrian channel then the unused indication
(Green or Yellow) of the FYA channel is ignored for Short Yellow.
2.5.6
SHORT CLEARANCE MONITORING
Configuration:
All channels will be monitored for a short clearance fault.
Test Preformed:
When a channel has a Green or Walk that turns off, a conflict channel cannot display a Green,
Walk, or Yellow for at least 2.7 seconds. When each Green or Walk turns off a 2.7 second timer is started. If a
conflicting Green, Walk, or Yellow turns on for at least 100 milliseconds the 2.7 second timer must have reached
zero or a fault will be generated. The normal voltage thresholds for this test are: Reds – ON when above 70V
RMS
and OFF when below 50V
RMS
, Greens, Walks, and Yellows – ON when above 25V
RMS
and OFF when below
15V
RMS
.
Fault Action:
The monitor transfers the Output relay contacts to the fault condition (continuity between the
Normally Open and Common contacts), illuminates the
SHORT CLR
indicator on the front panel, and sets the
Minimum Clearance Failure bit (bit 74) and Spare Bit #5 (bit 71) of the Type 129 Frame to 1. The Signal
Sequence log and the Prior Faults log will record this fault.
Resetting the Fault:
The monitor remains in this fault condition until the unit is reset by the activation of the front
panel reset pushbutton or the activation of the reset input. Power loss or power interruption will not reset this fault.
The Reset log will record the resetting of this fault.
Modifying Inputs:
Red Enable
: All short clearance testing will be disabled when this input is below 70V
RMS
.
Load Switch Flash bit (bit 112) of the Type 0 Frame
: All short clearance testing will be disabled when this bit
is set to one.
Feature Interactions:
LED Thresholds
: When LED Thresholds is enabled the monitor senses Greens, Yellows, Reds, and Walks as
ON when their voltage is above 70V
RMS
and OFF when below 50V
RMS
for the short Yellow test.
Flashing Yellow Arrow Left Turns
: Following a Green or Flashing Yellow Arrow indication on a FYA
channel the Yellow Arrow of the FYA channel will be checked for short clearance monitoring.
If FYA GREEN SOLO is selected and IGNORE UNUSED CHAN is YES the Yellow signal of the FYA
parent channel is ignored for Short Clearance.
If FYA SOLO is selected, the channel must have both RED ENABLE and FIELD CHECK/DUAL
INDICATION OFF, no MYCD jumper, and is not selected as a pedestrian channel then the unused indication
(Green or Yellow) of the FYA channel is ignored for Short Clearance.
