Wavetronix VDR24 Radar - Manual (Page 44)

Power Up and User Interface Navigation
44 VDR24 Radar Detection System, Rev 1.0
7.3.2. Verify XR and IR Circuits
As stated previously, the state of the XR and IR circuits influence the behavior of the radar
detection system. For instance, when the island relay circuit (IR) is activated, or unpowered, the
VDR24 assumes that a train is occupying the crossing so detection is suppressed. This section
is intended to verify that the XR and IR signals are properly connected to railroad equipment, by
measuring the applied voltage at the XR and IR terminals and viewing the corresponding state
of the VDR 24 front panel indicators. Located above the point where wire connections are made
in the pluggable terminal strips are small holes where readings may be taken with a voltmeter.
FFiigguurree 2244 -- M
Meeaassuurriinngg XXR R aanndd IIR R VVoollttaaggee LLeevveellss
7.3.2.1. Verify XR Circuit
Verify that with the XR circuit not active (powered) that a B12-N12 Battery voltage is present
across the XR+ and XR- terminals on the side of the VDR24. Also verify that the XR indicator on
the VDR24 front panel is illuminated in green during this condition. Then simulate the XR signal
in the activated, or unpowered, state and verify that the XR indicator on the VDR24 front panel
turns red.
7.3.2.2. Verify IR Circuit
Verify that with the IR circuit not active (powered) that a B12-N12 Battery voltage is present
across the IR+ and IR- terminals on the side of the VDR24. Also verify that the IR indicator on
the VDR24 front panel is illuminated in green during this condition. Then simulate the IR signal
in the activated, or unpowered, state and verify that the IR indicator on the VDR24 front panel
turns red.
7.3.3. Verify Radar Sensor Voltage Levels
The VDR24 is ideally powered by B12-N12 battery
voltages available in the railroad equipment house. In
accordance with standard AREMA practices, this power
supply is surge protected and isolated within the VDR24
power supply. This isolated supply is then made available
to the components that comprise the Island Radar system.
Regardless of the battery power supply connected to the
VDR24, it provides approximately 24.5 volts DC to the
radar sensors. While the radar sensors themselves can
operate on as low as 12 volts, utilizing the higher voltage
maximizes communication noise immunity and permits the
home run cabling that extends between the sensors and
the VDR24 controller to be 500 feet or greater in length.
FFiigguurree 2255 -- C Coonnffiirrm miinngg R Raaddaarr
VVoollttaaggee LLeevveellss
Voltage Measurements
Taken Here