Specifications

RailCorp Engineering Manual — Signals — Equipment Manual

Cerberus Level Crossing Monitor Field Equipment Manual TMG E1261

Issued August 2012 UNCONTROLLED WHEN PRINTED Version 2.1

This output operates in conjunction with the No Fault and No Warning outputs. This

output is ON when a fault or warning condition has been detected with the

operation of the level crossing equipment. The output remains on until the fault or

warning condition has been reset. If this output is flashing it indicates the

maintenance disable state.

11 Timer test

Used to control both the non-vital battery test timer and the battery test relay.

1.10 Analogue inputs

The level crossing monitor has 8 analogue inputs.

Analogue input number 1 is used to monitor the Level Crossing battery voltage. No

connection is required from the level crossing battery to analogue input 1 as the battery

voltage is measured through the power supply input wires used to power the monitor.

This input is electrically conditioned for a 0 to 20 volts DC input voltage. The Battery

voltage is is considered to have changed when the voltage is more than 0.95 volt different

than the last logged value.

Analogue inputs 2 to 5 are electrically conditioned for a 0 to 5 volts DC input voltage.

These are normally used to monitor the Level Crossing lamp currents in the range of 0 to

20 amps DC via the Current Sensor units. The Current Sensor that has a linear output

voltage of 0 to 5 volts in response to a lamp current of 0 to 20 amps.

For a standard level crossing two sets of lamps are connected to each flasher unit. An

electronic flasher flashes between the two sets of lamps at about 43 times per minute.

The Current Sensors are connected to the common leg of the two sets of lamps. The two

sets of lamps are identified as Flasher Up and Flasher Down. While the lamps are

flashing the Current Sensor is measuring the current both sets of lamps. To allow the

level crossing monitor to know which set of lamps relates to the current being measured a

digital input (via a VIO) is used to monitor the state of the flasher (Flasher Up or Flasher

Down or in the case of Safeflash - Bank 1 or Bank 2). This digital input tells the level

crossing monitor which set of lamps is currently lit and the monitor than knows the current

reading for each set of lamps.

A change is considered to have occurred on a lamp analogue channel when a different

number of lamps are determined to be operating.

Analogue inputs 6 to 7 are electrically conditioned for a 0 to 5 volts DC input voltage.

They are normally spare and may be used with other sensors to monitor additional

flashing lamps OR log voltage, current or temperature. A possible use for the spare

inputs is to use a Vital Analogue Interface module (supplied by Signal Engineering) to

directly monitor DC track relay voltages. Another useful application is the monitoring of

the location hut temperature and even monitoring of the rail temperature.

Analogue input 8 is electrically conditioned for a 0 to 5 volts DC input voltage. It is

normally used to monitor the Level Crossing battery test current in the range of 0 to 20

amps DC. To monitor the battery test current it uses a Current Sensor (same unit as used

for the lamps) that has a linear output voltage of 0 to 5 volts in response to a lamp current

of 0 to 20 amps. A change is considered to have occurred when the current is more than

1.6 ampere different than the last logged value.