The Control Unit performs all the logic functions of AWS, Overspeed Sensor and Train Stop, taking inputs from the AWS Receiver and the TPWS Trainborne Aerial and providing a direct output to the brake control circuit, which operates the emergency brake, and an output to reset the AWS Receiver via the Acknowledge Button.

The Control Unit operates all the TPWS visual and audible indicators that are split between the Alarm and Indicator Unit and the Control Panel.

An output from the Control Unit to a test loop in the aerial is used for verifying the operation of the Aerial and its associated circuitry.

Outputs are also provided for the On Train Monitoring Recorder (OTMR) and Vigilance Equipment.

Control Unit Terminal Box

Connections both from and to the Control Unit are made via a Terminal Box located next to the Control Unit.

The Terminal Box replicates the physical location of the terminals, which exist in the original AWS Junction Box in addition to providing additional terminals for the Train Stop and Overspeed Sensor functions.

For ‘new fit’ installations the Control Unit Terminal Box can be omitted and connections made directly to the Control Unit Connector.

Description Part Number
TPWS Control Unit 606108-02