Salient Features:

The SSBPAC (D) is of 2 out of 3 hardware architecture with implementations of the fail safety principles. It complies with the CENELEC standards and conforming to Safety Integrity Level - 4 (SIL-4).

• The system incorporates auto features and eliminates manual co-operations from other end for Line Clear and Line Close operations.
• Emergency cancellation at the receiving station.
• Automatic Train On Line.
• Automatic Line Close after sequence proved at receiving end and section is free.
• Simplified Block Back / Block Forward Operations.
• Cooperative Cancellation.
• Line Clear Block Key (LCB Key) to prevent automatic granting of Line Clear.
• Station Master Key (SM Key) to prevent unauthorized panel operations.
• Fully solid state and relays are only for final vital outputs.
• Single Line Working with provisions for shunting with shunt key EKT
• Event logging operations and data storage in built in the system.
• Data logger network interface.
• Communication media: (1 pair cable in quad or on voice channel in OFC.)
• Block bell and telephone on separate pair of quad or voice channel of OFC.
• Two repeater relays to repeat input status at the other end.

Safety Features

• Safe shutdown if the output is less restrictive.
• Mine field in the non-program area for trapping the CPU.
• Inputs and Outputs are exchanged and validated among 3 CPUs in Inter Processor communication before delivering to independent voter module.
• Continuous monitoring of system cycle time. In case of deviation safe shutdown of system.
• 2 Bit bi-state control for all the vital output relays.
• Continuous monitoring of output for every 50ms.
• Online Hardware diagnosis and self checking.
• Fault detection and negation failsafe measures.

Advantages:

• Less maintenance and requires no periodical over-hauling in consideration with the electromechanical systems.
• It considers signal overlap distance for granting line clear, which is not available in some of the present systems.
• It has inbuilt data logging capability which logs all the panel operations, events, relays status and other information.
• All the panel indications are with LEDs.
• No need for next train on PLC after push back operation.