BPAC using Block Panel & UFSBI

Block Proving Axle Counter with Block Panel & UFSBI

Introduction

The Block Proving with Axle Counter using Block Panel & UFSBI (as per IRS:S-105/2012 Ver.0) is a non-cooperative, push-button-operated Block Instrument engineered for safe Absolute Block Working. Fully compliant with IRS:S-105/2012 Ver.0, the system integrates Last Vehicle Verification (LVV) data from axle counters for both single and double-line railway sections. A rugged, dedicated push-button Block Panel provides clear audio-visual indications for critical operational parameters.

Interlocking circuits are implemented using either robust Q-series relays or a CENELEC SIL-4 certified Solid-State Electronic Block Logic Module (EBLM), ensuring galvanic and optical isolation to support deployment in both Railway Electrified (RE) and Non-Railway Electrified (Non-RE) territories.

The system is media-independent, supporting operation over copper cable, optical fiber (OFC), or microwave infrastructure, without compromising its inherent fail-safe design.
Comprehensive schematic diagrams for single and double-line configurations offer insights into system placement, functional architecture, and operational requirements.

Block Panel with UFSBI (as per IRS:S-105/2012 Ver.0) using Relays

Single Line Block Panel (as per IRS:S-105/2012 Ver.0)

Double Line Block Panel (as per IRS:S-105/2012 Ver.0)

Operational Advantages of the EBLM-Based Block Panel with

UFSBI

Dual Hardware Logic Resolving: By employing purely hardware-based logic, the system eliminates risks associated with software-induced hang-ups. Two independent SIL-4 certified hardware logic units operate in a hot-standby configuration within just 4U rack space, providing performance equivalent to two full relay racks while saving space and energy.
Distance Independence: The system is capable of supporting block sections beyond conventional limits (10–12 km), accommodating communication over wireless, E1 (2 Mbps) channels, or dark OFC up to 20 km/40 km, and optionally up to 80 km.
High Availability Architecture: Designed for mission-critical applications, the system integrates redundant block logic modules, uninterruptible power supplies, and dual-path communication links with automatic failover, ensuring continuous operation.
Flexible Media Interface: Industrial-grade modem options are available for long distance Quad operation (upto 30 dB loss), E1 (2 Mbps), dark OFC, and wireless (2.4 / 5.8 GHz) media, enabling adaptable deployments.

Maintenance Advantages

Reduced Maintenance Overhead (EBLM Configuration): The absence of mechanical components in the EBLM minimizes the need for periodic overhauls.
Enhanced Component Reliability: The transition to digital EBLM design reduces the number of Q-series relays from 31 to just 5 per unit, significantly increasing system reliability.
Media-Independent Operation: Seamless performance across optical fiber, wireless, and copper media without hardware modifications enhances operational flexibility during routine or emergency conditions.
High System Availability: Hot-standby EBLM configurations ensure complete redundancy, maintaining operation without disruption during a single-unit failure.
Comprehensive Status Monitoring: Real-time health monitoring of TGTR, TCFR, ASCR, and UFSBI relays, fully integrated with datalogger systems, enables actionable diagnostics.
Simplified Fault Diagnosis: Numerical error codes and onboard diagnostics streamline fault identification and significantly reduce downtime.
Visual Status Indicators: LED indicators for all relay and EBLM states further reduce Mean Time to Repair (MTTR).
On-Board Diagnostics: Diagnostic LEDs on PCB facias offer maintenance teams instant visibility into system health, simplifying troubleshooting.

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Dual EBLM (Electronic Block Logic Module) in

2 out of 2 (SIL-4) Hot-Standby Configuration

UFSBI with Relays Full_EBLM_edited_edited.jpg

Block Panel with UFSBI (as per IRS:S-105/2012 Ver.0) using Dual EBLM (Electronic Block Logic Module)

Dual UFSBI with Dual EBLM_edited_edited.

Block Panel with Dual UFSBI

(as per IRS:S-105/2012 Ver.0) using

Dual EBLM (Electronic Block Logic Module)

A closer look at EBLM (Electronic Block Logic Module) Card

Safety and Reliability Features

Fail-Safe Communication: The system utilizes a Fail-Safe Mux UFSBI with 2-out-of-3 architecture to ensure SIL-4 compliant exchange of critical relay states, guaranteeing both safety and availability.
Proven Block Logic: Both relay-based and EBLM versions utilize RDSO-approved interlocking logic, validated across more than 6,000 installations, demonstrating long-term reliability.
High Availability with Maximum Safety: Dual 2-out-of-2 SIL-4 certified logic modules maximize operational availability without compromising stringent safety standards.
Robust Input Validation: Inputs undergo bi-state validation and de-bounce filtering with optical isolation exceeding 1 kV to ensure noise immunity and signal integrity.
Independent Output Voting: Outputs from the Fail-Safe Mux UFSBI are independently validated by a 2-out-of-3 voter card, enhancing fault tolerance and block signal safety.
Critical Power Control: Critical Power Control Modules, equipped with dual health-check relays and electronic supervisory circuits, enforce safe shutdown protocols in the event of anomalies.
Fail-Safe State Retention: Fail-safe Q-series latching relays ensure that TGTR and TCFR states are securely maintained, even during power interruptions or equipment failures, guaranteeing continuous safety.

Conclusion

With its cutting-edge fail-safe design, media-independent operation, and high-availability architecture, the Block Proving with UFSBI system, enhanced with fully digital EBLM upgrades, represents a major advancement in railway signalling technology. It offers uncompromising safety and reliability across both RE and Non-RE environments while simplifying maintenance and supporting long-distance operations. Its backward-compatible architecture ensures a smooth, cost-effective transition from legacy relay-based systems—making it the ideal choice for modernising and future-proofing railway signalling infrastructure.