ABB DSSS 171 3BSE005003R0001 Voting Unit

The ABB DSSS 171 (3BSE005003R0001) is a voting unit developed for high-integrity automation systems requiring advanced redundancy and fault tolerance. This module plays a vital role in safety instrumented systems (SIS) by implementing 2-out-of-3 (2oo3) or 1-out-of-2 (1oo2) voting logic to determine the most reliable signal from multiple redundant inputs.

Used primarily in ABB’s INFI 90 and Harmony distributed control systems, the DSSS 171 ensures accurate decision-making in safety-critical applications such as emergency shutdowns, process interlocks, and fire and gas detection. It compares multiple input signals and outputs a result only when the configured voting logic is satisfied, improving fault detection and increasing the availability of the control system.

The DSSS 171 is housed in a rugged enclosure suitable for industrial environments and is designed to meet the highest standards for safety and reliability.

Product Specifications

Product Applications

The DSSS 171 is specifically designed for environments where redundancy, fault tolerance, and system integrity are paramount. Key application areas include:

• Emergency Shutdown Systems (ESD)

  Ensures that shutdown signals are accurate and not triggered by a single faulty sensor.

• Fire and Gas Detection Systems

  Implements voting logic for flame detectors, gas sensors, and thermal monitors.

• High-Integrity Pressure Protection Systems (HIPPS)

  Prevents overpressure incidents in pipelines and vessels through validated logic voting.

• Process Interlocks in Petrochemical Plants

  Validates conditions before allowing machinery start-up or shutoff sequences.

• Safety Instrumented Systems (SIS)

  Forms part of the logic solver in systems requiring SIL 2 or SIL 3 compliance.

• Nuclear and Power Plants

  Used in critical safety and alarm processing where failure is not an option.

Product Advantages

The ABB DSSS 171 offers several key benefits that make it essential in modern safety and control architectures:

• Increased System Availability

  Allows continued operation even if one input signal fails, minimizing unnecessary shutdowns.

• Improved Safety Integrity

  Supports safety-rated configurations (SIL 2/3) in compliance with IEC 61508 standards.

• Flexible Logic Configuration

  Supports multiple voting strategies including 2oo3 and 1oo2 for diverse safety scenarios.

• Easy Integration

  Designed to work seamlessly within ABB Harmony and INFI 90 environments.

• Compact and Robust Design

  Occupies minimal space in control cabinets while delivering critical safety functions.

• Diagnostics Capability

  Detects input mismatches and flags potential sensor or signal issues early.

• Fail-Safe Output Behavior

  Ensures a predictable state during system or power failure.

• Long Service Life

  Built for continuous operation in demanding industrial applications.

Frequently Asked Questions (FAQ)

1. What is the core function of the DSSS 171 voting unit?

   It performs logic-based voting on multiple redundant input signals to determine the most reliable output for safety-related decisions.

2. Which voting strategies are supported by this unit?

   The unit supports both 2-out-of-3 (2oo3) and 1-out-of-2 (1oo2) logic configurations, depending on system design requirements.

3. Can this unit be used in a Safety Instrumented System (SIS)?

   Yes, it is designed to be compliant with IEC 61508 and supports SIL 2/3 applications.

4. Is it compatible with both analog and digital signals?

   It can process either type, depending on the system configuration and the connected modules.

5. Does the DSSS 171 require external power supply connections?

   No, it draws 24 V DC power directly from the system backplane, simplifying wiring.

6. How does the module behave in case of a failed input?

   It continues to function based on the configured voting logic, providing a fault-tolerant output.

7. Is the unit hot-swappable during system operation?

   Yes, it can typically be replaced without shutting down the entire system, though best practices should be followed.

8. Does the module include built-in diagnostics?

   Yes, it detects inconsistencies or failure in input signals and can flag them for maintenance teams.

9. What is the expected service life of the DSSS 171?

   When operated within specified conditions, it offers a long lifecycle, often exceeding 10+ years of continuous service.

10. Can it be used in non-ABB systems?

    While technically possible, it is optimized for ABB INFI 90 and Harmony systems and should be used accordingly for full functionality and support.