440R-D22R2 | Allen-Bradley | Guardmaster Dual Input Safety Relay

Configured for monitoring safety-critical circuits, the Allen-Bradley 440R-D22R2 (440R-D22R2 Safety Relay) provides direct electrical execution of dual-channel signal monitoring and fail-safe state transition within industrial automation platforms.

Hardware Specifications

Fail-Safe State Execution

The 440R-D22R2 utilizes a solid-state logic architecture to monitor dual-channel inputs for inconsistencies, such as short circuits or open-circuit faults. Upon detection of a safety violation, the relay executes an immediate transition to a fail-safe state, interrupting the control output to inhibit machine operation. This internal monitoring ensures that any single component failure within the safety relay does not result in the loss of the safety function. The solid-state auxiliary output provides real-time status feedback to the higher-level controller, maintaining loop integrity without the mechanical latency associated with traditional electromechanical relays.

Frequently Asked Questions

Q: Can the 440R-D22R2 be configured for single-channel monitoring?

A: The relay is specifically designed for dual-channel (2-channel) input monitoring to meet the required safety integrity levels. Single-channel wiring is generally insufficient to achieve the diagnostic coverage required by the internal logic of this safety device.

Q: What is the significance of the solid-state auxiliary output?

A: The solid-state auxiliary output provides a high-speed status indication of the safety relay's internal state. Unlike mechanical contacts, it does not suffer from contact welding or bounce, offering consistent feedback signal transitions for diagnostic purposes.

Field Installation Guidelines

1. Mount the relay vertically on a 35 mm symmetrical DIN rail to ensure adequate airflow through the enclosure vents.
2. Terminate all inputs and outputs using the provided screw clamp terminals; ensure proper wire gauge selection to meet the current carrying capacity of the connections.
3. Verify that the dual input channels are wired to meet the specified synchronization time to prevent nuisance tripping during normal operation.
4. Shield all input and output cabling if routed near high-voltage lines or variable frequency drives to minimize electromagnetic interference (EMI).
5. Perform a functional safety verification test after installation, simulating a fault condition to confirm the relay interrupts the machine control circuit as intended.