SR3D Safety Control Unit – Reliable Safety Solution for Machines and Systems

The SR3D safety control unit is a versatile solution for monitoring and safely shutting down machines and systems. With three safe relay outputs and an auxiliary contact (monitoring contact), it ensures a reliable safety function in the event of danger. The SR3D meets the highest safety requirements up to PL e / SILCL 3 and is certified by TÜV Rheinland and Germanischer Lloyd.

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### Application Areas of the SR3D

• Emergency stop circuits (single or dual-channel)
• Safety guard monitoring on machines and systems
• Continuous operation combustion plants (according to EN 50156-1 and EN 746-2)
• Use on ships (certified by Germanischer Lloyd)

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### Key Features and Benefits

• 2 possible start behaviors:
- Monitored manual start
- Automatic start

• Safety level: PL e, SILCL 3
• Cross-fault and ground-fault monitoring for increased cable security
• 3 safe, redundant, diverse relay outputs for maximum safety
• 1 auxiliary contact (monitoring contact) for device status monitoring
• Connection options:
- Emergency stop buttons
- Safety switches
- Contactless safety switches
- Safety components with OSSD outputs

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### Functionality and Safety Concept
The SR3D safety control unit guarantees safe separation of safety circuits in accordance with EN 60204-1. It meets the requirements for the stop function up to PL e / SIL 3 according to EN ISO 13849-1 and IEC 61508.
In normal operation, the emergency stop circuit (e.g., safety door or emergency stop button) remains closed, allowing the machine to operate. If the safety function is triggered (e.g., by opening the safety door), the SR3D immediately opens the enabling current paths and brings the machine to a safe state.

Additional Safety Functions

• Redundancy and Diversity: Uses force-guided relays to ensure that the safety function is maintained even if a fault occurs in the device.
• Cyclic monitoring of relay outputs to detect faults such as contact welding.
• Feedback loop to monitor downstream contactors or expansion modules.
• LED display of switch status for quick diagnosis and maintenance.

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### Technical Specifications

• Protection class: IP54 (installation in control cabinets required)
• Operating voltage: AC 115 V / 230 V – Maintain a minimum distance of 10 mm to adjacent devices
• Mounting: On a 35 mm DIN rail according to EN 60715 TH35
• Distance to adjacent devices: Minimum of 10 mm for the AC 115 V / 230 V version

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### Standards and Certifications

• EN ISO 13849-1 (PL e)
• IEC 61508 (SIL 3)
• EN 60204-1 (safe separation of safety circuits)
• EN 50156-1 / EN 746-2 (for combustion systems)
• Certified by TÜV Rheinland and Germanischer Lloyd

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### Conclusion
The SR3D safety control unit is the ideal solution for monitoring and shutting down machines in emergency stop and safety guard monitoring systems. With its redundant, diverse relay outputs and force-guided relays, it offers maximum operational safety.