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

The SR3D safety control unit allows the safe and rapid shutdown of moving machine parts in the event of a hazard. With three safe relay outputs and an auxiliary contact (monitoring contact), the SR3D ensures a high safety level up to PL e / SIL 3. Thanks to its versatile use, it is suitable for emergency stop circuits, safety guard monitoring, and applications in combustion systems and ships.

Application Areas of the SR3D
The SR3D safety control unit is used in the following areas:

• 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
• Maritime applications (certified by TÜV Rheinland and Germanischer Lloyd)

Key Features and Benefits

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

• Operation up to: PL e, SILCL 3, Category 4
• Cross-fault and ground-fault monitoring to ensure line integrity
• 3 safe, redundant, diverse relay outputs for maximum safety
• 1 auxiliary contact (monitoring contact) for status monitoring
• Connection options:
- Emergency stop buttons
- Safety switches
- Contactless safety switches
- Safety components with OSSD outputs

Functionality and Safety Concept
The SR3D ensures safe separation of safety circuits according to EN 60204-1 and fulfills the stop function requirements up to PL e / SIL 3 according to EN ISO 13849-1 and IEC 61508. If the emergency stop circuit is activated (e.g., by pressing an emergency stop button or opening a safety door), the SR3D immediately interrupts the enabling current paths and stops the machine.

Additional Safety Functions

• Force-guided relay contacts ensure that the safety function is maintained even if a fault occurs in the device.
• Cyclic monitoring of relay outputs to detect contact welding or failures.
• Feedback loop to monitor downstream contactors or expansion modules.
• LED display of switch status for quick diagnosis and maintenance.

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
• Climatic conditions: Ensure proper heat dissipation in the control cabinet to prevent overheating
• Distance to adjacent devices: Minimum of 10 mm for AC 115 V / 230 V version

Standards and Certifications
The SR3D meets the following safety standards and requirements:

• 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

Conclusion
The SR3D safety control unit is a reliable solution for monitoring and shutting down machines and systems in emergency stop and safety guard monitoring systems.