Safety Coupling Relays – Reliable Signal Transmission in Safety-Critical Applications

In the process industry, safety-related signals, such as the output signals of a safety controller, must be reliably coupled to the peripheral devices. Conventional coupling relays are unsuitable for this purpose, as they interrupt the safety chain and can no longer guarantee a safe shutdown in the event of a hazard.

Safety coupling relays solve this problem. With their redundant design and self-monitoring functions, they enable the standard-compliant coupling of safety-related signals up to the highest safety levels of SIL 3 and PL e. This ensures that the safety chain remains intact even in the event of a fault.

Typical applications of safety coupling relays:

• Galvanically isolated coupling of 24V digital signals to 230V – Protects the control system from voltage surges and provides galvanic isolation.
• Safe coupling of sensor signals to the controller – Connects safety-related sensors, such as pressure monitors or limit switches, to the control system.
• Contact amplification for controllers with limited output power – Amplifies the output power when control systems can only switch low loads.
• Filtering of test pulses sent by safety controllers – Prevents false alarms by detecting and filtering test pulses.

The use of safety coupling relays ensures the secure transmission of signals between the control system and peripheral devices. This is particularly important in safety-critical applications where an uninterrupted safety chain is essential.

Technical Data:

• Safety Levels: Up to SIL 3 / PL e according to EN ISO 13849-1 / IEC 61508
• Redundancy: Redundant relays with self-monitoring
• Signal Transmission: Galvanically isolated coupling of 24V to 230V
• Functions:
- Safe coupling of sensor signals (e.g., pressure monitors)
- Contact amplification for controllers with limited output power
- Filtering of test pulses from safety controllers

• Applications: Process industry, mechanical engineering, safety-critical control systems