AiVibeSafety Relay
A safety relay is a self-monitoring safety device that evaluates signals from safety inputs such as emergency stop buttons, guard switches and light curtains and switches outputs redundantly to stop hazardous motion when a demand or fault occurs.
A safety relay typically monitors dual-channel inputs, checks that both channels agree within a set time and switches redundant output contacts. Electromechanical versions use force-guided, or mechanically linked, contacts so that a welded contact can be detected, while electronic versions use redundant semiconductor circuits and self-tests. Manual or monitored reset functions ensure that clearing the input alone does not restart the machine, and feedback loops monitor the external contactors the relay controls.
Safety relays are used on individual machines and small systems with a limited number of safety functions, such as an emergency stop circuit or a guard door interlock. They are simple to configure, need no programming and provide a defined, certified function, often rated up to PL e under ISO 13849 or SIL 3 under IEC 62061 when used as specified. Configurable safety controllers bridge the gap between basic relays and safety PLCs.
As the number of safety functions grows, wiring and expansion modules multiply, and diagnostics remain limited compared with programmable safety controllers, which favours safety PLCs on larger machines. The rating of the relay alone does not determine the achieved PL or SIL; input devices, wiring, output contactors and fault exclusions all count. Installation, testing and validation must follow the manufacturer's documentation and applicable standards and be carried out by qualified personnel.
Key points
- Monitors dual-channel safety inputs and switches redundant outputs
- Force-guided contacts or self-tests reveal internal faults
- Monitored reset prevents restart when an input is simply cleared
- Suited to machines with few safety functions; no programming needed
- The whole safety function, not the relay alone, sets the achieved PL or SIL
Where AiVibe comes in
AiVibe designs and manufactures the AiAmbA AI Factory, whose edge devices and AI agents let people talk to PLC, CNC and robot controllers in plain language. Agents only propose changes, a trained operator confirms each one, and the AI Factory never replaces a machine's control or safety systems.