Glossary · Systems engineering and MBSE
Interaction hazard
In machine safety and systems engineering, an interaction hazard is a hazard created or changed by interaction between system elements or machines. It does not exist, or exists differently, when each element is considered on its own.
- Integrated systems
- Functional safety
In one sentence
An interaction hazard arises only when machines or system elements interact, so it is invisible in the risk assessment of each part alone.
Example
A conveyor restarts automatically when a downstream robot signals “ready”, while an operator is still clearing a jam at the transfer point: neither machine alone has this hazard.
How it applies
- Machine safety: Identify interaction hazards systematically with a coupling analysis of every interface, and add them to the risk assessment of the whole system.
- Integrated systems: Typical sources are start and stop signals across machines, shared zones, handovers of material and differing operating modes. Unexpected startup triggered by a neighbor is a classic case.
- Technical documentation: Supplier manuals rarely describe interaction hazards, because suppliers do not know the integration. The integrator's instructions must cover them.
- Evidence: Validation of the integrated system should include tests at the interfaces, such as stops and restarts triggered from one machine while another is in maintenance mode.