Glossary · Automation fundamentals, platforms and components
Protective door
Also known as: Guard door, Safety door
German: Schutztür
In machine safety, a protective door is a movable guard, hinged or sliding, that closes an access opening to a hazard zone. It is normally interlocked so that hazardous machine functions cannot operate while it is open, and may additionally be locked while hazards persist.
- Automation components
- Functional safety
In one sentence
A protective door is a movable, usually interlocked guard that closes an access opening to a machine's hazard zone.
Example
The robot cell's sliding protective door has an interlocking switch with guard locking that stays locked until the spindle has come to a standstill.
How it applies
- Engineering: A protective door is designed as a Movable guard per ISO 14120 and interlocked per ISO 14119. If the hazardous motion cannot stop before a person reaches it, Guard locking is required, often released only after Standstill is detected.
- Maintenance: Hinges, switches and actuators wear out. Periodic checks must confirm that the door still stops or prevents hazardous functions and that the interlock has not been bypassed.
- Documentation: The operating manual explains how to open the door safely, what stops when it opens and how to restart. Describe the emergency release or escape release where fitted.
Protective door vs. fixed guard
A fixed guard needs a tool to remove it and is used where access is rare. A protective door is opened in normal operation, so its safety depends on the interlock and the control system behind it.