Can a light curtain be used as a primary safeguard to stop robot motion if a person enters the guarded zone?

• A. False
• B. True
• C. Only with interlock
• D. Not recommended as standalone safeguard

Answer: (B)

Light curtains act as protective barriers that detect intrusion across a defined guarded zone. When any beam is interrupted, a safety-rated controller can immediately command the robot to stop, provided the curtain and its wiring are configured as a safety function with the appropriate performance level. Because it directly senses presence in the protected area and can trigger an immediate stop, a light curtain can be the primary safeguard for halting hazardous robot motion. Proper integration, certification, and safe restart procedures are essential to ensure the device delivers a reliable protective function. While additional safeguards can be used for redundancy or access control, a correctly specified light curtain can serve as the main protective barrier.