Which device uses beams of light between a transmitter and receiver to protect personnel from entering the restricted area?

• A. Teach Pendant
• B. Light Curtains
• C. Safety Fences
• D. Pressure Mats

Answer: (B)

The concept being tested is safeguarding a hazardous area with a light-based barrier that detects intrusion. A safety light curtain uses an infrared transmitter and a matching receiver positioned to create a field of light beams across an access point. If a person or object breaks any of those beams while the area is protected, the safety controller immediately stops the machine or switches it to a safe state, preventing entry into the restricted zone.

This approach is specifically about beams of light spanning the opening, providing non-contact protection that quickly responds to intrusion. It’s different from a teach pendant, which is just an operator control device; it doesn’t create a protective zone. It’s also distinct from safety fences, which are physical barriers, and from pressure mats, which detect presence on a floor surface without covering an opening with a light-beam curtain.

So the device that matches "beams of light between a transmitter and receiver to protect personnel from entering the restricted area" is the light curtain.