Hello everyone,

I’m looking for advice on how to monitor a small LED lighting system and use its status as a safety-related input for a Pilz safety relay (PLe / SIL3 application).

My setup:

• 4 LED light modules
• Each module: 300 mm, approx. 4–5 W, 24 V DC (≈0.208 A)
• All four modules are connected in parallel → total current ≈0.83 A
• The LEDs are used as a safety-critical illumination indicator, so I need to detect if the LED current drops (undercurrent) or if a module fails.

I was considering using a current monitoring relay (e.g., DOLD BA 9053 or similar), but I am unsure:

1. How to wire the LED load correctly through the monitoring input (i/k).
2. Whether these types of current relays are suitable for such low DC current levels.
3. If they are appropriate or certified for PLe / SIL3 safety functions.
4. If there is a recommended schematic or a safer method to monitor the LED strip and provide a dual-channel signal to a Pilz safety relay.

If anyone has experience with:

• Monitoring LED strips as a safety input
• Using current relays for DC loads
• Achieving PLe / SIL3 with signal monitoring
• Or a wiring diagram for this type of setup

…I would really appreciate your guidance, example schematics, or product recommendations.

Thank you in advance.

 

Certainly a current monitor could sense if one light assembly failed open, or shorted, but probably not if the light just became dim.
BUT the ACCURATE wayto verify that a light source is lighting is with a light sensor. Unfortunately that gets complicated rather quickly.
Probably a supplier of alarm systems or security systems will have a light sensor that could sense the level of illumination.