Hi,

Sorry I am new to safety standards.

Currently I have an interlock circuit design with guard door hardwire in series to the safety relay (MSR127).
Additional device such as curtain light and safety sensor, OSSD are connected to a safety relay (G7SA) which will be connected in series with the guard door.

However, if we would like to add general photoelectric sensor (through-beam, retro-reflective, etc) which will hardwire to safety relay (G7SA) and it will be connected to the above interlock circuit.

Does using normal sensor connected to safety relay, still conform to the safety type or category?
Some supplier do advise for any sensor use for safety interlock must conform to safety standards.

Thanks in advance for any replies.

 

Stick with the company design. any "home brew" improvements, will have to be tested, in a variety of tests with different objects, at least 60,000 times.

 

No need to apologize for being new to safety standards; it's important to ensure safety in your designs. When it comes to safety circuits, using sensors that are not specifically designed and certified for safety applications can introduce potential risks and may not conform to safety standards. Safety-rated sensors, like those designed for Functional Safety, are built to meet specific reliability and fail-safe criteria, ensuring that they can reliably detect unsafe conditions and initiate a safe shutdown if needed. Using non-safety-rated sensors in a safety-critical circuit can compromise the overall safety of the system and may not meet regulatory requirements. It's advisable to consult with safety standards (e.g., ISO 13849 or IEC 61508) and work with sensors that are certified for safety applications to ensure compliance and safety.

 

As with any interlock system, layout your ladder diagram (or logic) , to establish the level of redundancy required.
Your photoelectric sensor, can be considered, but you have to sort out how it fails, to avoid over-riding the pre-existing safety interlocks. Ultimately you want a "mansafe" design, even if the controls fail.

Some applications require more than simple redundancy for safe operation. Remember you may be liable should you "improvement" result in serious injury or death.