Suitable for more demanding safety applications where higher risk is involved, ensuring stringent safety measures. This is a lower safety category compared to Type IIIC, offering a good level of safety but with less redundancy and complexity. Used in applications with moderate safety requirements where the risk is less and where a simpler, cost-effective solution is sufficient.
Type IIIA still ensures that both pushbuttons are pressed simultaneously but with fewer safety features compared to Type IIIC. http://www.pilz.com It’s appropriate for lower-risk applications where the safety requirements are not as stringent. Used in applications with moderate safety requirements where the risk is less and where a simpler, cost-effective solution is sufficient.