In this post, I’ll discuss two safety-related parameters: safe speed and safe standstill. Speed control is a very common machine function. Conveyors, mixers, pumps, and many other applications rely on variable-speed drives. Some speed parameters are also safety-related because variations in speed can increase the risk to workers. See this post for more information on…Read More
CSA Z432 Public Review Open!
CSA Z432 Public Review is open. If you are a user, a builder of machinery, or an evaluator of machinery, this is your opportunity to see the draft of this important standard and to make comments to help the Technical Committee improve the standard on your behalf. Note: The start of the public review period…Read More
Understanding Safety Functions: the Safety-related stop function
The most used safety function on machinery is the safety-related stop function. The requirements discussed in this post are not generally applicable to process-related stop functions unless the process and safety stop functions share the same control system hardware and software.Read More
Manual reset using an HMI
Update: Things have changed a bit since this post was first published in 2021. There are now some safety-rated HMIs available from big controls companies like Siemens, so if you are considering this approach, consult with your controls vendor to see if their HMIs can meet the requirements of ISO 13849-1. Ed. – 2022-05-10 Question: Can…Read More
Can Emergency Stop be used as an “on/off” control?
Every couple of months I get an email asking me if there is any reason why e-stop functions can’t be used as the primary power control (on/off button) for machinery. Following a recent exchange, I thought I would share the reasons for why this is such a bad idea. The short answer The short answer…Read More