Control Functions

Interlock Architectures – Pt. 4: Category 3 – Control Reliable

Posted on
Category 3 Architecture Logic Block Diagram
This entry is part 4 of 8 in the series Cir­cuit Archi­tec­tures Explored

Cat­egory 3 sys­tem archi­tec­ture is the first cat­egory that could be con­sidered to have sim­il­ar­ity to “Con­trol Reli­able” cir­cuits or sys­tems as defined in the North Amer­ic­an stand­ards. It is not the same as Con­trol Reli­able, but we’ll get to in a sub­sequent post. If you haven’t read the first three posts in this series, you may […]

Control Functions

Interlock Architectures – Pt. 5: Category 4 — Control Reliable

Posted on
This entry is part 5 of 8 in the series Cir­cuit Archi­tec­tures Explored

Ed. note: I’ve made a few updates to this art­icle since it was first pub­lished in 2011, with the most recent today, 6-Dec-18. – DN – The most reli­able of the five sys­tem archi­tec­tures, Cat­egory 4 is the only archi­tec­ture that uses mul­­tiple-fault tol­er­ant tech­niques to help ensure that com­pon­ent fail­ures do not res­ult in an unac­cept­able […]

Control Functions

Interlock Architectures Pt. 6 – Comparing North American and International Systems

Posted on
industrial Control Console
This entry is part 6 of 8 in the series Cir­cuit Archi­tec­tures Explored

I’ve now writ­ten six posts, includ­ing this one, on the top­ic of cir­cuit archi­tec­tures for the safety-related parts of con­trol sys­tems. In this post, we’ll com­pare the Inter­na­tion­al and North Amer­ic­an sys­tems. This com­par­is­on is not inten­ded to draw con­clu­sions about which is “bet­ter”, but rather to com­pare and con­trast the two sys­tems so that […]