Short circuit protection: Take the right precautions to prevent faults in your fieldbus system

摘要

As we all know, if we do not have a reliable control system with availability as close as possible to 100 per cent, we quickly lose faith in the system and circumvent this with "jumpers," loops in manual and the like that defeat the purpose. The same is true for a fieldbus system. Heck, even "finicky" analyzers have a minimum acceptable availability of 95 per cent. A key part of any control system is the infrastructure that carries the signals from the field devices to the controllers, because without signals there, will not be data on which to control nor a means to manipulate the final control elements (valves, VFD, VSD, etc.) to adjust the process operating conditions. It therefore amazes me that for the sake of a few dollars, the same people who ask for "redundant everything" to maintain high reliability do not take basic precautions during the design, specification and installation of their fieldbus systems to prevent a single fault from adversely affecting the entire network.