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MAY-JUN 2018

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INTECH MAY/JUNE 2018 37 SPECIAL SECTION high-tech production line, the prob- lem had to be complex. Everyone had a complex theory about the prob lem they worked to find with sophisticated test equipment. Workarounds Based on the urgency of the problem, it might be necessary to implement a tem- porary workaround solution to restore operations to some level. A workaround is typically used when there is a special cir- cumstance, such as a lack of parts to fix the problem immediately and properly. Gen- erally, the controller or automation will not perform up to normal specifications using the workaround. Workarounds on complex systems have to be done con - sidering the implications so you do not create unstable or unsafe operations. For example, bypassing a faulty safety s witch to keep the process running would not be an appropriate workaround. Process troubleshooting Joseph Alford, consultant, Automation Consulting Services, has more than 35 years of experience and is a highly active ISA member. He shared his thoughts on process troubleshooting: "One of the most important traits that a process operator can have is the ability to quickly and accurately diagnose process upsets and respond accordingly. Chances are that, for new processes/plants, vari- ous process abnormal situation analy- sis techniques were used by engineers and scientists in developing the process. These may have included FMEA [failure modes and effects analysis] or perhaps "rationalization" exercises as part of spec- ifying alarm parameters, and may have resulted in the creation of graphics, such as fault trees or fishbone "cause-effect" diagrams (also known as Ishikawa dia- grams) and content in an alarm manage- ment database. Regardless, some thought and documentation regarding process failure modes was undoubtedly pursued in developing a manufacturing process. "There are several challenges in the pursuit of effective process troubleshoot- ing. One challenge is that there are usu- ally several possible causes to a given process upset (e.g., an abnormal tank pressure reading may be due to a pres- sure sensor failure, seal or gasket failure, relief or control valve failure, or out-of- control exothermic reaction). Many of the possible causes will not be immedi- ately detectable with relevant sensors, so cannot be automatically reduced to a single probable cause. So, to help opera- tors with manual troubleshooting, what is useful is an online callable list of the possible causes and some indication of the probability of their occurrence and/ or priority in checking them out, that is, what root cause should the operator check first? "A second challenge is the need to make process troubleshooting informa- tion as quickly and easily available to operators as possible (i.e., time is mon- ey, and time delays in troubleshooting and responding to process upsets will often result in an escalation in the sever- ity of the process upset). So, things like fault trees, fishbone diagrams, or alarm rational ization databases should not re- main as items in hard documents but should be distilled into useful infor - mation for op- erators and made available online as part of the hu - man-machine in- terface in systems they routinely use (e.g., process con - trol computers)." Assumptions Withhold judg- ment until you have gathered in - formation without jumping to con - clusions. Cables with bar rel con- nectors screwed together made up the network. S u c c e s s f u l l y t r o u b l e s h o o t - ing and solving a problem can be immensely rewarding. One phrase that I found helpful when troubleshooting was from my AC/DC fundamentals professor in college. He started every class by stating, "Where does the reasoning begin?" n ABOUT THE AUTHOR Bill Lydon (blydon@isa.org) is chief editor for InTech. He has more than 25 years of industry experience in building, industrial, and process automation. View the online version at www.isa.org/intech/20180606. RESOURCES Troubleshooting: A Technician's Guide www.isa.org/troubleshoot A Guide to the Automation Body of Knowledge (Chapter 31 on trouble- shooting) www.isa.org/autobok Convert Your Mobile Device into a HART Communicator … with our Advanced HART-based Products C O N N E C T > C O N F I G U R E > D O C U M E N T Complete DD-based HART Communicator for any device - PC, Tablet, Phone. Your choice! Complete DD-based HART Communicator for any operating system - Windows, iOS, Android. Your choice! Full line of registered HART Modems - USB, RS232, Bluetooth, Bluetooth Low Energy Your choice! Use your own host device or one of our complete systems. Hazardous area options available. Significant cost savings • Mobile convenience • Satisfaction guaranteed NEW! iOS Version now available!

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