MAY-JUN 2018

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INTECH MAY/JUNE 2018 35 SPECIAL SECTION I know this firsthand, because in the beginning of my career I did a great deal of controls and au- tomation system troubleshooting and gained in- valuable knowledge and experience. Working with systems that have problems means you observe unusual patterns of data and operation that need to be considered when designing control and au- tomation applications. For example, an engineer can understand the impact of a critical sensor fail- ure and use that information to design an applica- tion to set the process into a safe operating mode when the censored value reflects a failure. Troubleshooting Ideally, troubleshooting is an orderly process of understanding the problem, identifying the cause or causes of the problem, and implementing solu- tions to return operations to normal. The problem to be addressed is determined by the difference between proper operation and how it is working abnormally. Once the cause is identified, the ap propriate actions can be taken to either correct the issue or mitigate the effects. The latter is some- times referred to as a "workaround." The alternative to an orderly and systematic troubleshooting approach is often referred to as "shot gunning," that is, making a big mental leap without verifying the source of the problem and then taking an action like replacing a part. For example, a car will not start, and the trouble- shooter assumes the cause is a worn-out battery and immediately replaces it—which does not fix the problem. The problem might be a faulty start- er motor, starter switch, broken power cable, or something else. There is a difference between "shot gunning" and an "educated guess." Without experience, re placing parts without diagnosis is like playing roulette in a casino; the house is against you. Trou- bleshooters with a great deal of ex perience learn patterns and symptoms they have seen before and may at times replace a part without further diag- nosis. Experienced troubleshooters typically only use a strategy, and they believe there is a high probability it will fix the problem. General method Controls and automation systems with problems are acting abnormally, not functioning as they were originally designed. Examples of things that can create problems include sensors with errone- ous readings, loose electrical connections, net- work communication errors, electrical interfer- ence from newly installed equipment, overheated control cabinets, power supply problems, and powerful fluctuations. Software-based systems have created some new dimensions that also have to be included in troubleshooting. When you consider all local lines of software code, there is a much higher level of complexity compared to hardware systems. In my experience, there are two major categories of software-related issues: l Problem after a software update. For example, after an update the software does not recognize FAST FORWARD l Troubleshooting control and automation systems is a fundamental skill that is valuable throughout your career. l Troubleshooting is ideally an orderly process, but be prepared for unusual and abnormal situations. l Successfully troubleshooting and solving a problem can be immensely rewarding.

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