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Learn More - opens in a new window or tab Any international shipping is paid in part to Pitney Bowes Inc. Learn More - opens in a new window or tab. Related sponsored items Feedback on our suggestions - Related sponsored items. Wheelock's Latin by Richard A. LaFleur; Frederic M. Practical Electronics Troubleshooting by James Perozzo. Troubleshooting Electric Motors. Report item - opens in a new window or tab. Item specifics Condition: Good : A book that has been read but is in good condition. Very minimal damage to the cover including scuff marks, but no holes or tears.
The dust jacket for hard covers may not be included. Binding has minimal wear. The majority of pages are undamaged with minimal creasing or tearing, minimal pencil underlining of text, no highlighting of text, no writing in margins. No missing pages. See all condition definitions - opens in a new window or tab. About this product. Rocky Mountain Textbooks. Visit my eBay store. Search Store. Items On Sale. Includes over 30 figures and tables; fully indexed. This book discusses the wireless communication concepts and terminology needed to apply wireless control in the process industry, such as how By David W.
Spitzer The book presents the electrical, hydraulic, chemical, and instrumentation information necessary to technically evaluate and The book is intended for those readers involved in factory automation systems as well as process, including readers who are already experienced and The goal of this edition is to simplify and demystify the procedure of tuning control systems. By William L. Mostia, Jr. Symptom patterns can be repetitious i. It may have information on circuits, system analysis, or troubleshooting that can lead to a solution.
It may also provide voltage, current, or indicator readings, test points, and analytical procedures. Often manuals use troubleshooting tables or charts to assist you. Can you determine a cause and propose a solution to solve the problem? This is a decision point for moving on to the step of proposing a solution. If this proves insufficient, add another piece of information, and so on. Keep doing this until you have sufficient information. The direct process is generally based on three methods: experience, historical documentation, and use of the manual.
But be careful to not jump the gun and move on to testing a solution before you have firmed up all your facts. There may be costs associated with testing the solution that can be prevented with a little forethought. First, experience is the quickest means of troubleshooting problems. If you have seen a particular problem before, you already know the solution.
The more experience you have, the better your chances that this will occur. Not all experience is equal, however. Ten years of mediocre experience may not equal one year of excellent experience. Good experience will have you working on such things as unfamiliar systems, complex systems, difficult systems, poorly documented systems, sophisticated systems, and other challenging work. Avoid repetitive or unchallenging work.
Second, your facility may have documented a prior experience with the problem at hand, and the solution. Historical documentation may be in a plant maintenance management system or kept manually in a loop file or equipment log. The troubleshooter may also keep personal records on troublesome instruments or systems.
And third, read the manual. You would be surprised how many times people do not read it and consequently do not know the simplest things about their systems. Common problems and their solutions are usually described in the manual or given in tables or flowcharts. Test points and procedures are commonly provided. Here you collect information, analyze it, and decide if you have enough to propose a solution.
If not, then you go back to Step 2 to collect more information, and so on, until you have a proposed solution. This iterative process may work when you have lots of information, or even just a single piece of information such as a test voltage or current. It is illustrated in Figures and by the paths that return to previous steps. Now you will need a logical process to make this iterative procedure successful.
First, try the linear or walk-through approach. This is a step-by-step process illustrated in Figure that you follow through a system. The first step is to decide on an entry point. If the entry point tests correctly, then you test the next point downstream in a linear signal path. If this test Mostia Conversely, if the entry point is found to be bad, choose the next entry point upstream and begin the process again.
As you move upstream, each step narrows down the possibilities. Branches must be tested at the first likely point downstream of the branch. For example, suppose a pressure signal is reading incorrectly in the DCS. The DCS signal is not zero, so there appears to be a signal from the field and consequently the problem is probably not loss of power , but the signal is dead—it does not move when compared to the signal prior to the problem. There is no field indicator, so you choose an entry point at the process pressure tap where the pressure sensor connects to the process.
You find this tap to be clean. Next, you check the pressure transmitter, which also checks out correctly, as does the power. The next thing you check is the DCS input card, which tests bad. You can also use the linear approach when a likely entry point is not known by choosing a point of entry generally either one end of a loop or circuit or the middle and working from there.
You choose a likely point, or the midpoint of the system, and test it. If it tests bad, then the upstream section of the system contains the faulty part. The upstream section is then divided in two parts and the system is tested at the dividing point. If the test is good, the downstream section contains the bad part and is then divided in two, and so on until the cause of the problem is found. If on the other hand, the test is bad, then the upstream section contains the bad part. It is divided into parts and tested again, and so on until the bad part is found.
In fact, you may propose several solutions based on your analysis. Usually the proposed solution will be to remove and replace or repair a bad part. In some cases, however, your proposal may not offer complete certainty of solving the problem and will have to be tested, or another, more certain solution tried instead. If you have several possible solutions, propose them in the order of their probability of success. If this is roughly equal, or other operational limitations come into play, use other criteria.
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You might propose solutions in the order of the easiest to the most difficult. Sometimes in a plant that cannot shut down operations, the right approach is proposing what you can do without a shutdown. In other cases, there may be cost penalties in such things as labor, consumable parts, and lost production associated with trying various solutions; you may propose to try the least costly option.
Most of the time, however, you will try to find a compromise between the above criteria.
Do not try several solutions at once. Management will sometimes push for a shotgun approach due to time or operational constraints, but you should resist it; with a little analytical work, you may be able to solve the problem and meet management constraints at a lower cost. With the shotgun approach, you may find that you do not know what fixed the problem, and it will be more costly both immediately and in the long term. If you do not know what fixed the problem, you may be doomed to repeat it.
Troubleshooting: A Technician's Guide, Second Edition
In the story, some people are considering going to Abilene, though none of them really wants to go. They end up in Abilene, though, because everyone in the group figures that everyone else wants to go to Abilene. This is sometimes caused by having high-level people or strong-willed people involved. At this step you must determine if the solution needed is more general than the specific one proposed. In most cases, a specific solution will be repairing Mostia For example, you replace a bad transmitter, which solves the transmitter problem.
But what if replacing the transmitter only results in the new transmitter going bad? Suppose a transmitter with very long signal lines sustains damage from lightning transients. The specific solution would be replacing the transmitter; the general solution might be to install transient protection on the transmitter as well. Or suppose you have a systematic failure where the transmitter was specified with the wrong diaphragm material, which has corroded out; it will only corrode out again after a period of time.
Replacing the failed transmitter with the correctly specified transmitter is the more general solution. If you find your mistake, then move on to propose another solution. In some cases, testing a solution results in the repair, as when replacing a transmitter both tests the solution and repairs the problem.
Even in this case, there will generally be some additional work to be done, such as tagging, updating the database, and updating maintenance records, in order to complete the repair. If the repair includes replacement, take care on modern microprocessor devices that you transfer the complete configuration of the failed instrument to the replacement.
Otherwise, you may solve the immediate problem but introduce a new problem with a faulty configuration. If the repair involves a programming change, take care that you do not introduce a bug. All programming changes must be fully tested. Communication with operators and termination of permits will also be necessary to complete the work. Document the repair so that future troubleshooting is made easier. This is particularly true if the problem is unusual or unique.
In repairing an instrument or system, take care not to damage it or leave it in a manner that might cause problems later. For example, be sure to tighten all terminal screws and installation bolts, replace and secure all covers, and check for damaged insulation, screws, or bolts. He has the situation under manual control at this point.
This is a fairly good problem definition. It identifies the process vessel and the control loop involved, what the control loop is not doing correctly, and how the operator is compensating for the problem. A: I had a low-level alarm and the level sight glass on the tank confirmed the low level. Q: How are you determining the level? A: Joe is watching the sight glass on the tank and keeping me informed on the radio.
You also collect other data. For example, you determine that the trend is flat with no noise. You need to do some testing in the field to gather more information. You go back to Step 2, get appropriate permits, and tell the operator that you will be doing field testing.
In the field, testing the process taps indicates the taps are clean. You then repeat Step 3 and analyze the new information: Since there are two indications of a signal power and a signal and the process tap is clean, it appears that the transmitter is the problem. You then repeat Step 4 to determine whether there is now sufficient information.
You decide that there is. One is in stock. Indicator and DCS now agree with the sight glass. Consideration is given to the Mostia A check of the maintenance records indicates that the last time there was a problem with this transmitter was four years ago, and there were no indications of transient or abuse problems. So a specific solution replacing the transmitter appears to be appropriate.
Field tagging is verified to be in place on the new transmitter. If this was a modern microprocessorbased device, the full configuration of the old transmitter would be transferred to the new transmitter. Maintenance records are updated. The operator is notified of the repair completion and permits are cleared. When trying to identify a problem, you have to strip away subjective elements and get to the meat of the situation.
Do not let vendors off the hook when trying to solve a problem just because they say it is not their equipment. Ask questions and make them justify their position. Ask them questions, even if your questions do not have a direct relationship to the immediate problem wait until after they have finished troubleshooting your problem. Get them to explain their equipment. Many times they are more than happy to do that for someone who is interested.
Sometimes they will even provide information or documentation not in their manuals. The skill of recognizing the need for additional knowledge is a key to being successful at troubleshooting. Understanding what the system measures, controls, or accomplishes can separate process, operational, and instrumentation functions and give you a clearer picture of what each part does.
In some cases it is not necessary to understand how the particular system works, but to understand how that class of systems works. By reading the manual and understanding the basic principles, the details of a particular system can be filled in. For example, understanding how one brand of control valve works can allow you to work successfully on another brand. Information about the particular system includes how the system is used, how it is hooked up, and how it is powered. This information usually comes from drawings, plant documents, and vendor documents. The primary drawing is generally the loop drawing, as illustrated in Figure This drawing shows the wiring and provides references to other drawings and documents for the instruments.
In more complicated systems, additional wiring diagrams and system drawings may be used. Organization can help assure that you gather enough information to lead to the correct path. Otherwise, the troubleshooting path you take may be the wrong one. Even if you have all the information organized, but fail to analyze it properly, the same thing happens. Look for information that relates to the problem you are troubleshooting. Discard information that clouds the issue. Look not only for facts, but also for causal relationships and patterns.
How we think about instrument systems is influenced by their complexity. Concentrate on a particular device or part of a system as the culprit the little picture and you may fail to realize that something else is affecting that device, making it appear to be the culprit the big picture. This commonly happens when the process causes the problem or there is coupling between systems. A complex system may overwhelm you with the amount of data available.
You must typically divide the system up logically into smaller systems and deal with each in turn. How we think about a system is also influenced by how much we can determine about it using our senses, and what we must measure. Consider the simple pneumatic control system shown in Figure Much of this loop can be comprehended using our senses—we can see links, levers, and flapper nozzles move, feel and hear air pressure, and so forth. We can also move many of these elements ourselves and see the effects.
Most of the components are easily examined by the naked eye when taken apart. If we consider the loop as an electronic loop, as in Figure , we have many of the same components, but the signal components are wires. Now we cannot see or feel much and must use measuring devices to understand what is going on. In a microprocessor-based digital system Figure , we still have the wires, but we can see even less of what is going on, even with test equipment. With digital communications, we cannot measure the signal but must use a protocol analyzer to see what is going on.
In digital systems, information is transferred via continuous analog values voltage and current to transient digital signals zeros and ones at high speed. Note that the drawings are very similar, but the actual internal operation is quite different. The first instruments were mechanical: we could see and touch much of what they were doing. Then with pneumatic instruments we could see and touch some of what they were doing, but had to get some information using a pressure gauge. With electrical instruments, we could see less of what they were doing, and certainly not touch them, but we could read what they were doing with a volt-ohm meter VOM ; they still were made of individual components.
With electronic instruments, we could see little of what they were doing inside, and individual components gave way to integrated and digital circuits and measurements; individual signals became a lot harder to see. Consider a simple system of a mA level transmitter that sends a signal to a DCS. We can easily measure the mA signal. The signal may interact with other signals, other information, and software constructs; it may eventually come out on a CRT screen, or influence the position of a control valve through a controller.
Each of these levels in the development of instruments represents levels of abstraction, and each changes the way we conceptualize the instruments at that level. We must also know what abstraction level to think about when we begin troubleshooting. The wrong level will lead us astray. Troubleshooting requires the ability to think at the different levels of abstraction in which instrumentation operates.
We can no longer rely on analog measurements or digital snapshots alone, but must be able to think about how data flows through systems. To do this we must have a method or framework that allows us to approach and analyze problems logically. Sometimes the line is straight, or logical, and the next step flows from the previous. At other times, illogical steps produce a line that is not so straight. Many times people troubleshoot a system unsuccessfully; then another person asks a couple of questions about the problem and the solution jumps right out. This happens when we have all the information necessary to solve the problem but are not looking in the right place.
This can be the result of one-dimensional thinking. We can think in three dimensions. By analogy, consider driving a car: when you just concentrate on driving down a road, you are thinking in one dimension; when you navigate using a map, you are thinking in two dimensions.
If in addition to your navigating, you are worried about whether your old car will keep running as you ascend the high mountain pass that the road crosses, you are thinking in three dimensions. A common symptom of dimensional thinking is looking for something and later finding it right in front of you. Data analysis is often one dimensional—we follow a path through the data, ignoring other possibly useful data. Stepping back and taking a break can help get you out of the one-dimensional trap.
This is like a military patrol looking for enemies that looks forward, sweeps right and left, and looks for tracks and disturbed bushes to no avail; but they fail to look up in the trees where snipers lurk.
Four-dimensional thinking involves time. Events in a system occur at various times. You may be at the right place in three dimensions but at the wrong time. When system failures occur can be important when analyzing troubleshooting data. Five-dimensional thinking is not a linear process—it is at the level of intuition, subconscious understanding, or gut feeling. This can lead you astray at times, or it can be the source of good ideas. This is part of the art of troubleshooting.
Some intuition comes with experience and training, and some is a talent or a habit of mind, but it should not be ignored. It can save you when all other methods fail. We will discuss this type of thinking in the next chapter. It is much like going on a trip to a place you have never visited. If you do not have a good map, you may never get to where you want to go. Troubleshooting can be defined as the means used to determine why something is not working or not performing its designated task or function.
TRUE B. FALSE 2. A framework is A. A specific troubleshooting framework is A. Which of the following are types of troubleshooting frameworks? Plant dialect is A. Dividing a system in successive halves until you find the problem is called A.
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Troubleshooting can fail for which of the following reasons? Goettsche, L. While these frameworks work most of the time, some problems require less systematic techniques to complement the logical frameworks. Normally, you will begin to use these other techniques only after the logical analysis has failed to suggest a viable solution. Defining the problem, gathering information, and performing analysis still take place when you use these methods.
You may need to approach troubleshooting from a different point of view because a system may be too complex or sophisticated to troubleshoot with the knowledge available to you. Sometimes manufacturers provide only limited information about what goes on inside the equipment. Maybe the problem is transient in nature, or is in a complex system with communication links between components and multiple power systems and grounds, as in a multiple variable-speed drive system.
For modularized systems or those with easily replaceable components, substitution may reveal the component that is the cause of the problem. First, define the problem and gather and analyze as much information as you can. Note that these steps are no different than the initial steps in the structured framework methodology. Then select a likely replacement candidate and substitute a known good component for it. If the problem goes away, you have at least found a partial solution. Then evaluate to see if a more general solution is needed.
For example, if the component can be repaired on-site, either troubleshoot it further to find the lower-level cause of the problem or return it to the manufacturer for analysis. By substituting components until the problem is found, the substitution method may find problems where there is no likely candidate, a group of candidates, or even a vague area of suspicion.
One potential problem with modular substitution, though, is that a higherlevel cause can damage the replacement component as soon as you install it. This may confuse the issue if the failure is immediate as you will generally have the same symptoms after the replacement. If the failure is not immediate, this will give you a clue that the real cause of the problem is external to the module. The use of this method can raise the overall maintenance cost due to extra module cost and the cost of inventory of replacement modules.
Even more problematic are cases in which the higher-level cause does not damage the replacement right away. Another form of this method is to substitute or insert a known good signal or value into a system to see where a problem comes from. If you insert a known good signal and the downstream part works properly, then the problem is upstream. The converse is also true. Another example of fault insertion would be inserting a bad value into a point in a computer program to see how the program responds.
A third example might be inserting a transient into a system, such as a simulation of a voltage sag. For example, if a communication link with ten independent devices talking to a computer is not communicating properly, you might remove the boxes one at a time until the offending box is found. Once the problem device has been detected and repaired, the removed devices should be reinstalled one at a time to see if any other problems occur.
For example, there might be too many boxes on a communication link, cables that are too long, cable mismatches, wrong cables, impedance mismatches, or too many repeaters. In these situations, sections of the communication system can be disconnected to see what happens. To detect whether a system is grounded in two places, try lifting a ground to see if things get better. If you are lifting a safety ground, take care that you are protected while doing this. One common problem for which this method is useful is when a shield is grounded in two places, causing a ground loop; if the regular shield ground is disconnected and the system improves, then another ground connection on the same shield may be the problem.
For example, on a new communication system like the one mentioned above, the boxes were removed one at a time and replaced, but no offending box was found. This could also have been detected if the devices were removed one at a time and not replaced and a point was found where the system worked.
Draw an imaginary circle or boundary around the device or system; then see what interfaces such as signals, power, grounding, environmental, and EMI cross the circle. Then isolate and test each boundary crossing. Obviously, if you do not identify all the boundary crossings, you may miss the one causing the problem. Often this is just a mental exercise that helps you think about external influences, which then leads to a solution.
Figures and illustrate this concept. This is somewhat like having a mouse in your house. You generally cannot see it, but you can see what it has done. How do you catch the mouse? You set a trap. In sophisticated systems, you may have the ability to set additional alarms or identify trends to help track down the cause of the problem.
For less sophisticated systems, you may have to use external test equipment or build a trap see Figure Power monitors such as the Dranetz see Figure are often used for power problems. A storage scope may also be used to trap transients. Portable data loggers can be connected to monitor variables over time and dump the results into a computer, where the information can be graphed or evaluated. If you are the programmer, consider putting in diagnostic print statements and having a software switch or switches turn them on and then print the results to a log file.
You can use multiple levels of diagnostics with different switches to trap in different places. One troubleshooting method is to break systems down from complex to simple. This involves finding the simple parts that function to make the whole. A common example of this is a varying or oscillating control loop. By placing the control loop in manual moving from automatic control [complex] to manual control [simple] , one can determine if the automatic part of the system commonly the tuning is causing the problem or if the problem is being caused by the process or other external inputs.
Another example is a cascade loop where you have a master loop and a slave loop. Cascade loops are commonly used to isolate variations in the slave loop measured variable from causing variations in the master loop measured variable the desired control variable. Breaking down this kind of loop involves breaking the cascade by placing the master loop in manual or breaking the loop at the slave controller to see if the problem goes away, which can tell you which loop or if the process is causing the problem. Computer control, either cascade or direct digital control, can be troubleshot sometimes by breaking the computer link, though this may be done for you as it is typically the first thing an operator does when he has a control problem in this type of system.
Hierarchical systems are another type of system that can be sometimes troubleshot using this method by isolating the different hierarchical levels from each other and reconnecting to find the problem. A sub-unit can typically be broken down into a black box representation as shown in Figure This person may not solve the problem but may ask questions that make the cause apparent or that spark fresh ideas for you.
This process allows you to stand back during the discussions, which sometimes can help you distinguish trees from forest. During troubleshooting or problem solving, threads of thought may develop, one Mostia The more experience you have, the more threads develop during the troubleshooting process.
Can you cultivate intuition? Experience suggests that you can, but success varies from person to person and from technique to technique. For example, tell your mind to think about whether grounding is the problem, and see what ground-related ideas develop. Try some kind of relaxation technique; once you are relaxed, let ideas flow until one comes along that can help. Experiment with different techniques and see what works for you. Out-of-the-box thinking means approaching a problem from a new perspective, not being limited to the usual ways of thinking about it.
This can, however, be a developed skill. There are books available to help develop the skill, and you should keep an eye out for different troubleshooting perspectives as your experience develops and adapt them to your troubleshooting style. You will find people who have this skill; learn from them. Never be too proud to learn a skill from someone else! An example might be an oscillating control valve. To your surprise, the oscillation continues. What else could cause the oscillation? You have concentrated on a hardware solution. But what about the process?
Could it cause the problem? For example, could an upstream pump be cycling? If you also consider the process side, you may reach the solution sooner. How can you practice out-of-the-box thinking? How can you shift your perspective to find another way to solve the problem? Too big? But even using techniques like thinking out of the box, we can still use problem definition, fact-gathering, and analysis to define and narrow the problem.
The substitution method A. The fault-insertion method A. Which method checks all the external interfaces to a system? Part of the discussion will be background information to help you understand what is required for these areas. We will also look at work-tagging, permitting, and work procedures. Though this may be a review of procedures and practices similar to those of your workplace, the intent of this chapter is to emphasize safe troubleshooting, and it never hurts to review the basics.
You may, however, wish to discuss any differences with your supervisors. First, let us consider two basic questions: What does safety have to do with troubleshooting? And why is troubleshooting different from normal maintenance? Troubleshooting exposes you to hazards that other maintenance activities do not. Troubleshooting often requires interaction with or work around energized circuits and running machinery. Troubleshooting may require interaction with active control loops and safety systems. It also has many of the same dangers that any activity in an industrial facility has— working in hazardous areas, around hazardous materials and hot pipes, on dangerous equipment, at heights, in constricted areas, and with equipment that operates continuously.
Some are apparent or identified, but some are invisible. Failure to perform any job safely is a no-win situation for both the technician and the company. While many safety practices depend on the hazards involved, certain general safety practices apply to all work. Orderliness, organization, and good housekeeping are essential to your safety and to the safety of others. There is no reason for you to perform an unsafe act to accomplish your work or to take chances that will endanger yourself or others.
The care exercised by others cannot always be relied on. Never take safety for granted. Many errors have nothing to do with safety, but those that do can lead to an accident. These are the errors we must try to prevent. Remember, under small errors lurk a large error. Human errors that affect industrial settings can be classified into six general categories: slips or aberrations, lack of knowledge, over- or undermotivation, impossible tasks, mindset, and errors by others.
This can come from inattention or distraction. Have you ever planned to go shopping after work but missed your turn because you were driving on autopilot? As a troubleshooter, you should beware of being on autopilot on routine troubleshooting or simple tasks. Inattention can also come from thinking about one thing while doing another thing. Humans have a very difficult time doing two tasks at once. Always concentrate on the task at hand. Distraction can come from other activities occurring nearby. Again, always concentrate on the task at hand. That can sometimes be hard to do when there is a guy nearby breaking up concrete with a jackhammer.
If you cannot concentrate on the job at hand, try to remove the distraction or do the task at a time when the distraction is not there. It may also come from failure to ask questions or from making assumptions. If you do not feel you have enough information, experience, or training to do a task safely, do not do it. Talk to your supervisor and get some help. Be wary of generalizing too much from your training: if you do not fully understand the system you are working on, you may reach incorrect and dangerous conclusions Mostia Seek out good teachers, and never turn down training or retraining.
Lack of knowledge can also come from incomplete or faulty job instructions or from faulty information about the troubleshooting problem. One has to consider all the information given in a job and ensure that all is considered carefully in regards to safety. Do not do unsafe things just to complete the job quickly. It may give you some spare time, but habitually doing repairs in an unsafe manner will eventually cause an accident. The same goes for getting praise from your boss for being fast; it just is not worth it if you have to do something dangerous to get it. Undermotivation can come from problems at home or at work.
When you have to do a task, leave these problems at the door of the shop. Do not let them make you take a safety risk. Examples of this are valves that are located where they cannot be operated safely, access at unsafe heights or in constricted areas, or jobs located too close to operational hazards. For these kinds of tasks, step back and figure out how the task can be done safely. If you cannot figure it out, get help. Do not take unnecessary risks.
For example, one technician stuck his hand into an electronic device and received a shock.