While this book cannot guarantee the above results, the content should provide an automation engineer with a proven path to career and technical success. Ebook Tips For A Successful Automation Career currently available at caite.info for review only, if you need complete ebook Tips For A. Successful. Greg McMillan along with Hunter Vegas have written Tips for a Successful Automation Career.
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Tips for a Successful Automation Career - Ebook download as PDF File .pdf ), Text File .txt) or read book online. Tips for a Successful Automation. Ebook Tips For A Successful Automation Career currently available at. caite.info for review only, if you need complete ebook Tips for a Successful Automation Career [Gregory McMillan, Hunter Vegas] on caite.info *FREE* shipping on qualifying offers. Do you want to: • Know.
The upset will be seen in the OUT or flow manipulated by a loop affected by the change. Does a low dielectric constant require the use of coaxial guided wave probes? In a short time. A capillary seal consists of the seal itself which is a flexible diaphragm. Is the immersion length long enough to minimize heat conduction error e. Demonstrate and Prototype Improvements via Dynamic Models.
Emerson Automation Experts. Posted Thursday, September 13th, under Education. Leave a Reply Click here to cancel reply. Subscribe to site RSS Or, subscribe by email: Please do. Just link back to the post and drop me a quick email so I can share your work. Some might well have been. If a plant offers resistance to a new idea. One way to avoid problems when considering making changes is to develop a network of automation engineers in a couple of plants. That will invariably require a lot of time and money and will probably force you to re-learn the hard lessons already learned by your predecessors.
If possible. Do not be scared to try new equipment or software but be wise in deciding when and where to try it. There may be some aspect of the process that will not allow the proposed technology to work. Do not assume that everyone who went before you were idiots. ISA or other technical societies can be an excellent means of doing that.
When considering a new technology. Realize that the first version of nearly every software product will be rife with bugs and problems. This is Tip 7. I have met many people who were infinitely smarter than I, and their intelligence was obvious to me within a few sentences of conversation. Conversely, I have met other people who were quick to inform me of their supposedly advanced intellect, and in most cases they were not very bright at all.
Do not get hung up on showy displays of college degrees, awards, etc. I know a great many people who never received a degree of any kind, yet they are some of the most knowledgeable and respected engineers in the field.
Similarly, I know too many people who have advanced college degrees and have awards and recognition plaques all over their office walls, yet they are incapable of doing the simplest engineering designs. Like most people, I have tremendous respect for a person who is obviously brilliant yet downplays it.
If a person is extremely intelligent, it will be obvious to everyone after a casual conversation. However, the people who brag about their own intelligence are rarely as smart as they want you to think they are. The most talented and brilliant people will often say the least and listen the most. Ironically, people like that are often not very gifted at all, but carry on the show to make themselves look that way.
Do not ever allow yourself to be counted in that number. On the other hand, it is quite impressive to meet individuals who do not have anything on their wall, constantly downplay themselves and their accomplishments, and yet are true geniuses. Within moments of meeting and talking to a person like that, you know that he or she IS a genius, and yet they will never make mention of it.
That is the person you want to emulate. Never, EVER look down on a person because they lack the education or position that you have achieved. From the CEO to the lowest level employee, everyone knows something that you do not and they can often be valuable sources of information and new ideas.
Treat them with respect, as you would want to be treated, and you will be amazed what they can teach you. Do not be one of them. These people are fairly rare, but they do exist. They typically have strong, aggressive personalities and are smart enough to adapt their personality style to the situation. Dealing with such a person can be trying at times, but at least they have intelligence to back their bravado and their knowledge can be extremely helpful when you are faced with a technical dilemma.
Even though many technicians and operators may lack higher education, they are usually extremely knowledgeable of the plant and its operation. Their knowledge of the process and its hidden interactions and problems as well as the effort it takes to keep the plant running is invaluable to an engineer.
Foster a strong relationship with them and listen when they offer information. They can be an excellent audience for evaluating new automation ideas and will often tell you what problems or pitfalls you might encounter.
What is more, once they realize that they are being heard, they will provide new ideas and suggestions that might never have occurred to you.
Cultivate those relationships, and you will reap rewards throughout your career. Learn to be that person. This is Tip 8. The power of politics and of human emotion can be mind-boggling and utterly baffling to engineers who are taught throughout their lives to apply sound logical principles and facts to decision-making.
I cannot begin to count the number of times when I have found myself desperately trying to apply logic to a situation where absolutely none could be applied. You cannot change the fact that politics and emotion are often intimately involved in a situation, but you can recognize that they exist and act accordingly. For better or worse, engineers tend to be less emotionally driven than most.
Therefore, they can get confused and blind-sided when people make a snap judgment based on feelings or when people choose a course of action dictated by some hidden political agenda rather than one based on the sound, logical principles that have been delivered for review.
This can be most baffling to members of our profession. The fact is people often make their decisions based on emotion or politics, and the political or emotional angle often outweighs the logical argument. Unfortunately, most engineers do NOT think this way, and tend to assume others evaluate problems and information the same way that they do. However, all is not lost if you recognize and accept this fact and adapt accordingly.
If emotion and politics are afoot, then learn the rules and play the game! This is NOT an invitation to wade into corporate politics—life is too short—but this is a suggestion to study and understand the role of emotion and politics in decision-making so that their effects no longer appear as a surprise. As ironic as it might sound, once the emotional or political angles of an issue are known, logic can be applied to resolve it.
You need only apply a different set of rules. For instance if the decision becomes an emotional one, frame the arguments to cater to that mindset. The effects of politics or emotion often get much worse when there is an audience. People will defend a poor position to the death before they will retreat in front of their peers. Sometimes it is better to talk through disagreements one-on-one after the meeting and out of sight of others.
Better yet, try not to let the situation develop to that point. Despite the fact that most engineers consider themselves to be extremely logical, they can be emotional themselves. If you find yourself banging heads with a manager or co-worker, consider standing back and examining the situation as a disinterested third party or discussing it with a disinterested third party. It may be that YOUR emotions are clouding the issue. On rare occasions, people will ignore all of the politics and emotions swirling around an issue and will make a sound, logical decision.
Oh how I wish this was the rule rather than the exception! As an aside, you can eliminate a lot of conflict in your lifetime by simply avoiding discussing topics which are certain to create conflict in the first place. Many topics religion, political candidates, favorite sports teams, etc.
If both parties agree, there is really not much to discuss. Why fight the battle? Always be aware of the emotional and political angles of an issue.
If either is present, then recognize that the rules have changed and adapt accordingly. Never try to apply logic where it does not belong. This is Tip 9. How to Determine the Reliability of an Actuator automation.
Such a design works wonderfully when new. At that point. Either of the designs will last much longer. While the vendors will argue the pros and cons of one design versus the other.
The piston o-ring fails. Eventually the actuator will not stroke at all. The third item is rather subtle. Once this o-ring begins to wear.
Despite innumerable glossy. A cheap design will employ a single round o-ring on the piston. Two of the items will make ANY actuator fail — undersizing and poor air quality.
Find at least two acceptable actuator designs and get both vendors on your bid list. In other words. Most of the actuator failures can be attributed to three things: A poor o-ring design will make an actuator fail quickly.
If the actuator is properly sized and the air quality is good. By contrast. The actuator was undersized from the start see Tip The design of this o-ring is what usually determines how long an actuator will last in service. But also watch out for actuator limit switch covers that employ individual screws that are not captive in the cover. Some designs use a shorter stroke and a diaphragm instead of a piston with an o-ring.
Some employ a scotch yoke mechanism. Over the course of many years of plant experience. Note that actuators have different torque values at either end of the stroke so be sure to check both ends of the table when doing the sizing. If the instrument air quality is good. Pick a good design. Once a good actuator design is chosen.
Such an arrangement can have its uses. The entire concept of using control valves for the available pressure drop and for controllability at low flow rates was utterly lost on him. We went round and round until I finally got the client to install spool pieces at each valve location so we could easily replace the butterfly valves with a different valve if we encountered control problems in the future. This is Tip An automation engineer must understand these limitations and specify this type of valve only where appropriate.
This arrangement is much cheaper than a standard control valve. A lot of those spool pieces and butterfly valves got replaced. These valves CAN be used in throttling applications. Such a narrow range of control and poor turndown rarely suits most control valve applications.
The recovery factor for a butterfly or ball valve is generally poor compared to a control valve. Butterfly valves are not so easily modified.
One of the more heated arguments I had with a client involved his extreme desire to use line size butterfly valves for controlling his process. In an attempt to reduce cost. Typical control logic would look something like this: These valves usually torque into the seat very hard and take a great deal of force to crack open from a fully closed position.
If accurate control at low flow rates and cavitation is not a concern. If the valve is used to throttle in this regime. Carefully evaluate the application before selecting a valve type. Do not skimp on the design to save a few dollars. Beware of using butterfly valves with class VI shutoff in any kind of a throttling application unless the valve is normally at least one-third open.
Take time to understand the strengths and weaknesses of the various valve offerings. For nearly the same money. Benefits and Shortcomings of Vortex Flowmeters automation.
Every instrument is well suited for some applications and perfectly awful for others. These next few tips discuss the more common types of flowmeters and provide an insight into how they work, when they should be used, and when they should be avoided. I will begin with a brief description of how each meter works, and then discuss the pros and cons.
Greg McMillan provides a good discussion of Coriolis meters later in the book so that type of meter is not included here. Vortex flowmeters can be an excellent choice for a large variety of applications. However, certain limitations associated with this type of meter can make it a poor choice in some applications. Have you ever watched a flag wave in the wind? It actually waves because the flag pole generates eddies whirlpools, or vortices on alternating sides of the pole, which move past the flag.
The vortex flowmeter works the same way. Small sensors in or behind the bar detect the vortices and count them. The rate of vortex creation is chiefly dependent upon the rate of flow but is also dependent upon the viscosity of the fluid. If the fluid is too viscous or the flow too low, the meter will not shed any vortices at all. The flowmeter converts the meter count into a fluid velocity and determines a volumetric flow rate by multiplying the fluid velocity by the cross sectional area of the meter.
Works in gas, steam, and liquid applications. Is insensitive to fluid conductivity. It generally has a lower pressure drop than an orifice meter. Vortex flowmeters require turbulent flow to operate and will cease to read as the fluid transitions from the turbulent flow regime to the transitional or laminar flow regime. See further information on this below.
Vortex flowmeters make effective if unintended start-up strainers. The vortex shedding bar bluff body across the meter is great for catching bolts, drink cans, oyster shells, and all kinds of other debris wandering down the line. When material gets caught on the body, the meter will either read inaccurately or not at all. Some vortex flowmeters use small ports to measure the vortices. These can plug with polymer or solids, keeping the meter from functioning.
The design of the vortex measuring sensors is the chief difference between meters and the sensor design will allow some meters to work in certain applications where others will not. High vibration or entrained solids can be problematic for vortex meters, which may detect and count solid particles or vibrations as if they are actually flow. Like an orifice meter, the vortex meter requires an upstream and downstream meter run to establish a good flow profile.
This run should be no less than 15 diameters upstream and 5 diameters downstream, but most vendors like to see at least 25 diameters upstream and 10 diameters downstream. A vortex flowmeter measures volumetric flow—not mass flow. It can calculate a mass flow based on an assumed density, but if the fluid density changes, the reading will be in error. The low flow cutoff is the chief limitation of a vortex flowmeter, and it makes the meter unsuitable for any application where measuring low flows at high turndown is required.
The low flow cutoff point is determined by the viscosity of the fluid and thus may vary with fluid temperature and composition. Highly viscous fluids cannot be measured with a vortex meter. While most vortex flowmeters are poorly suited for measuring liquids which tend to polymerize, some meters employ a proprietary sensor design that is not easily plugged and has a constant flow of liquid around the sensors to help keep them clean. Such units can work where others tend to fail.
For high temperature applications, be sure to specify a remote mounted transmitter head. The electronics do not like being cooked, and a locally mounted transmitter will not last long. Be on the lookout for centering rings if the meter is a wafer type. The pipe fitters tend to leave these in the box and just bolt the meter between two flanges. If the meter is not centered, it will be inaccurate. Vortex flowmeters are a good choice for measuring the flow rate of any reasonably clean fluid where measurement at very low flows is not required.
The Good, the Bad and the Ugly of Magmeters automation. Early in my career, I was asked to specify a meter to measure the sideboiler bottom flow of an ammonia vaporizer. The sideboiler boiled off the ammonia for the process, and over time water would build up in the bottom of the sideboiler and had to be drained off through the meter. Given the high conductivity and the need to measure low flows, I considered a magmeter magnetic flowmeter to be a good choice for the application.
Two weeks after the meter was installed, Operations called in a panic saying that the meter was reading zero even though liquid was obviously pouring through it. A quick investigation showed I had failed to consider the fact that if too much water was drained off, pure ammonia would go through the meter. Ammonia has extremely low conductivity, and at that point, the meter could not function and read zero.
Since then, I always ask for the conductivity of the fluid during normal AND upset conditions! Similar to the vortex meter, a magmeter can be an excellent choice for a large variety of applications, but it too has limitations.
Understanding these limitations can help avoid a misapplication of this technology. When a conductor moves through a magnetic field, it generates a voltage. The higher the velocity of the conductor with the magnetic field strength held constant , the higher the voltage generated. A magmeter uses this phenomenon to measure flow. In this case, the fluid is the conductor, and it flows through a non-conductive line sized tube that has a magnetic field passing from top to bottom.
The meter has a pair of small electrodes one on either side of the tube , which detect the resulting voltage and calculate a fluid velocity. The velocity times the cross sectional area of the meter provides a volumetric flow rate.
Some meters include an additional electrode at the top and bottom of the tube to detect whether or not the pipe is full. A half full pipe will read high because the calculation assumes that the pipe is full. Therefore, the meter can be used to measure strong acids and caustics. Even if the electrodes must be made of an exotic metal platinum, tantalum, etc. It can also work well for viscous fluids. Two to three diameters upstream and downstream are usually all that is required.
Older models required a separate source of VAC power. The 2-wire devices are cheaper to install. Most require at least 5 micromho, though some units can measure below that. If the fluid temperature is high, be sure to specify a remote mounted transmitter. These rings complete the circuit that allows the voltage to be generated. Recognize that these rings will also touch the fluid and should utilize the proper material of construction. If these electrodes are exposed to air they will generate a non-conductive oxide coating which will keep the meter from operating immediately.
Once they are again exposed to the acid, it will burn the coating off but this can take some time and the meter may not function at all during this time. It can calculate a mass flow based on an assumed density but if the fluid density changes, the reading will be in error. Beware of gravity flow measurements when using a magmeter. Unless the meter is properly located, partially empty pipe conditions will occur, and the meter may be inaccurate.
Always ask about the upset conditions that the meter might see. As mentioned previously, steam- outs can irreparably damage the meter and very low conductivity conditions can prevent the meter from reading at all. Many magmeters employ a combination of AC and DC excitation on the coils to provide a means of detecting and compensating for coating of the sensing electrodes.
While this may not make them impervious to coating conditions, it will allow the meter to continue to operate longer before a cleanout is required.
A magmeter is an excellent choice for measuring the flow rate of a conductive liquid with reasonable accuracy. This meter is also well suited for measuring the flow rate of viscous liquids, acids, caustics, and slurries. It is even possible to measure the differential pressure across the inside and outside of an elbow to determine flow rate. Such meters are often used for custody transfer applications. The pressure drop can be measured to calculate flow.
Note that the turndown of these meters can also be quite limited. This section will try to briefly provide the strengths and weaknesses of the offerings and alert you to the possible pitfalls of using this type of meter. The differential pressure can be generated in a number of ways.
If a fluid is forced to pass through a restricted area. An orifice plate is the most common. Works in gas. Flow nozzles. The DP meter is one of the oldest means of flow measurement. Because the overall energy must remain the same. A well designed orifice installation can be extremely accurate. I only have space to hit the highlights and suggest that you pick up any of several books on the subject if you want to know more about this type of meter.
There have been whole books written about differential pressure DP flow devices orifices. Just like every other flowmeter. Pitot tubes. At a high level. Averaging pitot arrays can accurately measure gas flow in odd shaped ducts with minimal meter runs. A segmented wedge meter can be combined with capillary seals to provide flow measurement of viscous.
If a high turndown is required. The pressure drop rises quickly as the flow increases. Few processes exist that cannot be handled by at least one version of the DP flowmeter. This same arrangement can also handle some solids entrainment. The slightest bit of erosion on an orifice plate or pitot tube nozzle can have an enormous impact on accuracy. Impulse lines are also prone to plugging in many applications.
Each type of differential pressure flowmeter has a variety of pros and cons but the sheer number of types provides many options to the engineer. The permanent pressure drop of most orifice plates is about two-thirds of the measured differential pressure. The square relationship between differential pressure and flow greatly limits the turndown of most DP meters. Orifice type meters have been around for a long time and have been extremely well studied. Orifice meters do NOT have a low flow cutoff like vortex meters.
Integral flow orifices can measure extremely low flow rates. Because the DP transmitter is usually well removed from the process. In addition. The length of the meter run. Note that these distances depend upon the particular type of DP meter used.
The impulse lines on liquid and steam meters usually require freeze protection. Like a vortex meter. Vortex meters have been gradually replacing orifice type meters. Such a run must usually be at least 25 diameters upstream and 10 diameters downstream. If these conditions can vary. DP meters are sensitive to installation. Hundreds of constants and factors now exist. DP flowmeters can be used in a wide range of temperatures and pressures. The energy cost can be significant over the life of the meter.
A capillary seal consists of the seal itself which is a flexible diaphragm. Specifying a capillary seal assembly is a perfect example of this. Choosing the correct capillary seals for a particular transmitter installation seems like a minor thing. Here is a brief list of items that can cause an engineer serious problems: This may require coiling up the unused length of capillary on one side.
If one leg is longer or one seal is bigger. Many an engineer has failed to grasp this and has gone through several meters until they got one that worked. If the seals are the same size and the capillaries are the same length.
Smaller diameter tubing has reduced volume and tends to cause less zero shift. To master engineering design. Differential pressure transmitters will often. How to Specify a Capillary Seal Assembly automation. Capillary seals are used to isolate a pressure or differential pressure transmitter from the process by transferring pressure from the process to a remote mounted transmitter.
This can be a big problem if the seal fluid has a high viscosity. Smaller diaphragm seals have less volume and tend to have reduced temperature-related zero shift problems. Picking the right combination of features to suit the application can be challenging. Some processes are prone to plugging of the impulse line. An engineer is constantly balancing one criterion against another. There will often be several factors to consider.
When pressure is applied to the seal. The problem is that all hydraulic fluids expand with temperature. In this scenario. Because this arrangement has a large seal on only one side. Some hydraulic fluids are designed to handle vacuum. Here is a quick list of things to consider: When faced with specifying this type of meter.
If this happens. There may not be a fluid available that will suit your application. Many a pipefitter has pulled them out of the box and bolted them up without the proper gaskets and spacers. These meters are NOT cheap and the specifying engineer can ill afford a couple of iterations to get it right.
If your process could encounter high vacuums at high temperatures. A higher range transmitter can be used. Never use a single seal. A common scenario is trying to measure the differential pressure across a distillation column.
Be extremely careful to select knowledgeable technicians to install capillary seals. Most transmitters will only allow a zero shift of four to five times the maximum range. Trade-offs abound. Check with the plant to make sure this is not a concern.
If the process temperature fluctuates. Vacuum lowers the boiling point of the fluid and if the hydraulic fluid boils. A failure to achieve that understanding can place the entire project in jeopardy. Either way you are well ahead by raising the question.
Many project teams find it useful to map out the process on a large wipe board in the project team area during the discussions.
Clean outs. Either the team does not understand the process nearly as well as they think they door the original program was in error. The folly of this approach was usually not discovered until late in the project possibly during start-up.
Armed with this knowledge you can not only design the system correctly.
Then take the time to talk through the process with the plant engineers and operations staff. If you are the project leader. If the process documentation is sparse or not updated. Be sure to inquire about the normal process flow and any non-routine cleanout.
This thorough understanding of the process is absolutely critical to project success. Watch Out: In many systems. Even if the job is a control system retrofit with no significant software changes. When asked the operators will often say. This tip seems obvious. Process understanding is a crucial first step in any automation project.
They can also be the most difficult to program due to various interactions and undocumented operations. There really are none. Before beginning any major project. As a student in high school. A ninth grade teacher hammered me for this.
I realized this same approach is just as critical to any kind of software development. This method can eventually work. Many a project team has failed to do this and has blown the entire labor budget trying to patch and cobble something together only to ultimately step back.
I struggled when writing papers. Once the design is complete. I had a lot to say. Resist the urge to just sit down and bang out code. Save the team a lot of wasted effort.
He preached the concept of first creating an outline to assemble the main concepts in a meaningful and logical way. If you first outline the major components and think through how the parts will interact. When faced with a major creative endeavor. This applies to any major undertaking such as writing a paper.
You will save yourself hours of wasted effort. Tnis is Tip This concept applies to any major project but is especially true for software development. Take the time to lay out a design and get the underlying structure right before you begin. This is a lesson I never forgot. One portion of the design can be completed and released for detailed software development while the other areas are being designed and outlined. Keeping everything straight can be difficult.
If the programmers are allowed to begin in advance with no direction. This same documentation can be used for testing and checkout purposes at the end of the project and provided to the customer for future reference.
Due to tight schedules. Start with a high level outline to list the concepts and the order of presentation. This same advice is invaluable for writing a paper or creating a presentation. This is a common failure area of large projects. When multiple people or vendors are part of project. Concurrent engineering is possible if it is done correctly.
Once a detailed outline has been created. For instance. Here is a sample of some of the messaging an operator should see: If the system is on hold for 10 minutes. Nothing frustrates an operator more than working on a control system that provides vague. Operators want to know what is going on. Tell the operator what is going on! If a phase goes to hold. Take the time to do messaging right. This is one of those tips that you cannot appreciate until you have worked on a control system that did NOT have adequate messaging programmed in it.
If a programmer is not a good speller. Two lines are usually necessary because many batch processes have multiple operations occurring simultaneously and providing two message areas avoids overlap.
Imagine running a complex or dangerous process and not having any feedback to tell you what is happening or if anything is happening at all! Or perhaps just as bad. The extra effort to do this is minimal. See Appearance Matters Tip The messaging can be displayed in a two line message bar at the bottom of the screen that is used for active phase messaging and for operator questions and responses.
Creating detailed messaging is easy once the phase templates have been configured to include it. If the messages are generic or non-existent.
The various phases write to these variables so that the operator gets used to seeing phase related messaging in the same place. These message bars can be placed on several graphics as appropriate. A trick to making messaging easy is to create one or two operator message variables that appear in the message lines on the bottom of the page.
Messaging can make or break a control system. Operations will be calling Engineering all night long looking for help to identify problems and get the process running again. If the information is detailed and useful. Buying high-quality instrumentation does NOT mean that the buyer has to get fleeced and pay list price. The competition keeps both of them honest. Spend the extra money and buy a brand that the plant knows and trusts.
Always have at least two major vendors qualified for each type and brand of instrumentation. Also consider the synergy and free time for creativity from standardization afforded by sole sourcing. To keep the price down. Some instrument brands stand so far above the others that it simply is not worth investigating another vendor. Automation engineers are under a lot of pressure to keep the price down.
Be sure you have investigated and confirmed there is a significant design. Some instruments are cheap for a reason. Please note that this tip is NOT suggesting that cheaper equipment does not deserve a chance. Short term. Sometimes a vendor discovers a better technology or a cheaper method of manufacturing that DOES produce an instrument that is lower in cost and is just as good or better.
How many times has an engineer been asked. Do not skimp on instrumentation. Automation is expensive. Buy good quality equipment and it will last for years. Buying of the untested units for a large project is just asking for trouble.
If the system will double in size. This concept is particularly true when running fiber optic cable. If the project budget is so tight that larger cables or spare capacity cannot be installed. Install slightly bigger field junction boxes and cable trays so that more cables can be added later. Running a cable with less than 12 fibers is pointless. Occasionally an automation project involves a machine or a process that is so mature that future expansion is unlikely. Even if the spare capacity was not included in the original budget.
If the spare capacity is included in the original project estimates. This is not a common occurrence. The labor to run a 6 fiber. Plants adore spare capacity because it allows the execution of process improvement projects at a much reduced cost. During system design. Oversize conduits. Always ask about future expansion plans during the design phase of an automation project.
Install spare wire capacity whenever possible. In the long run. Over my career I cannot think of a single time when I regretted running spare cables or oversizing field junction boxes. The incremental purchase cost of a 36 pair cable over a 24 pair cable is practically negligible when compared with the labor cost of running either cable.
By knowing how the ultimate system might appear. A common rule of thumb for most systems is to add at least 25 percent spare capacity to the original design. Depending upon the future plans of the plant. If the cabinet incorporates these features. In an attempt to add fuses. Between this installation and several others like it.
A single fault in the field can take out all the points on a card and might take out the entire cabinet. The increased cost of using individual fuses will be quickly recovered by the reduced time to troubleshoot and resolve field wiring problems.
Build this into your standard cabinet designs and be sure to specify it in your third-party skid package specifications. The technicians cannot even SEE the lower terminals. If any of the 50 shorted. Almost none of these cards use indicating fuses and some of them require the entire card to be removed in order to replace one fuse! The blown fuse light is difficult to miss.
Such a disconnect provides an easy means for the technicians to take series current measurements or connect their handheld communicators. One or two instances of bringing production back on line within minutes rather than hours or days will easily pay for the initial installation.
With the advent of computers. I worked in a large continuous process plant that had alarms coming in constantly. The panelboard operator had silenced two high alarms.
One piece of information that IS useful. Alarm management has become all the rage lately. Even though the tank had redundant level transmitters and we had one of the more alert panelboard operators on shift.
There were only so many points available. Addressing this expansive topic in a few pages is not possible. Add conditional logic that generates a common alarm when a piece of equipment trips rather than generating 10 or 15 alarms that essentially indicate the same condition. Many operators use the alarm list to determine what tripped the equipment. If the first out information can be indicated on a graphic. Enable alarms on instruments that matter and on process nonconformances that the operator can do something about.
When faced with a constant stream of annunciation. Generate an alarm report to Maintenance. If a process is running out of spec but not in a critical range. Automatically disable alarms on out-of-service equipment. An engineer has several ways to address this problem. We had a case where a process flow was accidently diverted to the wrong tank.
At one time. The proliferation of instrumentation busses has provided access to a plethora of information. Having alarms for the sake of having alarms only ensures that ALL alarms will be ignored—even the ones that matter. When configuring new systems. Many control systems default to having all the alarms enabled. Doing this can dramatically reduce the total alarm count without requiring much effort. In this way. This method provided increased alarming when a loop was in manual but did not generate alarms on a point in automatic unless it deviated too far from setpoint.
High and low alarms were not enabled unless the controller was in manual. An occasional review of the most active alarms will allow the plant to identify these points and modify the programming to reduce their frequency or address their cause. One solution to this problem is to allow operators the ability to suppress alarms.
One plant only enabled setpoint alarms when a controller was in automatic. Such alarms annunciate when the process variable is beyond the allowable range around the current setpoint. Some plants do not allow the operators to suppress alarms because they are concerned that critical alarms will be turned off and never restored. On a new system. Alarm management is a never ending effort. The panel equipment may start overheating because a larger power supply was specified.
Failure to evaluate even one item can have serious or even catastrophic consequences. Looking at spec sheets might be the very definition of boredom. In the normal course of a job. Details matter—take the time to chase them. Engineering is by definition a detail-oriented profession. I noticed this and was able to pursue a different path early in the design process.
I realized that channels 1 through 4 and channels 5 through 8 shared a common ground on the card. Everything matters. If you copy that design and modify it without understanding what went into the original design decisions. I was working on a large automation retrofit project of a chemical plant that had numerous thermocouples scattered throughout the structures.
Wire size. Automation is particularly challenging because the engineering skill set is so diverse. The field of automation demands extreme attention to detail. If you are not a detail person. A vendor suggested a particular thermocouple card that I had never used.
There was an odd footnote about channel-to- channel isolation that caught my eye. If I happened to get thermocouples from two different columns on the same group of channels. Many large engineering firms send a spec sheet with a smattering of process information to the vendors and let them generate the instrument specifications.
Young engineers are notorious for working fast but missing details. This practice invites disaster. One of the best ways to address this problem is to pick up a highlighter and learn how to color the lines as you work.
Checklists such as those found at the end of this book can also be an invaluable way to make sure everything has been considered and evaluated. Vendors often plug information into sizing software and generate impressive specifications and calculations. If this is not a natural tendency.
If you are doing an instrument takeoff. In short. If you are checking drawings. Always cross check vendor sizing calculations for instrumentation. Successful automation engineers HAVE to be detail-oriented. The vendor cannot possibly know the process details or the abnormal conditions that the instrument might encounter.
After an engineering team leader has worked with a team for any length of time. It is always worth running a rough cross check on their sizing and then reading through the entire specification to make sure the materials of construction are as required for the application.
What happens if the operator presses the wrong button? What happens if no button is pressed at all? If power is lost. Anticipating every failure is difficult.
Automation engineers love to create gloriously complex solutions. Operators are forever using the equipment in ways that were never intended and if the software is not designed to handle it.
Gravity always works at least on planet Earth. Complicated systems find new and interesting ways to fail. Despite what their name might imply. Having dual feeds can allow a control panel to continue operating despite the failure. Whenever possible go for the simplest. I have also worked in a chemical plant that encountered FIVE simultaneous failures.
Sometimes it takes a multivariable predictive control model to do that. During testing try hitting the wrong buttons and try to force the program to step through the sequence in a different way to see what happens. With so many computers and gadgets available. Simple systems work reliably. While this will drive the programmers crazy. As an automation engineer. Equipment breaks.